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Author Topic: How soon could we go ice free?  (Read 13360 times)

Cid_Yama

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Re: How soon could we go ice free?
« Reply #50 on: May 31, 2017, 02:33:10 PM »
magnamentis, that's the ability for warm-blooded creatures (including us) to lose metabolic heat.  If we cannot lose the heat generated by our own metabolic processes, we experience cell death both apoptotic and necrotic, leading to death.  Any place that experiences temperatures that make it thermodynamically impossible to lose metabolic heat, even for a few hours, becomes uninhabitable.

Parts of Iran, Pakistan and India have already come close. 

Pi26

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Re: How soon could we go ice free?
« Reply #51 on: May 31, 2017, 03:23:13 PM »
magnamentis, that's the ability for warm-blooded creatures (including us) to lose metabolic heat.  If we cannot lose the heat generated by our own metabolic processes, we experience cell death both apoptotic and necrotic, leading to death.  Any place that experiences temperatures that make it thermodynamically impossible to lose metabolic heat, even for a few hours, becomes uninhabitable.

Parts of Iran, Pakistan and India have already come close.

...See also:

https://www.nytimes.com/2015/06/07/opinion/sunday/the-deadly-combination-of-heat-and-humidity.html?_r=0


http://petergardner.info/2017/01/wet-bulb-temperatures-and-an-uninhabitable-earth/

binntho

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Re: How soon could we go ice free?
« Reply #52 on: May 31, 2017, 03:54:10 PM »
This is I presume based on the wet-bulb temperature which takes into account both temperature and humidity.

I remember reading that in the heat wave in India last year the wet-bulb temperature was very close to the "fatal" zone of 35C, which can be reached by e.g. 46C temperature and 50% humidity (or 35C temperature and 100% humidity). Looking at Wikipedia, a heatwave in Iran and Iraq last year reached wet-bulb temperatures of 38,4C .

With increased warming, both temperature and humidity are set to rise, although not sure about relative humidity.

Archimid

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Re: How soon could we go ice free?
« Reply #53 on: May 31, 2017, 07:35:18 PM »
The human body is an engine. A machine that uses energy (food) to do work with the inevitable by product of heat. It has an optimal operating temperature as well as thermal limits both high and low. The average human operating temperature is 37C.

The human engine also has a cooling system whose principal components are skin, water and the surface area of the body. The human cooling system works by transferring heat from the body to the environment by means of perspiration, conduction and radiation. Like all other cooling systems a gradient must exist to transfer the heat. When the environment is hotter than the human engine radiation, conduction and convection work against the body. At that point excess heat is transferred to the environment by perspiration alone.

Water is a vital component of the cooling system both inside the human engine and in the environment. When the environmental temperature is higher than 37C the evaporation of water is the only way to cool the engine. Even at temperatures of  45C the human body can operate by evaporating heat away.  That's when water in the environment plays a role. The more water in the environment the more difficult to evaporate water excreted by the skin. 




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Jim Williams

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Re: How soon could we go ice free?
« Reply #54 on: May 31, 2017, 08:11:03 PM »
I don't quite know how the conversation got here, but the usual solution warm blooded animals use for both extreme heat and extreme cold is to burrow underground where the temperatures tend to be much more consistent.

This has already been happening in several places, such as Montreal and Australia.

crandles

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Re: How soon could we go ice free?
« Reply #55 on: May 31, 2017, 08:53:39 PM »
8C in 83 years would be incredibly rapid warming. That is about 5 times faster than current fast rates of warming which would likely require somewhere near 5 times the forcing. Oceans have enormous thermal inertia and take an awful long time to warm up.

So 7C to create zone of habitability is not really in lifetime of anyone reading and understanding this unless you get a really strong clathrate gun runaway scenario which is not expected.

May as well worry about sun blowing up or a giant asteroid impacting Earth, they are highly unlikely events.

Long before we get to areas of uninhabitability, we perhaps should be concerned about weather patterns ruining harvests. Even with this while one crop in one country can take a hammering, it is rare for many countries to be hit similarly and if one crop does badly another crop may do well. So it would take extraordinary weather weirding to cut all crop production by 50%. And even with that, we waste about 50% of food and you can bet if crop yield fell dramatically that wasted food would suddenly be viewed as important and carefully managed and people would start planting more food crops in their gardens.

So civilisation/society may well be fairly resilient to dramatic weather weirding.

Jim Williams

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Re: How soon could we go ice free?
« Reply #56 on: May 31, 2017, 09:15:23 PM »
Long before we get to areas of uninhabitability...
While I basically agree with you I think I would say "general uninhabitability" here rather than "areas."  I think there are a few "hot spots" where we might see significant die-offs.

gerontocrat

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Re: How soon could we go ice free?
« Reply #57 on: May 31, 2017, 09:24:51 PM »
Is there not a thread about livability somewhere.
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wili

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Re: How soon could we go ice free?
« Reply #58 on: May 31, 2017, 09:39:30 PM »
Arch wrote: "Even at temperatures of  45C the human body can operate by evaporating heat away."

Not at high humidity levels. Even at 35C, the human body can not evaporate heat away if the humidity is 100%. This is very well established science. If you have a different take, please go get it published in a major science journal. I'm sure many will be deeply impressed by your knowledge there.  ::)

Crandles, note that Cid's article was the first to come out about ten years ago. Since then, as I pointed out, many places have nearly hit the 35C wbt point, and more will inevitably follow. I believe follow up studies have concluded that we will not have to wait for a 7C global temp above pre-industrial levels to start seeing areas reaching and exceeding this figure, but don't have time right now to track them down.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Archimid

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Re: How soon could we go ice free?
« Reply #59 on: May 31, 2017, 10:34:56 PM »
Arch wrote: "Even at temperatures of  45C the human body can operate by evaporating heat away."

Not at high humidity levels. Even at 35C, the human body can not evaporate heat away if the humidity is 100%. This is very well established science.

Of course. I thought that was implied in the last sentence. "The more water in the environment the more difficult to evaporate water excreted by the skin." But you are correct. Thanks for the clarification.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Neven

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Re: How soon could we go ice free?
« Reply #60 on: May 31, 2017, 10:36:31 PM »
Hmmm, maybe I should change the thread title to 'How soon could we go sweat-free?'.  ;)
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Archimid

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Re: How soon could we go ice free?
« Reply #61 on: May 31, 2017, 11:34:37 PM »
My apologies Neven. I could write more to bring it back on topic but the leap is too large. I would like to make points about heat conditioning of the human body, anomaly distribution by latitude and the danger of flash heat wave being greater than that of average temperature but that would get me only to global warming. To get back to how soon we go ice free  I would have to make some heavy contortions. Mod away.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Pi26

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Re: How soon could we go ice free?
« Reply #62 on: June 01, 2017, 12:40:22 AM »
Hmmm, maybe I should change the thread title to 'How soon could we go sweat-free?'.  ;)


But not before year 3500?

magnamentis

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Re: How soon could we go ice free?
« Reply #63 on: June 01, 2017, 02:57:03 AM »
magnamentis, that's the ability for warm-blooded creatures (including us) to lose metabolic heat.  If we cannot lose the heat generated by our own metabolic processes, we experience cell death both apoptotic and necrotic, leading to death.  Any place that experiences temperatures that make it thermodynamically impossible to lose metabolic heat, even for a few hours, becomes uninhabitable.

Parts of Iran, Pakistan and India have already come close.

i think that's more or less what i said or at least wanted to point at, just that i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid (humidity is a key factor beside heat) that's where we disagree, not the physical process itself i'm fully aware of that, basic knowledge IMO
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wili

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Re: How soon could we go ice free?
« Reply #64 on: June 01, 2017, 04:52:01 AM »
mag, I'm afraid I am finding your prose incomprehensible. Specifically:

"..i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid..."

you don't think we (which we) are at what limit to do what exactly?

Billions living in hotter more humid [conditions?] that what?

Are you intending to be 'not even wrong' here?

https://en.wikipedia.org/wiki/Not_even_wrong
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Tetra

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Re: How soon could we go ice free?
« Reply #65 on: June 01, 2017, 08:33:06 AM »
Could we get a big melt out in June and be ice free by July?

Based on Nares being open, Chukchi and Beaufort melting early, and chances for high export of thick ice via Fram?

That and the fact many areas will be open water in high summer for the first time.

I'm so stressed over this...we could all be dead in months. Definitely don't have a year left.

seaicesailor

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Re: How soon could we go ice free?
« Reply #66 on: June 01, 2017, 08:57:28 AM »
Wasn't this the theme of the OP? Aw man not start again

Andreas T

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Re: How soon could we go ice free?
« Reply #67 on: June 01, 2017, 09:32:11 AM »
mag, I'm afraid I am finding your prose incomprehensible. Specifically:

"..i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid..."

you don't think we (which we) are at what limit to do what exactly?

Billions living in hotter more humid [conditions?] that what?

Are you intending to be 'not even wrong' here?

https://en.wikipedia.org/wiki/Not_even_wrong
If you look at magnamentis' (is that latin for "grosskopfert"?) almost one thousand posts you will see he is never wrong  ;)

be cause

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Re: How soon could we go ice free?
« Reply #68 on: June 01, 2017, 11:45:28 AM »
Come on Tetra,pack it in ...
be the cause of only good
and love all beings as you should
and the 'God' of all Creation
will .. through you .. transform all nations :)

oren

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Re: How soon could we go ice free?
« Reply #69 on: June 01, 2017, 12:02:49 PM »
Could we get a big melt out in June and be ice free by July?

Based on Nares being open, Chukchi and Beaufort melting early, and chances for high export of thick ice via Fram?

That and the fact many areas will be open water in high summer for the first time.

I'm so stressed over this...we could all be dead in months. Definitely don't have a year left.
Tetra seriously, enough with this shite. No we will not have ice free in July. And even if we do by some celestial intervention, no we will not all be dead within months. Stop it. I would stronly suggest that you follow the melting season thread for several months, at the end of which you will be much smarter, and meanwhile just lurk quietly.
If you wish to smarten up more quickly, go read the 2016 melting season thread from its beginning, read through every post, and imagine it's 2017 as you go along. You will get a very good feel for how it goes.
btw, Beaufort was worse in 2016, and Nares was worse in 2007. We are still alive.

Tetra

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Re: How soon could we go ice free?
« Reply #70 on: June 01, 2017, 12:07:36 PM »
Okay. I will do that.

Self imposed exile until I learn to get a grip on myself.


magnamentis

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Re: How soon could we go ice free?
« Reply #71 on: June 01, 2017, 02:30:52 PM »
mag, I'm afraid I am finding your prose incomprehensible. Specifically:

"..i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid..."

you don't think we (which we) are at what limit to do what exactly?

Billions living in hotter more humid [conditions?] that what?

Are you intending to be 'not even wrong' here?

https://en.wikipedia.org/wiki/Not_even_wrong
If you look at magnamentis' (is that latin for "grosskopfert"?) almost one thousand posts you will see he is never wrong  ;)

a very bad translation and a false conclusion. we mostly learn through errors, mistakes and awareness of ignorance (of what we don't know), hence the opposite is the case because
great minds are only great in comparison to small narrow minds but still extremely ignorant and small when it comes to universally available knowledge, especially with a bit of imagination and phantasy.

further the correct translation of the latin term is not something i will apologize for, those who know me can assess whether it's true or "grosskopfert" and for all others only envy or the fear it might be true can hold as an explanation to make such poisoned statement. since that grosskopfert word is an austrian word it would probably suffice to provide some kind of a "Title" to satisfy some specific needs  for the "schmäh" LOL but this is not the place where i have to do that while of course it's there.

all my nicknames have not been invented by myself, there are more of that kind while this one provides the best energy and is less blunt. how i calculate that is another story LOL but normally those who can translate from latin have less problems with other fellow humans of their kind while exceptions exist for everything.
http://magnamentis.com
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Cid_Yama

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Re: How soon could we go ice free?
« Reply #72 on: June 01, 2017, 04:46:55 PM »
Swell-headed?

Use of the archaic form of fantasy seems a bit pedantic.  Unless, of course, you just misspelled it.

Just yanking your chain.   ;D
« Last Edit: June 01, 2017, 05:54:28 PM by Cid_Yama »

Ned W

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Re: How soon could we go ice free?
« Reply #73 on: June 14, 2018, 04:20:12 PM »
I'm moving this discussion here, per Neven's observation that it was off-topic in the "2018 melt season" thread:

I think a large part of the issue here is that most scientists acknowledge that they cannot be sure how complex systems will respond to stresses in the future, and therefore they speak and write in terms of probability.  Thus Archimid states there is a chance, but only a very low chance that the Arctic would melt out this year, and that the probability increases in future years as the Earth (probably) warms up.  It really is the only sensible way to speak of the future.  If we toss ten pennies, it is unlikely that all ten will come up heads, but it is also possible, and we can assign a (low) numerical probability to that.

It is difficult to predict possible outcomes in the case of huge natural systems like the Arctic, but we can ascribe probabilities based upon trends, algorithms, computer models etc.  Then the experts argue about it all, gather more evidence and recalibrate their predictions, which is how it should be in science.  And we continue to be surprised, and often humbled, by how the planet and the Arctic responds.

Quote
No chance of an ice-free Arctic for at least 20 years.

That is false. There is a very low chance this year, increasing  every year that gets warmer and the weather more extreme. Saying there is no chance it will happen before 2037 is simply not true.
This year the uncertainties are the early opening of the Bering, a thin CAB, no ice North of Svalbard and the ever present warmer planet.
What if I said 15 years instead? Would that satisfy you?
There really is no chance of an ice-free Arctic for at least 15 years, but probably more like 20 years. The ice extent will continue to extend in winter, and will continue to bulge up and thicken against the CAA and Greenland. That the whole thing could be less than 15% in a few years is unlikely.
Much smaller ice-pack bunching up? Yes.
Zero ice-pack anywhere, and just some icebergs distantly floating around? No chance.

Here's one way to think about this.  First, here's the historical record of JAXA annual (daily) minima:



The blue zigzag line are the actual observations, the green smooth line is a LOESS smoothing function with a 10-year timescale, the red smooth line is a 30-year LOESS function, and the blue dot with error bars is the current forecast for 2018.

That graph suggests a variety of possible future scenarios.  Here are four examples or "scenarios".  The first scenario is based on the idea that the 10-year LOESS model (green line above) shows a "stepwise" decrease, where extent drops sharply for a few years, then levels off for a few years, then drops again:



In that scenario, the ice could be around a lot longer than most of us expect -- potentially, there might not be an "ice-free" day (let alone month or summer) until 2080 or later.

If we focus instead on the red line (30-year LOESS) from the first graph, it tells a different story -- a slow decrease in the 1980s and 1990s, followed by a slightly faster decrease after 2000, with the apparent "flattening" over the past decade being just noise.  In my scenario 2 below, the post-2000 decrease continues unabated:



This scenario has an "ice-free" day sometime around 2035-2055.

A third scenario assumes that in 2020 we have another downward "bend" like in 2000, followed by a steeper loss of ice:



That suggests an "ice-free" day somewhat earlier, between 2030-2040. 

Finally, a fourth scenario, that basically ignores the historical record and assumes that the ice suddenly collapses after 2020:



Personally, I think scenario 3 is most likely.  I would expect to see "ice-free" days in September routinely by the mid-2030s, with the first one perhaps occurring only 10-15 years from now given the apparent increase in interannual variability.

After that, I would rate scenario 2 as next-most likely, with scenarios 1 and 4 as potentially plausible but less likely.

FWIW ... I put "ice-free" in quotes throughout this post, because I personally dislike the standard definition of "ice-free" as under 1 million km2 of ice.  See this comment:

https://forum.arctic-sea-ice.net/index.php/topic,143.msg122338.html#msg122338

and this map (another simulation):


Ken Feldman

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Re: How soon could we go ice free?
« Reply #74 on: June 14, 2018, 06:29:33 PM »
There are a variety of approaches to predicting when the arctic will go ice free.  (Since I'm going to be quoting from peer-reviewed science in this post, I'll use the standard definition of less than 1 million sq. km of ice remaining).

Global climate models use physics, tracking energy flows and predicting future forcings from elevated greenhouse gas levels.  In the past, they've missed the extreme melt seasons like 2012 and were overly conservative, general predicting that the Arctic wouldn't go ice free until late in the century.  For the IPCC AR5 report issued in 2013, they were updated and the paper linked to below evaluated the models for ability to reproduce the variability in observed melt seasons like 2012.  The models most able to reproduce that variability predict an ice free arctic in the 2050s under a high emissions scenario.  If emissions are significantly reduced, arctic sea ice minimums would level off around 1.7 million km2.

http://www.pnas.org/content/110/31/12571

Quote
This paper addresses the specter of a September ice-free Arctic in the 21st century using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that large spread in the projected timing of the September ice-free Arctic in 30 CMIP5 models is associated at least as much with different atmospheric model components as with initial conditions. Here we reduce the spread in the timing of an ice-free state using two different approaches for the 30 CMIP5 models: (i) model selection based on the ability to reproduce the observed sea ice climatology and variability since 1979 and (ii) constrained estimation based on the strong and persistent relationship between present and future sea ice conditions. Results from the two approaches show good agreement. Under a high-emission scenario both approaches project that September ice extent will drop to ∼1.7 million km2 in the mid 2040s and reach the ice-free state (defined as 1 million km2) in 2054–2058. Under a medium-mitigation scenario, both approaches project a decrease to ∼1.7 million km2 in the early 2060s, followed by a leveling off in the ice extent.

Another paper looked at the observed trends and then used a variety of statistical methods to fit the data.  Depending on the method used, the arctic would have it's first ice free summer in the 2030s.

http://www.mdpi.com/2072-4292/10/2/230

Quote
An ice-free Arctic summer would have pronounced impacts on global climate, coastal habitats, national security, and the shipping industry. Rapid and accelerated Arctic sea ice loss has placed the reality of an ice-free Arctic summer even closer to the present day. Accurate projection of the first Arctic ice-free summer year is extremely important for business planning and climate change mitigation, but the projection can be affected by many factors. Using an inter-calibrated satellite sea ice product, this article examines the sensitivity of decadal trends of Arctic sea ice extent and statistical projections of the first occurrence of an ice-free Arctic summer. The projection based on the linear trend of the last 20 years of data places the first Arctic ice-free summer year at 2036, 12 years earlier compared to that of the trend over the last 30 years. The results from a sensitivity analysis of six commonly used curve-fitting models show that the projected timings of the first Arctic ice-free summer year tend to be earlier for exponential, Gompertz, quadratic, and linear with lag fittings, and later for linear and log fittings. Projections of the first Arctic ice-free summer year by all six statistical models appear to converge to the 2037 ± 6 timeframe, with a spread of 17 years, and the earliest first ice-free Arctic summer year at 2031

That article is worth reading because it discusses the weakness of using varying curve fitting methods and how they're sensitive to the data inputs.  One of the methods, an exponential fit, shows the first year the arctic will be ice free as 2014!


Dharma Rupa

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Re: How soon could we go ice free?
« Reply #75 on: June 14, 2018, 06:43:27 PM »
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

« Last Edit: June 14, 2018, 06:48:38 PM by Dharma Rupa »

Ken Feldman

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Re: How soon could we go ice free?
« Reply #76 on: June 14, 2018, 07:02:47 PM »
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

http://www.climatechange2013.org/report/

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.

Richard Rathbone

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Re: How soon could we go ice free?
« Reply #77 on: June 14, 2018, 07:44:08 PM »
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

http://www.climatechange2013.org/report/

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.

I think the state of the models as revealed in that IPCC report is pretty well summed up  in Dharma Rupa's comment.

I see some signs that it will be better next time around, but an informed reading of the 2013 report is not going to inspire any confidence in model predictions of future Arctic Sea Ice cover.

jdallen

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Re: How soon could we go ice free?
« Reply #78 on: June 14, 2018, 08:02:26 PM »
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

http://www.climatechange2013.org/report/

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.
No insults please. Dharma Rupa is not a denialist, nor dismissing research.  I think he (And I now) are pointing out that we are attempting to derive system behavior from an *effect* rather than a cause, or at least, an rather incomplete one.

We have very incomplete data. For instance, we have only a vague sense of how total ocean enthalpy is increasing in the Arctic.  We dont know a lot about heat inflow from currents.  Atmospheric chemistry is changing.  Weather itself is a dynamic property that will completely turn our expectations on their heads.

We need much better data about heat, and weather will make a certain prediction impossible even with that.

What we are left with is probabilities and unanswered questions.
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Dharma Rupa

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Re: How soon could we go ice free?
« Reply #79 on: June 14, 2018, 09:40:43 PM »
No insults please. Dharma Rupa is not a denialist, nor dismissing research.

Given the fact that I think we have completely underestimated the effects of the Industrial Revolution a couple hundred years ago, denial is a river in Egypt.

I just don't see any reason to accept the models as tablets from God.  They are people doing their best with the current understanding.  The people who bow down before those models, however, are idiots.


magnamentis

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Re: How soon could we go ice free?
« Reply #80 on: June 14, 2018, 09:42:16 PM »
Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.

there are a few problems:

a) he is right

b) you are asking a question while seeking confirmation for an already made up mind

c) you jump to false conclusion based on someone tells the truth

b + c are very modern and horrible attitudes IMO, beside other factors denying the truth brought the world very it currently stands and will bring either doom or at least more disaster to mankind.

further i find it interesting that someone who in the process of discarding facts blames others doing the same, interesting but not surprising because that too is human behaviour as long back as
the records are showing ;)

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Dharma Rupa

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Re: How soon could we go ice free?
« Reply #81 on: June 14, 2018, 10:16:43 PM »
To make my position clear.  I think the evidence supporting Global Warming is overwhelming.  I also think the evidence supporting the models is basically NONE.

jdallen

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Re: How soon could we go ice free?
« Reply #82 on: June 14, 2018, 10:48:19 PM »
To make my position clear.  I think the evidence supporting Global Warming is overwhelming.  I also think the evidence supporting the models is basically NONE.
I'll temper what I said earlier.  I think models are useful to help discern the trend.  I don't think they have the skill yet to be narrowly predictive.  Multiple models processing the same data producing similar results are useful - very useful - as they can instruct us where to look next for better detail.

My own take is, that we hit an inflection point in 2007, and started on an irreversible change in system behavior.  We'll hit another I think when we drop below ~1 million KM2.

In between I figure that starting with 2007, we have a cumulative 1% chance of hitting that sub 1million KM2 mark.  Weather year over year is the wildcard.  Increasing system heat is the force raising potential for that melt-out.
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Re: How soon could we go ice free?
« Reply #83 on: June 15, 2018, 12:27:38 AM »
To make my position clear.  I think the evidence supporting Global Warming is overwhelming.  I also think the evidence supporting the models is basically NONE.
I'll temper what I said earlier.  I think models are useful to help discern the trend.  I don't think they have the skill yet to be narrowly predictive.  Multiple models processing the same data producing similar results are useful - very useful - as they can instruct us where to look next for better detail.

My own take is, that we hit an inflection point in 2007, and started on an irreversible change in system behavior.  We'll hit another I think when we drop below ~1 million KM2.

In between I figure that starting with 2007, we have a cumulative 1% chance of hitting that sub 1million KM2 mark.  Weather year over year is the wildcard.  Increasing system heat is the force raising potential for that melt-out.

I tend to agree.  It will take another change to push the ice below the 1 million mark.  What that occurs is anyone’s guess, and the models are no help.

Ken Feldman

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Re: How soon could we go ice free?
« Reply #84 on: June 15, 2018, 01:15:41 AM »
Here's a summary of the updates in models made between the IPCC Fourth Assessment Report, AR4, (published in 2007) using the CMIP3 models and AR5 (published in 2013) using the CMIP5 models with respect to sea ice:

Quote
The CMIP5 simulations have recently become available (15). Relative to the CMIP3, a more diverse set of model types is included in the CMIP5 (i.e., climate/Earth system models with more interactive components such as atmospheric chemistry, aerosols, dynamic vegetation, ice sheets, and carbon cycle). Further, a number of improvements in physics, numerical algorithms, and configurations are implemented in the CMIP5 models. For example, some CMIP5 models include more realistic sea ice thermodynamics and dynamics in sea ice components, displaced pole to eliminate the singularity in sea ice and ocean components, better treatments of subgrid parameterizations in all of the components, and higher resolution in all of the components. Finally, a new set of scenarios called representative concentration pathways (RCPs) are used in the CMIP5 simulations (16).

And here's a 2017 paper that evaluates the results of the models that have been better at simulating observed conditions:

https://link.springer.com/article/10.1007/s13131-017-1029-8

Quote
This paper is focused on the seasonality change of Arctic sea ice extent (SIE) from 1979 to 2100 using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). A new approach to compare the simulation metric of Arctic SIE between observation and 31 CMIP5 models was established. The approach is based on four factors including the climatological average, linear trend of SIE, span of melting season and annual range of SIE. It is more objective and can be popularized to other comparison of models. Six good models (GFDL-CM3, CESM1-BGC, MPI-ESM-LR, ACCESS-1.0, HadGEM2-CC, and HadGEM2-AO in turn) are found which meet the criterion closely based on above approach. Based on ensemble mean of the six models, we found that the Arctic sea ice will continue declining in each season and firstly drop below 1 million km2 (defined as the ice-free state) in September 2065 under RCP4.5 scenario and in September 2053 under RCP8.5 scenario. We also study the seasonal cycle of the Arctic SIE and find out the duration of Arctic summer (melting season) will increase by about 100 days under RCP4.5 scenario and about 200 days under RCP8.5 scenario relative to current circumstance by the end of the 21st century. Asymmetry of the Arctic SIE seasonal cycle with later freezing in fall and early melting in spring, would be more apparent in the future when the Arctic climate approaches to “tipping point”, or when the ice-free Arctic Ocean appears. Annual range of SIE (seasonal melting ice extent) will increase almost linearly in the near future 30–40 years before the Arctic appears ice-free ocean, indicating the more ice melting in summer, the more ice freezing in winter, which may cause more extreme weather events in both winter and summer in the future years.

Ned W

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Re: How soon could we go ice free?
« Reply #85 on: June 15, 2018, 02:37:55 AM »
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

I would disagree with DR's comment, because it seems much too sweeping in its scope.

It begins with a statement about "the models" but doesn't differentiate among many different types of models used for many different purposes in the Arctic. CESM is a model, PIOMAS is a model, colleagues of mine have their own model of how light is transmitted through sea ice to feed phytoplankton below.  Are they all equally and utterly worthless? 

The next sentence goes beyond carping about models to assert that the entire "science" (with scare quotes, natch!) of Arctic sea ice is "more like alchemy" ... in other words, it's all worthless.  Not just the models, all science (or "science") in the Arctic.

I don't agree, to put it mildly. 

bbr2314

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Re: How soon could we go ice free?
« Reply #86 on: June 15, 2018, 05:29:23 AM »
I think stronger wintertime volume/extent losses may not necessarily correlate to the same occurring as we move forward in the summer months, i.e., additional volume deficits have the possibility of becoming increasingly seasonally lopsided.

It is important to note that the phenomena re: albedo / continental SWE observed in 2018, if rolled forward in the same way the posts in this thread project the losses of 2007 and 2012 (but worse) b the 2020s, likely results in an impossibility of an entirely blue Arctic.

The albedo feedbacks from excess water vapor / heat will translate into far greater and heavier continental snows, and if we ever manage summer extent numbers even half that of 2012, I would think the implications for the following winter would be catastrophic across large portions of the Northern Hemisphere.

So I would say that we are never going to see a truly blue Arctic of under 1M KM2 area/extent. But I think 1.5-2M or so is quite possible and when it does happen it will probably be the catalyst for a major reset a la 2013-2014 but even more prolonged / potent. From that point forward we may have enough cascading albedo momentum to head rather quickly off a cliff into "Younger-er Dryas".

Archimid

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Re: How soon could we go ice free?
« Reply #87 on: June 15, 2018, 05:52:02 AM »
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof. Volume has all the information of extent already in the calculation. Finally but most important, volume is a measure of the enthalpy of the ice.

Second the Maximum is a better measure than the Minimum. The maximum is the most sensitive to global warming as the winters are getting warmer much faster than the summers are getting warmer. From the maximum you can subtract the expected melt and obtain an expected minimum.

The attached graph shows the Maximum Volume according to PIOMAS from 1979-2018. Many analysis including mine acknowledge that after 2007 there was a significant change in the Arctic. The volatility of both anual losses and annual gains increased dramatically.  I think it is fair to say that there was a change in the system after 2007

I used a linear trend line using the years 2007-2018 and extended it until 2035. I then calculate the average and SD of the losses from 2007-2017.  The bottom lines represent the average, 1SD and 2SD. When the linear trend meets the bottom line Arctic sea ice volume is 0. Like real 0, not virtual.

As you can see if things behave as they behaved in the last 10 years, we'll be without an arctic in less than 10 years.

So when someone said

Quote
No chance of an ice-free Arctic for at least 20 years.

That statement is false. As I said before, there is a very low chance this year, only because we have more volume of ice than in 2017. As the globe keeps warming, winters will warm faster, less ice will be made until one year with low maximum meets a record melt year.
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jai mitchell

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Re: How soon could we go ice free?
« Reply #88 on: June 15, 2018, 06:29:23 AM »
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL065504

Quote
In the Arctic, it is estimated that approximately 60% of the warming induced by increasing greenhouse gases (GHG) concentrations over the twentieth century has been offset by the combined response to other anthropogenic forcing agents [Najafi et al., 2015], which are dominated by aerosols. Furthermore, Fyfe et al. [2013] argued that the observed decreasing trend in Arctic‐averaged surface temperature between 1939 and 1970 was mainly due to cooling from anthropogenic sulphate aerosols that overwhelmed a significant warming by well‐mixed greenhouse gases (GHG). After 1970, the forcing from continuously increasing GHG concentrations and black carbon emissions overwhelmed the forcing from declining sulphate aerosol loading, which led to a warming of the Arctic [Fyfe et al., 2013].

the 66percentile confidence interval shows a potential ice-free arctic as early as 2020 under RCP 2.6




-----------
http://acmg.seas.harvard.edu/publications/2017/breider_decadal_arctic_2017.pdf

Quote
Our results show that anthropogenic aerosol yields a negative forcing over the Arctic, with a TOA RF of -0.19 ± 0.05 W /m2 in the present day (2005–2010) and even greater forcing -(0.67 ± 0.06 W/m2 ) in the early 1980s. We find that the 1980–2010 emission reductions in anthropogenic aerosols in the developed world may have contributed +0.27 ± 0.04 K warming to present-day Arctic temperatures at the surface or approximately 25% of the observed Arctic warming. About two thirds of the warming can be attributed to forcing from anthropogenic aerosols over the Arctic, with the rest from forcing over midlatitudes

Our results do not take into consideration RF from aerosol-cloud interactions (indirect effects) or deposition of BC to snow or ice surfaces. As context for our results, we note that AMAP [2015] estimated RFs from aerosol cloud interactions considering both anthropogenic and natural sources of +0.10–0.13 W/ m2 for BC and -0.40–0.75 W/ m2 for sulfate over the Arctic. In another multimodel study, Jiao et al. [2014] reported an RF from BC deposition to Arctic snow and ice of +0.17 W /m2
 
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Viggy

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Re: How soon could we go ice free?
« Reply #89 on: June 15, 2018, 06:41:32 AM »
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

I would disagree with DR's comment, because it seems much too sweeping in its scope.

It begins with a statement about "the models" but doesn't differentiate among many different types of models used for many different purposes in the Arctic. CESM is a model, PIOMAS is a model, colleagues of mine have their own model of how light is transmitted through sea ice to feed phytoplankton below.  Are they all equally and utterly worthless? 

The next sentence goes beyond carping about models to assert that the entire "science" (with scare quotes, natch!) of Arctic sea ice is "more like alchemy" ... in other words, it's all worthless.  Not just the models, all science (or "science") in the Arctic.

I don't agree, to put it mildly.

To be completely honest, I thought I agreed with DR's point of view till I read Ned's. Calling current climate models alchemy is the equivalent of saying the Wright Brothers didn't contribute to the history of flight.

We are working with a system where not all the variables are known but it is definitely possible to know them all. And if all the variables are known, then a solution can always be obtained. Saying that our understanding of '5' of the '25' variables isn't of value is a gross misunderstanding of the scientific process.

You are meant to have high expectations of your own work, and others are meant to question it and your pride in your work is meant to defend against those criticisms. Expectations from the work done is the cornerstone of the science. IMO
« Last Edit: June 15, 2018, 07:04:55 AM by Viggy »

Feeltheburn

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Re: How soon could we go ice free?
« Reply #90 on: June 15, 2018, 07:25:42 AM »
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

If the DMI modeled ice thickness has any validity, you should be very happy since the ice volume is significantly higher than the past few years at this date. As a result, it is doubtful the arctic will be ice free this year (or any year in the foreseeable future). Also, the NW passage is not likely to open this year. Just my guess.
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Dharma Rupa

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Re: How soon could we go ice free?
« Reply #91 on: June 15, 2018, 01:47:15 PM »
To be completely honest, I thought I agreed with DR's point of view till I read Ned's. Calling current climate models alchemy is the equivalent of saying the Wright Brothers didn't contribute to the history of flight.

Alchemy became Chemistry.

Tom

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Re: How soon could we go ice free?
« Reply #92 on: June 15, 2018, 02:13:43 PM »
The problem I see with applying linear trends to estimate the "ice-free" date is that it doesn't make sense to me that the arctic will continue being able to melt xxx km3 of ice each year.

I assume that as the ice volume reduces it will retreat into the CAB, where it will be more resistant to melt (shorter melting season etc).

Currently the melting season starts first in the peripheral seas.  As warming continues in winter and max volume reduces, presumably comparatively more of the reduction in winter volume will be in the periphery than in the CAB, so it won't be there to be easily melted at the beginning of the melt season.

I'm sure this will make the ice in the CAB easier to melt, but not by enough to make up for the overall volume reduction.

In summary, I think that as the winter max volume reduces the volume of ice melted each year will decline, and there will be a slowing of the rate-of-change in volume reduction (a long-tail decline)

Having posted all this obviously I should point out that I'm just making stuff up based on opinions from this forum  :)  I also think that the system is incredibly complex and trying to predict the future is a fools errand.
« Last Edit: June 15, 2018, 02:49:40 PM by Tom »

Archimid

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Re: How soon could we go ice free?
« Reply #93 on: June 15, 2018, 02:42:35 PM »
Quote
As a result, it is doubtful the arctic will be ice free this year

True

Quote
(or any year in the foreseeable future)

False
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josh-j

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Re: How soon could we go ice free?
« Reply #94 on: June 15, 2018, 02:43:46 PM »
If the DMI modeled ice thickness has any validity, you should be very happy since the ice volume is significantly higher than the past few years at this date. As a result, it is doubtful the arctic will be ice free this year (or any year in the foreseeable future). Also, the NW passage is not likely to open this year. Just my guess.

Archimid beat me to it but there is a massive difference between "this year" and "any year in the foreseeable future". I agree with you regarding the former, but certainly not the latter - and I doubt many scientists studying the ice would agree either.

Daniel B.

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Re: How soon could we go ice free?
« Reply #95 on: June 15, 2018, 03:43:20 PM »
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof. Volume has all the information of extent already in the calculation. Finally but most important, volume is a measure of the enthalpy of the ice.

Second the Maximum is a better measure than the Minimum. The maximum is the most sensitive to global warming as the winters are getting warmer much faster than the summers are getting warmer. From the maximum you can subtract the expected melt and obtain an expected minimum.

The attached graph shows the Maximum Volume according to PIOMAS from 1979-2018. Many analysis including mine acknowledge that after 2007 there was a significant change in the Arctic. The volatility of both anual losses and annual gains increased dramatically.  I think it is fair to say that there was a change in the system after 2007

I used a linear trend line using the years 2007-2018 and extended it until 2035. I then calculate the average and SD of the losses from 2007-2017.  The bottom lines represent the average, 1SD and 2SD. When the linear trend meets the bottom line Arctic sea ice volume is 0. Like real 0, not virtual.

As you can see if things behave as they behaved in the last 10 years, we'll be without an arctic in less than 10 years.

So when someone said

Quote
No chance of an ice-free Arctic for at least 20 years.

That statement is false. As I said before, there is a very low chance this year, only because we have more volume of ice than in 2017. As the globe keeps warming, winters will warm faster, less ice will be made until one year with low maximum meets a record melt year.

Estimating when the minimum will approach zero based on the maximum measurements is the real falsehood.  The warmer winters/cooler summers have resulted in less ice range over the year.  How can you determine an "expected ice loss", when it is constantly in flux? 

Ned W

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Re: How soon could we go ice free?
« Reply #96 on: June 15, 2018, 04:09:32 PM »
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL065504

Quote
In the Arctic, it is estimated that approximately 60% of the warming induced by increasing greenhouse gases (GHG) concentrations over the twentieth century has been offset by the combined response to other anthropogenic forcing agents [Najafi et al., 2015], which are dominated by aerosols. Furthermore, Fyfe et al. [2013] argued that the observed decreasing trend in Arctic‐averaged surface temperature between 1939 and 1970 was mainly due to cooling from anthropogenic sulphate aerosols that overwhelmed a significant warming by well‐mixed greenhouse gases (GHG). After 1970, the forcing from continuously increasing GHG concentrations and black carbon emissions overwhelmed the forcing from declining sulphate aerosol loading, which led to a warming of the Arctic [Fyfe et al., 2013].

the 66percentile confidence interval shows a potential ice-free arctic as early as 2020 under RCP 2.6



I'm a bit confused.  Where in the Gagne et al. paper that you cite do you find that claim ("the 66percentile confidence interval shows a potential ice-free arctic as early as 2020 under RCP 2.6")?

I don't see that anywhere in the paper.  What I do see is this:
Quote
Indeed, there is a significant difference between the onset of Arctic ice‐free summers in each scenario [...]

The RCP 4.5 simulations project the year of onset for the ensemble mean to be 2045 [...] with the ensemble range to be from 2036 to 2049. [...]

In the RCP 2.6 simulations, the ensemble mean year of onset is 2048 [...] and the ensemble spans the years 2042 to 2075,

while for RCP 8.5 simulations, the ensemble mean year of onset is 2033 [...] and the ensemble ranges from 2032 to 2044.

So that seems to be saying that under RCP 2.6, ice-free conditions in the Arctic appear between 2042 to 2075 in the model ensemble, not 2020, and it's not a "66% confidence interval".

I don't see the number "66" or the word "confidence" anywhere in the paper, nor the year "2020" anywhere except in a minor note about the changing forcing from black carbon.

Archimid

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Re: How soon could we go ice free?
« Reply #97 on: June 15, 2018, 04:18:56 PM »
The expected ice loss is the average of the ice lost every melting season from maximum to minimum. The variation of that loss is captured with the standard deviations. The average volume loss for the 2007-2017 is 18.09, with a standard deviation of 1.075.
 
If the winter degradation continues as it has steadily for decades, it's just a matter of a very bad year like 2012 and 0 will be true.

From here on we can discuss known and unknown negative and positive feedbacks all you want, but that is the current state of things.
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binntho

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Re: How soon could we go ice free?
« Reply #98 on: June 15, 2018, 04:41:20 PM »
These three graphs from Arctische Penguin really say it all. Linear trend shows 0 volume in 2033, exponential in 2023 while gomperz curve seems to trend to the mid thirties. So a ballpark guess of 2025-2035 ?

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Re: How soon could we go ice free?
« Reply #99 on: June 15, 2018, 04:49:17 PM »
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof.
...
I used a linear trend line using the years 2007-2018 and extended it until 2035.


If the winter degradation continues as it has steadily for decades,

Just an observation: you attack others for their assumptions being incorrect, then immediately draw a wrong conclusion and use your own big iffy assumptions.

Just because extent and volume must hit zero does not mean there has to be a poof. It is quite possible for both extent and volume to slow down their rate of decline so they both reach zero at the same time which is well after the linear trends.

I can follow what you are saying as an explanation of what you think is the situation but with big iffy assumptions, that doesn't make it correct.