Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: Cid_Yama on March 28, 2018, 05:03:07 PM

Title: Abrupt sea ice loss
Post by: Cid_Yama on March 28, 2018, 05:03:07 PM
Quote
when analyzing seasonal differences of sea ice retreat, Eisenman et al. (2011, p. 5332) found that “some GCMs become seasonally ice free during the 1900–2100 simulation period. This leads to winter ice cover retreating faster than summer ice cover after the latter reaches zero.” Moreover, abrupt Arctic winter sea ice loss was recently detected in model simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) (Drijfhout et al. 2015). CMIP5 provides results from current comprehensive climate models and allows us to compare their response to anthropogenic forcing (Taylor et al. 2012).

The most striking winter sea ice decline occurs in the Earth system model of the Max Planck Institute for Meteorology, MPI-ESM (Giorgetta et al. 2013; Notz et al. 2013), where an ice area of several million square kilometers disappears within only a few years (Fig. 1). Winton (2006, 2008) showed that in the version of MPI-ESM that he analyzed, this transition is accompanied by an increased ice–albedo feedback, concluding that this feedback is responsible for the high rate of winter sea ice loss. The ice–albedo feedback plays a role for winter sea ice because the seasonal cycle of sea ice area lags the insolation cycle by approximately three months. Thus, ice volume and area are near their annual maximum when the sun rises in March. Li et al. (2013) further speculated that a convective cloud feedback proposed by Abbot and Tziperman (2008) could also play a role for the winter sea ice loss in MPI-ESM: In an Arctic Ocean without winter sea ice, the warmer and wetter conditions could trigger the formation of convective clouds, resulting in enhanced downwelling longwave radiation at the surface and reduced cooling to space. This warming due to the cloud radiative effect would then help to keep the Arctic ice-free.

In this study we propose a different explanation for the abrupt sea ice loss in MPI-ESM that also explains the sensitive Arctic winter sea ice area in the other models: the freezing temperature imposes a threshold for the formation of winter ice. Where the ocean no longer cools to the freezing temperature in winter, sea ice can essentially disappear from one winter to the next. If the basinwide conditions are spatially homogeneous enough, this mechanism can result in a rapid sea ice loss in a large area.

In the following, we first show that Arctic winter sea ice area is more sensitive to warming than summer sea ice area in CMIP5 models. We then outline the essence of our explanation using an idealized ice-thickness distribution (ITD) model that resolves many thickness classes in contrast to the slab model by Eisenman and Wettlaufer (2009). To show that the mechanism is indeed active in comprehensive climate models, we show consistent sea ice area and thickness changes in these models. Thereafter, we present additional simulations with MPI-ESM, showing that neither surface albedo nor radiative cloud feedbacks can explain the abrupt sea ice loss in this model. Furthermore, we demonstrate with a simple box model, capturing the essence of the ice-area parameterization in MPI-ESM, that our thermodynamic argument is sufficient to explain the abrupt ice loss. We finally argue why other feedbacks are unlikely to play a dominant role also in other complex climate models and discuss important differences between the Arctic and the Southern Hemisphere.
https://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0466.1
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on March 28, 2018, 05:16:22 PM
While I'm a bit skeptical of the models (until I see reasonable stats on skill), I have long held that when the Arctic decides to melt-out it won't matter what time of year it is.

Comes down to Ocean Heat and the fact that H2O is the primary greenhouse gas -- I guess that means it all comes down to water.  CO2 is the trigger, not the bullet.
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on March 28, 2018, 05:26:39 PM
Quote
While Screen et al. 2011 focused on the number of cyclones as a possible factor to explain the September variability, this study looks to see individual cyclone’s effects on abrupt sea ice loss as a possible factor of the September variability. For example, Simmonds et al. 2012 noted that a single cyclone was associated with a large reduction in SIE during the summer of 2012. This cyclone, now known as the “Great Arctic Cyclone,” likely contributed to the 2012 all-time minimum in Arctic SIE. Furthermore, Ogi et al. 2009 noted that wind forcing on sea ice accounted for a 50% variance of September year-to-year SIE, while Rigor et al. 2002 showed that the thin sea ice during the summer over the Arctic is particularly vulnerable to atmospheric winds. Motivated by the observations that a cyclone can have an impact on SIE, this study aims to determine whether individual synoptic events are generally a significant contributor to abrupt sea ice loss.
link (https://www.caps.ou.edu/reu/reu16/finalpapers/Gutierrez-Paper.pdf)
Title: Re: Abrupt sea ice loss
Post by: Ken Feldman on March 28, 2018, 06:33:58 PM
It's important to read how they run the simulations in the models.  Here's what they did in the paper above:

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The loss of Arctic sea ice during the whole year that we examine here only occurs under the large radiative forcing of the RCP8.5 simulations. In these simulations, the CO2 concentration is prescribed and shows an accelerating increase until the year 2100 (implying a radiative forcing from well-mixed greenhouse gases of 8.5 W m−2), followed by a stabilization period with a decelerating increase (Meinshausen et al. 2011). In the year 2250, the CO2 concentration reaches its final level of almost 2000 ppm.

If we continue on a high emissions path as described by the paragraph above, loss of the winter Arctic sea ice will be the least of our worries.  Note that the current goals of international agreements are to stabilize concentrations at 450 ppm and that some organizations are work toward an eventual reduction to 350 ppm by studying ways to take CO2 out of the atmosphere and sequester it.
Title: Re: Abrupt sea ice loss
Post by: Tor Bejnar on March 28, 2018, 07:02:40 PM
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CO2 is the trigger, not the bullet.
Nice slogan, and functionally true!

CO2 is causing the problems of Global Wierding (https://en.wiktionary.org/wiki/global_weirding).  What'll kill us is floods, heatwaves, fires, starvation (due to loss of food production caused by unseasonable/excessive rain/hail/freeze/thaw/drought) and poison ivy (it particularly likes increased CO2 - or at least make walking in my woods unpleasant).  Farmers have always had to contend with weather; now they have to attempt to contend with weather-gone-amok!
Title: Re: Abrupt sea ice loss
Post by: Neven on March 28, 2018, 09:02:32 PM
Cid_Yama, I've merged the two threads you opened and given them a more generic name.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on March 28, 2018, 11:14:24 PM
Quote
CO2 is the trigger, not the bullet.
Nice slogan, and functionally true!

CO2 is causing the problems of Global Wierding (https://en.wiktionary.org/wiki/global_weirding).  What'll kill us is floods, heatwaves, fires, starvation (due to loss of food production caused by unseasonable/excessive rain/hail/freeze/thaw/drought) and poison ivy (it particularly likes increased CO2 - or at least make walking in my woods unpleasant).  Farmers have always had to contend with weather; now they have to attempt to contend with weather-gone-amok!

I'll punt on the poison ivy, I don't react to it all that much.


I suspect that more people will suffer from global warming than will benefit, but I will note that the rise of the Kahns was probably due to a number of years of unusual rainfall in the Stepps allowing their horses to flourish.

Title: Re: Abrupt sea ice loss
Post by: Daniel B. on March 29, 2018, 12:12:05 AM
Quote
CO2 is the trigger, not the bullet.
Nice slogan, and functionally true!

CO2 is causing the problems of Global Wierding (https://en.wiktionary.org/wiki/global_weirding).  What'll kill us is floods, heatwaves, fires, starvation (due to loss of food production caused by unseasonable/excessive rain/hail/freeze/thaw/drought) and poison ivy (it particularly likes increased CO2 - or at least make walking in my woods unpleasant).  Farmers have always had to contend with weather; now they have to attempt to contend with weather-gone-amok!

I will take the wait and see attitude regarding the farmers.  To date, there has been a net benefit, due to increased rainfall and longer growing seasons.  If the rainfall increases dramatically, then that might lead to decreased output, but that might take a long time to reach.
Title: Re: Abrupt sea ice loss
Post by: Archimid on March 29, 2018, 02:20:41 AM
I will take the wait and see attitude regarding the farmers.  To date, there has been a net benefit, due to increased rainfall and longer growing seasons.  If the rainfall increases dramatically, then that might lead to decreased output, but that might take a long time to reach.

Daniel B. While yields for many grains and important crops are up you can't say climate change has been a net benefit. Most likely the gains are technological improvements surpassing climate related losses. It is likely that without climate change the gains would have been much greater.
Title: Re: Abrupt sea ice loss
Post by: wili on March 29, 2018, 05:37:14 AM
ummmm...this all seems pretty far off topic to the thread's title...but since it has gone this direction already, may I add:

https://www.politico.com/agenda/story/2017/09/13/food-nutrients-carbon-dioxide-000511

The great nutrient collapse

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The atmosphere is literally changing the food we eat, for the worse. And almost nobody is paying attention.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on March 29, 2018, 01:54:40 PM
ummmm...this all seems pretty far off topic to the thread's title...but since it has gone this direction already, may I add:

https://www.politico.com/agenda/story/2017/09/13/food-nutrients-carbon-dioxide-000511

The great nutrient collapse

Quote
The atmosphere is literally changing the food we eat, for the worse. And almost nobody is paying attention.

Maybe one last OT, then I will cease.  That is all rather straight-forward, and not surprising.  Plant growth is determined by its limiting factor.  Increase that factor, and growth increases.  If that factor is water, sunlight, CO2, etc., then that will lead to increased carbohydrate production in the leaves and subsequently, fruit.  Unless nutrients are added to the soil, the uptake of these minerals will remain roughly the same (unless increased photosynthesis helps the plant pull in more), but be distributed over greater plant volume.  The caloric value of the food will increase as photosynthesis increases, but the mineral fraction will decrease.  A single plant will produce food with the overall same mineral content, but be distributed over more or larger fruits.  Not exactly junk food as the author contends.
Title: Re: Abrupt sea ice loss
Post by: Tor Bejnar on March 29, 2018, 04:33:18 PM
Quote
Severe drought conditions extend well into Kansas and Colorado. Close to half of the winter wheat in Kansas—the nation’s largest producer of the crop—was ranked in poor or very poor condition by the U.S. Department of Agriculture as of Sunday. “The wheat hasn’t gone downhill, it’s never been uphill,” farmer Jay Warner told the McPherson Sentinel.
yesterday's Weather Underground "Category 6" article (https://www.wunderground.com/cat6/flood-threat-back-texas-ohio-valley)

Of course, droughts have happened before, but with the abrupt sea ice loss we have experienced these past few decades [I was trained to think geologically], they're more common now (and strike more quickly).

I blame these OT comments to the change in thread title.  (But I might just be rationalizing.)
Title: Re: Abrupt sea ice loss
Post by: Neven on March 30, 2018, 09:44:12 AM
Maybe one last OT, then I will cease.  That is all rather straight-forward, and not surprising.  Plant growth is determined by its limiting factor.  Increase that factor, and growth increases.  If that factor is water, sunlight, CO2, etc., then that will lead to increased carbohydrate production in the leaves and subsequently, fruit.  Unless nutrients are added to the soil, the uptake of these minerals will remain roughly the same (unless increased photosynthesis helps the plant pull in more), but be distributed over greater plant volume.  The caloric value of the food will increase as photosynthesis increases, but the mineral fraction will decrease.  A single plant will produce food with the overall same mineral content, but be distributed over more or larger fruits.  Not exactly junk food as the author contends.

I guess you didn't read all the way to:

Quote
These experiments and others like them have shown scientists that plants change in important ways when they’re grown at elevated CO2 levels. Within the category of plants known as “C3”―which includes approximately 95 percent of plant species on earth, including ones we eat like wheat, rice, barley and potatoes―elevated CO2 has been shown to drive down important minerals like calcium, potassium, zinc and iron. The data we have, which look at how plants would respond to the kind of CO2 concentrations we may see in our lifetimes, show these important minerals drop by 8 percent, on average. The same conditions have been shown to drive down the protein content of C3 crops, in some cases significantly, with wheat and rice dropping 6 percent and 8 percent, respectively.

CO2 is plant food, like steroids are muscle food. Looks great, but is it healthy?

And while food production is up (by squeezing everything we can out of dead soil with the help of fossil fuels), food quality continues its steady decline. And we wonder why people are getting sicker and dumber.

Thanks, wili, that was the best OT I've read in a while.  ;)
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on March 31, 2018, 09:20:32 PM
Maybe one last OT, then I will cease.  That is all rather straight-forward, and not surprising.  Plant growth is determined by its limiting factor.  Increase that factor, and growth increases.  If that factor is water, sunlight, CO2, etc., then that will lead to increased carbohydrate production in the leaves and subsequently, fruit.  Unless nutrients are added to the soil, the uptake of these minerals will remain roughly the same (unless increased photosynthesis helps the plant pull in more), but be distributed over greater plant volume.  The caloric value of the food will increase as photosynthesis increases, but the mineral fraction will decrease.  A single plant will produce food with the overall same mineral content, but be distributed over more or larger fruits.  Not exactly junk food as the author contends.

I guess you didn't read all the way to:

Quote
These experiments and others like them have shown scientists that plants change in important ways when they’re grown at elevated CO2 levels. Within the category of plants known as “C3”―which includes approximately 95 percent of plant species on earth, including ones we eat like wheat, rice, barley and potatoes―elevated CO2 has been shown to drive down important minerals like calcium, potassium, zinc and iron. The data we have, which look at how plants would respond to the kind of CO2 concentrations we may see in our lifetimes, show these important minerals drop by 8 percent, on average. The same conditions have been shown to drive down the protein content of C3 crops, in some cases significantly, with wheat and rice dropping 6 percent and 8 percent, respectively.

CO2 is plant food, like steroids are muscle food. Looks great, but is it healthy?

And while food production is up (by squeezing everything we can out of dead soil with the help of fossil fuels), food quality continues its steady decline. And we wonder why people are getting sicker and dumber.

Thanks, wili, that was the best OT I've read in a while.  ;)

Actually I did read the entire thing.  Hence my comment about increased caloric content, but decreased mineral content.  Simple mathematics; if you increase the total volume, but keep a particular element constant, its percentage must decrease.  The added volume is still nutritious foodstuffs, which is the primary concern in undernourished countries.
Title: Re: Abrupt sea ice loss
Post by: wili on March 31, 2018, 09:40:41 PM
(Is it time to split these increasingly absurd and off topic postings into another thread? Or should we all just drop it?)

The extra carbon adds starches and sugars and probably some fiber, not 'nutritious stuff.' I most of the world now, including most of the world's poor areas, obesity...getting to much of sugars and starches and often not enough of real nutrients...is as major an issue as is the malnutrition that comes from not getting enough calories.

Quote
Once considered a problem only of high-income countries, obesity rates are rising worldwide and affecting both the developed and developing world. These increases have been felt most dramatically in urban settings...

https://en.wikipedia.org/wiki/Obesity

Title: Re: Abrupt sea ice loss
Post by: Neven on March 31, 2018, 09:52:44 PM
Actually I did read the entire thing.  Hence my comment about increased caloric content, but decreased mineral content.  Simple mathematics; if you increase the total volume, but keep a particular element constant, its percentage must decrease.  The added volume is still nutritious foodstuffs, which is the primary concern in undernourished countries.

I see what you mean now. Maybe they could've explained it better. The way I understood it, less nutrients get taken up because the 'space' is taken up by more carbohydrates. If I've understood you correctly, you say that the plant grows bigger (volume is increased), while taking up the same amount of nutrients.

I've just read a book about how plants interact with soil life. They get their minerals through 'exudates' which they exchange with bacteria and fungi. I don't know how that would change if the plant contains more carbohydrates because of increased atmospheric CO2.

If the science is correct, this could seriously affect health, on top of the mineral depletion that has been taken place for a while now. In that sense, it has the same effect as junk food.
Title: Re: Abrupt sea ice loss
Post by: Neven on March 31, 2018, 09:55:20 PM
(Is it time to split these increasingly absurd and off topic postings into another thread? Or should we all just drop it?)

We should drop it, or continue here (https://forum.arctic-sea-ice.net/index.php/topic,317.msg148040.html#msg148040).

Apparently, the subject of this thread doesn't attract enough comments on its own. Of course, it's been discussed indirectly elsewhere.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on March 31, 2018, 09:57:06 PM
(Is it time to split these increasingly absurd and off topic postings into another thread? Or should we all just drop it?)

We should drop it, or continue here (https://forum.arctic-sea-ice.net/index.php/topic,317.msg148040.html#msg148040).

Apparently, the subject of this thread doesn't attract enough comments on its own. Of course, it's been discussed indirectly elsewhere.

Agreed.  But at least we seem to understand each other now.  Sorry if my previous posts were unclear.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 02, 2018, 07:06:17 PM
OK...Given the topic, I have a question.  Is this the year we will see abrupt sea ice loss?
Title: Re: Abrupt sea ice loss
Post by: litesong on April 02, 2018, 08:03:53 PM
... the subject of this thread doesn't attract enough comments on its own.
Seems that this thread needs some new blood. So.......
A 2012 storm broke up much Arctic sea ice & winds drove the easier to move broken sea ice to the Atlantic Ocean. Ever since, AGW deniers have doted that Arctic sea ice is on the increase.  However, solar TSI has been languid for half a century, & low for the last 11+ years(including a 3+ year period setting a 100 year record low), which should have set Arctic sea ice sky high. Yet, recent Arctic sea ice Volume has ranged between 8000 to 12,000 cubic kilometers LESS than the average of the 1980's.
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on April 03, 2018, 06:20:11 AM
The two papers I posted had a purpose.  One, to introduce the concept that abrupt sea ice loss can actually happen.  And two, that there are factors in both winter and summer that could lead to it.

In the winter, which we have seen happen, ocean temperatures could retard sea ice growth, even to the point where water temperature is just too warm for sea ice to form. 

And in the summer, cyclones and anti-cyclones can form, and that warm winds across the ice can cause abrupt drops in sea ice extent, as well as break up and transport the ice out of the Arctic.  The great cyclone of 2012 giving us a taste.

The concept that synoptic scale events can be responsible for the annual variance of Sept minimums.  That both weather and climate have a role. 

   
Title: Re: Abrupt sea ice loss
Post by: Tor Bejnar on April 03, 2018, 04:08:13 PM
I imagine a widespread rainstorm in mid-May in the high Arctic would reduce the normally high albedo (~0.9) of snow-covered ice to medium albedo (~.7) icy snow and melt ponds (ref. (https://nsidc.org/cryosphere/seaice/processes/albedo.html)).  The consequences for the rest of the melting season would likely be extreme.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 03, 2018, 04:31:41 PM
I imagine a widespread rainstorm in mid-May in the high Arctic would reduce the normally high albedo (~0.9) of snow-covered ice to medium albedo (~.7) icy snow and melt ponds (ref. (https://nsidc.org/cryosphere/seaice/processes/albedo.html)).  The consequences for the rest of the melting season would likely be extreme.

If that were to occur, it would enhance melt.  May temperatures are typically still below freezing, especially if clouds are blocking the sun, so any precipitation will likely fall a snow.  That is assuming that any precipitation could fall.  The Arctic is essentially a desert, with very little precipitation, so I doubt that such a large rainstorm could occur in spring.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 04, 2018, 01:25:53 PM
If that were to occur, it would enhance melt.  May temperatures are typically still below freezing, especially if clouds are blocking the sun, so any precipitation will likely fall a snow.  That is assuming that any precipitation could fall.  The Arctic is essentially a desert, with very little precipitation, so I doubt that such a large rainstorm could occur in spring.

The big change in the Arctic in late 2015 was the Atlantification of the Ocean and increased humidity.  The Arctic is becoming less a desert, and more a maritime climate.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 04, 2018, 02:16:06 PM
If that were to occur, it would enhance melt.  May temperatures are typically still below freezing, especially if clouds are blocking the sun, so any precipitation will likely fall a snow.  That is assuming that any precipitation could fall.  The Arctic is essentially a desert, with very little precipitation, so I doubt that such a large rainstorm could occur in spring.

The big change in the Arctic in late 2015 was the Atlantification of the Ocean and increased humidity.  The Arctic is becoming less a desert, and more a maritime climate.

That is most likely true.  However, how much change will occur is open to speculation.  The following paper does a nice job examining the potentials during the most recent ice-free era:

https://www.sciencedirect.com/science/article/pii/S0277379113004162
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 04, 2018, 03:11:01 PM
Quote
The following paper does a nice job examining the potentials during the most recent ice-free era:

That paper doesn't say that. That paper says that it could have been ice free during the HTM under the parameters of the model. Comparing this model Arctic to present day might be slightly useful but only by understanding the difference between present day and the HTM.

The 3 biggest differences:

1. Laurentide Ice Sheet covered the Northern Hemisphere providing year round negative forcing until it melted.

2. CO2 was at 280 PPM. The extra forcing was due to solar radiation, not GHG's

3. The model in the paper works over a time period of 5,000 years, not 3 decades.

So yes, that model might offer clues, but what is happening now is different to what happened during the HTM. The paper is very clear that an ice free arctic during the HTM is not a forgone conclusion.
Title: Re: Abrupt sea ice loss
Post by: El Cid on April 04, 2018, 05:59:22 PM
Actually, their model is about very abrupt sea ice loss as can be seen on the attached picture. It seems relevant for 2 reasons:

1. Abrupt ice loss could happen
2. There could have been a long period (millenia) during the history of humanity without Arctic Ice, without any detrimential effects.

So my conclusions: abrupt sea ice loss could easily happen in our lifetime, but it will probably not lead to any catastrophe
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 04, 2018, 06:27:22 PM
Quote
2. There could have been a long period (millenia) during the history of humanity without Arctic Ice, without any detrimential effects

1. The Laurentide Ice Sheet existed then and not now. It is the melting of that ice sheet what kept global temperatures from reaching Eemian temperatures in combination with highly favorable NH albedo.

  I like how this image illustrates a possible ice less Arctic with a Laurentide ice sheet.

(https://sites.google.com/a/rsu4.org/wabanaki-of-maine/_/rsrc/1381945069681/time-line/laurentide%20ice%20sheet%20map%201.jpg)

2. At the temporal frames of this paper, which is in the thousands of years you can't say absolutely nothing about the impact it will have on modern society, which works on a yearly/decadal scale. Even if you could zoom in and examine yearly or decadal scales, human population then was in the millions and nomadic. Any climate change would have been easily adapted by migration.

Today there is no Laurentide Ice Sheet, 410PPMs of CO2 in the Atmosphere and 7 billion people most of whom live in places where the climate hasn't abruptly changed in millennia.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 04, 2018, 07:08:29 PM
Quote
2. There could have been a long period (millenia) during the history of humanity without Arctic Ice, without any detrimential effects

1. The Laurentide Ice Sheet existed then and not now. It is the melting of that ice sheet what kept global temperatures from reaching Eemian temperatures in combination with highly favorable NH albedo.

  I like how this image illustrates a possible ice less Arctic with a Laurentide ice sheet.

(https://sites.google.com/a/rsu4.org/wabanaki-of-maine/_/rsrc/1381945069681/time-line/laurentide%20ice%20sheet%20map%201.jpg)

2. At the temporal frames of this paper, which is in the thousands of years you can't say absolutely nothing about the impact it will have on modern society, which works on a yearly/decadal scale. Even if you could zoom in and examine yearly or decadal scales, human population then was in the millions and nomadic. Any climate change would have been easily adapted by migration.

Today there is no Laurentide Ice Sheet, 410PPMs of CO2 in the Atmosphere and 7 billion people most of whom live in places where the climate hasn't abruptly changed in millennia.

Paleo data shows that most of the Laurentide ice sheet was largely gone by 8000 years ago, which the authors acknowledged was a factor up until that time.  Paleo data shows a minimum around 6000 years ago, so the Laurentide ice sheet was a non-factor at that time.  The model in their paper agreed with this data.  The Greenland ice sheet and glaciers on the Canadian archipelago would likely act similarly to the Laurentide ice sheet, limiting potential ice loss.  They listed many different feedbacks mechanisms that would likely result, but realize that sufficient knowledge is lacking as to the strength of each.  They did emphasize that hysteresis effects are much smaller than other forcings, such that an ice-free state would not be irreversible.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 04, 2018, 07:13:26 PM
So my conclusions: abrupt sea ice loss could easily happen in our lifetime, but it will probably not lead to any catastrophe

Would you accept replacing "probably" with "possibly"?
Title: Re: Abrupt sea ice loss
Post by: Wherestheice on April 04, 2018, 08:36:53 PM
Actually, their model is about very abrupt sea ice loss as can be seen on the attached picture. It seems relevant for 2 reasons:

1. Abrupt ice loss could happen
2. There could have been a long period (millenia) during the history of humanity without Arctic Ice, without any detrimential effects.

So my conclusions: abrupt sea ice loss could easily happen in our lifetime, but it will probably not lead to any catastrophe

Not lead to a catastrophe??

It will change the climate in a very harsh way. loss of albedo, latent heating, possible methane. not to mention with no ice cap, greenland will melt faster. Humans have never lived in an ice free arctic, at least since civilazation began
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 04, 2018, 08:51:41 PM
Actually, their model is about very abrupt sea ice loss as can be seen on the attached picture. It seems relevant for 2 reasons:

1. Abrupt ice loss could happen
2. There could have been a long period (millenia) during the history of humanity without Arctic Ice, without any detrimential effects.

So my conclusions: abrupt sea ice loss could easily happen in our lifetime, but it will probably not lead to any catastrophe

Not lead to a catastrophe??

It will change the climate in a very harsh way. loss of albedo, latent heating, possible methane. not to mention with no ice cap, greenland will melt faster. Humans have never lived in an ice free arctic, at least since civilazation began

By civilization, do you just mean since the Greco-Roman era?
Title: Re: Abrupt sea ice loss
Post by: Wherestheice on April 04, 2018, 10:06:28 PM
Actually, their model is about very abrupt sea ice loss as can be seen on the attached picture. It seems relevant for 2 reasons:

1. Abrupt ice loss could happen
2. There could have been a long period (millenia) during the history of humanity without Arctic Ice, without any detrimential effects.

So my conclusions: abrupt sea ice loss could easily happen in our lifetime, but it will probably not lead to any catastrophe

Not lead to a catastrophe??

It will change the climate in a very harsh way. loss of albedo, latent heating, possible methane. not to mention with no ice cap, greenland will melt faster. Humans have never lived in an ice free arctic, at least since civilazation began

By civilization, do you just mean since the Greco-Roman era?

Before that. Research suggests modern humans have never been in an ice free arctic, let alone our civilazation https://www.nature.com/articles/ncomms6608 . An ice free arctic spells trouble for humans.
Title: Re: Abrupt sea ice loss
Post by: El Cid on April 04, 2018, 11:11:49 PM
So my conclusions: abrupt sea ice loss could easily happen in our lifetime, but it will probably not lead to any catastrophe

Would you accept replacing "probably" with "possibly"?

You could say possibly but I would stick to probably. Although we cannot know for sure but current models do NOT show such a sudden jump in temperatures - even with all of the Arctic Ice gone - that would cause any huge problems. I am not into modelling but the results I have seen show about 1-2-(at most 3) degree warming for NH midlatitudes for the next 20-30 yrs with the ice gone (from current levels). That is managable.
I have stated before that I see the overpopulation of Africa a much bigger problem. With twice as many people in 30-40 yrs than now, higher temps, changed rain-patterns, it would be a miracle if there would not be civil wars and mass exodus out of that continent...
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 04, 2018, 11:14:33 PM

Paleo data shows that most of the Laurentide ice sheet was largely gone by 8000 years ago, which the authors acknowledged was a factor up until that time.

What the authors acknowledge is that they completely ignored the laurentide ice sheet

Quote
4.7 Further Aspects
Other factors of potential importance for the sea ice cover not considered in our simulations
...
Factors like the persistence of e.g. the Laurentide ice sheet until 8000 years BP (Hughes et al., 1981; Lambeck et al., 2000) probably had an impact on the Arctic climate through effects associated with both freshwater supply and surface albedo.

Quote
Paleo data shows a minimum around 6000 years ago, so the Laurentide ice sheet was a non-factor at that time.


Yes, but when the model first enters hysteresis was 11k years ago. At that time the sheet was very large. When the laurentide ice sheets are added, does the model still enters hysteresis? Unknown because the model ignores it.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 05, 2018, 12:10:06 AM

Paleo data shows that most of the Laurentide ice sheet was largely gone by 8000 years ago, which the authors acknowledged was a factor up until that time.

What the authors acknowledge is that they completely ignored the laurentide ice sheet

Quote
4.7 Further Aspects
Other factors of potential importance for the sea ice cover not considered in our simulations
...
Factors like the persistence of e.g. the Laurentide ice sheet until 8000 years BP (Hughes et al., 1981; Lambeck et al., 2000) probably had an impact on the Arctic climate through effects associated with both freshwater supply and surface albedo.

Quote
Paleo data shows a minimum around 6000 years ago, so the Laurentide ice sheet was a non-factor at that time.


Yes, but when the model first enters hysteresis was 11k years ago. At that time the sheet was very large. When the laurentide ice sheets are added, does the model still enters hysteresis? Unknown because the model ignores it.

They ignored it, because it no longer existed.  It melted millenia earlier.
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 05, 2018, 12:31:48 AM
Quote
They ignored it, because it no longer existed.  It melted millenia earlier.

The model obtains hysterisis around 11.5ky ago.

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=2286.0;attach=99209;image)

There was significant ice in the NH at the time.

(https://antilandscaper.files.wordpress.com/2013/03/lgm-deglaciation.jpg)

Besides the Laurentian Ice Sheet, there were remanents of the Eurassian ice sheets all the way to 8ky ago

(https://ars.els-cdn.com/content/image/1-s2.0-S0277379117302068-gr6.jpg)

This model completely ignores both.
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 05, 2018, 02:24:38 AM
I would like to add that even if this model doesn't account for the ice sheets and even when proxies point to permanent cover at least at the CAB, contrary to the results obtained by this model I really like the model.

I think its result is closer to what is happening now than what was happening then, even if the warming is due to different reasons.

I imagine they didn't include the ice sheets because that would probably be years of extra research outside of their scope of interest.
Title: Re: Abrupt sea ice loss
Post by: El Cid on April 05, 2018, 07:55:42 AM


I think its result is closer to what is happening now than what was happening then, even if the warming is due to different reasons.


This could be true for all we know. The main point of the model is (to me) that ice loss can be very sudden, ie. happening in a few years/decades. This is most likely what we are experiencing now. Unfortunately, we do not know whether it happens in 1, 4, or 40 years from now and we also do not know what changes to atmospheric circulation it will cause...
Title: Re: Abrupt sea ice loss
Post by: josh-j on April 05, 2018, 09:11:32 AM
[I am not into modelling but the results I have seen show about 1-2-(at most 3) degree warming for NH midlatitudes for the next 20-30 yrs with the ice gone (from current levels). That is managable.
I have stated before that I see the overpopulation of Africa a much bigger problem. With twice as many people in 30-40 yrs than now, higher temps, changed rain-patterns, it would be a miracle if there would not be civil wars and mass exodus out of that continent...

3 degree warming at mid-latitudes is manageable? I suppose it depends what you mean by manageable but that seems a stretch.  What would such a rise correspond to as a global temperature anomaly?

Your argument around Africa seems plausible but I think that the forced migration and so on in various regions (not just Africa) could easily cause very serious problems to other countries. Plus food imports...

None of that means that everybody will die, of course. So I would be  step to know what your definition of "manageable" is as that seems key.
Title: Re: Abrupt sea ice loss
Post by: crandles on April 05, 2018, 01:01:30 PM

I am not into modelling but the results I have seen show about 1-2-(at most 3) degree warming for NH midlatitudes for the next 20-30 yrs with the ice gone (from current levels). That is managable.


1 Degree a decade? That is huge! Where have you seen that? (because I have heard of no such thing (Edit: perhaps I should clarify in future modelling))

I could believe 2 or 3 degrees (exc ghg effects) over 100 years or so.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 05, 2018, 01:12:39 PM

I am not into modelling but the results I have seen show about 1-2-(at most 3) degree warming for NH midlatitudes for the next 20-30 yrs with the ice gone (from current levels). That is managable.


1 Degree a decade? That is huge! Where have you seen that? (because I have heard of no such thing)

I could believe 2 or 3 degrees (exc ghg effects) over 100 years or so.

It did occur in the past, during the Bolling-Allerod warming.  However, that had extraordinary forces working then.

https://forum.arctic-sea-ice.net/index.php?topic=1952.0
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 05, 2018, 02:07:14 PM
Over at the Ice Free Arctic  thread Ken Feldman posted this

Quote
A 2011 study estimated that the albedo effect of an ice-free arctic for a month in late summer would increase from the current forcing of 0.11 watts per meter squared (W/m-2) to 0.30 W/m-2.  Using current estimates of climate sensitivity, that would lead to a global temperature increase of 0.15 degrees C. Here's the abstract from the study:

https://forum.arctic-sea-ice.net/index.php/topic,1886.msg145111.html#msg145111


So if the ice is gone for the last month of every year, over ten years the world is more than 1C warmer. I imagine that's where the number comes from.

That said, those calculations use local and temporal forcing changes and apply them to global yearly forcing changes. That misses the whole point. That global, annual .15C become several degrees at the local level of the Arctic. That's significant because it delays the onset of the freezing season.
Title: Re: Abrupt sea ice loss
Post by: crandles on April 05, 2018, 03:20:43 PM
From study abstract linked by Ken Feldman and reposted by Archimid above:

Quote
Results show that the globally and annually averaged radiative forcing caused by the observed loss of sea ice in the Arctic between 1979 and 2007 is approximately 0.1 W m−2; a complete removal of Arctic sea ice results in a forcing of about 0.7 W m−2, while a more realistic ice‐free summer scenario (no ice for 1 month and decreased ice at all other times of the year) results in a forcing of about 0.3 W m−2, similar to present‐day anthropogenic forcing caused by halocarbons. The potential for changes in cloud cover as a result of the changes in sea ice makes the evaluation of the actual forcing that may be realized quite uncertain since such changes could overwhelm the forcing caused by the sea ice loss itself, if the cloudiness increases in the summertime.

28 years of change produced .1 W/m^2

radiative forcings from https://en.wikipedia.org/wiki/Greenhouse_gas

Halocarbons 0.36 W/m^2
CO2 1.88
Methane 0.49
N20 0.17
Ozone 0.4
Total 3.3

So the 0.3W/m^2 is only about a tenth of GHG forcing (maybe fifth of the warming we see taking areosols as masking half the effect of GHGs).

Warming appears less than 0.2 C per decade so a fifth of that is 0.04C per decade.

Thus 1C per decade appears like 25 times stronger than what we are experiencing. For a 3 times stronger effect (of 0.3W/m^2 vs 0.1), this does not compute. Also note the 0.1W/m^2 took 28 years to build up.

Do let me know if I am getting my sums wrong.
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on April 05, 2018, 05:50:03 PM
Jim White at the 2014 AGU

How abrupt is abrupt? (https://www.youtube.com/watch?v=siWCXOypJh4)
Title: Re: Abrupt sea ice loss
Post by: Ken Feldman on April 05, 2018, 06:03:54 PM
Over at the Ice Free Arctic  thread Ken Feldman posted this

Quote
A 2011 study estimated that the albedo effect of an ice-free arctic for a month in late summer would increase from the current forcing of 0.11 watts per meter squared (W/m-2) to 0.30 W/m-2.  Using current estimates of climate sensitivity, that would lead to a global temperature increase of 0.15 degrees C. Here's the abstract from the study:

https://forum.arctic-sea-ice.net/index.php/topic,1886.msg145111.html#msg145111


So if the ice is gone for the last month of every year, over ten years the world is more than 1C warmer. I imagine that's where the number comes from.

That said, those calculations use local and temporal forcing changes and apply them to global yearly forcing changes. That misses the whole point. That global, annual .15C become several degrees at the local level of the Arctic. That's significant because it delays the onset of the freezing season.

It's 0.15C total, not an additional 0.15C every year.  Don't forget the planck (or blackbody) feedback, which is that the temperature increase leads to more heat being shed into space.

However, over time, that 0.3 W/m-2 (about a month of nearly ice free conditions) eventually grows to 0.7 W/m-2 (the whole spring and summer ice-free) as the Arctic continues to lose ice earlier during the summer, allowing for the Arctic Ocean to warm more.  Other studies have shown that it will take decades to go from the first nearly ice free September to the whole summer being ice free.
Title: Re: Abrupt sea ice loss
Post by: crandles on April 05, 2018, 06:16:07 PM
Jim White at the 2014 AGU

Edited my post above.

Yes there may be records of 1C a year for 5 years or even 5 to 10C a year in the past.

Note the part I quoted

I am not into modelling but the results I have seen show about 1-2-(at most 3) degree warming for NH midlatitudes for the next 20-30 yrs with the ice gone (from current levels).

was about modelling the next 20-30 yrs

The next 20-30 years will be much like the last 20-30 years pretty much whatever we do.
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on April 05, 2018, 06:39:24 PM
No, it won't.

And it's beyond us being able to do anything.  Self-reinforcing feedbacks have kicked in. 
Title: Re: Abrupt sea ice loss
Post by: crandles on April 05, 2018, 07:18:07 PM
No, it won't.

And it's beyond us being able to do anything.  Self-reinforcing feedbacks have kicked in.

(https://www.ipcc.ch/publications_and_data/ar4/wg1/en/fig/figure-spm-5-l.png)

And your source hopefully specifying next 20 to 30 years?

Of course, you will be able to find a few individuals like Prof Wadhams saying such things so preferably something that has widespread support not just some nutter saying it.

(IOW I think you need a reality check.)
Title: Re: Abrupt sea ice loss
Post by: El Cid on April 05, 2018, 07:20:07 PM

I am not into modelling but the results I have seen show about 1-2-(at most 3) degree warming for NH midlatitudes for the next 20-30 yrs with the ice gone (from current levels). That is managable.


1 Degree a decade? That is huge! Where have you seen that? (because I have heard of no such thing (Edit: perhaps I should clarify in future modelling))

I could believe 2 or 3 degrees (exc ghg effects) over 100 years or so.

I am from Europe, and Europe (NH midlatitudes) is expected to warm this much:

https://www.eea.europa.eu/data-and-maps/indicators/global-and-european-temperature/global-and-european-temperature-assessment-5

"Annual average land temperature over Europe is projected to continue increasing by more than global land temperature during the 21st century. By the 2021-2050 period, temperature increases of between 1.0°C and 2.5°C are projected, and by 2071-2100 this increases to between 2.5°C and 4.0°C."

I also considered that most models still put ice-free arctic to happen after 2050, so they might underestimate temps IF the arctic becomes ice free soon.

So in 20-30 yrs time IF we lose all arctic ice, 1-2 degrees seem reasonable, 3 is probably a stretch.

Eastern and Northern European temperatures (see: https://data.giss.nasa.gov/gistemp/maps/) rose 1-1,5 degrees from the 80s to the 2010s (ie. 2010-17 annual averages vs 1980-1990), in a mere 30 yrs, with no sudden arctic ice loss. If we lose the ice, this could be higher, hence my numbers of 1-2 (possibly 3).
Title: Re: Abrupt sea ice loss
Post by: crandles on April 05, 2018, 07:53:03 PM
Latest version (published Sept 2017) says
https://www.eea.europa.eu/data-and-maps/indicators/global-and-european-temperature-4/assessment

Quote
The global average temperature will continue to increase throughout this century as a result of projected further increases in greenhouse gas concentrations. The CMIP5 climate projections summarised in the IPCC AR5 project that global temperature will increase by mid-century (2046–2065 relative to 1986–2005) by 0.4–1.6 °C for RCP2.6, 0.9–2.0 °C for RCP4.5, 0.8–1.8 °C for RCP6.0 and 1.4–2.6 °C for RCP8.5; the warming projections for the end of the century (2081–2100) are 0.3–1.7 °C for RCP2.6, 1.1–2.6 °C for RCP4.5, 1.4–3.1 °C for RCP6.0 and 2.6–4.8 °C for RCP8.5. All projections show greater warming over land than over the oceans. Projected warming is strongest in the Arctic at about twice the global average. These patterns are consistent with the observations during the latter part of the 20th century

So global average 1.4–2.6 °C is reported but over 40-60 years.
Land temperatures are expected to rise faster and there is lots of land in mid latitudes (northern hemisphere).

Half it and add a bit does get to around 1C to 2C over land in 20-30 years. Still a little short of 1C per decade and this is mainly from GHGs whereas ice free for a month is a smaller forcing like a tenth of GHG forcing if my sums above are correct.

Still you got closer than I expected.
Title: Re: Abrupt sea ice loss
Post by: El Cid on April 05, 2018, 09:19:30 PM
Also let's not forget, that IF/WHEN the Arctic becomes ice-free, that would most likely cause changes to the atmospheric circulation.

Now, I know that this is very speculative but if the Arctic is ice free, then the Icelandic low could shift to the Arctic or to the Barents for example, most likely bringing warmer winds during the autumn/winter(?) to Northern/Central Europe...
Title: Re: Abrupt sea ice loss
Post by: jdallen on April 06, 2018, 01:05:52 AM
I'm finding the content presented in Jim Whites video very compelling, enough so I went ahead and watched the whole thing.

When, not if we have and blue Arctic summer, I find myself agreeing  that the rate of change in the northern hemisphere will accelerate abruptly, as we pass a tip over threshold that breaks the existing weather pattern and transitions rapidly into a new one.  I think it could happen in my remaining lifetime.
Title: Re: Abrupt sea ice loss
Post by: Archimid on April 06, 2018, 04:08:16 AM
Halocarbons 0.36 W/m^2
CO2 1.88
Methane 0.49
N20 0.17
Ozone 0.4
Total 3.3

So the 0.3W/m^2 is only about a tenth of GHG forcing (maybe fifth of the warming we see taking areosols as masking half the effect of GHGs).

Warming appears less than 0.2 C per decade so a fifth of that is 0.04C per decade.

In the Arctic, the warming is 2, maybe 3 times higher than global temperatures. It is important differentiate between local and global effects.

Quote
Thus 1C per decade appears like 25 times stronger than what we are experiencing. For a 3 times stronger effect (of 0.3W/m^2 vs 0.1), this does not compute.

Albedo forcings are local to the Arctic and only during summer. CO2 forcing is global and uniform throughout the year. However in the Arctic the warming is 2-3 times higher than the global average. Albedo change is just one of the many forcings that are causing the temperature difference. It is a small one relative to others as you well said, however it's influence will increase as extent decreases.

I think the biggest forcing at work is the lack of volume to melt.  Because of the enthalpy of fusion of ice a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space. If anything it cools the globe a bit.

I think the other large forcing is the atmosphere sending heat waves and water vapor into the Arctic. That's another factor that makes no direct difference in global temperatures but make a huge difference in Arctic temperatures.

CO2 is there of course, but it is more powerful as a global influencer of temperatures. Elevated global temperatures eventually lead to more heat into the Arctic, but CO2's direct impact as a greenhouse gas is not as large for Arctic amplification considerations. Methane and water vapor might be a different matter.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 06, 2018, 04:30:36 PM

I think the biggest forcing at work is the lack of volume to melt.  Because of the enthalpy of fusion of ice a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space. If anything it cools the globe a bit.


Yes, this is not trivial.  The heat of fusion of water is 333.55 J/g, while the specific heat of water is 4.186 J/g-C.  Using a straight-forward calculation, and an average volumetric loss of 320 km3/yr, the annual heat used to melt the ice is ~107 pJ (peta = 10^15).  That amount of heat would raise the surface temperature of the Arctic Ocean (14 million km2 to a depth of 200 m) by 0.37 C.  Obviously this is rather simplistic, and other factors will come into play (such as heat lost to space), but it is significant.
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 06, 2018, 05:03:53 PM

I think the biggest forcing at work is the lack of volume to melt.  Because of the enthalpy of fusion of ice a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space. If anything it cools the globe a bit.


Yes, this is not trivial.  The heat of fusion of water is 333.55 J/g, while the specific heat of water is 4.186 J/g-C.  Using a straight-forward calculation, and an average volumetric loss of 320 km3/yr, the annual heat used to melt the ice is ~107 pJ (peta = 10^15).  That amount of heat would raise the surface temperature of the Arctic Ocean (14 million km2 to a depth of 200 m) by 0.37 C.  Obviously this is rather simplistic, and other factors will come into play (such as heat lost to space), but it is significant.

Quote
a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space.

I thought heating of the oceans is the number one factor in any longer term view of AGW.
No, I am totally convinced that an ocean body that has more than 1000 times the capacity to absorb and store energy than the atmosphere and is soaking up more than 90% of the excess energy trapped by rising co2 ppm is numero uno. Atmospheric temperature change is surely far more of a resulting side-effect of rising global ocean heat content and is quickly lost to space without further energy inputs.  So diminishing sea ice (especially early in the melting season) increases the energy available for long-term storage in the oceans (down to at least 2,000 metres). This energy can then be released at leisure to confound the predictions of atmospheric scientists.

My pure speculation is that a gradually warming Arctic ocean will gradually weaken winter sea ice volume allowing even lower winter maximum extents and even stronger early melt ........ until??
Title: Re: Abrupt sea ice loss
Post by: RoxTheGeologist on April 06, 2018, 05:49:15 PM

I think the biggest forcing at work is the lack of volume to melt.  Because of the enthalpy of fusion of ice a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space. If anything it cools the globe a bit.


Theses are old numbers - back from 2008.

Water: A greenhouse gas, like carbon dioxide, it represents around 80 percent of total greenhouse gas mass in the atmosphere and 90 percent of greenhouse gas volume. Water vapor and clouds account for 66 to 85 percent of the greenhouse effect, compared to a range of 9 to 26 percent for CO2.

Just off the top of my head, I would think a warm ice free Arctic is going to contribute much more water to the atmosphere than a cold one...

Title: Re: Abrupt sea ice loss
Post by: FishOutofWater on April 06, 2018, 07:32:16 PM
Water vapor acts as a multiplier of the effects of greenhouse gases such as CO2, methane and CFCs that have relatively long atmospheric lifetimes. Open ocean water is a continuous source of water vapor to the Arctic region so the loss of sea ice is a powerful amplifier of the greenhouse effect in the Arctic. Sublimation of snow and ice is not nearly as effective a means of getting water vapor into the atmosphere as winds blowing over open ocean. We're already seeing large warmings in the Barents and Bering sea regions where open water has replaced ice and the added water vapor is affecting the whole Arctic.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 06, 2018, 07:38:03 PM
True, but not all that water will remain as vapor.  Some will condense into clouds, which will produce a negative feedback, blocking some of the 24-hour sunlight.
Title: Re: Abrupt sea ice loss
Post by: crandles on April 06, 2018, 07:44:26 PM
Usual explanation of water cycle with temperature change is
The water cycle is fast; 11 day average residency time. Absolute humidity will increase, relative humidity not much change. Contributes more..? yes and precipitates out quite quickly.

Arctic might be a little different with generally descending dry air that already gets moister as it travels south and warms up. Maybe it gets moister further north? Maybe that is still 'absolute humidity will increase, relative humidity not much change'?
Title: Re: Abrupt sea ice loss
Post by: FishOutofWater on April 06, 2018, 08:26:09 PM
Well we left out a major factor, storm tracks. We are seeing stormier conditions over open waters in the Arctic and subarctic as ocean water enhances baroclinic processes compared to sea ice. That's increasing atmospheric advection of heat from the north Atlantic and north Pacific basins.

This stormier situation way also change the relative humidity of an air column over the Arctic.

Thanks concerning the water residency time. I knew it was short but didn't remember the number.
Title: Re: Abrupt sea ice loss
Post by: jdallen on April 06, 2018, 09:46:38 PM
True, but not all that water will remain as vapor.  Some will condense into clouds, which will produce a negative feedback, blocking some of the 24-hour sunlight.
Clouds don't help in winter. In fact, they hurt.

Clouds may not help enough in summer.  There is still the matter of downwelling long wave radiation as well as the latent heat in the water vapor itself.

The feedback from clouds will be overtaken as total system enthalpy increases.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 06, 2018, 11:05:48 PM

I think the biggest forcing at work is the lack of volume to melt.  Because of the enthalpy of fusion of ice a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space. If anything it cools the globe a bit.


Theses are old numbers - back from 2008.

Water: A greenhouse gas, like carbon dioxide, it represents around 80 percent of total greenhouse gas mass in the atmosphere and 90 percent of greenhouse gas volume. Water vapor and clouds account for 66 to 85 percent of the greenhouse effect, compared to a range of 9 to 26 percent for CO2.

Just off the top of my head, I would think a warm ice free Arctic is going to contribute much more water to the atmosphere than a cold one...

CO2 is the trigger.  H2O is the bullet.
Title: Re: Abrupt sea ice loss
Post by: wili on April 06, 2018, 11:33:46 PM
" H2O is the bullet."

And heat

And wind

And drought...
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 07, 2018, 12:13:14 AM
True, but not all that water will remain as vapor.  Some will condense into clouds, which will produce a negative feedback, blocking some of the 24-hour sunlight.
Clouds don't help in winter. In fact, they hurt.

Clouds may not help enough in summer.  There is still the matter of downwelling long wave radiation as well as the latent heat in the water vapor itself.

The feedback from clouds will be overtaken as total system enthalpy increases.

There is a large albedo difference between clouds and open water.  Also, it reduces the water vapor effect in the atmosphere.
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on April 09, 2018, 05:59:08 AM
Quote
Of course, you will be able to find a few individuals like Prof Wadhams saying such things so preferably something that has widespread support not just some nutter saying it.

(IOW I think you need a reality check.)

Go ahead Crandles, bury your head in the sand.  You aren't using it anyway.  If you think I'm about to reiterate all of the self-reinforcing feedbacks already identified, you need to rub your two brain cells together and try to get a spark.

BTW, Peter Wadhams credentials speak for themselves.  Some anonymous nutter on a website disparaging him, doesn't change the facts.

Go crawl back under your denier rock.  I hear WUWT calling you. 

Title: Re: Abrupt sea ice loss
Post by: Neven on April 09, 2018, 09:24:41 AM
Or maybe you hear Neven calling, saying you shouldn't get this worked up.  :)
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 10, 2018, 03:27:31 PM
Quote
Of course, you will be able to find a few individuals like Prof Wadhams saying such things so preferably something that has widespread support not just some nutter saying it.

(IOW I think you need a reality check.)

Go ahead Crandles, bury your head in the sand.  You aren't using it anyway.  If you think I'm about to reiterate all of the self-reinforcing feedbacks already identified, you need to rub your two brain cells together and try to get a spark.

BTW, Peter Wadhams credentials speak for themselves.  Some anonymous nutter on a website disparaging him, doesn't change the facts.

Go crawl back under your denier rock.  I hear WUWT calling you.

Cid, yes his credentials speak for themselves.  However, some of his recent claims are a bit eccentric, don't you think?  Like three British scientists being murdered? 
Title: Re: Abrupt sea ice loss
Post by: Jim Hunt on April 11, 2018, 11:41:11 AM
However, some of his recent claims are a bit eccentric, don't you think?

Prof. Wadhams is a very nice fellow. Perhaps too nice for his own good? For much more on that "story" see:

http://GreatWhiteCon.info/2015/07/professor-peter-wadhams-complaint-to-ipso/

My conclusion?

Quote
The moral of this tale would seem to be “Don’t speak to journalists without taping the conversation” and “Don’t speak to journalists without saying the magic words ‘off the record’ first” or quite possibly simply “Don’t speak to journalists”!
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 11, 2018, 01:48:28 PM
However, some of his recent claims are a bit eccentric, don't you think?

Prof. Wadhams is a very nice fellow. Perhaps too nice for his own good? For much more on that "story" see:

http://GreatWhiteCon.info/2015/07/professor-peter-wadhams-complaint-to-ipso/

My conclusion?

Quote
The moral of this tale would seem to be “Don’t speak to journalists without taping the conversation” and “Don’t speak to journalists without saying the magic words ‘off the record’ first” or quite possibly simply “Don’t speak to journalists”!

I think your last statement sums it up best.  Journalists are not objective.  They have their own agenda, and are just looking for anything that supports their own views.  Still, he should have never made those innuendos - especially to a journalist.
Title: Re: Abrupt sea ice loss
Post by: Steven on April 11, 2018, 07:12:01 PM
I think it's pretty clear that Wadhams shouldn't be taken seriously anymore.  He's promoting (https://web.archive.org/web/20140719032122/http://www.spiritoday.com/cambridge-professor-peter-wadhams-on-matters-of-life-and-death-and-higher-consciousness) pseudo-scientific nonsense about ghosts, mediumship and paranormality as well as various conspiracy theories.  He seriously believes that he has precognitive dreams in which he can foresee future events.  That is probably the reason for the unscientific predictions that he has been making in recent years (e.g. here (https://www.arcus.org/sipn/sea-ice-outlook/2015/june)), which are an easy target for climate deniers who use extremists like Wadhams to ridiculize the entire climate science community.
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on April 12, 2018, 10:35:58 AM
Yes, and he also believes that Christ existed.  I myself have experienced Déjà vu and it seemed I had experienced it earlier, perhaps in a dream.

We all have personal beliefs that perhaps can't (as of yet) be proven by science.  I'll bet you do to.  Does that make everything else about you suspect?

Jung spoke of synchronicity and wrote a book.  He hung out with the Madame Blavatsky crowd.

Quote
“Broadly speaking, although there are some differences, I think Buddhist philosophy and Quantum Mechanics can shake hands on their view of the world. We can see in these great examples the fruits of human thinking. Regardless of the admiration we feel for these great thinkers, we should not lose sight of the fact that they were human beings just as we are.”

 – The Dalai Lama

According to Quantum Physics there is no such thing as matter, it is all energy that is constantly coming into existence and disappearing at time scales so small we can't comprehend.

Can you tell me what consciousness is?  No?

You act as if reality is fixed and known by you and can therefore judge others.
   
You also demonstrate a form of bifurcation fallacy.  Binary thinking.  Perhaps you should look to the plank in your own eye.
 
Title: Re: Abrupt sea ice loss
Post by: be cause on April 12, 2018, 11:17:22 AM
 As a shamanic  Christian I would consider limiting myself to the world of non-quantum science about as drastic as losing both my arms . I even dare predict that abrupt sea ice loss is upon us . :)
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 12, 2018, 11:53:59 AM
Prof. Wadhams is in good company.

https://en.wikipedia.org/wiki/Isaac_Newton%27s_occult_studies

Quote
Isaac Newton's occult studies
English physicist and mathematician Isaac Newton produced many works that would now be classified as occult studies. These works explored chronology, alchemy, and Biblical interpretation (especially of the Apocalypse). Newton's scientific work may have been of lesser personal importance to him, as he placed emphasis on rediscovering the occult wisdom of the ancients. In this sense, some[1] believe that any reference to a "Newtonian Worldview" as being purely mechanical in nature is somewhat inaccurate.

After purchasing and studying Newton's alchemical works, economist John Maynard Keynes, for example, opined in 1942 at the tercentenary of his birth that "Newton was not the first of the age of reason, he was the last of the magicians." In the Early Modern Period of Newton's lifetime, the educated embraced a world view different from that of later centuries. Distinctions between science, superstition, and pseudoscience were still being formulated, and a devoutly Christian biblical perspective permeated Western culture.
Note: He suggested a  date for the apocalypse of 2060.

Is Prof. Wadhams still publishing science stuff? He is still writing articles for the papers

https://www.washingtonpost.com/news/theworldpost/wp/2018/01/08/carbon-emissions/?noredirect=on&utm_term=.e5e93534636d

"Saving the world with carbon dioxide removal"
Title: Re: Abrupt sea ice loss
Post by: El Cid on April 12, 2018, 01:30:28 PM
Science is science, religion is religion. Mixing up the two is not very lucky. Science is and should be based on observations, facts, and replicable experiments not on visions. I dare say this exactly because I had out-of-body experiences. They had nothing to do with abrupt sea ice loss  :)
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 12, 2018, 01:35:54 PM
Science is science, religion is religion. Mixing up the two is not very lucky. Science is and should be based on observations, facts, and replicable experiments not on visions. I dare say this exactly because I had out-of-body experiences. They had nothing to do with abrupt sea ice loss  :)

Science is a religion.  Can we get back to discussing the ice?
Title: Re: Abrupt sea ice loss
Post by: Neven on April 12, 2018, 02:33:11 PM
And then, abruptly, they discussed sea ice loss again.  ;) ;D
Title: Re: Abrupt sea ice loss
Post by: Sterks on April 12, 2018, 05:24:40 PM
Science is science, religion is religion. Mixing up the two is not very lucky. Science is and should be based on observations, facts, and replicable experiments not on visions. I dare say this exactly because I had out-of-body experiences. They had nothing to do with abrupt sea ice loss  :)

Science is a religion.  Can we get back to discussing the ice?

super off topic but absolutely necessary: science is NOT a religion.
Now back to discussing the ice if you wish
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 12, 2018, 06:02:31 PM
Sorry, but couldn't resist.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fatheistcartoons.tumblr.com%2Fimage%2F127390849804&hash=c3f21108169fd1d1afcc80f8e0349a94)
Title: Re: Abrupt sea ice loss
Post by: Gray-Wolf on April 20, 2018, 11:40:04 AM
I think that we have been nudging toward what will appear on paper as a 'sudden drop' in sea ice because of the changes going on in the central region and the way the 15% or more measure skews the picture?
As I understand it the measure was not intended for the central pack but to capture ice edge ice cover?
As such we have been seeing central arctic square becoming less and less ice covered by seasons end but still over the 25% 'cut off' and so still measured as 100% covered.
Over the past 4 years we may have seen more and more fragmentation over the high Arctic with 20 or 30% less ice cover yet still end up with 'high' ( 4th /5th/6th lowest) finishes?
If we continue on this path then we may find that all of a sudden we appear to make a sudden lurch down as more open water introduces less than 15% covered sqaures and that 'permanent ice' blinking out?
With the central region I imagine more ice is lost to export than to melt in-situ. As we enter a time where both ocean entrances see rapid transition to open water ice has far more space to roam into as the season progresses ( and melt there in lower lat/warmer waters) leaving even more space for ice to drift into.
Early rapid melt of the peripherals and unfavourable winds could see the central ice 'drifted' away from the pole and so uncover lots of squares usually permanently ice covered?
The DMI 80N graph will be our first warning as it rises above the 'near freezing values' that the ice melt ( and latent heat of fusion) pegs it to.
Will it be this year?
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 20, 2018, 02:06:28 PM
The DMI 80N graph will be our first warning as it rises above the 'near freezing values' that the ice melt ( and latent heat of fusion) pegs it to.

I have to agree with this as the correct signal for a Blue Ocean Event rather than some arbitrary number.  When there is no longer enough ice to keep the temp in the far north pegged near 0 the Arctic will be effectively ice free.
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 20, 2018, 02:11:16 PM
I think that we have been nudging toward what will appear on paper as a 'sudden drop' in sea ice because of the changes going on in the central region and the way the 15% or more measure skews the picture?

I have also wondered if the extent measure was grossly underestimating the true loss of sea ice coverage. So I've been looking at area as well (NSIDC spreadsheets).

The answer is - no. Area decline tracks extent decline very closely. (In addition, since January 2008 the dreaded pole hole has been a mere 0.029 million km2 and so cannot screw up the data over the central arctic).

Mind you, I think at some time there will be a sudden extent/area drop when volume loss reduces the average thickness of remaining ice to n cms, where n is just under 1 metre? Mere speculation by a gerontocrat who might see it, or might not.

The graphs below are for September and March 1979 to 2017 averages. Similar or what.
Title: Re: Abrupt sea ice loss
Post by: Daniel B. on April 20, 2018, 03:50:57 PM
Yes, over time both area and extent have tracked each other quite well.  According to NSIDC, the seasonal difference between the two is due to melt ponds; area measurements see these as open water, while they are too small to be detected by extent.  Hence, summer area is proportionally lower than winter.  Hence, extent is more readily used.
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 20, 2018, 05:32:57 PM
Yes, over time both area and extent have tracked each other quite well.  According to NSIDC, the seasonal difference between the two is due to melt ponds; area measurements see these as open water, while they are too small to be detected by extent.  Hence, summer area is proportionally lower than winter.  Hence, extent is more readily used.

"True yeah, man" as we used to say in Liberia when I was there. BUT (there is always a "but" ), this thread is "Abrupt sea ice loss". The divergence of area from extent decline is modest over time.

What I am suggesting is that there is no historical data to support a major abrupt sea ice loss sustained over time. The 2007 and 2012 events have been submerged into the long-term trend. I admit that in both 2007 and 2012 I was at least half-convinced the tipping point had come. But it had not.

Wait and see? N'est ce pas?
Title: Re: Abrupt sea ice loss
Post by: Tor Bejnar on April 20, 2018, 06:36:31 PM
Just came across this old projection made soon after the 2012 record was achieved.  A lot of us on Neven's blog, at the time, thought this might come to pass.
(https://sites.google.com/site/arctischepinguin/home/piomas/grf/zero.png)
Note: 2018 would achieve < 1 million km2 per this projection.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 20, 2018, 06:48:33 PM
What I am suggesting is that there is no historical data to support a major abrupt sea ice loss sustained over time.

There might not be much historical evidence, but there is quite a bit of geological evidence.
Title: Re: Abrupt sea ice loss
Post by: Pmt111500 on April 20, 2018, 07:06:37 PM
What I am suggesting is that there is no historical data to support a major abrupt sea ice loss sustained over time.

There might not be much historical evidence, but there is quite a bit of geological evidence.


Plus the older ice has been mostly lost already.
Title: Re: Abrupt sea ice loss
Post by: RoxTheGeologist on April 20, 2018, 07:52:48 PM
What I am suggesting is that there is no historical data to support a major abrupt sea ice loss sustained over time.

There might not be much historical evidence, but there is quite a bit of geological evidence.


Plus the older ice has been mostly lost already.

It's really hard to define 'abrupt' geologically. That could mean 1000 years in the Pliocene or millions years in the Cambrian. If you want to get down to decade time scales,  then the only real resolution is in Quaternary ice logs.

e.g.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC34297/

where they have shown rapid changes occur over 40 years.
Title: Re: Abrupt sea ice loss
Post by: Wherestheice on April 21, 2018, 11:09:59 AM
could anyone provide some info on the current status of the multi-year ice in the arctic?
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 21, 2018, 12:18:23 PM
Found the attached maps in this Article. Not a lot of old ice left

http://nsidc.org/cryosphere/sotc/sea_ice.html

Note to the Maps:-
Old v. new ice in Arctic, March 1990 and 2016: These maps show sea ice age of late March 1990 (left) and 2016 (right), around the time of the winter maximum. Younger, thinner ice appears in shades of blue; older, thicker ice appears in shades of pale green and white. Ice-free ocean water is dark gray, and land areas are light gray. Image courtesy NOAA Climate.gov.
Title: Re: Abrupt sea ice loss
Post by: crandles on April 21, 2018, 12:19:45 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fnsidc.org%2Farcticseaicenews%2Ffiles%2F2018%2F03%2FFigure4-350x453.png&hash=8c80e9237accd4a53a7a21c81b39debd)
high res:
http://nsidc.org/arcticseaicenews/files/2018/03/Figure4.png

Quote
Figure 5. This figure shows the distribution of Arctic sea ice according to stage of development, , as of February 22, 2018. Pink shows new ice; purple shows young ice; blue shows first year thin ice; orange shows first year medium ice, red shows first year thick ice, brown shows old ice, and while shows glacial ice.

Credit: U.S. National Ice Center

.


(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fnsidc.org%2Farcticseaicenews%2Ffiles%2F1954%2F10%2Ffigure4b-350x469.png&hash=d16574e5e6e8692a1c293968e55c466d)
http://nsidc.org/arcticseaicenews/2017/10/
Quote
Figure 4b. Sea ice age distribution at the annual minimum extent for 1985 (upper left) and 2017 (upper right). Time series (bottom) of different age categories the minimum extent for 1985 to 2017. Note that the ice age product does not include ice in the Canadian Archipelago. Data from Tschudi et al., EASE-Grid Sea Ice Age, Version 3

Credit: W. Meier/National Snow and Ice Data Center, M. Tschudi et al.

Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 21, 2018, 12:29:25 PM
could anyone provide some info on the current status of the multi-year ice in the arctic?

And this :-
https://www.climate.gov/news-features/featured-images/2017-arctic-report-card-arctic-sea-ice-keeps-getting-younger-and

As reported in the 2017 Arctic Report Card, sea ice older than four winters made up 16 percent of the Arctic sea ice pack in March 1985. In March 2017, it made up less than 1 percent.  Meanwhile, first-year ice constituted roughly 55 percent of the Arctic sea ice pack in March through the 1980s. In March 2017, first-year ice comprised nearly 80 percent of the ice pack.

Title: Re: Abrupt sea ice loss
Post by: Shared Humanity on April 21, 2018, 02:00:58 PM
If the increase in stored heat in the oceans is the most significant factor in the long term loss of sea ice and some here have argued that it is, then the obvious progression of MYI to FYI all along the Pacific side of the Arctic must indicate a tremendous growth in ocean heat.
Title: Re: Abrupt sea ice loss
Post by: FishOutofWater on April 21, 2018, 02:56:27 PM
Yes, there has been a tremendous increase in ocean heat in the NH oceans and seas. The heat has worked its way into the Arctic seas.

(https://data.nodc.noaa.gov/woa/DATA_ANALYSIS/3M_HEAT_CONTENT/FIGURES/3month_heat/hc_20172017_10-12.jpg)

Compare that to what it was like sixty years ago.

(https://data.nodc.noaa.gov/woa/DATA_ANALYSIS/3M_HEAT_CONTENT/FIGURES/3month_heat/hc_19571957_10-12.jpg)
Title: Re: Abrupt sea ice loss
Post by: Rascal Dog on April 21, 2018, 02:57:16 PM
Reading this thread, I see two different issues somewhat confused.
1) Summer Arctic sea ice loss
2) Year round Arctic sea ice loss.

The first is discussed in https://doi.org/10.1016/j.quascirev.2013.10.022
This study suggests that there was a period of very low summer ice cover. This might be abrupt, but is a much smaller change to the climate system than winter loss of sea ice. Figure 5 shows that the modeled size of the abrupt change is roughly 0.5W/m^2, compared with double CO2 of 3.7 W/m^2. Also the ice cover impact is regional rather than global. We are likely to see most summer Arctic sea ice free by roughly mid-century, according to the IPCC and other sources.

The second is discussed in https://doi.org/10.1038/ncomms6608
The last time that the winter ice cover might have been not present was the mid Pliocene warm period. This is probably beyond 2100. The possible impacts are larger.
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 21, 2018, 03:15:17 PM
Reading this thread, I see two different issues somewhat confused.
1) Summer Arctic sea ice loss
2) Year round Arctic sea ice loss.

We are likely to see most summer Arctic sea ice free by roughly mid-century, according to the IPCC and other sources.

The last time that the winter ice cover might have been not present was the mid Pliocene warm period. This is probably beyond 2100. The possible impacts are larger.

The IPCC reports are a consensus, and have to get through a final process which is highly political. Each five years a new set of reports comes out, each time the dates seem to come somewhat closer. They also assume that CO2 mitigation efforts (and later BECCS etc) will happen on schedule. So far they have not - the Paris Accord commitments are insufficient to keep AGW below 2 degrees, and Government actions are already below those commitments.

The IPCC scenarios are also either completely lacking or optimistic about a host of other stuff - e.g. methane stored in the shallow Arctic Seas and the treeless high latitudes of Asia and Canada especially.

I probably am one of those comparative optimists who see a continuation of current rates of decline in extent/area/volume for some years yet.  But mid-century for ice-free summer and 2100 for ice-free winter? No - only if there is a vast investment by Governments in changing how the world works.
Title: Re: Abrupt sea ice loss
Post by: Rascal Dog on April 21, 2018, 03:54:43 PM
Quote
But mid-century for ice-free summer

I'll learn sometime how to be both brief and cover enough. OK, maybe not, I'm an old dog and that is a new trick.

There is a fairly tiny change of an ice-free summer any year now. There is a tiny chance the first ice free summer would be after 2060 or so. I wrote "mid-century", too brief. Even with perfect knowledge of the dynamics, random variations aka weather will vary the first summer of ice free by decades.

Year round Arctic sea ice free is a still harder problem.
Title: Re: Abrupt sea ice loss
Post by: Shared Humanity on April 21, 2018, 06:00:48 PM
With regards to year round ice free, I still have a very hard time trying to understand what would prevent ice forming in the long, relatively cold winter night any time soon. Would it look like today's ice? No. Will some form of ice form on large sections of the Arctic Ocean and peripheral sees? How could it not?
Title: Re: Abrupt sea ice loss
Post by: mitch on April 21, 2018, 06:39:45 PM
A year round ice free Arctic requires a couple of things: (1) relatively warm water coming into the Arctic Basin and sufficient stirring by storms to bury the large fresh water runoff into the basin, (2) relatively high greenhouse gases to provide a heat cap, and (3) development of winter cloud cover to trap outgoing heat. 

If it truly was ice-free in the early Pliocene, the estimated atmospheric CO2 content was about 400 ppm, like the last couple of years. However, the Pliocene oceans were a huge heat reservoir because the deep ocean was much warmer then.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 22, 2018, 12:21:41 AM
I'd like to point out that we have had a devil of a time trying to define "ice free."
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 22, 2018, 01:07:45 AM
If it truly was ice-free in the early Pliocene, the estimated atmospheric CO2 content was about 400 ppm, like the last couple of years. However, the Pliocene oceans were a huge heat reservoir because the deep ocean was much warmer then.

As in how much warmer? The data we have says that over 90% of heat trapped by additional CO2 ppm has been sucked up by the oceans over the last 50? 100? 200? years . Any sources to compare Pliocene global ocean heat content with today?

If that data does exist, it must be immensely important.
Title: Re: Abrupt sea ice loss
Post by: Wherestheice on April 22, 2018, 05:07:16 AM
Found the attached maps in this Article. Not a lot of old ice left

http://nsidc.org/cryosphere/sotc/sea_ice.html

Note to the Maps:-
Old v. new ice in Arctic, March 1990 and 2016: These maps show sea ice age of late March 1990 (left) and 2016 (right), around the time of the winter maximum. Younger, thinner ice appears in shades of blue; older, thicker ice appears in shades of pale green and white. Ice-free ocean water is dark gray, and land areas are light gray. Image courtesy NOAA Climate.gov.

Thank you!
Title: Re: Abrupt sea ice loss
Post by: Pmt111500 on April 22, 2018, 06:40:42 AM
Wouldn't the surface of the ice free Arctic Ocean at least at +5C to keep the mixing going on even in winters when no doubt some snow and hail would reach the surface? There would need to be a quite thick layer of it to completely melt the whole amout of 0 degree snow falling during the whole winter. The energy to melt the whole of sea ice in summer is already there but is there enough to keep incessant winter snow from freezing the surface, I much doubt it.
Title: Re: Abrupt sea ice loss
Post by: binntho on April 22, 2018, 07:35:27 AM
With regards to year round ice free, I still have a very hard time trying to understand what would prevent ice forming in the long, relatively cold winter night any time soon. Would it look like today's ice? No. Will some form of ice form on large sections of the Arctic Ocean and peripheral sees? How could it not?
Ocean currents could play a large part in any year-round ice free Arctic. As an example, it's cold enough at the moment for large areas to freeze over in the Chukchi sea at 70N. On the other side of the Pole, the north Atlantic is not freezing at 70N and hasn't for thousands of years. This year there is even a year-round patch of open ocean reaching to 80N north of Svalbard. Not only is it not freezing over but actually melting the steady stream of ice that moves into it from the north.

An ice-free Arctic in summer could change ocean dynamics sufficiently so that the seas will have a very hard time refreezing. Long-fetch waves could stir up warmth from below, and the warm currents might extend their reach further north.

Ice would presumably still form along the coasts and in sheltered areas, but an open Arctic may become too dynamic for refreeze, and higher ocean temperatures could keep air temperatures above the -11 or so needed for the ocean surface to freeze.

I think this is not an unlikely scenario, and it's the only mechanism I can see that could cause a year-round ice free arctic within the next century or more.
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 22, 2018, 01:56:31 PM
If it truly was ice-free in the early Pliocene, the estimated atmospheric CO2 content was about 400 ppm, like the last couple of years. However, the Pliocene oceans were a huge heat reservoir because the deep ocean was much warmer then.

As in how much warmer? The data we have says that over 90% of heat trapped by additional CO2 ppm has been sucked up by the oceans over the last 50? 100? 200? years . Any sources to compare Pliocene global ocean heat content with today?


So I've had a look at Global Ocean Heat (0-700 metres only so far) and thought about how much it might increase and from what source - the obvious being increases in ppm. The data I used is from NASA going back to 1959.

I attach 2 graphs - they are the same except for the trend line but both project global ocean heat increase as CO2 concentration rises to 450 ppm.

The first is linear and shows an increase of about 7 x 10^22 joules.

The first 2nd is polynomial (x2), has a much better R2 value of over 0.95, and shows an increase of about 20 x 10^22 joules, which is enough to fry just about everything. hence I called it the Armageddon Scenario.

By any measure the oceans have accumulated a lot of heat in the last 50 years. Do we have any data on the pliocene?

ps: I should not do this stuff with a hangover
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 22, 2018, 03:02:40 PM
ps: Quote from Polar Science Center (in PIOMAS monthly update)

Quote
"The energy required to melt the 16,400 Km3 of ice that are lost every year (1979-2010 average) from April to September as part of the natural annual cycle is about 5 x 1021 Joules.

To melt the additional 280 km3 of sea ice, the amount we have have been losing on an annual basis based on PIOMAS calculations, it takes roughly 8.6 x 1019 Joules"

In the year mid 2016 to mid 2017 global ocean heat content (0-700 metres) increased by 1.8 x 1022 Joules.

In other words the 2016-17 annual global heat increase was over 200 times the energy required to melt that 280 km3 of Arctic Sea ice.

IT makes one think, does it not?

Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on April 22, 2018, 04:32:43 PM
In other words the 2016-17 annual global heat increase was over 200 times the energy required to melt that 280 km3 of Arctic Sea ice.

IT makes one think, does it not?

If we take the size of the Arctic as an order of magnitude estimate of 10% of the world's ocean and ignore energy distribution issues that would indicate that we only have about 20 times as much energy available for melting rest of the ice cap than we need.

Getting that energy there is the questionable step, however, we have been seeing trains of storms into the Arctic lately.
Title: Re: Abrupt sea ice loss
Post by: mitch on April 22, 2018, 06:18:14 PM
On Pliocene ocean heat content--the data are pretty sparse prior to the Pleistocene.  What I can find has bottom water temperatures around 4-5 deg C prior to 4 million years ago versus about 2 deg C today.  This would represent the temperature to about 2 km depth, so roughly 3/4 of the ocean.  The Pliocene ocean had a very large ocean heat content that would stabilize the system. 
Title: Re: Abrupt sea ice loss
Post by: Sebastian Jones on April 22, 2018, 06:36:35 PM
On Pliocene ocean heat content--the data are pretty sparse prior to the Pleistocene.  What I can find has bottom water temperatures around 4-5 deg C prior to 4 million years ago versus about 2 deg C today.  This would represent the temperature to about 2 km depth, so roughly 3/4 of the ocean.  The Pliocene ocean had a very large ocean heat content that would stabilize the system. 
Wow! That is a massive amount of heat! I'm not as arithmetically inclined as Gerontocrat, so working out just how much heat is required to warm up the entire global ocean that much is beyond me ( I have a distressing tendency to lose or gain zeros...). I wonder if we have already "baked in" that amount of warming? My guess is no. How long would it take to warm this amount of water? Do you have a source for this?
Title: Re: Abrupt sea ice loss
Post by: gerontocrat on April 22, 2018, 07:06:38 PM
On Pliocene ocean heat content--the data are pretty sparse prior to the Pleistocene.  What I can find has bottom water temperatures around 4-5 deg C prior to 4 million years ago versus about 2 deg C today.  This would represent the temperature to about 2 km depth, so roughly 3/4 of the ocean.  The Pliocene ocean had a very large ocean heat content that would stabilize the system.

Average depth of the oceans is, I think, about 3.8 kms. The increase in average ocean temperatures ( 0-2000 metres) in the last 60 years is only about 0.1 degrees celsius. So the Pliocene ocean was incredibly warm ?

(Isn't it great when stuff one saved ages ago actually becomes of use)
Title: Re: Abrupt sea ice loss
Post by: binntho on April 23, 2018, 07:29:31 AM
Although not directly linked to sea ice loss, this article by Dr. David Page might be of interest - if what he says is correct, we may see significant changes in the whole planet, not only the Arctic.
http://arctic-news.blogspot.it/
Title: Re: Abrupt sea ice loss
Post by: Stephan on May 18, 2018, 09:17:39 PM
In other words the 2016-17 annual global heat increase was over 200 times the energy required to melt that 280 km3 of Arctic Sea ice.

IT makes one think, does it not?

If we take the size of the Arctic as an order of magnitude estimate of 10% of the world's ocean and ignore energy distribution issues that would indicate that we only have about 20 times as much energy available for melting rest of the ice cap than we need.

Getting that energy there is the questionable step, however, we have been seeing trains of storms into the Arctic lately.

;-)  This could be achieved much easier. Let's charter one million big container ships and fill them with warm subtropical Atlantic or Pacific water and get them up towards to the pole to release it there. These ships will run with dirty diesel oil, and their big energy consumption may be visible both in the Keeling curve as well as in a thin layer of soot that they exhaust...
Title: Re: Abrupt sea ice loss
Post by: Alexander555 on May 18, 2018, 09:50:39 PM
I don't think you need a million ships for that. That ice on the Arctic serves as a refrigerator for a big part of all the seas on this planet. And lets assume that the sea will release that heat if the air/water close to it is colder. And as far as i see it, we are not far from the point that the sea is going to hold much more heat than what it's doing today. When the arctic warms further. And the problem is that in many places far from the north pole it will also become harder to relace that heat. Because they are all getting warmer. It's not so long that i have been looking to these Climate reanaliser anomaly pics, maybe a little more than six months. But that area north of the equator is always brown, the full six monts. For the moment there is a little blue in the north of Africa. But in general it's even less. It's because of these 2 extremes that the sea is going to store more heat. That means it's going to get warmer. At least , that's what i think. But i can be wrong. But i think it's going to get warmer faster in the next years.
Title: Re: Abrupt sea ice loss
Post by: Stephan on May 18, 2018, 10:27:25 PM
It is for sure much more complicated. Looking at (air) temperature anomalies is of course not sufficient. And to use only the sea surface temperature is also not sufficient. The whole water body must be looked at - and I am pretty sure that there is a lot of un-knowns or at least un-certainties when it comes down to a precise analysis of temperature gradient and its change in deeper seas worldwide. But I think your analysis of a faster-and-faster increasing temperature (at least worldwide averaged) is correct. And in some years to come the water temperatures in the (deeper) Arctic Ocean are high enough to damage the ice from below to such an extent that the thickness can't increase even if the air temperature in winter is very low. Also the quality and physical stability of the ice-pack has already declined (see the reports of expeditions to the North Pole which become shorter because there is not sufficient ice stability for helicopters or small airplanes).
So once the time will come that the ice is so weak and thin that certain events like huge storms very far in the north or wavy jet streams that pull a lot of mild moist air towards the pole have an easy game to push most of the ice away in a short period of time...
Title: Re: Abrupt sea ice loss
Post by: GoSouthYoungins on May 19, 2018, 12:19:33 AM
It seems to me abrupt loss will happen soon. Maybe this year, almost definitely in the next 5 years.  Atmospheric temps keep rising rapidly. Ocean temps keep rising rapidly. The Pacific and Atlantic encroach on the Arctic more and more each year. The thick old stuff north of greenland and the CAA finally met its end last summer. FASTER THAN FORECAST, and by an absurd margin. The arctic is currently like barely refrozen slushy. And this year summer appears to be about two weeks early.

Maybe an unexpected negative feedback changes everything: cloudy summers with clear winters, or the AMOC starts dumping heat farther south. Seems unlikely.
Title: Re: Abrupt sea ice loss
Post by: Dharma Rupa on May 19, 2018, 01:54:45 AM
And as far as i see it, we are not far from the point that the sea is going to hold much more heat than what it's doing today.

The Arctic Ocean already has plenty of heat about 50 meters from the surface, and decreasing.
Title: Re: Abrupt sea ice loss
Post by: jdallen on May 19, 2018, 04:59:47 AM
And as far as i see it, we are not far from the point that the sea is going to hold much more heat than what it's doing today.

The Arctic Ocean already has plenty of heat about 50 meters from the surface, and decreasing.
Overall, total ocean enthalpy is rising by about 10 Zetajoules a year (10^22).  That's about 20 times  current total annual world energy consumption.
Title: Re: Abrupt sea ice loss
Post by: litesong on May 21, 2018, 05:13:05 PM
The increase in average ocean temperatures ( 0-2000 metres) in the last 60 years is....about 0.1 degrees celsius.
Hi gerontocrat.....On other websites (dominated by AGW deniers), I've considered the following (& been pooh poohed):
The present Arctic sea ice has reduced by almost 2 million square kilometers(AGW generated) since the 1980's, while the sun is at its highest elevation above the Arctic horizon. Arctic Ocean absorption of solar energy has increased. Now, wherever there are downwellings within these excess AGW generated Arctic sea waters(not ice any longer), excess AGW heat is transported to Arctic continental shelves or into the Arctic Ocean depths for long term storage.
This would be one mechanism for the Arctic Ocean to be even warmer than the average global ocean water temperature increase.
Title: Re: Abrupt sea ice loss
Post by: magnamentis on May 22, 2018, 12:58:10 AM
The increase in average ocean temperatures ( 0-2000 metres) in the last 60 years is....about 0.1 degrees celsius.
Hi gerontocrat.....On other websites (dominated by AGW deniers), I've considered the following (& been pooh poohed):

[humor]

don't be masochistic ( posting in their forums ) LOL

[/humor]
Title: Re: Abrupt sea ice loss
Post by: litesong on May 22, 2018, 03:44:39 AM
....don't be masochistic ( posting in their forums ).....
That could be true. B-B-B-b-b-but, look what I found out!!! AGW deniers, when they try to use mathematics, have made errors as great as 1000 TIMES, 500 million TIMES & the greatest error was 1,000,000,000,000,000 TIMES.
 Yeah, gerontocrat has the right idea. Beat them up with mathematics.
Title: Re: Abrupt sea ice loss
Post by: magnamentis on May 22, 2018, 08:49:26 PM
....don't be masochistic ( posting in their forums ).....
That could be true. B-B-B-b-b-but, look what I found out!!! AGW deniers, when they try to use mathematics, have made errors as great as 1000 TIMES, 500 million TIMES & the greatest error was 1,000,000,000,000,000 TIMES.
 Yeah, gerontocrat has the right idea. Beat them up with mathematics.

it was kidding, to join the lion's cage is brave and a valid option of course, i just can't digest too much of their arguments and the reason is not even sea-ice related only.

people who deny global warming and the human role in the pace of that GW, are not only having a very horrible impact to this planet and it's inhabitants in this context. they're often the same people who are as major mass directly or indirectly responsible for many other catastrophic developments, last but not least violence, crimes, wars, mobbing, racism, terrorism and i.e. school shootings.

many of them are psychopaths or close to that IMO and they hide behind the fact that they're in many cases a majority and then it's the same majority that votes and elects our "rulers" i.e. the donald and and the GWB with his puppet players like Dicky Ch.
Title: Re: Abrupt sea ice loss
Post by: sophiewilson0191 on June 08, 2018, 05:01:26 AM
Climate Change becomes a big problem all over the world.
The most affected creatures are the animals.
New Research Combats The Poor Reasoning that Influences Climate-Change Denial (https://www.evolving-science.com/environment/new-research-combats-poor-reasoning-influences-climate-change-denial-00583)
Title: Re: Abrupt sea ice loss
Post by: Cid_Yama on June 17, 2018, 12:42:45 PM
Seems that there are many that don't grok that the ice loss will be non-linear.