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Author Topic: Study: Loss of Arctic's Reflective Sea Ice Will Advance Global Warming by 25 Yrs  (Read 1150 times)

TeaPotty

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Loss of Arctic's Reflective Sea Ice Will Advance Global Warming by 25 Years
https://scripps.ucsd.edu/news/research-highlight-loss-arctics-reflective-sea-ice-will-advance-global-warming-25-years

Quote
Losing the remaining Arctic sea ice and its ability to reflect incoming solar energy back to space would be equivalent to adding one trillion tons of CO2 to the atmosphere... this roughly equates to 25 years of global CO2 emissions.

The authors of the study conclude that the loss of sea ice will add a globally-averaged 0.7 watts per square meter (W/m2) of solar heating to the Earth system, 0.21 W/m2 of which has already occurred between 1979 and 2016... equivalent to an increase in CO2 concentration from 400 to 456.7 parts per million... It would advance global warming by 25 years

TerryM

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Loss of Arctic's Reflective Sea Ice Will Advance Global Warming by 25 Years
https://scripps.ucsd.edu/news/research-highlight-loss-arctics-reflective-sea-ice-will-advance-global-warming-25-years

Quote
Losing the remaining Arctic sea ice and its ability to reflect incoming solar energy back to space would be equivalent to adding one trillion tons of CO2 to the atmosphere... this roughly equates to 25 years of global CO2 emissions.

The authors of the study conclude that the loss of sea ice will add a globally-averaged 0.7 watts per square meter (W/m2) of solar heating to the Earth system, 0.21 W/m2 of which has already occurred between 1979 and 2016... equivalent to an increase in CO2 concentration from 400 to 456.7 parts per million... It would advance global warming by 25 years


Sounds reasonable :(
When the last ice has melted in the cooler it's time for a run to the beer store (and that's without albedo)!
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Rod

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These studies are always very interesting.  We all agree that the loss of the sea ice will be very bad. However, the authors assumed that the amount of cloud cover would remain constant.

That does not seem accurate based upon what we have observed.  As more open water is formed, the clouds quickly form above it.  Additionally, by the time large amounts of ice have melted, solar insulation has started to decrease significantly. 

Albedo is not the only important cooling function the ice provides.  The latent heat of fusion seems much more important based on my observations as a layperson. 

In any event, losing the sea ice will be very bad and we should all hope it does not happen. 


petm

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Makes me wonder how much it will add once the knock-on effects of reduced / eliminated land snow cover are included...

nanning

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<snippage>
In any event, losing the sea ice will be very bad and we should all hope it does not happen.
Hi Rod, I don't understand what you mean.
We know the sea ice will vanish in the not-too-distant future. What do you mean by hope?
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Archimid

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Any free links to the article?

The global effect of an ice less arctic is not very significant to me. I want to know the local effect not the global. The local effect is the real threat.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.


Rich

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Hi Rod, I don't understand what you mean.
We know the sea ice will vanish in the not-too-distant future. What do you mean by hope?
[/quote]

I think doomers refer to it as hopium.

DrTskoul

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Hi Rod, I don't understand what you mean.
We know the sea ice will vanish in the not-too-distant future. What do you mean by hope?

I think doomers refer to it as hopium.
[/quote]

Simple , pray we are lucky that some unknown mechanism will manifest itself to save the ice.

Archimid

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Not free. I followed your link, had to log in ( give information) and then directly request access to the paper. Haven't received it yet.

Here is the abstract of the paper:
Quote
During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years.

From here:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL082914
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nanning

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<snippage>
Simple , pray we are lucky that some unknown mechanism will manifest itself to save the ice.
Thank you, I had to laugh out loud for some time.
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crandles

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Quote
Hence, we focus on the baseline estimate scenario in which cloud conditions remain unchanged from the present. We find that the complete disappearance of Arctic sea ice throughout the sunlit part of the year in this scenario would cause the average planetary albedo of the Arctic Ocean (poleward of 60◦N) to decrease by 11.5% in absolute terms. This would add an additional 21 W/m2 of annual-mean solar heating over the Arctic Ocean relative to the 1979 baseline state. Averaged over the globe, this implies a global radiative heating of 0.71 W/m2 (Figure 2).

So it appears they are looking at the sunlit part of the year only.

The albedo impact is substantial during the summer leading to less ice. But we also know the effect of less ice in the winter is a loss of more heat due to less insulation by the ice.

If these are not netted off, is this just a way of saying albedo feedback is positive, things are going to get worse while ignoring the negative feedback(s)? Should we avoid getting carried away and dislike the 'equivalent to one trillion tons of CO2 emissions or 25 years of emissions' as misleading?

Or am I not understanding?



kassy

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Quote
Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year.

They are calculating the max result of the measurement not real earth conditions.
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Archimid

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This is what I wanted to know.

Quote
We find that the complete disappearance of Arctic sea ice throughout the sunlit part of the year in this scenario would cause the average planetary albedo of the Arctic Ocean (poleward of 60◦N) to decrease by 11.5% in absolute terms. This would add an additional 21 W/m2 of annual-mean solar heating over the Arctic Ocean relative to the 1979 baseline state.


I just finished a quick skim of the paper. That acceleration of global warming is by solar insolation alone.  It seems to me that they should've added enthalpy warming as well.

I would have love to see much of the analyses with respect to local temperatures and how 21W/m2 + enthalpy  compare with the local records.

Also, make sure to take a good look at Figure 1.
« Last Edit: July 28, 2019, 08:42:07 PM by Archimid »
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FishOutofWater

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Crandles, the increase in heat transfer from the ocean to the atmosphere when ice is thinner does not "net off" in terms of heat in the atmosphere. Yes, most of that heat eventually radiates out to space but before it does fall and winter temperatures in the Arctic are pushed upwards. The effects of less ice in the Bering, Chukchi and Beaufort seas have been pronounced over the past 5 years in Alaska. They have had several extraordinarily warm winters and late falls.

The ongoing build up of heat in the summer water layer in the Chukchi and Beaufort seas indicates that there is carry over from one warm summer to the next.

Obviously, the researchers simplified the problem so we should be careful about overextending the results, but your criticism misses some key issues about the build up of heat in the Arctic ocean/ice/atmosphere system.

philopek

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Crandles, the increase in heat transfer from the ocean to the atmosphere when ice is thinner does not "net off" in terms of heat in the atmosphere. Yes, most of that heat eventually radiates out to space but before it does fall and winter temperatures in the Arctic are pushed upwards. The effects of less ice in the Bering, Chukchi and Beaufort seas have been pronounced over the past 5 years in Alaska. They have had several extraordinarily warm winters and late falls.

The ongoing build up of heat in the summer water layer in the Chukchi and Beaufort seas indicates that there is carry over from one warm summer to the next.

Obviously, the researchers simplified the problem so we should be careful about overextending the results, but your criticism misses some key issues about the build up of heat in the Arctic ocean/ice/atmosphere system.

This and then in case of open water and considering the water was not open for just a few days in it's entirety, there is quite an amount of extra heat previously accumulated in the water and starting temps can be significantly higher, even much higher the more south or north, depending.

That means that a lot of this extra heat-loss will be extra-heat, means that part will not have an impact on the net balance but will have a significant impact on freezing onset in wide parts and that will influence the maximum thickness at the end of the freezing season and therefore impact the following melting season etc.

I think that this is part of what we are already able to observe during the last few years.

Last but not least there will be A LOT more moisture in the air and that again will impact the heat loss negatively for ice building and thickening.

Open water means oceanic climate and ice-cover yearlong means a dry desert in winter.

After all it will/does most probably depend on the relation between open water and remaining ice cover, kind of a tipping point, could be a soft tipping point instead of sudden death and the likes.

IMO we are exactly at that tipping point, slightly more and slightly earlier open water and
the system will topple towards a significantly different system. Which exactly i can't tell
could be something we know from lower latitudes but could be something entirely new.
« Last Edit: July 28, 2019, 09:59:40 PM by philopek »

crandles

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Crandles, the increase in heat transfer from the ocean to the atmosphere when ice is thinner does not "net off" in terms of heat in the atmosphere. Yes, most of that heat eventually radiates out to space but before it does fall and winter temperatures in the Arctic are pushed upwards. The effects of less ice in the Bering, Chukchi and Beaufort seas have been pronounced over the past 5 years in Alaska. They have had several extraordinarily warm winters and late falls.

The ongoing build up of heat in the summer water layer in the Chukchi and Beaufort seas indicates that there is carry over from one warm summer to the next.

Obviously, the researchers simplified the problem so we should be careful about overextending the results, but your criticism misses some key issues about the build up of heat in the Arctic ocean/ice/atmosphere system.

IMO we are exactly at that tipping point, slightly more and slightly earlier open water and
the system will topple towards a significantly different system. Which exactly i can't tell
could be something we know from lower latitudes but could be something entirely new.

Can't disagree with
"most of that heat eventually radiates out to space"

>"but before it does fall {and winter} temperatures in the Arctic are pushed upwards."

Can't disagree with the fall part, significant warming then.

Winter temperatures? Well, yes there has been rises and there will continue to be rises as GHGs increase and ice thickness decreases but significant warming like September/October from albedo effects over summer, well not hugely yet: Needs to delay freeze onset by about as much again as it has been delayed over last 30 years or so. I suspect the second month of delay will be harder to achieve than the first month of delay. Looking out in peripheral regions the freeze onset is later anyway so yes some of this effect will be pushing into December there. I expect there to be some ice edge retreat, so not sure I see this as particularly challenging to the idea that the winter feedbacks are also strong (stronger than many here seem to want to accept).

Different temperature pattern may well have significant effect on ecosystems.
so re "misses some key issues", yes well worth mentioning.

But the effect on net of melt and freeze....

>"IMO we are exactly at that tipping point, slightly more and slightly earlier open water and
the system will topple towards a significantly different system."

Ecosystems may well change dramatically. But as for the ice, I firmly believe the science is saying we are not close to a tipping point.


philopek

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Ecosystems may well change dramatically. But as for the ice, I firmly believe the science is saying we are not close to a tipping point.

Thanks for this info, i thought it could be but the assumption was not based on more than observing the last 3 years.

Good to know that it's probably different than what i assumed, always good to learn things from those with more insight.

TeaPotty

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Thanx petm! ;D

For the free full text try this:
http://eisenman.ucsd.edu/papers/Pistone-Eisenman-Ramanathan-2019.pdf


(NB: In general, use Google Scholar to search for free versions.)

Archimid

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I hope you all noticed Figure 1.

I'll post a quick snap here just in case you don't want to click.
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crandles

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I hope you all noticed Figure 1.

I'll post a quick snap here just in case you don't want to click.

Seems just like the IPCC said:

Global warming of 1.5C IPCC draft report

Quote
Sea-ice coverage and thickness also decrease in CMIP5-model simulations of the recent past, and are projected to decrease in the future (Collins et al., 2013). However, the modeled sea-ice loss in most CMIP5 models is much weaker than observed. Compared to observations, the simulations are weak in terms of their sensitivity to both global mean temperature rise (Rosenblum and Eisenman, 2017) and to anthropogenic CO2 emissions (Notz and Stroeve, 2016). This mismatch between the observed and modeled sensitivity of Arctic sea ice implies that the multi-model-mean response of future sea-ice evolution probably underestimates the sea-ice loss for a given amount of global warming. To address this issue, studies estimating the future evolution of Arctic sea ice tend to bias correct the model simulations...

Who'd have thunk it, supporting evidence for what the IPCC says  ;) [/sarc]

jai mitchell

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note to all,

The study is looking at annual average increases in radiative forcing as a result from summer albedo decrease.  The article references an earlier study that found the arctic forcing was 6.4 Watts per meter squared. 

Nasa using the same data found that the summer season radiative forcing over the same period in the Barents Sea was 60 Watts per meter squared. 

So the total forcing globally of 0.7 Watts per meter squared is globally and annually averaged.

Note that they are not looking at the 8C of regional fall warming in the arctic that will massively increase permafrost emissions at this stage of Arctic decline.
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