Arctic Sea Ice : Forum

Cryosphere => Permafrost => Topic started by: Tigertown on March 23, 2017, 03:17:07 AM

Title: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 23, 2017, 03:17:07 AM
 Neven, feel free to move if there is a better location, please.
@bbr2314
I have always appreciated your enthusiastic input on the forum, and I don't won't to go against you for the sake of arguing alone, but I don't see how any amount of snow and the associated increased albedo could mathematically cancel out the amount of heat energy the Earth is absorbing, much less cause a reversal. Most of the heat is being absorbed in the oceans, which cover vastly more sq. km's  than land area, and especially land area that is even subject to snow cover at all. I don't have the info to do the math, but I am sure there are some on here that do.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 23, 2017, 03:54:36 AM
Thank you for starting a new thread! :)

I have no idea re: math into this, either, and I could most definitely be wrong. But, at the end of the day, the chief input re: heat on Earth is the sun.

If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

Given this, I suspect that we have vastly underestimated albedo's impact on overall global climate. Even if the amount of land that is snowcovered in a given year only increases by 10%, that is an absolutely *huge* amount of solar energy (~3% of planetary total!) that is now being deflected back into space.

If someone can provide more concrete numbers or throw my ideas into the garbage can either would be appreciated.

Of course, we currently are dealing with shrinking amounts of Arctic sea ice, which also has significant impacts re: albedo and most certainly is a huge contribution to overall warming and the seemingly runaway melt we are now seeing up north.

To my eyes, this will continue until there is almost no ice up north, and the Arctic will continue taking up more and more heat until there is enough snow on the continents to counteract the differential.

The key thing to note here is that though the Earth may have vastly more ocean than land, the impact of losing the ice up north can indeed be more than countered by expansion of snowpack over land in terms of raw area (e.g., we currently have 13.5M KM2 of icepack; it is certainly not inconceivable that if this dropped another 50% during wintertime, that the 6.75M KM2 differential is more than made up for by increased extent and duration of overland snows).

Consider that the Arctic bears the brunt of solar input during summer -- so the albedo impact of its losses are most felt during this time when it takes in energy -- but areas lower in latitude deal with much more solar energy earlier and later in the year (especially the Himalayas). That means that while the loss of Arctic icepack albedo is very detrimental during summer, it is somewhat less relevant to total global energy uptake vs. mid-upper latitude snowfall changes, which matter much more in spring/fall.

Final note: the increase in snowfall also has implications for the oceans/sea ice. It seems to my eyes that the only areas of sea ice that are holding steady or increasing on an annual basis are those in the upper-mid-latitudes (Hudson Bay, Labrador Sea, Sea of Okhotsk). This adds a relatively minimal amount of sea ice, but this too contributes to the reflectance of solar energy back into space, in areas that receive much more sunlight than the Arctic much earlier in the year. Of course, they still melt out, but the contribution is not insignificant.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: budmantis on March 23, 2017, 04:36:18 AM
Thanks TT for starting this thread. I like some of BBR's ideas and would like to hear more without the constant reminder that the discussion is "off topic".
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 23, 2017, 04:47:34 AM
@bbr2314
 I appreciate that you are willing to discuss this without being dogmatic about the matter, and hopefully some others can add to the discussion, as well.

Regarding this topic, on the one hand the extra albedo from the snow would reflect more short wave radiation from sunlight, and therefore there would be less long wave radiation from land trying to escape only to be trapped by ghg's. On the other hand the added moisture in the air would absorb more shortwave radiation to begin with. This effect is now believed to be the biggest problem with warming over the long term. So again, it seems the warming is one way, at least as far as I can tell.

www.washington.edu/news/2014/11/10/global-warming-not-just-a-blanket-in-the-long-run-its-more-like-tanning-oil/ (http://www.washington.edu/news/2014/11/10/global-warming-not-just-a-blanket-in-the-long-run-its-more-like-tanning-oil/)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 23, 2017, 05:02:39 AM
@bbr2314
 I appreciate that you are willing to discuss this without being dogmatic about the matter, and hopefully some others can add to the discussion, as well.

Regarding this topic, on the one hand the extra albedo from the snow would reflect more short wave radiation from sunlight, and therefore there would be less long wave radiation from land trying to escape only to be trapped by ghg's. On the other hand the added moisture in the air would absorb more shortwave radiation to begin with. This effect is now believed to be the biggest problem with warming over the long term. So again, it seems the warming is one way, at least as far as I can tell.

www.washington.edu/news/2014/11/10/global-warming-not-just-a-blanket-in-the-long-run-its-more-like-tanning-oil/ (http://www.washington.edu/news/2014/11/10/global-warming-not-just-a-blanket-in-the-long-run-its-more-like-tanning-oil/)

Hmm. I wonder re: last point (added moisture in air).

Wouldn't snowfall generally lead to colder temperatures (by way of reflectance), at least for the duration of the snowpack's existence in sub-freezing temperatures? Perhaps while it is snowing there would be more absorbing of radiation, but after it is on the ground, I would think that all else being equal, a snow-covered landmass at sub-freezing temps normally has *drier* air than non-snow-covered land in above-freezing temps for the locations we are discussing.

Obviously Antarctica is a bit of a dramatic comparison, but it is the world's driest continent despite its entirety being snow-covered.

Perhaps I am wrong here, but I think the impact on albedo outweighs any impacts re: moisture availability in the air, and with snowpack allowing colder temperatures, that would generally indicate that areas covered by snow experience drier airmasses. Of course we see intervals of moisture (and either building of snowpack, or its destruction due to accompanied warmth), but with precipitation seemingly coming in longer intervals of heavier durations, this would actually counter the idea that more moisture is generally available (instead, things are generally drier, but the sporadic instances of precipitation when they *do* occur are heavier). I am rambling a bit but hopefully that makes some sense.

Finally, I believe that combining these albedo feedbacks with the rapid degradation of both Greenland and Antarctic ice sheets could perfectly explain why we see periods of cooling onset so rapidly -- it takes a while to warm to a certain point, but thereafter the Earth rapidly flips into an ice age due to how these feedbacks work (i.e. Younger Dryas). Besides the tentative fact that an open Arctic results in ++NHEM snowfall, you have to lump on the cumulative impacts of AMOC slowdown/shutdown as well as the impacts of melt in the Southern Ocean. These amplify the albedo feedbacks further.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 23, 2017, 05:12:44 AM
The air in the Arctic was dry in the past, but not anymore. There seems to be so much moisture now that it cannot be contained. I am no expert on that subject, and am sure there are others that can clarify.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 23, 2017, 05:31:31 AM
The air in the Arctic was dry in the past, but not anymore. There seems to be so much moisture now that it cannot be contained. I am no expert on that subject, and am sure there are others that can clarify.
Correct! But I am not talking about the Arctic re: decreasing/stable moisture, as it is definitely warming & moistening (also due to the loss of albedo); I am referencing land areas that are newly-covered by snow when they usually aren't.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 23, 2017, 05:36:20 AM
The air in the Arctic was dry in the past, but not anymore. There seems to be so much moisture now that it cannot be contained. I am no expert on that subject, and am sure there are others that can clarify.
Correct! But I am not talking about the Arctic re: decreasing/stable moisture, as it is definitely warming & moistening (also due to the loss of albedo); I am referencing land areas that are newly-covered by snow when they usually aren't.
I understand that, but I think the moisture problem may exist everywhere or at the very least, in many places other than the Arctic.  I will be open minded and wait on other thoughts in that regard though.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Sarat on March 23, 2017, 05:52:02 AM
A few thoughts,
Open water is a much more effective heat sink than open ground, making it hard for the snow cover to shift the balance.
Not much of snow cover survives the summer so all that melt water fully contributes to the "double edge sword effects" mainly river  runoff into the arctic, errosion of permafrost, trapping heat in late fall. Unless we start to see buildup of multiyear snow I think the extra cover is not doing much good for the warming.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wehappyfew on March 23, 2017, 06:39:16 AM
More snow in late spring and summer would be a negative feedback due to albedo...

Warmer Arctic --> more evaporation --> more snow fall --> reflects SW radiation in the summer --> cooler Arctic.

But we don't see more snow surviving into summer, we see less and less snow cover in the summer - check the Rutgers data or the NOAA snow cover data. More extensive snow cover and thicker snow appears in the winter, when the sun is not shining... no albedo negative feedback.

Instead, we have a positive feedback...

Warmer Arctic with more open water --> more evaporation --> thicker snow on the ice  --> insulates the ice from bottom freeze --> thinner ice, melts sooner --> more open water in summer --> reduced albedo = warmer --> more evaporation... and more open water also makes more evaporation --> more snow.

Also, thicker snow on land insulates the permafrost, preventing it from radiating away the heat gained during melt season. The top surface of the snow is much colder, but the bottom is warmer, just like a blanket. When the snow melts in spring, the permafrost starts out warmer than usual.

...

Another effect of snow might be possible... consider this scenario, tell me if it makes sense:

Snow falling on open water makes slush, which soon solidifies into solid ice if it's cold enough. If the Arctic ocean surface is a little warmer, and if much heavier snow falls on the water forming a very thick slush layer, it might not be able to freeze solid.

Solid ice has a much higher thermal conductivity than water, so a thick slush layer would act as insulation on the bottom of the ice, trapping water in its voids, preventing heat from conducting upwards through the ice as quickly... in addition to the air/snow insulation effect on the top of the ice.

This would be consistent with the observations that Arctic ice seems "rotten" and weak. Maybe it has more slush within it than historically.

Plausible?
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: oren on March 23, 2017, 12:19:22 PM
A couple of comments:
Are we talking about more snow thickness, or more snow extent? only the latter has any albedo effect.

I seem to recall that we have positive snow anomalies in winter, and negative in spring. I would not be surprised if the annual net change in albedo times insolation is actually negative. This needs quantification, as it is the whole basis of bbr's hypothesis.

As the Younger Dryas has been mentioned - it has a very good explanation unrelated to albedo. When the Laurentide ice sheet retreated, large accumulations of icy meltwater were trapped on land, and periodically discharged into the ocean causing a temporary drop in global temps.
From Wikipedia: The prevailing theory is that the Younger Dryas was caused by significant reduction or shutdown of the North Atlantic "Conveyor", which circulates warm tropical waters northward, in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. Geological evidence for such an event is thus far lacking.[47] The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. An alternative theory suggests instead that the jet stream shifted northward in response to the changing topographic forcing of the melting North American ice sheet, bringing more rain to the North Atlantic which freshened the ocean surface enough to slow the thermohaline circulation.[48]
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Neven on March 23, 2017, 12:25:24 PM
For those of you who haven't heard about it, you may be interested in reading about the Ewing-Donn theory (Wikipedia (https://en.wikipedia.org/wiki/Ice_age#Positive_feedback_processes)) from the 1950's,  which posited that ice ages were caused by this negative feedback of snowfall anomalies. Also read this excellent summary (http://history.aip.org/climate/simple.htm#S2ED) on Spencer Weart's Discovery of Global Warming website that places the theory in historical context.

Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: johnm33 on March 23, 2017, 02:31:36 PM
This map illustrates the high ground south of the Arctic where any evaporation from the warming ocean is likely to precipitate out as snow. For me the most at risk area is the uplands of Eastern Siberia and Mongolia, but you have to allow that anywhere from northern Spain to the Chukchi are possiblities. My own thinking is that until Laptev is ice free in November and December we have no idea how much snow a random weather event can drop here or how persistent it will be, but I suspect it will rapidly expand to the point where the northern slopes will carry permanent snow. IF that happens the climate in Siberia will reverse being much colder in the southern uplands and more like permanent springtime by the ocean, and in time an enduring cold wind falling out of the mountains flowing east over China. http://topex.ucsd.edu/marine_topo/gif_images/global_topo_large.gif (http://topex.ucsd.edu/marine_topo/gif_images/global_topo_large.gif)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wili on March 23, 2017, 02:51:00 PM
I'll chime in and state the obvious: most of the added snow falls in the winter when there in no insolation to either be absorbed or reflected.

So the albedo effect is minimal.

One other thing: the melting tundra is sprouting more and more bushes and trees that stick out of the snow. That creates a very big change in albedo, considerably warming areas that are becoming so forested (and 'bushed'), at least when the combination of sun and snow exist there.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Archimid on March 23, 2017, 03:44:21 PM
Thanks TT for making this thread.

A couple of comments:
Are we talking about more snow thickness, or more snow extent? only the latter has any albedo effect.

I seem to recall that we have positive snow anomalies in winter, and negative in spring. I would not be surprised if the annual net change in albedo times insolation is actually negative. This needs quantification, as it is the whole basis of bbr's hypothesis.


I agree with this. When talking about albedo the  important measure is snow extent. Snow thickness is almost irrelevant.

I think snow thickness is relevant in other ways. Snow is an accumulation of excess winter cold that is consumed during spring and summer.  Water in the atmosphere during winter accumulates "cold" to the point that it turns to snow and falls to the ground. Without the water in the atmosphere temperatures would have instead dropped to a lower temperature. During spring and summer the cold stored in snow is used up, resulting in a colder air temperatures than without snow and a smoother transition to summer temperatures.


As the world warms there is more humidity in the air, thus temperatures rise to convert that water into snow during fall and winter.  However the rapid fall of spring snow hints that the accumulation of snow during winter has failed to store enough cold to counteract the ongoing warming. So even when there is more cold accumulated in winter, the snow is melting faster. Judging by the extent measure is not even enough snow to provide a negative feedback in the form of albedo.


For the question: Is the increase in snow fall during fall and winter enough to provide a negative feedback in the form of higher albedo? The answer so far seems to be no.

As the globe warms it is likely that humidity will increase even more. Maybe it will eventually be enough snow to provide a longer lasting albedo negative albedo feedback? I don't think so because winter temperatures are already significantly higher for most of the NH. More water will just raise the temperature even more.







 
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 23, 2017, 03:57:16 PM
Thanks TT for making this thread.

A couple of comments:
Are we talking about more snow thickness, or more snow extent? only the latter has any albedo effect.

I seem to recall that we have positive snow anomalies in winter, and negative in spring. I would not be surprised if the annual net change in albedo times insolation is actually negative. This needs quantification, as it is the whole basis of bbr's hypothesis.


I agree with this. When talking about albedo the  important measure is snow extent. Snow thickness is almost irrelevant.

I think snow thickness is relevant in other ways. Snow is an accumulation of excess winter cold that is consumed during spring and summer.  Water in the atmosphere during winter accumulates "cold" to the point that it turns to snow and falls to the ground. Without the water in the atmosphere temperatures would have instead dropped to a lower temperature. During spring and summer the cold stored in snow is used up, resulting in a colder air temperatures than without snow and a smoother transition to summer temperatures.


As the world warms there is more humidity in the air, thus temperatures rise to convert that water into snow during fall and winter.  However the rapid fall of spring snow hints that the accumulation of snow during winter has failed to store enough cold to counteract the ongoing warming. So even when there is more cold accumulated in winter, the snow is melting faster. Judging by the extent measure is not even enough snow to provide a negative feedback in the form of albedo.


For the question: Is the increase in snow fall during fall and winter enough to provide a negative feedback in the form of higher albedo? The answer so far seems to be no.

As the globe warms it is likely that humidity will increase even more. Maybe it will eventually be enough snow to provide a longer lasting albedo negative albedo feedback? I don't think so because winter temperatures are already significantly higher for most of the NH. More water will just raise the temperature even more.

Couple comments!

Yes, extent is more important than thickness when it comes to albedo (in that additional thickness gives very little additional albedo beyond a certain point). BUT!

Thickness becomes important when considering the rest of your argument, i.e., duration of snowcover during spring/summer, in that if wintertime areas that receive snowcover see much more of it than normal, they will be more prone to retaining their snowcover until later dates than normal. This is very important to albedo and it ultimately results in more extent than normal, it just may take a while to get to this point.

For instance: we may be at +1-2M of avg wintertime snow vs. 1990s in some spots in Quebec and Siberia; it may not take more than 1-2 additional meters of wintertime snowfall to begin to really prolong the duration of snowcover in these regions.

I think that snow has been melting faster until now (and may continue to do so for some time) as we have only begun unraveling the first component in the see-saw of Arctic sea ice vs. continental snowcover (since the Arctic, despite its failing sea ice, is still at 13.5M KM2).

As the Arctic continues to drop, I anticipate a sustained and continued annual rise in NHEM snowcover volume. This comes with token extent increases in winter, but major changes in both fall and spring. We have already seen fall extent anomalies begin to take off in a dramatic fashion -- spring anomalies, IMO, would be next.

While extent is fairly normal at the moment, we are *well* beyond +1SD vs normal volume, and probably somewhere between +2 and +3SD (i.e., possibly a record for the modern era! but without data who knows).

(https://www.ccin.ca/home/sites/default/files/snow/snow_tracker/nh_swe.png)

The Finnish graph exemplifies how the trend in fall is even more dramatic (it discounts mountainous regions). In fact, this past October/November we had roughly *double* the snow/water equivalent of the era of record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fglobalcryospherewatch.org%2Fstate_of_cryo%2Fsnow%2Ffmi_swe_tracker.jpg&hash=7d01448218c9fe1555d12dad667406c0)

In my eyes it would seem that there is a very strong relationship between declining sea ice volume and rising continental snow volumes; in fact, a decent portion of the Arctic sea ice volume we have lost vs. normal is resting on the continents, and adding the ~700KM3 of surplus snow we have back into current sea ice volume produces a total much closer to "normal".

This, to me, suggests causation and not correlation.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: oren on March 23, 2017, 05:38:50 PM
If wintertime extent is fairly normal, then there is currently no albedo anomaly, just extra snow that seems to melt very quickly when spring arrives, therefore gaining no annual anomaly. And since the ocean's albedo anomaly could bring extra summer heat, the nearby conintents could become even warmer than they currently are in summer.
Regarding snow surviving in Siberia or Canada, I seem to remember nearly 30oC in Siberia at some point last summer or the one before, maybe the same in Alaska too. Can't build an ice sheet under such conditions. I personally fail to see the possible changes in weather or circulation that could save the continental snow for next year. Or even for enough time to give a significant anomaly.

Is there any chart of snow extent anomaly through the year for the last couple of years? Could help quantify my gut feeling.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Archimid on March 23, 2017, 06:41:20 PM
I think that the current trend speaks for itself. There is much more snowfall  during fall and winter but also much more melting in spring, enough to overwhelm winter snow. From: http://climate.rutgers.edu/snowcover/chart_seasonal.php (http://climate.rutgers.edu/snowcover/chart_seasonal.php)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: IMeretricious on March 23, 2017, 07:34:01 PM
Thickness becomes important when considering the rest of your argument, i.e., duration of snowcover during spring/summer, in that if wintertime areas that receive snowcover see much more of it than normal, they will be more prone to retaining their snowcover until later dates than normal. This is very important to albedo and it ultimately results in more extent than normal, it just may take a while to get to this point.

This doesn't augur well with what is actually happening in terms of positive depth anomalies translating into later melt dates. My intuition is that for snowpack of any considerable depth, the insulating capacity of snow will completely dominate any albedo effects. Firstly, albedo has much less of an effect in winter, so positive extent anomalies between October and March are going to be pretty limited. Secondly, any impact albedo will have during the melt season will be mitigated by the fact that melting snow accumulates debris on the surface, and in general will have a substantially lower albedo than fresh snow.

When recreating in avalanche terrain, knowing the temperature gradient of the snowpack is important. A rule of thumb often taught is the bottom of the snowpack is 0°C unless you know the ground is permafrost. Places cold enough to have permafrost that get plenty of snow typically won't have it because the snow will provide too effective a blanket for winter temperatures to cool the ground effectively.

But to suggest that this insulating effect is two-sided doesn't consider the seasonal dynamics of snowpacks. Loose, low density fresh snow has the best insulating capacity, whereas a dense, water-saturated and isothermal spring snowpack has effectively none, with essentially only the latent heat of fusion and albedo to moderate the warming of the ground. Of course, albedo is meaningless if the snowpack is being rained on, and longwave radiation balance has a very strong effect. A little bit of haze an ambient humidity can mean the difference between a firm spring snowpack and slush. If the increase in snow cover is because of increased moisture over northern landmasses, this change will also have the effect of speeding up melt.

Finally, it's worth considering what happens to saturated snowpacks on a slope. In the wintertime, slopes under 30° are generally considered stable. In the spring, however, clear skies are essential to keeping snow on slopes of any significant angle, because without the ability to radiate away heat absorbed during the day, the snowpack loses all cohesion and slides right down to the ground on slopes as little as 15°. This is even more common at higher latitudes because there is less night sky to refreeze the surface.

The net effect of this is congruent with observations: deeper snowpacks will not lead to later meltouts because melt is extremely dependent on weather and the same extra moisture bringing increased snowfall in the fall and winter brings overcast skies and rain in the spring. In fact, I would not be surprised to see northern latitudes, especially mountainous regions, to see huge increases in average snowpack depth going along with significantly earlier melt times.

So for feedbacks involving depth, we are essentially left with more insulation in the fall and winter, when the warming effect this has will be the greatest, and no albedo anomalies in the spring and summer to offset this.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: magnamentis on March 23, 2017, 09:03:31 PM
The air in the Arctic was dry in the past, but not anymore. There seems to be so much moisture now that it cannot be contained. I am no expert on that subject, and am sure there are others that can clarify.
Correct! But I am not talking about the Arctic re: decreasing/stable moisture, as it is definitely warming & moistening (also due to the loss of albedo); I am referencing land areas that are newly-covered by snow when they usually aren't.

in fact much less land is coverd by snow, i.e. all of nothern europe and big parts of eastern europe remain mostly snowfree or snowpoor as compared to i.e. when i was a child about 55 years ago. taking specific spots that due to warmer and wetter conditions have a bit more snow in some years is not target leading but misleading. i have observed for quite some time that you want to convince us that an ice age lays ahead. ok that's an opinion but so far of IMO (and thats also an opinion LOL) that i won't even enter a discussion. there has never been an ice age at times when i.e. CO levels were so high and still increasing, that alone tells the story but then there is much more that tells a future of warming and not one of cooling (overall, not locally) there will always be local counter effects due to air and water currents as well as shifting vertical air movement areas but the planet earth will get warmer as long as we add heat and heat containing factors. of course the process will not be linear at all times but persistent in the long run.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 23, 2017, 09:23:38 PM
The air in the Arctic was dry in the past, but not anymore. There seems to be so much moisture now that it cannot be contained. I am no expert on that subject, and am sure there are others that can clarify.
Correct! But I am not talking about the Arctic re: decreasing/stable moisture, as it is definitely warming & moistening (also due to the loss of albedo); I am referencing land areas that are newly-covered by snow when they usually aren't.

in fact much less land is coverd by snow, i.e. all of nothern europe and big parts of eastern europe remain mostly snowfree or snowpoor as compared to i.e. when i was a child about 55 years ago. taking specific spots that due to warmer and wetter conditions have a bit more snow in some years is not target leading but misleading. i have observed for quite some time that you want to convince us that an ice age lays ahead. ok that's an opinion but so far of IMO (and thats also an opinion LOL) that i won't even enter a discussion. there has never been an ice age at times when i.e. CO levels were so high and still increasing, that alone tells the story but then there is much more that tells a future of warming and not one of cooling (overall, not locally) there will always be local counter effects due to air and water currents as well as shifting vertical air movement areas but the planet earth will get warmer as long as we add heat and heat containing factors. of course the process will not be linear at all times but persistent in the long run.

So...

1)

in fact much less land is coverd by snow, i.e. all of nothern europe and big parts of eastern europe remain mostly snowfree or snowpoor as compared to i.e. when i was a child about 55 years ago.

^I am speaking hemispherically re: charts/etc. Some regions see more warmth, some more cold. Europe has been warmer in general so far and not that snowy. Alas.

2)

"i have observed for quite some time that you want to convince us that an ice age lays ahead. ok that's an opinion but so far of IMO (and thats also an opinion LOL) that i won't even enter a discussion. there has never been an ice age at times when i.e. CO levels were so high and still increasing, that alone tells the story but then there is much more that tells a future of warming and not one of cooling (overall, not locally) there will always be local counter effects due to air and water currents as well as shifting vertical air movement areas but the planet earth will get warmer as long as we add heat and heat containing factors. of course the process will not be linear at all times but persistent in the long run."

I am not trying to convince anyone an Ice Age lays ahead, merely stating that we should not ignore feedbacks and the potential for negative ones is equal to positive ones despite AGW (IMO). Our dataset is extremely limited but what we *do* know is that when the Earth is in an Ice Age, it generally does not warm past a certain point without flipping back into a colder state.

Where your post is specifically wrong is where you say "there has never been an ice age at times when i.e. CO levels were so high."

We still have ice sheets covering Greenland and Antarctica which means that we actually *are* still in an Ice Age, so by default that statement is incorrect. Whether we exit the current Ice Age or plunge back into the depths of the freezer is the question facing humanity today. Given recent history of the past few million years, Younger Dryas etc argue we are more likely to pivot back to cold versus lose all the ice on Greenland/Antarctica, though you *are* correct that we have (seemingly) never had an ice age at a time when CO2 levels were so high as they are today, which means that either direction is possible.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 23, 2017, 09:41:19 PM
Also: I am actually pretty sure Eastern Europe has been fairly cold/snowy this winter?

On a related note, I am wondering if a mechanism to explain the European warmth can be found in the ice-free Kara/Barentz.

These promote warm air rising into the Arctic as well as into Greenland, while simultaneously encouraging the cold Arctic/Greenland airmasses to drop south on the backside of these intrusions. This usually happens either through Quebec or to the east of Greenland.

In either case, as the airmasses plunge south they are now seemingly heading towards Spain and Morocco/Algeria, (or alternately S through Scandi. into Eastern Europe) where the former have allowed the Atlas Mountains to be very snowy relative to normal which promotes cold and snow over the rest of NRN Africa. These airmasses get "stuck" south of the very warm Mediterranean waters and travel east, with Turkey and Iran lying in the path of both Arctic Express trains, translating into the extreme cold and snow anomalies that we are now seeing in both of those regions.

That leaves much of continental Europe relatively warm as it is stuck in the "in between" of airmasses plunging to the west and to the east, with the ones coming from the west facing the natural heat barrier of the Mediterranean, which pushes them south.

Hopefully this makes some sense?? It also explains why we see the Sahara turn into a wet environment every couple thousand years, coincident with +++snowpack in the mountains of Algeria and Morocco.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: misfratz on March 24, 2017, 12:58:33 AM
We've seen the data presented in this thread that shows a decline in spring snow cover extent at the same time as an increase in winter snow mass. So the only remaining question is whether we think it is possible that a future increase in winter snow mass might overwhelm the current trend in spring snow extent to lead to an increase in spring snow extent, and thus a cooling feedback.

Well, there would have to be a lot of extra snow to survive the extra warmth that exists in spring, that has lead to the observed decline in spring snow cover extent.

The other things that strikes me about this is that the proposed feedback cuts against itself. The warmer world leads to extra snowfall, the extra snowfall survives into spring/summer to cause an albedo feedback, which leads to cooling, which reduces winter snowfall, and so carbon dioxide reasserts itself as the dominant climate driver.

In order to overcome the carbon dioxide warming effect the albedo effect would have to not just be stronger than last year, but it would have to be stronger than in the 1950s, when spring snow cover extent was considerably greater than now, when the albedo effect was not strong enough to stop carbon dioxide from warming the planet and reducing spring snow cover extent.

I could, perhaps, envisage a major one-off cooling event managing to create a sufficiently large knock to the climate system to increase snow cover extent such that an albedo feedback kicked in... were it not for the fact that we already had a couple of such events over the last two centuries or so, with the eruptions of Tambora and Krakatoa in 1815 and 1883, respectively. These large volcanoes did cause significant cooling for several years, cooling that would, I presume, have increased snow cover extent, particularly in spring when the generally lower temperatures would have delayed the spring melt, but even they were not strong enough to kick the climate into a cooling feedback loop.

It is possible that the orbital parameters are a bit different now, perhaps more conducive to this feedback, with less solar insolation in spring - the typical way that the Milankovitch Cycle is though to trigger ice ages. But I doubt it.

This is an interesting idea, but I think that the relatively recent volcanic eruptions demonstrate that the snow cover albedo feedback is not strong enough to create a cooling to overwhelm the warming effect from greenhouse gases if, somehow, extra winter snow were suddenly able to translate into increased spring snow cover extent.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 24, 2017, 02:58:30 AM
This map illustrates the high ground south of the Arctic where any evaporation from the warming ocean is likely to precipitate out as snow. For me the most at risk area is the uplands of Eastern Siberia and Mongolia, but you have to allow that anywhere from northern Spain to the Chukchi are possiblities. My own thinking is that until Laptev is ice free in November and December we have no idea how much snow a random weather event can drop here or how persistent it will be, but I suspect it will rapidly expand to the point where the northern slopes will carry permanent snow. IF that happens the climate in Siberia will reverse being much colder in the southern uplands and more like permanent springtime by the ocean, and in time an enduring cold wind falling out of the mountains flowing east over China.

http://topex.ucsd.edu/marine_topo/gif_images/global_topo_large.gif (http://topex.ucsd.edu/marine_topo/gif_images/global_topo_large.gif)

I don't know for certain that something like this will happen, but I think it is reasonable that it could possibly. Regional climate transitions are appearing to have at least started in many places, and therefore in one way bbr could have a valid theory. I can't see it happening globally or even hemisphere-wise, but regionally, maybe.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wili on March 24, 2017, 03:57:35 AM
Many good points, misfraz.

Let's also not forget the rather obvious fact that there is more snow in the winter in the Arctic because there is more water vapor in the air in the Arctic now. The more snow there is indicates the more vapor there is.

Water vapor is a very powerful GHG, of course. And GHGs have their strongest effects in the winter (or at night, which is the same thing in the Arctic).

So I'm guessing it's basically mathematically impossible for whatever albedo damping (negative) feedback increased snow may have to beat out the exacerbating (positive) feedback of the very water vapor that has to be there to create said snow.

But maybe I'm missing something somewhere?

(I think I read somewhere recently also that the level of downwelling longwave radiation that such GHGs create in the Arctic is the strongest indicator of when melting of ice will begin. But I can't recall the source now.)

bbr wrote:

"...feedbacks and the potential for negative ones is equal to positive ones despite AGW (IMO). ...when the Earth is in an Ice Age, it generally does not warm past a certain point without flipping back into a colder state."

This strikes me as quite wrong or at least misleading.

Perhaps you could present any studies that suggest that our current (and probable future) anthropogenic GHG forcing plus the very many large exacerbating feedbacks are balanced out by damping feedbacks on any time scale shorter than tens of thousands of years, at least.

And the earth during this relatively cool last few million years has has been 'flipping back to a colder state' because of Milankovich cycles, not primarily because of powerful damping feedbacks kicking in. Again, if you have studies that show that it is feedbacks and not Milankovich orbital wobbles that are the prime trigger for periods of increased glaciation, please present them.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wili on March 24, 2017, 04:10:26 AM
(duplicate...not sure how that happened)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 24, 2017, 04:18:54 AM
wili
Quote
(I think I read somewhere recently also that the level of downwelling longwave radiation that such GHGs create in the Arctic is the strongest indicator of when melting of ice will begin. But I can't recall the source now.)

Neven mentioned that in the melting thread     http://onlinelibrary.wiley.com/doi/10.1002/2016GL069330/full (http://onlinelibrary.wiley.com/doi/10.1002/2016GL069330/full)
Quote
Melt onset is determined by downwelling longwave radiation. From Mortin et al. (2016):

"The timing of melt onset affects the surface energy uptake throughout the melt season. Yet the processes triggering melt and causing its large interannual variability are not well understood. Here we show that melt onset over Arctic sea ice is initiated by positive anomalies of water vapor, clouds, and air temperatures that increase the downwelling longwave radiation (LWD) to the surface. The earlier melt onset occurs; the stronger are these anomalies. Downwelling shortwave radiation (SWD) is smaller than usual at melt onset, indicating that melt is not triggered by SWD. When melt occurs early, an anomalously opaque atmosphere with positive LWD anomalies preconditions the surface for weeks preceding melt. In contrast, when melt begins late, clearer than usual conditions are evident prior to melt. Hence, atmospheric processes are imperative for melt onset. It is also found that spring LWD increased during recent decades, consistent with trends toward an earlier melt onset."
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Martin Gisser on March 24, 2017, 05:07:20 AM
If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

Given this, I suspect that we have vastly underestimated albedo's impact on overall global climate. Even if the amount of land that is snowcovered in a given year only increases by 10%, that is an absolutely *huge* amount of solar energy (~3% of planetary total!) that is now being deflected back into space.

If someone can provide more concrete numbers or throw my ideas into the garbage can either would be appreciated.
Climate denial garbage can, imho.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: FredBear on March 24, 2017, 06:36:34 AM
The way I see it is that thicker snow insulates more at night/winter, producing even lower surface temperatures (particularly over land, as the sea-ice is forming later/is thinner than in earlier years). Therefore less energy is being radiated from the underlying surfaces.
But when the seasons shift the warming climate results in melt starting earlier and the "snow-off" dates are getting earlier in spite of the thicker snow. This then contributes feed-back for increasing the Arctic warming.

I have not seen thicker snow = more persistant snow. Even in the Arctic 2m ice can melt out over the summer, and that is a lot of snow equivalent.  Even at higher altitudes snow-lines are retreating up mountains and glaciers so warming is beating cooling.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wili on March 24, 2017, 06:57:22 AM
Thanks, Tt.

MG--succinctly put!

FB--Nice point!
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: solartim27 on March 24, 2017, 07:09:00 AM
Yes it is possible, once you get glaciders down to California
https://www.seas.harvard.edu/news/2017/03/perfect-storm-of-fire (https://www.seas.harvard.edu/news/2017/03/perfect-storm-of-fire)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: DrTskoul on March 24, 2017, 10:22:46 AM
If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

Given this, I suspect that we have vastly underestimated albedo's impact on overall global climate. Even if the amount of land that is snowcovered in a given year only increases by 10%, that is an absolutely *huge* amount of solar energy (~3% of planetary total!) that is now being deflected back into space.

If someone can provide more concrete numbers or throw my ideas into the garbage can either would be appreciated.
Climate denial garbage can, imho.

Btw, way underestimated effect of albedo means way underestimated effect of CO2. Climate sensitivity does not discriminate between forcings....
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Shared Humanity on March 24, 2017, 02:39:35 PM
If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

Given this, I suspect that we have vastly underestimated albedo's impact on overall global climate. Even if the amount of land that is snowcovered in a given year only increases by 10%, that is an absolutely *huge* amount of solar energy (~3% of planetary total!) that is now being deflected back into space.

If someone can provide more concrete numbers or throw my ideas into the garbage can either would be appreciated.
Climate denial garbage can, imho.

Garbage can is too small. You're gonna need a dumpster for that.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 24, 2017, 02:58:52 PM
If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

Given this, I suspect that we have vastly underestimated albedo's impact on overall global climate. Even if the amount of land that is snowcovered in a given year only increases by 10%, that is an absolutely *huge* amount of solar energy (~3% of planetary total!) that is now being deflected back into space.

If someone can provide more concrete numbers or throw my ideas into the garbage can either would be appreciated.
Climate denial garbage can, imho.

Garbage can is too small. You're gonna need a dumpster for that.
I have not denied anything, and saying ignorant things/attacking different points of view when I have clearly said *I could be very wrong and I would like evidence* over and over again is how you end up with an ignorant and uninformed perspective. I am 100% on board with AGW/climate change and the fact that you cannot consider that it could have unforeseen consequences that could be even worse than what happens in a warming world shows you are the denier, not me.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 24, 2017, 03:05:26 PM
The way I see it is that thicker snow insulates more at night/winter, producing even lower surface temperatures (particularly over land, as the sea-ice is forming later/is thinner than in earlier years). Therefore less energy is being radiated from the underlying surfaces.
But when the seasons shift the warming climate results in melt starting earlier and the "snow-off" dates are getting earlier in spite of the thicker snow. This then contributes feed-back for increasing the Arctic warming.

I have not seen thicker snow = more persistant snow. Even in the Arctic 2m ice can melt out over the summer, and that is a lot of snow equivalent.  Even at higher altitudes snow-lines are retreating up mountains and glaciers so warming is beating cooling.
So far, we have not seen snow persist through summer in any of these northern locations -- no disagreement there.

I suspect the tipping point may start gradually but begins once we see our first summer where snow *doesn't* melt at all locations that normally see this happen. This is currently very difficult, but how much more additional snow do we need in parts of Siberia and Quebec for this to be a more realistic possibility?

Additionally, one must consider the regional forcings that will soon dominate climate in these regions. While the Arctic continues to lose volume, Hudson Bay will likely remain relatively steady given its surroundings as well as the fact that it has always melted out every year.

What happens when the Arctic Ocean is mostly ice-free in June/July but Hudson Bay is not? I suspect that would encourage longer durations of colder airmasses across much of Canada (especially Quebec) through the summer. And consequently, that also increases the potential for certain regions to begin building snowcover through spring and at least the early part of summer, at least relative to the 20th century.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Neven on March 24, 2017, 05:14:36 PM
bbr2314, did you have a look at the Ewing-Donn theory yet, and why it was rejected ultimately?
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 24, 2017, 05:40:00 PM
bbr2314, did you have a look at the Ewing-Donn theory yet, and why it was rejected ultimately?
I've read the links but I missed the part about why it was rejected, can you re-link to the specific bits? Appreciate it!

Also I think Ewing-Donn misses the component of AMOC shutdown/freshwater release from Greenland/Antarctica.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: FredBear on March 24, 2017, 06:34:09 PM
bbr2314 - think this may be the relevant bit:--
Ewing and Donn worked to patch up the holes in their theory by invoking additional phenomena, and for a while many scientists found the idea intriguing, even partly plausible. But ultimately the scheme won no more credence than most other theories of the ice ages.(51) "Your initial idea was truly a great one," a colleague wrote Ewing years later, "...a beautiful idea which just didn't stand the test of time."

As to additional snow - the continuing retreat of existing snowfields under global warming will result in lower total albedo for the earth for the forseeable future. (Subject to no catastrophic aerosols suddenly being produced - and warmer climates would make it more difficult for volcanoes to squirt SO2 high into the stratosphere anyway.)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: misfratz on March 24, 2017, 08:00:11 PM
So far, we have not seen snow persist through summer in any of these northern locations -- no disagreement there.

I suspect the tipping point may start gradually but begins once we see our first summer where snow *doesn't* melt at all locations that normally see this happen. This is currently very difficult, but how much more additional snow do we need in parts of Siberia and Quebec for this to be a more realistic possibility?
The problem you are missing is that the trend is in the opposite direction, with reductions in snow cover extent in spring. So it cannot happen gradually, because it is already happening rapidly in the other direction.

Your hypothesis clearly requires a large shock in addition to the observed extra winter snow, but as I have argued past large volcanoes have not been large enough. It's also worth noting that the Younger Dryas cooling was ultimately a temporary reaction to a freshwater injection to the north Atlantic - it too was not able to overcome the boundary forcing.

You presented an interesting idea, but a lot of evidence contrary to that idea has been presented and you seem to be ignoring it.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Archimid on March 25, 2017, 03:24:23 PM
In my understanding of the climate system I have not ruled out yet that rapid global warming may lead to rapid global cooling. I think it will take rapid Greenland/Antarctic melt followed by a sharp increase in volcanism. Under that scenario, the albedo and aerosol changes might be enough to cause   a global winter lasting anywhere from years to decades.

But I'm talking about ridiculous amounts of melt and an equally ridiculous increase in volcanism.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Shared Humanity on March 25, 2017, 04:30:01 PM
Large positive snow anomalies in the Fall and early Winter (driven, at least in part, by wide expanses of open water in the Arctic) and dramatic negative anomalies in the early Spring (caused by a rapidly warming planet) is the worst possible scenario as the vast stretches of permafrost are insulated from the winter cold and then subjected to a lengthening warm season.

The changes occurring are accelerating.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tigertown on March 25, 2017, 05:19:33 PM
Large positive snow anomalies in the Fall and early Winter (driven, at least in part, by wide expanses of open water in the Arctic) and dramatic negative anomalies in the early Spring (caused by a rapidly warming planet) is the worst possible scenario as the vast stretches of permafrost are insulated from the winter cold and then subjected to a lengthening warm season.

The changes occurring are accelerating.
I guess that is like a one-two punch. And the permafrost is melting, like crazy fast. Nobody could have foreseen how fast it is melting.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: solartim27 on March 25, 2017, 07:42:04 PM
But I'm talking about ridiculous amounts of melt and an equally ridiculous increase in volcanism.
I should have quoted from the article in my previous post:
Yes it is possible, once you get glaciers down to California
https://www.seas.harvard.edu/news/2017/03/perfect-storm-of-fire (https://www.seas.harvard.edu/news/2017/03/perfect-storm-of-fire)
Quote
What caused the largest glaciation event in Earth’s history, known as ‘snowball Earth’?
Geologists and climate scientists have been searching for the answer for years but the root cause of the phenomenon remains elusive.
Now, Harvard University researchers have a new hypothesis about what caused the runaway glaciation that covered the Earth pole-to-pole in ice.
The research is published in Geophysical Research Letters.
Researchers have pinpointed the start of what’s known as the Sturtian snowball Earth event to about 717 million years ago — give or take a few 100,000 years.  At around that time, a huge volcanic event devastated an area from present day Alaska to Greenland.
Quote
“Cooling from aerosols doesn’t have to freeze the whole planet; it just has to drive the ice to a critical latitude. Then the ice does the rest,” said Macdonald.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: johnm33 on March 25, 2017, 08:30:41 PM
In my understanding of the climate system I have not ruled out yet that rapid global warming may lead to rapid global cooling. I think it will take rapid Greenland/Antarctic melt followed by a sharp increase in volcanism. Under that scenario, the albedo and aerosol changes might be enough to cause   a global winter lasting anywhere from years to decades.

But I'm talking about ridiculous amounts of melt and an equally ridiculous increase in volcanism.
That's looking a long way out, I'm thinking not of global cooling or an ice age, although the eventual distibution of ice masses may bare some resemblance, but more of a mechanism that emerges to halt a runaway greenhouse effect. That means increased evaporation from a warmer Arctic, precipitating out somewhere high enough and remote enough from any ocean to survive summer melt, and with minimal change of elevation between there and the sea, so the Altai mountains/Mongolia fit the bill in Eurasia, and southwest of Hudson going towards Montana in the Americas. I know too little about atmospherics to think properly about this, but it seems to me if you add the latent heat of evaporation to that of freezing/melting thats a way of lifting vast amounts of energy from the Arctic and dumping it far to the south high up in the[now dry] atmosphere, plus if this kicks off as a random but powerful weather event the transformation of the vapour to solid, and consequent loss of volume, could be self reinforcing. Once established, and it may take a number of false starts, it's possible that it would create it's own weather systems. 
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: DrTskoul on March 25, 2017, 09:52:44 PM
In my understanding of the climate system I have not ruled out yet that rapid global warming may lead to rapid global cooling. I think it will take rapid Greenland/Antarctic melt followed by a sharp increase in volcanism. Under that scenario, the albedo and aerosol changes might be enough to cause   a global winter lasting anywhere from years to decades.

But I'm talking about ridiculous amounts of melt and an equally ridiculous increase in volcanism.
That's looking a long way out, I'm thinking not of global cooling or an ice age, although the eventual distibution of ice masses may bare some resemblance, but more of a mechanism that emerges to halt a runaway greenhouse effect. That means increased evaporation from a warmer Arctic, precipitating out somewhere high enough and remote enough from any ocean to survive summer melt, and with minimal change of elevation between there and the sea, so the Altai mountains/Mongolia fit the bill in Eurasia, and southwest of Hudson going towards Montana in the Americas. I know too little about atmospherics to think properly about this, but it seems to me if you add the latent heat of evaporation to that of freezing/melting thats a way of lifting vast amounts of energy from the Arctic and dumping it far to the south high up in the[now dry] atmosphere, plus if this kicks off as a random but powerful weather event the transformation of the vapour to solid, and consequent loss of volume, could be self reinforcing. Once established, and it may take a number of false starts, it's possible that it would create it's own weather systems.

There is no homeostasis.... there is no mechanism that emerges...
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 01:28:03 AM
In my understanding of the climate system I have not ruled out yet that rapid global warming may lead to rapid global cooling. I think it will take rapid Greenland/Antarctic melt followed by a sharp increase in volcanism. Under that scenario, the albedo and aerosol changes might be enough to cause   a global winter lasting anywhere from years to decades.

But I'm talking about ridiculous amounts of melt and an equally ridiculous increase in volcanism.
That's looking a long way out, I'm thinking not of global cooling or an ice age, although the eventual distibution of ice masses may bare some resemblance, but more of a mechanism that emerges to halt a runaway greenhouse effect. That means increased evaporation from a warmer Arctic, precipitating out somewhere high enough and remote enough from any ocean to survive summer melt, and with minimal change of elevation between there and the sea, so the Altai mountains/Mongolia fit the bill in Eurasia, and southwest of Hudson going towards Montana in the Americas. I know too little about atmospherics to think properly about this, but it seems to me if you add the latent heat of evaporation to that of freezing/melting thats a way of lifting vast amounts of energy from the Arctic and dumping it far to the south high up in the[now dry] atmosphere, plus if this kicks off as a random but powerful weather event the transformation of the vapour to solid, and consequent loss of volume, could be self reinforcing. Once established, and it may take a number of false starts, it's possible that it would create it's own weather systems.
I think you have hit the nail on the head 100% re: what I am attempting to describe.

I fully acknowledge everyone's comments re: current feedbacks and the current decline in spring snowcover. That is not what I am debating, though it is undeniable that spring extent has fallen in recent years.

However, if one were looking at the data back in the 60s/70s (if we had the data then), one may  have come to the same conclusion re: fall snowcover then (irreversible decline). My point is not that this is not happening today -- it is that the mechanism resulting in increasing fall/wintertime snowcover will soon overwhelm spring/summer snowcover as well, even if it may take another 5-10 years to kick into gear.

I suspect we are already at the bottom of the trendline re: spring snowcover (again, could be wrong), and that as the situation up north continues to unravel, we will see a rapid uptick beginning. Already, this year seems to be bucking the trendline in spite of the record warmth. Perhaps we aren't +1SD in extent, but we are within range of normal, and in terms of volume, we are still *way* above normal.

RE: Neven & the comments on Ewing-Donn -- to my eyes, it still seems to be plausible? The comments afterwards seem to me to indicate that we still do not fully understand how ice ages come about, so it certainly does not seem to have been discounted as a plausibility as we head into the future (though perhaps in the past it was not a mechanism for change, that does not mean it cannot be in the future given our unprecedented situation re: GHG emissions simultaneous with an ongoing albeit seemingly waning ice age).

On its own, Ewing-Donn may be merely plausible, but I believe they ignored the impacts of freshwater melt/AMOC shutdown. Combining the theory of Ewing-Donn with the findings of Hansen et al and their anticipated cooling based on AMOC shutdown and Antarctic melt *alone*, leads me to believe that if anything, Hansen's anomalies may be underestimating the impact of the freshwater melt. When you join these two theories together, I believe we can make much better sense of ice ages. That is also not to say Milankovich cycles are unimportant -- clearly, they matter -- but we are currently in a situation where both human and natural forcings are at a seemingly unprecedented head-to-head battle that, IMO, can easily overwhelm the relatively minimal changes in solar forcings that have previously led to climactic changes (i.e., in lieu of a massive asteroid impact or supervolcano, humans are the confounding atmospheric variable).
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 01:43:22 AM
Here are the Hansen maps btw in case anyone has not seen:

http://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016.pdf (http://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016.pdf)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 05:35:19 AM
...in the midst of all the doom and gloom I have found a tidbit of relatively good news: despite his death (RIP and thank you for all the wonderful contributions), the efforts of Andrew Slater continue to be available on his website, and it seems that at least the snow component continues to update. He may be gone but he will not be forgotten, and the latest charts from his website certainly speak to the prospects of glaciers in California -- in fact across almost the entirety of the west, snow-water-equivalent this year is #1 for the date!

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fcires1.colorado.edu%2F%7Easlater%2FSNOW%2FRANK%2Fall_rank_swe.gif&hash=8189c92d83fd544321e8149455b62c0c)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fcires1.colorado.edu%2F%7Easlater%2FSNOW%2FDAY_TS%2Fpercentage_dots.gif&hash=352dc9e3e523d03dcc72f8e387f5fd11)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 06:12:09 AM
RE: what it takes for snow to make it through the summer, I have found the below with regards to glaciers in Sweden.

https://lup.lub.lu.se/student-papers/search/publication/1332886

Quote
Since the mid 1970s the general retreating trend for glacier in Scandinavian have ceased and
some glaciers have even started to advance. This is due to a more maritime influence on the
climate, which means increased precipitation in winter and lower summer temperature. A more
maritime climate can be said to be favourable for glacier growth. Under such climate conditions
is it possible that new glaciers are forming? The aim of this project is to assess the climate
conditions that are needed to initiate a glacier in empty cirques in a small mountain massif, the
Rassepautasjtjåkka massif, northern Sweden. The study area is of interest since the cirques are
located just below the glaciation limit. Since there are no moraines or other signs of glaciation in
the area it is still uncertain when the cirques were formed. Using a gridbased temperature index
ablation model, that takes into account the topographic effects on melt, the melt during the
summer was calculated and the snow that remains at the end of the melt season is what can
constitute the ground to a new glacier. Weather data has been collected in the cirques every third
hour for the last eight years and this was used as input to the model. The summer mean
temperature needs to be lowered between –2 °C and –3 °C from the current climate before snow
will remain after a melt season. An increased initial snow cover of today between 100-150%
(under otherwise equal conditions) will have the same effect i. e remaining snow at the end of the
melt season. When increasing the initial snow cover with 50% and lower the summer mean
temperature by –2 °C, snow will be left in the cirques after a melt season.
The climate conditions
that are required to create a re-glaciation are not met by conditions evaluated from proxy-data
from the Holocene. Therefore it can be concluded that glacier has not existed in the
Rassepautasjtjåkka massif during the Holocene and that the origin of the cirques extends further
back than the Holocene. According to future climate scenarios that predict increased temperature
and increased precipitation glaciers will not form in the cirques in the future spanned by the
predictions.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Neven on March 26, 2017, 08:57:54 AM
But that's where the problem is, right? The temperatures will not lower in the foreseeable future.

Quote
My point is not that this is not happening today -- it is that the mechanism resulting in increasing fall/wintertime snowcover will soon overwhelm spring/summer snowcover as well, even if it may take another 5-10 years to kick into gear.

The mechanism, ie global warming via CO2 forcing, is going to continue to increase as well and overwhelm fall/wintertime snowcover. At some point snow will turn into rain.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: S.Pansa on March 26, 2017, 09:40:03 AM
@bbr2314

I find your arguments pretty unconvincing. I think you severely overestimate the magnitude of this negative feedback. Why?
Apart from the fact that your claim goes against current climate science it goes against  pretty much everything we know about past climates too.

Just have a look at Shakun etal (2012) (http://www.atm.damtp.cam.ac.uk/mcintyre/shakun-co2-temp-lag-nat12.pdf) and how the transition to our current interglacial worked. Skeptical Science has a nice write up (https://skepticalscience.com/skakun-co2-temp-lag.html) of the paper.
The main steps are as follows (quoting from there) :

1) "Earth's orbital cycles trigger the initial warming (starting approximately 19,000 years ago), which is first reflected at the highest latitudes" (see the first attached fig.)
2) "This Arctic warming melted large quantities of ice, causing fresh water to flood into the oceans."
3)" This influx of fresh water then disrupted the Atlantic meridional overturning circulation (AMOC), in turn causing a seesawing of heat between the hemispheres."
4) "The Southern Hemisphere and its oceans warmed first, starting about 18,000 years ago."
5)"The warming Southern Ocean then released CO2 into the atmosphere starting around 17,500 years ago, which in turn caused the entire planet to warm via the increased greenhouse effect."

Evidently we didn't turn back into a new Ice age - due to a year-round snow cover nor sth. else - back then (see second figure), when the CO2 concentration was at around 220 ppm.
Why on earth should we tumble into an ice age now (or get a snow cover that lasts through the summers ), when we have 400 ppm CO2 in the air?

Yes, the fresh water influx will - or already does - disrupt the AMOC (see point 3 above and Hansen) and it will give us a very rough ride to where we headed.
But this is not a year-round snow covered NH nor an Ice Age - just have a look at the Paleo-record of  Lake El’gygytgyn during the late Pliocene (for instance in Grette-Bingham etal 2013, Science (https://www.geo.umass.edu/climate/papers2/BrighamGrette_Science2013.pdf))

From the abstract:
Quote
... Evidence from Lake El’gygytgyn, NE Arctic Russia, shows that 3.6-3.4 million years ago, summer temperatures were ~8°C warmer than today when pCO 2  was ~400 ppm.
See also third attachment

To sum it up: No, snow cover will not survive the summer in the years to come & no Ice Age is cometh.

Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: misfratz on March 26, 2017, 11:17:20 AM
But that's where the problem is, right? The temperatures will not lower in the foreseeable future.

Quote
My point is not that this is not happening today -- it is that the mechanism resulting in increasing fall/wintertime snowcover will soon overwhelm spring/summer snowcover as well, even if it may take another 5-10 years to kick into gear.

The mechanism, ie global warming via CO2 forcing, is going to continue to increase as well and overwhelm fall/wintertime snowcover. At some point snow will turn into rain.
That gives me another idea for an interesting bit of analysis. The wintertime average zero degree isotherm is presumably marching northwards. But how fast?

I'll add it to the list.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 08:01:54 PM
@bbr2314

I find your arguments pretty unconvincing. I think you severely overestimate the magnitude of this negative feedback. Why?
Apart from the fact that your claim goes against current climate science it goes against  pretty much everything we know about past climates too.

Just have a look at Shakun etal (2012) (http://www.atm.damtp.cam.ac.uk/mcintyre/shakun-co2-temp-lag-nat12.pdf) and how the transition to our current interglacial worked. Skeptical Science has a nice write up (https://skepticalscience.com/skakun-co2-temp-lag.html) of the paper.
The main steps are as follows (quoting from there) :

1) "Earth's orbital cycles trigger the initial warming (starting approximately 19,000 years ago), which is first reflected at the highest latitudes" (see the first attached fig.)
2) "This Arctic warming melted large quantities of ice, causing fresh water to flood into the oceans."
3)" This influx of fresh water then disrupted the Atlantic meridional overturning circulation (AMOC), in turn causing a seesawing of heat between the hemispheres."
4) "The Southern Hemisphere and its oceans warmed first, starting about 18,000 years ago."
5)"The warming Southern Ocean then released CO2 into the atmosphere starting around 17,500 years ago, which in turn caused the entire planet to warm via the increased greenhouse effect."

Evidently we didn't turn back into a new Ice age - due to a year-round snow cover nor sth. else - back then (see second figure), when the CO2 concentration was at around 220 ppm.
Why on earth should we tumble into an ice age now (or get a snow cover that lasts through the summers ), when we have 400 ppm CO2 in the air?

Yes, the fresh water influx will - or already does - disrupt the AMOC (see point 3 above and Hansen) and it will give us a very rough ride to where we headed.
But this is not a year-round snow covered NH nor an Ice Age - just have a look at the Paleo-record of  Lake El’gygytgyn during the late Pliocene (for instance in Grette-Bingham etal 2013, Science (https://www.geo.umass.edu/climate/papers2/BrighamGrette_Science2013.pdf))

From the abstract:
Quote
... Evidence from Lake El’gygytgyn, NE Arctic Russia, shows that 3.6-3.4 million years ago, summer temperatures were ~8°C warmer than today when pCO 2  was ~400 ppm.
See also third attachment

To sum it up: No, snow cover will not survive the summer in the years to come & no Ice Age is cometh.
I think the research you presents has some valid points but 1) I do not believe that model-simulated biomes can be verified with any sort of comprehensive accuracy, especially at a grid scale of 50KM, and 2) I think the key point you are missing in my argument (and in yours) is that at all stages of ^ post, the Earth *has* been in an ice age, and continues to exist in an ice age.

Just because the Laurentide has almost disappeared does not mean we are not in an ice age; we still have Greenland and Antarctica, which contain vast amounts of ice that would not exist if we were not still in an ice age.

I believe it has been established that at the height of the last glacial maximum, the Arctic Ocean was ice-covered; my big question is what was the Arctic Ocean's state at the *start* of the last glacial maximum? This is a question I have not been able to answer and I suspect the answer is ice-free. I also suspect that the more heat the Arctic accumulates/the longer it remains ice-free in the context of the ongoing ice age, the *more* glaciation occurs after it hits this state (i.e., the heat influx continues until the continents/ice sheets can sufficiently overwhelm the mechanism through both albedo and freshwater feedbacks).
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 08:30:37 PM
But that's where the problem is, right? The temperatures will not lower in the foreseeable future.

Quote
My point is not that this is not happening today -- it is that the mechanism resulting in increasing fall/wintertime snowcover will soon overwhelm spring/summer snowcover as well, even if it may take another 5-10 years to kick into gear.

The mechanism, ie global warming via CO2 forcing, is going to continue to increase as well and overwhelm fall/wintertime snowcover. At some point snow will turn into rain.
Globally the temperature may not lower, but regionally, as Hansen's charts and maps show, it is already beginning to happen in certain spots and is likely to become more prominent as AMOC shutdown continues.

More importantly, as the linked study re: glaciers in Sweden shows, it seems that high-altitude regions in Sweden (and likely elsewhere) merely need 100-150% of past snowcover averages to achieve a snowpack that does indeed last for the summer, even if temperatures remain steady.

I believe that combining the imminent temperature trends projected by Hansen with the increasing moisture resulting from an ice-free Arctic shows the above to be more than plausible, and if that is the case, we can see a clear mechanism for reglaciation that does not rely on model-ology and paleoclimate simulations.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 26, 2017, 08:39:05 PM
Finally, not to post too many times, I have been reading into the "Karakorum anomaly". This stabilization and increase in ice mass across the Western Himalayas and Karakorum range only began in approximately 1995-2000, with a steady trend towards growth continuing since then. While data is still sparse for 2011+ I suspect that those snow maps from the Canadian ice service are indeed accurate as they corroborate the recent trends in the region.

http://adsabs.harvard.edu/abs/2015EGUGA..17.1686Z (http://adsabs.harvard.edu/abs/2015EGUGA..17.1686Z)

In the face of overwhelming melt, we must look at examples like the Karakorum, which run completely contrary to past notions of what would happen, and ask: why is this occurring?

I would postulate that the impact of additional water vapor (and consequent glacial advance) manifests earlier in the highest altitudes of the Northern Hemisphere, and slowly begins advancing downward in elevation (similar to the ideas put forth by johnm23). The relatively slight warming we have seen in these regions has now seemingly reversed as snowcover has become more impressive on a year-round basis.

I suspect that over the next ten years we will see this continue across the Karakorum and Western Himalayas while also witnessing similar reversals in trendlines in areas even further down in elevation, like the peaks of the Rockies, Alps, and mountains of Southwest Asia. So far any positive anomalies have seemingly been restricted to altitudes of 5KM+, but as the other moisture feedbacks continue to accelerate (i.e., ++snowcover), they will begin to occur in many other regions as well.

It is important to note that the above does ***NOT*** discount overall global warming or anthropogenic climate change, and would also seem to directly refute the notion presented by several posters & papers in this thread that CO2 is the end-all. Of course CO2 is very important, but I believe (and the crux of my argument has been) that albedo feedbacks are even more crucial. I would compare CO2 + albedo to a match with a tub of gasoline; on its own, the gasoline is whatever, but when you add fire, boom. 

EDIT: I may have been wrong about elevation, it seems trend has been slightly positive in highest elevations but most positive in lowest elevations of the Karakorum, here is a full paper which is quite interesting on the subject:

http://sci-hub.io/10.1007/s00703-016-0440-6 (http://sci-hub.io/10.1007/s00703-016-0440-6)
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wili on March 26, 2017, 09:37:11 PM
"...which run completely contrary to past notions of what would happen..."

I think that, once again, you aren't representing the science accurately here.

No serious scientist ever suggested that we have perfect knowledge of what would happen in every location at every point. And I have read fairly often of expectations that some glaciers and areas are likely to experience increases in snow and ice for a while. There is, after all, what, some 7% more water vapor in the atmosphere. That's got to come down somewhere. And where it's cold enough, it will come down as snow.

Saying that this increase in this area is "completely contrary to past notions" is like saying that the increased snowfall in New England in the last couple years is somehow contrary to climate models.

It's not.

And again, no, increased snowfall in a couple of specific regions in no way shows that "...albedo feedbacks are even more crucial [than CO2 forcing]..."

Increased water vapor is an expected consequence of increased CO2 driven warming, and it has always been assumed that in certain locations that this will mean more snow fall.

You seem perfectly willing to pretty much completely ignore the many cogent points made counter to your main claim, so I will endeavor to (not) respond in kind going forward.

Best of luck in an uncertain world.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: oren on March 27, 2017, 12:16:57 AM
Well said wili.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: sidd on March 27, 2017, 07:52:44 AM
"my big question is what was the Arctic Ocean's state at the *start* of the last glacial maximum? This is a question I have not been able to answer and I suspect the answer is ice-free. "

Not likely.

https://ic.ucsc.edu/~acr/BeringResources/Articles%20of%20interest/Central%20Artic/Norgaard-Pedersen%20et%20al%202003.pdf

nice paper ruling out 1000m+ ice, which is interesting, since you need big ice for Lomonosov grounding as discussed in  another paper i posted elsewhere

doi:10.5194/tc-2017-37

sidd


Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Iceismylife on March 28, 2017, 06:28:37 PM
<snip>

If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

<Snip>
My gut feeling on this is that Albedo has been the climate change driver from 1700-ish on. GHGs are just now catching up in importance.

More show fall means more light reflected back to space and more IR radiated to space.  But there is a thread on albedo warming potential.  In that thread the comment was made that snow early has less effect than snow late does.  That is as it relates to Arctic sea ice loss.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on March 29, 2017, 12:32:27 AM
<snip>

If more of the Earth's surface is reflecting more sunlight back into space (and dissipating heat more readily at nighttime as well), I would think that actually has a *larger* impact than changes in GHGs, which alter the distribution of heat retained by the Earth, not the overall amount of heat it actually takes in. The only things that can alter the latter are A) changes in the sun's output or B) changes in the Earth's reflectance/albedo.

<Snip>
My gut feeling on this is that Albedo has been the climate change driver from 1700-ish on. GHGs are just now catching up in importance.

More show fall means more light reflected back to space and more IR radiated to space.  But there is a thread on albedo warming potential.  In that thread the comment was made that snow early has less effect than snow late does.  That is as it relates to Arctic sea ice loss.
I could see that being possible/likely.

But I would actually go back farther than 1700 in terms of GHGs/albedo impact. Not in weighing one more than the other, but in re-thinking our current knowledge of what caused the changes to the earth's climate.

I do not think it is coincidental that the Little Ice Age followed the largest period of human death in our species' history. This period followed three main events; the Mongol conquest and killing of much of Asia, the Black Death, and the discovery of the Americas with the consequent genocide of ~100 million people in that episode alone.

Combined, I think we can clearly see that depopulation was a major driver (or was likely a major driver) of the Little Ice Age. This was probably not just due to a reduction in GHG emissions; the changes to continental albedo must also have been fairly dramatic, and an ensuing uptick in forested areas (although relatively short term) would have also provided a massive carbon sink. Think of all the fields/etc that went fallow & sprouted trees after the people who had tended them for several centuries died of plague, Mongols, or smallpox. That is probably at least several percentage points of Earth's total land mass!

Traveling back further in time, the "Medieval Warm Period" followed the advances and innovations of both Rome and China, which also coincided with the population peak ~1250. And while we like to think of modern humans as some kind of exceptional race, we are anything but -- and this "exceptionalism" also applies to our preconceived notions re: GHGs and the Industrial Revolution (in that, 99.9999% of people believe that GHGs only became significant following the IR).

This is far from true. In fact, papers show that total atmospheric copper emissions from the Romans and Chinese were hugely impressive, and it would take until approximately 1850-1900 for modern emissions to equal that which was put out between 1,500-2,000 years ago! Techniques for industry were dirtier by orders of magnitude compared to today's processes, so even though they may have used less resources than we do today, their processes for extracting and refining were evidently adequate enough to rival the societies of ~1900 Europe in their total emissive capacities.

Going back even further, I suspect that while Milankovitch cycles may have been the primary climate driver pre-humans, early agriculture & late hunter-gatherer societies were equally transformative, and were the point at which humans overwhelmed the global system. The changes to planetary albedo began with the destruction of megafauna, and culminated with the advent of agriculture, both of which affected decent percentages of the planetary land surface despite very low human populations.

Somewhat of a digression, but I find the subject of pre-IR human-induced climate change extremely interesting, and when you consider the historical evidence/coincidences between the planet's climate and human society, it seems that the latter has led the former, and not vice versa.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: misfratz on March 30, 2017, 12:39:05 AM
I do not think it is coincidental that the Little Ice Age followed the largest period of human death in our species' history. This period followed three main events; the Mongol conquest and killing of much of Asia, the Black Death, and the discovery of the Americas with the consequent genocide of ~100 million people in that episode alone.

Combined, I think we can clearly see that depopulation was a major driver (or was likely a major driver) of the Little Ice Age. This was probably not just due to a reduction in GHG emissions; the changes to continental albedo must also have been fairly dramatic, and an ensuing uptick in forested areas (although relatively short term) would have also provided a massive carbon sink. Think of all the fields/etc that went fallow & sprouted trees after the people who had tended them for several centuries died of plague, Mongols, or smallpox. That is probably at least several percentage points of Earth's total land mass!
Look up the Ruddiman hypothesis. He argues that forest regrowth lead to a reduction in carbon dioxide concentrations and thus cooling.

My understanding is that, in albedo terms, forests are darker than farmland, and so would cause warming, rather than cooling, were it not for the carbon dioxide effect.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: misfratz on March 30, 2017, 12:40:37 AM
<Snip>My gut feeling on this is that Albedo has been the climate change driver from 1700-ish on. GHGs are just now catching up in importance.
I'm confused. Why not look up the numbers on albedo change as opposed to greenhouse gases rather than rely on your gut feeling?

Scientists have been looking at the relative drivers of climate change for some time, they may have some answers...
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: DrTskoul on March 30, 2017, 12:41:39 AM
I do not think it is coincidental that the Little Ice Age followed the largest period of human death in our species' history. This period followed three main events; the Mongol conquest and killing of much of Asia, the Black Death, and the discovery of the Americas with the consequent genocide of ~100 million people in that episode alone.

Combined, I think we can clearly see that depopulation was a major driver (or was likely a major driver) of the Little Ice Age. This was probably not just due to a reduction in GHG emissions; the changes to continental albedo must also have been fairly dramatic, and an ensuing uptick in forested areas (although relatively short term) would have also provided a massive carbon sink. Think of all the fields/etc that went fallow & sprouted trees after the people who had tended them for several centuries died of plague, Mongols, or smallpox. That is probably at least several percentage points of Earth's total land mass!
Look up the Ruddiman hypothesis. He argues that forest regrowth lead to a reduction in carbon dioxide concentrations and thus cooling.

My understanding is that, in albedo terms, forests are darker than farmland, and so would cause warming, rather than cooling, were it not for the carbon dioxide effect.

That sound about right. Also forests affect the local hydrological cy le and and cloud formation with an additional cooling effect.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: bbr2314 on June 09, 2017, 05:40:13 PM
More snow in late spring and summer would be a negative feedback due to albedo...

Warmer Arctic --> more evaporation --> more snow fall --> reflects SW radiation in the summer --> cooler Arctic.

But we don't see more snow surviving into summer, we see less and less snow cover in the summer - check the Rutgers data or the NOAA snow cover data. More extensive snow cover and thicker snow appears in the winter, when the sun is not shining... no albedo negative feedback.

Instead, we have a positive feedback...

Warmer Arctic with more open water --> more evaporation --> thicker snow on the ice  --> insulates the ice from bottom freeze --> thinner ice, melts sooner --> more open water in summer --> reduced albedo = warmer --> more evaporation... and more open water also makes more evaporation --> more snow.

Also, thicker snow on land insulates the permafrost, preventing it from radiating away the heat gained during melt season. The top surface of the snow is much colder, but the bottom is warmer, just like a blanket. When the snow melts in spring, the permafrost starts out warmer than usual.

...

Another effect of snow might be possible... consider this scenario, tell me if it makes sense:

Snow falling on open water makes slush, which soon solidifies into solid ice if it's cold enough. If the Arctic ocean surface is a little warmer, and if much heavier snow falls on the water forming a very thick slush layer, it might not be able to freeze solid.

Solid ice has a much higher thermal conductivity than water, so a thick slush layer would act as insulation on the bottom of the ice, trapping water in its voids, preventing heat from conducting upwards through the ice as quickly... in addition to the air/snow insulation effect on the top of the ice.

This would be consistent with the observations that Arctic ice seems "rotten" and weak. Maybe it has more slush within it than historically.

Plausible?

Wanted to bump this... as this seems to be the first year since the mid-80s with the exception of 95 or 96 that May has seen a glaringly positive snowfall anomaly.

http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=5 (http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=5)
 
The departure was larger in Eurasia than North America though both saw positive anomalies... I would chalk this up to the Himalayas having more area than the Rockies + the very staunch endurance of the Siberian pack.

But more importantly: does this confirm that even with all the heat energy we've accumulated, that we *could* indeed see a snowball effect given increasing open water near the North Pole, and corresponding moisture feedbacks? The rhetoric around opposition to my arguments for this potential focused on the recent lack of spring snowcover... which 2017 proved is *not* an absolute, even with temps at the warmest levels they have ever been (or very close).

Beyond the Rutgers graphs, snowcover anomalies continue to be impressive as we approach the solstice. Per the Canadian maps we are over +1SD in extent still, and per the Finnish volume graph, we are... well... above and beyond what any year has seen previously at this time.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fglobalcryospherewatch.org%2Fstate_of_cryo%2Fsnow%2Ffmi_swe_tracker.jpg&hash=7d01448218c9fe1555d12dad667406c0)

It is important to note that although the relative % of the NHEM that is snowcovered is still quite low, compared to normal it is, if the Finnish graph is to be believed, many many standard deviations removed from normal. I would argue that given June insolation's far greater values than January's, the impact of this residual/in some areas still-growing snowpack is greater now than at any point in the winter. The question is whether this will allow the Arctic to retain some integrity this year, and on that point, I think the answer is no, which begs the question of how low the volume goes this year (both for ice and snowcover), and subsequently, whether 2018 continues the rather extraordinary bucking of the decadel trends we have seen this year.

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/plot_anom_sdep.png)

I would posit that the enduring anomalies in the Himalayas will outlast Siberia and may even survive the summer, setting up explosive fall growth for the NHEM as we see 1) an extraordinary amount of mountaintop snowcover survive the NHEM summer, and 2) record low sea ice volume as we enter the fall months.

The Himalayan anomalies could also further the deterioration of the Arctic as we see the Siberian anomalies continue to erode (and unlike the Himalayas, parts of which continue to see massive snowfalls, snow is mostly finished/only falling in relatively token amounts along the Siberian coast). As Siberia loses its snowpack, I suspect that the jet stream will be able to waft enormous amounts of heat up and over the Himalayas (with the snowpack there encouraging +500MB height anomalies to the north), and that air is going to head directly into the heart of the Arctic.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: wehappyfew on June 09, 2017, 08:49:25 PM
bbr,

Time to re-examine your priors. You seem to be stuck in a loop of self-delusion. Very little of your last post makes any sense, very little is factually correct, and the conclusions you have drawn are unsurprisingly detached from current reality as the rest of us experience it.

Sorry to be so harsh, but you must work much harder to incorporate Feynman's maxim for doing good science...

"The first principle is that you must not fool yourself—and you are the easiest person to fool."

You have fooled yourself. That is plain to see. Until you see it yourself, there is no hope.

Example 1st:

Quote
...recent lack of spring snowcover... which 2017 proved is *not* an absolute, even with temps at the warmest levels they have ever been (or very close).

May snow cover was indeed anomalously high compared to recent years, but temperatures were NOT at the "warmest levels" ever. Not even close. May 2017 was the 2nd COLDEST in the last 15 years north of 60degN.

See:

https://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=60&lat2=90&lon1=0&lon2=360&iseas=0&mon1=0&mon2=0&iarea=1&typeout=1&Submit=Create+Timeseries (https://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=60&lat2=90&lon1=0&lon2=360&iseas=0&mon1=0&mon2=0&iarea=1&typeout=1&Submit=Create+Timeseries)

Example B:

Quote
The Himalayan anomalies could also further the deterioration of the Arctic as we see the Siberian anomalies continue to erode (and unlike the Himalayas, parts of which continue to see massive snowfalls, snow is mostly finished/only falling in relatively token amounts along the Siberian coast). As Siberia loses its snowpack, I suspect that the jet stream will be able to waft enormous amounts of heat up and over the Himalayas (with the snowpack there encouraging +500MB height anomalies to the north), and that air is going to head directly into the heart of the Arctic.

The jetstream flowing away from the Himalayas heads towards Japan and the Pacific Ocean, almost never towards the Arctic.

...

The negative feedback due to above average snow cover in May is rapidly dissipating. The first week of June saw a huge shift in the Rutgers maps:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fclimate.rutgers.edu%2Fsnowcover%2Fpng%2Fdaily_dn%2F2017152.png&hash=137475a7005499eab20941c970af630b)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fclimate.rutgers.edu%2Fsnowcover%2Fpng%2Fdaily_dn%2F2017159.png&hash=00281e457c5d6423b26cbb89bca2e1d7)

Now the positive feedbacks will kick in. Will the Siberian and Canadian tundra warm faster due to the extra insulation of thicker winter snow cover?





Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: FishOutofWater on June 16, 2017, 10:50:13 PM
I regret to inform you all but the intensification of the NH jet stream associated with the heavy snow pack over N Eurasia was associated with decreased trade winds over the eastern tropical and subtropical north Atlantic. Atlantic water temperatures have surged above normal from the coast of western to the coasts of Spain and Norway. The warming off of N Europe is associated with the strong jet stream troughing southeast of Greenland associated with the strong westerlies and strong temperature gradient southeast of Greenland. We are going to soon see a positive feedback from positive water vapor anomalies.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: VeliAlbertKallio on July 07, 2017, 12:59:37 PM
My added reference to the Ewing-Donn Lake-Snow Effect of the Arctic Ocean may justify posting this note on three main effects of the Blue Ocean Event once it materializes:

Following Neven's suggestion* (copied below) I re-enclose here the two links that I originally posted on 27th June to "The 2017 Melt Season" thread. Which better fits this thread:

Once the Blue Ocean event materializes on the North Pole and the Arctic Ocean becomes ice-free in the summertime, this leads almost immediately to:

1) rapid acceleration of land-based snow and ice melting that begin to mop up the heat sea ice no longer takes for its melting. These will lead to the risk of very rapid sea level jump and other effects as per the evidence I gave at the UK Houses of Parliament in April: https://www.academia.edu/33000316/MPs_to_review_UKs_role_in_Arctic_sustainability_-_24th_April_2017.docx (https://www.academia.edu/33000316/MPs_to_review_UKs_role_in_Arctic_sustainability_-_24th_April_2017.docx)

2) massive acceleration of seabed based methane release risk like reported in this recent article which was since then re-posted here by others. This link: http://envisionation.co.uk/index.php/nick-breeze/203-subsea-permafrost-on-east-siberian-arctic-shelf-now-in-accelerated-decline (http://envisionation.co.uk/index.php/nick-breeze/203-subsea-permafrost-on-east-siberian-arctic-shelf-now-in-accelerated-decline)

3) I add a third effect to sea level and other land-based effects to these effects. Once there are no sea ice floes left at the Central Arctic Basin, the sea ice growth no longer advances from the North Pole to the South (towards the ocean's perimeter). Now the re-freeze must progress inversely from the perimeter in the south towards the North Pole at the centre of the ocean. This inversion of the direction in spreading of the sea ice's margin growth leads to 4-8 weeks' delay.
Since sea ice has a tendency to be packed against coastal barriers, it will be two delays:

(A) re-freezing must wait until the coastal margin reaches the freezing point (sea ice leads currently begin to cool down from 25th July onwards at CAB and are the first area to freeze)  - for the coastal margins to reach the point, a delay is up to two months (positive methane feedback).

(B) the churning of the ocean keeps waters in the Central Arctic and the North Pole increasingly open even in midwinter due to the open waters there mixing vertically. In addition, the growing temperature gradients between a stubbornly-warm ocean center in winter and the rapidly cooling continental landmasses in wintertime (around its perimeter) cause wind and wave actions. The waves break the ice and the winds then will push broken ice towards the Atlantic Ocean and the shorelines where newly formed ice accumulates along seasides. The center remains open and releases heat and snow storms: the Ewing-Dunne 'Lake Snow Effect' of the Arctic Ocean. (The 1950's idea of Maurice Ewing and William Donn that the Ice Ages were caused by the ice-free Arctic Ocean acts like snow cannon to accumulate so much precipitation that it could not possibly melt away during the subsequent short summers of high latitudes.) Even temporary ice shelves may be produced along the shorelines by intense storms piling up sea ice i.e. along the Ellesmere Island and the Queen Elizabeth Islands, topped up with massive snowfalls.

In other words (B) the Central Arctic winter hole will form that delay the onset of sea ice formation and makes it much thinner and volatile for breaking - hence further lowering of the spatial viscosity of the Arctic Sea ice. The warmer and wetter winters bode badly for methane clathrates and methane which can escape from the ocean unhindered by sea ice layer.

- - - - -
*Hi Albert, There are various threads to talk about consequences (check the Permafrost category, for instance, there are several threads on methane) or politics. I want to keep the melting season thread as uncluttered as possible, because that's the best-read thread at the moment, and long, off-topic comments are highly off-putting. So, either stay on-topic or keep it short. And if people reply to something off-topic, please invite them to a more appropriate thread and continue the conversation there. It will also make it easier to find at a later time. Thanks, Neven
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Shared Humanity on July 07, 2017, 04:05:11 PM
The air in the Arctic was dry in the past, but not anymore. There seems to be so much moisture now that it cannot be contained. I am no expert on that subject, and am sure there are others that can clarify.
Correct! But I am not talking about the Arctic re: decreasing/stable moisture, as it is definitely warming & moistening (also due to the loss of albedo); I am referencing land areas that are newly-covered by snow when they usually aren't.

The simple fact is that a warmer world results in an increased moisture load across the planet. Yes, this is contributing to a trend of increased snowfall in the northern hemisphere, something I would expect to continue.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Shared Humanity on July 07, 2017, 04:27:26 PM
For those of you who haven't heard about it, you may be interested in reading about the Ewing-Donn theory (Wikipedia (https://en.wikipedia.org/wiki/Ice_age#Positive_feedback_processes)) from the 1950's,  which posited that ice ages were caused by this negative feedback of snowfall anomalies. Also read this excellent summary (http://history.aip.org/climate/simple.htm#S2ED) on Spencer Weart's Discovery of Global Warming website that places the theory in historical context.

Thank you for this link to the "Discovery of Global Warming" website. A very good read.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Shared Humanity on July 07, 2017, 04:39:12 PM
But that's where the problem is, right? The temperatures will not lower in the foreseeable future.

Quote
My point is not that this is not happening today -- it is that the mechanism resulting in increasing fall/wintertime snowcover will soon overwhelm spring/summer snowcover as well, even if it may take another 5-10 years to kick into gear.

The mechanism, ie global warming via CO2 forcing, is going to continue to increase as well and overwhelm fall/wintertime snowcover. At some point snow will turn into rain.

A decades long trend in Chicago as more and more precipitation is rain and the snow that does fall melts out in a matter of days.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Neven on July 07, 2017, 09:47:40 PM
Thank you for this link to the "Discovery of Global Warming" website. A very good read.

If you like the website, you should consider buying and reading Weart's book. That's what truly convinced me that AGW isn't a hoax.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: oren on July 08, 2017, 12:24:26 PM
VAK, one thing is bothering me with what you wrote.
Quote
Once there are no sea ice floes left at the Central Arctic Basin, the sea ice growth no longer advances from the North Pole to the South (towards the ocean's perimeter). Now the re-freeze must progress inversely from the perimeter in the south towards the North Pole at the centre of the ocean.
Do we know this for sure? Surely at a low enough temps the sea surface will freeze. Admittedly open water impede the drop in temps, but still what you wrote seems more like an assumption rather than a substantiated claim.
The fact that sea ice typically grows from other sea ice doesn't mean it can't do that spontaneously as well.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Rob Dekker on August 14, 2017, 07:24:49 AM
VAK, one thing is bothering me with what you wrote.
Quote
Once there are no sea ice floes left at the Central Arctic Basin, the sea ice growth no longer advances from the North Pole to the South (towards the ocean's perimeter). Now the re-freeze must progress inversely from the perimeter in the south towards the North Pole at the centre of the ocean.
Do we know this for sure? Surely at a low enough temps the sea surface will freeze. Admittedly open water impede the drop in temps, but still what you wrote seems more like an assumption rather than a substantiated claim.
The fact that sea ice typically grows from other sea ice doesn't mean it can't do that spontaneously as well.

I agree, oren. I find it doubtful that after a Blue Ocean Event that ice would need to grow from the perimeter. The insolation difference between 90 deg North and perimeter at 60 North in September is a whopping 200 W/m^2 :

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.physicalgeography.net%2Ffundamentals%2Fimages%2Finsolation_latitude.gif&hash=a8e1cc23311451c7f6209a2b0451db8a)

That kind of difference in insolation makes it very likely that ice (post September) will simply start from the highest latitude and grow towards lower latitude.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Rob Dekker on August 14, 2017, 07:36:59 AM
Regarding land snow cover, and its potential as a 'negative' feedback, let us get the facts strait :
For starters, I encourage everyone to read this article by tamino :

https://tamino.wordpress.com/2012/10/05/snow-2/

It investigates the effect of snow cover over the past 3 decades, and it concludes that it is definitively a 'positive' feedback. Just look at the snow cover loss over the months :
(https://tamino.files.wordpress.com/2012/10/snowchangebar.jpg)

which suggests that land snow cover is lost in summer much more than it is gained in winter.

Or read this follow-up article :
https://tamino.wordpress.com/2012/10/08/snowice-by-request/

which asserts :

Quote
The net change estimated as the difference of the beginning and ending values of the trend line is about 880 TW. If spread over the entire surface of the earth, and if the difference in TOA albedo between snow/ice-covered and uncovered regions is 0.2, this accounts for a total climate forcing of about 0.34 W/m^2.

There you have it. Ice and snow loss imposes a 'positive' feedback on the planet's temperature, to the amount of some 0.34 W/m^2.

Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Archimid on August 14, 2017, 01:55:28 PM
I have yet to see an example of sea ice growing out of nothing in the middle of the ocean. What I have observed in the many graphs shared here is that ice grows from ice. I have never seen an example of ice growing out of nothing in the open oceans in those graphs.  I understand that would be a very difficult observation to make because for most of the record N80 was mostly ice.

Maybe someone has data on that?

I'm not saying ice can not grow out of nothing out in the ocean, but temperature, salinity and wave action must reach some sort of equilibrium for it to happen. Based on these assumptions I find it unreasonable to think equilibrium will be reached in September. I wouldn't be surprised it took weeks or months before it can get cold enough to form  "first ice". After that, I imagine it will grow faster than ever, but too late to even close the Bering. Then next melt season comes around and it is is all thin, salty, first year ice. The Arctic has a BOE even earlier than before, accumulating more sunlight for longer, further delaying the formation of first ice.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Shared Humanity on August 14, 2017, 01:55:59 PM
I have no doubt Tamino is correct. Those of us who have lived their entire lives in Chicago and old enough to remember will recall the brutally cold winters of the 60's, 70's and 80's. We would often get massive, late fall and/or early winter snowfalls, followed by long periods of brutally cold weather with night time temps plunging to as low as -20F. Snow would often remain on the ground for 3 straight months. This has not happened for decades and we have actually gone winters with the temps never falling below 0F. The snow is required for the cold temps to persist as they reinforce each other. Now, when we receive a heavy snowfall and we have a couple of times in the past 6 years (15 inches or more), it melts in a matter of days.

When I think about this, I begin to appreciate the frightening tipping point we have reached. An ice free Arctic, even seasonally, will forever alter NH climate and there is no way to go back.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: TerryM on August 14, 2017, 03:22:24 PM
I have no doubt Tamino is correct. Those of us who have lived their entire lives in Chicago and old enough to remember will recall the brutally cold winters of the 60's, 70's and 80's. We would often get massive, late fall and/or early winter snowfalls, followed by long periods of brutally cold weather with night time temps plunging to as low as -20F. Snow would often remain on the ground for 3 straight months. This has not happened for decades and we have actually gone winters with the temps never falling below 0F. The snow is required for the cold temps to persist as they reinforce each other. Now, when we receive a heavy snowfall and we have a couple of times in the past 6 years (15 inches or more), it melts in a matter of days.

When I think about this, I begin to appreciate the frightening tipping point we have reached. An ice free Arctic, even seasonally, will forever alter NH climate and there is no way to go back.


I'm East, and a little North of the Windy City near Toronto Canada, and the observable change here is that our local river very seldom freezes now, where in the past the spring breakup was celebrated as a major annual celebration.


Initially I had worried that Canada would suffer from a lack of fresh water as snow packs shrank. I hadn't taken increasing precipitation due to increasing evaporation from increasingly warm open water into account. I now feel that floods will do more damage than drought as warmer SSTs feed warmer air that advects south through the damaged polar vortex.


A near BOE will cause huge increases in  snowfall on nearby land. While the snow will melt away much earlier than in the past, the additional volume will more than compensate for the early melt.
Terry
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tor Bejnar on August 14, 2017, 04:31:54 PM
I have yet to see an example of sea ice growing out of nothing in the middle of the ocean. ...
From this 2009 article (http://www.nature.com/news/2009/090323/full/news.2009.183.html)
Quote
...
New ice can form in several different ways. When water is surrounded by ice packs, as has been common in the Arctic, areas of open water are small and there is little chance for wind to work up vigorous waves. In such calm conditions, ice forms in unbroken sheets called 'nilas'.

But now the Arctic has larger areas of open water, and more waves. "As soon as you introduce swell, you get an entirely different form of ice," says Jeremy Wilkinson of the Scottish Association for Marine Science in Oban, UK. Under these conditions, globs of ice crystals tossed about in the water combine to form first a soupy mixture called 'grease ice', and then 'pancakes' of thin ice a metre or two in diameter.
...
Picture credit:  More pancake ice is being spotted in the Arctic.   Glenn Grant/National Science Foundation
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Archimid on August 14, 2017, 05:11:21 PM
Thanks for the link TB.

To be me more specific, my concern is that without ice nearby, both the formation of frazil ice and its growth and evolution to more advanced stages will be significantly delayed.

 The articles that you point out describe ice creation as it has been observed in the past under relatively calmed conditions.  Please read the caveat of the experiment:

Quote
The team used a wave tank 30 metres long and 1.5 metres deep at the Arctic Environmental Test Basin in Hamburg, Germany, to test ice formation in calm conditions compared with choppy water and storms1. The team could not replicate the metre-high waves that might be seen in the ocean, so to mimic stormy conditions they increased the frequency of waves tens of centimetres high.

Although I admire their effort and creativity, one hundred 1 centimeter high waves are not the same thing as one 1 meter wave.

I think ice formation in September in the middle of a BOE is unlikely. Maybe when the sun is gone for long enough, snow might lower salinity and stop the momentum of the waves for long enough for significant ice to accumulate in the center. But it will be significantly delayed and starting from 0, not from 4 million.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tor Bejnar on August 14, 2017, 07:34:39 PM
a ten minute YouTube showing dense (most of the footage) to sparse (around minute 3-4) pancakes and ice-free ( briefly, around 4:20) with some white caps.
Waves Propagating through Pancake Ice in the Arctic Ocean  (https://www.youtube.com/watch?v=EyM06_ZvGbo)

Quote
Published on Nov 14, 2016
This footage was obtained in the Arctic Ocean (75 deg N, 150 deg W) on October 29, 2016. Only the long wavelengths are able to propagate through pancake ice.
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Tor Bejnar on August 14, 2017, 07:43:55 PM
The Balance of Ice, Waves, and Winds in the Arctic Autumn (https://eos.org/project-updates/the-balance-of-ice-waves-and-winds-in-the-arctic-autumn)

Quote
...
The collisions make floes round, such that they resemble pancakes. Because the pancakes are typically 1 meter or less in diameter, they are below the resolution of most satellite imagery. This means that they are observed only from nearby, from ships or airplanes, or by autonomous platforms with cameras.

Pancake ice is relatively ubiquitous in the Antarctic sea marginal ice zone, but it has rarely been observed in the Beaufort and Chukchi seas. However, it was the dominant newly formed ice type that we encountered during this field campaign. We observed pancake ice with far greater regularity during this field campaign than in recent early autumn cruises in the eastern Beaufort conducted through the Joint Ocean Ice Study/Beaufort Gyre Exploration Project.

Clearly, the presence of pancake ice shows that wind events and the surface waves that come with them are important to the autumn ice recovery in the western Arctic Ocean. Wind and wave actions are perhaps also linked to the known trend of younger, thinner ice throughout the seasonal cycle [e.g., Maslanik et al., 2011].

The prevalence of pancake ice has a large-scale effect on the autumn recovery of sea ice in the Beaufort and Chukchi seas. Figure 3 shows three maps of sea ice over 1 month; the daily progression is even more complex. As the wave motion declined (either in time or space), the pancakes often rafted together and thereby formed larger, thicker sea ice floes. The pancakes then consolidated (or “cemented”) into surface sheets that were rougher than nilas sheets; these sheets of pancake ice aggregates presumably survived and became the winter ice pack.

Sometimes, the pancakes’ dampening of the wave energy appeared to accelerate this cementing process, which eventually protected the interior pancakes from wave motions and allowed the larger floes to form. In some other events, however, strong wind- and wave-driven mixing of ocean heat prevented the ice edge from advancing, and the pancakes melted in place. Thus, the ice edge advanced one week, retreated the next, and eventually advanced again in an irregular pattern driven by the regional storm cycles.
...
Title: Re: Negative Feedback of Positive Snowfall Anomalies
Post by: Archimid on August 14, 2017, 11:26:13 PM
This is already off topic, but the nice links Tor posted deserve a response.

First the video. Freaking awesome. Thanks, I was mesmerized by it. But the location is right by the ice edge as can be seen in nullschool.

https://earth.nullschool.net/#2016/10/29/1800Z/ocean/primary/waves/overlay=sea_surface_temp/orthographic=-146.84,73.79,1500/loc=-150.007,75.352

The proximity to the ice edge gives this area some distinct advantages over open ocean areas. First, the air is flowing close to ice that means dryer and colder air is close by. Second having the ice pack so near help dampen the waves, allowing bigger chunks to accumulate.

This second link is even better because it had great information and it was very well written. But it suffers from the same problem as the video. Their whole study was near the ice edge. They were studying how ice grows when there is an ice sheet a few miles away. That is necessary research and I'm glad we got people on it but it does not apply to a BOE. Maybe as these people finish crunching the numbers they find the answer I'm looking for.


Thanks for your efforts Tor, but to me it remains an assumption that ice will grow in September the year of the first BOE. I believe that if it grows at all from the ocean it will start growing very late, and instead of starting from  4 million km2 it will start from 0.