Please support this Forum and Neven's Blog

Author Topic: Negative Feedback of Positive Snowfall Anomalies  (Read 2583 times)

S.Pansa

  • ASIF Citizen
  • Posts: 108
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #50 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) and how the transition to our current interglacial worked. Skeptical Science has a nice write up 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)

From the abstract:
... 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.

« Last Edit: March 26, 2017, 10:26:49 AM by S.Pansa »

misfratz

  • ASIF Lurker
  • Posts: 28
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #51 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.

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.

bbr2314

  • ASIF Citizen
  • Posts: 388
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #52 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) and how the transition to our current interglacial worked. Skeptical Science has a nice write up 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)

From the abstract:
... 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).

bbr2314

  • ASIF Citizen
  • Posts: 388
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #53 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.

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.

bbr2314

  • ASIF Citizen
  • Posts: 388
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #54 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

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
« Last Edit: March 26, 2017, 09:15:52 PM by bbr2314 »

wili

  • ASIF Upper Class
  • Posts: 1828
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #55 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.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

oren

  • ASIF Upper Class
  • Posts: 1057
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #56 on: March 27, 2017, 12:16:57 AM »
Well said wili.

sidd

  • ASIF Upper Class
  • Posts: 1096
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #57 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


« Last Edit: March 27, 2017, 08:39:55 AM by sidd »

Iceismylife

  • ASIF Citizen
  • Posts: 177
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #58 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.

bbr2314

  • ASIF Citizen
  • Posts: 388
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #59 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.

misfratz

  • ASIF Lurker
  • Posts: 28
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #60 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.

misfratz

  • ASIF Lurker
  • Posts: 28
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #61 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...
« Last Edit: March 31, 2017, 05:08:12 PM by misfratz »

DrTskoul

  • ASIF Middle Class
  • Posts: 731
    • View Profile
Re: Negative Feedback of Positive Snowfall Anomalies
« Reply #62 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.
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
― Richard P. Feynman