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Daniel B.

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Re: Ice-free Arctic
« Reply #150 on: March 09, 2018, 05:25:45 PM »
I am with gerontocrat on this.  The largest ice growth in the Arctic occurred following the summers with the two lowest minima (2012 and 2007).  Indeed, the winter ice growth has a strong [second order] inverse relationship with the previous summer's minimum.  Conversely, summer ice loss has a relatively poor relationship to the previous winter's ice maximum.  Additionally, the ice gained and lost each season has increased considerably in recent years; the average summer ice loss over the past decade has increased 13% from the previous three decades, while the winter ice gain has increased 12%.  Overall, the Arctic sea ice is declining, but at a slow rate, and not a rapid decline.

Archimid

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Re: Ice-free Arctic
« Reply #151 on: March 09, 2018, 05:39:34 PM »
Gerontocrat,  Have you looked at Tealights work at 

https://sites.google.com/site/cryospherecomputing/warming-potential/graphs

I believe he has your answer(more questions?) for albedo warming potential.
« Last Edit: March 09, 2018, 06:46:25 PM by Archimid »
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Ken Feldman

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Re: Ice-free Arctic
« Reply #152 on: March 09, 2018, 10:27:16 PM »

I post a response.  Initially, the ice will regrow and then melt again in summer.


Yes, but:

 1. Initial conditions in October will be very different from initial conditions of the past. To begin with there won be a giant slab of ice keeping the waves down and the humidity locked in the oceans. The water will be very warm from all the incoming radiation. The atmosphere will be very warm too.

2. Before ice can form all the extra heat and humidity must be vented and the waves calmed. That means that refreezing will begin late and from 0.

3. Winter temperatures are already crashing. After A BOE Arctic growth is bound to be anemic.

4. Come the melting season of the following year the ice will be thinner than ever, with a record low extent.

5. This means that the year following  the first ice-free year will be ice free again but much sooner, gathering more heat than ever.

6. See 1.

Quote
Eventually, if the Arctic warms enough, the Arctic will be ice free for more and more of the year.


Yep

Quote
However, when the Arctic cools, the ice will grow back.


And there is not reason for it to cool until GHG levels in the atmosphere are significantly lower. It can be centuries or millenia. Eventuall, regardless of CO2, milankovitch cycles guarantee that it will return.

The arctic gets really, really cold in winter.  Even when it's warmer than usual, it's still below freezing.  That's why most scientists who study the arctic don't think we'll see ice-free (less than 1,000,000 square km of ice) Septembers until the 2050s at the earliest.  And even then, if we reduce our emissions, the Arctic will refreeze every winter and the loss of sea ice will plateau.

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.

Full article in the Proceedings of the National Academies of Science (2013) here: http://www.pnas.org/content/110/31/12571

And here's a more recent article about the duration of ice-free portions of the Arctic during summer:  https://pubag.nal.usda.gov/catalog/5405017.  Here's the abstract:

Quote
Global warming and continued reduction in sea ice cover will result in longer open water duration in the Arctic, which is important for the shipping industry, marine mammals, and other components of the regional ecosystem. In this study we assess the length of open water duration in the Alaskan Arctic over the next few decades using the set of latest coupled climate models (CMIP5). The Alaskan Arctic, including the Chukchi and the Beaufort Sea, has been a major region of summer sea ice retreat since 2007. Thirty five climate models from CMIP5 are evaluated and twelve are selected for composite projections based on their historical simulation performance. In the regions north of the Bering Strait (north of 70° N), future open-water duration shifts from a current 3–4months to a projected near 5months by 2040 based on the mean of the twelve selected climate models. There is considerable north–south gradient in projected durations. Open water duration is about 1month shorter along the same latitudes in the Beaufort Sea compared with that in the Chukchi Sea. Uncertainty is generally ±1month estimated from the range of model results. Open-water duration in the Alaskan Arctic expands quickly in these models over the next decades which will impact regional economic access and potentially alter ecosystems. Yet the northern Alaskan Arctic from January through May will remain sea ice covered into the second half of the century due to normal lack of sunlight.


Archimid

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Re: Ice-free Arctic
« Reply #153 on: March 10, 2018, 02:15:14 AM »
First let me be very clear. Your post and my post are talking about two very different things.

you talked about:

When will the Arctic be sea ice free in the summer for the first time?

I talked about:

What happens after the first ice free Arctic, if anything?


So lets examine your claims:

Quote
The arctic gets really, really cold in winter.  Even when it's warmer than usual, it's still below freezing.  That's why most scientists who study the arctic don't think we'll see ice-free (less than 1,000,000 square km of ice) Septembers until the 2050s at the earliest.

And that is precisely why they are so wrong. The Arctic winter is already warming. It is warming very fast. This year we had local temperatures above 0 at the North Pole in February. The data set that best captures the winter warming is DMI's 2m temperatures north of 80.

http://ocean.dmi.dk/arctic/meant80n.uk.php

I suggest you examine winter temperature anomalies for the last 2 years and compare them to the rest of the dataset. The warming is obvious. This highly anomalous  but consistent warming at the Arctic happened exactly at the same time as global temperatures jumped to the record levels we have now. Projections are that the globe will warm much more.

Worst of all the warming experienced in the arctic over the last two years is not directly because of CO2. The warming is a result of hot humid air from the Pacific and Atlantic entering the Arctic and causing havoc on the ice. This is due to disturbances in the atmosphere caused by changes in sea ice and the global jet streams. The waviness of the jet streams forces warm southern air into the Arctic creating a redistribution of heat towards the Arctic. That is not in the models because it didn't work that way before.

Quote
And even then, if we reduce our emissions, the Arctic will refreeze every winter and the loss of sea ice will plateau.

The ice will plateau only if global temperatures plateau. For that we have to significantly reduce emissions very fast. As of right now, that is just a pipe dream, specially with the effort of many despicable people attempting to hide the risks.


About the two papers you posted

Wonderful papers made by serious scientist, but they are wrong. They both ignore the changes in the jet streams that a reduced Arctic sea ice (among other things) produces.

https://link.springer.com/article/10.1007/s00382-016-3367-1
Quote
The Arctic is currently undergoing drastic changes in climate, largely thought to be due to so-called ‘Arctic amplification’, whereby local feedbacks enhance global warming. Recently, a number of observational and modelling studies have questioned what the implications of this change in Arctic sea ice extent might be for weather in Northern Hemisphere midlatitudes, and in particular whether recent extremely cold winters such as 2009/10 might be consistent with an influence from observed Arctic sea ice decline. However, the proposed mechanisms for these links have not been consistently demonstrated. In a uniquely comprehensive cross-season and cross-model study, we show that the CMIP5 models provide no support for a relationship between declining Arctic sea ice and a negative NAM, or between declining Barents–Kara sea ice and cold European temperatures. The lack of evidence for the proposed links is consistent with studies that report a low signal-to-noise ratio in these relationships. These results imply that, whilst links may exist between declining sea ice and extreme cold weather events in the Northern Hemisphere, the CMIP5 model experiments do not show this to be a leading order effect in the long-term. We argue that this is likely due to a combination of the limitations of the CMIP5 models and an indication of other important long-term influences on Northern Hemisphere climate.


So as you see, the events we are just recently witnessing are not properly acknowledged in the models used in what you posted. Climate scientists were expecting unknown unknowns. This is one of them.

Edit:

I wanted to add the following, but posted by error.

Quote
In the regions north of the Bering Strait (north of 70° N), future open-water duration shifts from a current 3–4months to a projected near 5months by 2040 based on the mean of the twelve selected climate models

That is happening right now. See the Bering graph attached.




« Last Edit: March 10, 2018, 02:38:10 AM by Archimid »
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oren

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Re: Ice-free Arctic
« Reply #154 on: March 10, 2018, 10:55:34 AM »
Archimid, note that "north of Bering Strait" is actually the Chukchi Sea, not the Bering. And if you check my Chukchi gif and graph from upthread, you will see indeed that the seasons are lengthening as we speak and in a much higher rate than predicted. From 3-4 months to only "nearly 5 months" by 2040? I am certain the model is vastly underestimating.

gerontocrat

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Re: Ice-free Arctic
« Reply #155 on: March 10, 2018, 11:06:31 AM »
Gerontocrat,  Have you looked at Tealights work at 

https://sites.google.com/site/cryospherecomputing/warming-potential/graphs

I believe he has your answer(more questions?) for albedo warming potential.

Wonderful, Archimid. and a what a lovely piece of work by Tealight and Nico Sun. Indeed he does, answers and questions .

I compared 2016 with 2012.

In the 2012 Arctic spring, sea ice was comparatively high, very high, compared with other years in the 2010's. Low albedo warming potential. Then the big collapse and up goes albedo warming potential   - but.

In 2016, sea ice loss started early, but then became sort of average, with sea ice minimum hundreds of thousands of km2 greater than 2012. And despite that 2016 cumulative albedo warming potential for the year is higher by far than 2012.

i.e. low winter maxima and early melt is the most effective way to heat up the Arctic ocean.

The two graphs say it all.
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gerontocrat

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Re: Ice-free Arctic
« Reply #156 on: March 10, 2018, 11:51:25 AM »
JAXA is on holiday today - so a bit of spare time to rummage around the data.

Attached is a graph showing the average sea ice extent of the last 365 days for the last 2+ years. Yes, it looks backwards. As each new day is added, the value that day one year ago is taken off, and the new total is divided by 365.

So, on 8th March 218 extent was 190,000 km2 less than on 8th March 2017. The total for the year goes down by 190,000 but is then divided by 365. The annual average drops by just over 500 km2.
I like the graph, as it shows the slow decline in sea ice.

I put in a trendline, and had to go to the power of five to get a decent fit. It shows a big drop in the next 6 months or so. Is it possible? To my surprise - yes. 2017 ended up with a minimum of about 4.5 million, perhaps at least 500,000 km2 more than most people (including me) expected earlier in the season.

If melt is strong this year, extent could easily end up 750,000 km2 or more less than in 2017, meaning average annual extent could go down at 2,000 km2 per day or even a bit more. But that still means a long way to go to an ice-free Arctic.
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gerontocrat

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Re: Ice-free Arctic
« Reply #157 on: March 10, 2018, 05:10:07 PM »
ALBEDO ARCTIC OCEAN WARMING POTENTIAL

Two posts above I compared 2016 with 2012 to show how early melt was so much more important than a September record low  when looking at albedo effects on warming of the arctic ocean .

I forgot to add the graph. So here it is, courtesy of NSIDC, 2016 red, 2012 dotted dark green. It is extent, but for demonstration purposes OK though area would be better. I also attach again the cumulative albedo warming potential graph from Tealight to reinforce the correlation.
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Gray-Wolf

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Re: Ice-free Arctic
« Reply #158 on: March 10, 2018, 09:07:05 PM »
Oh I am now worrying about low solar impacts esp. the high pressure over the basin/Greenland that we saw last time!

The 2012 HP over Greenland led to that melt at summit if was so well positioned and brought us our record smashing  year in the basin.

I know we would need sympathetic naturals as well but I am sure that Low solar is the key to the trick working?

Over the period from half way down the cycle, to half way back up the cycle, saw the naturals have a few bites at the cherry that have not been repeated since half way up the cycle , peak solar to half way back down.

Now we are in that 'danger zone' again so how many seasons before the naturals assist enough to let the 'magic key' work again?

Have we now altered that naturals so much that it would have to be an even rarer conflagration of of them for the solar 'magic key' to work or are we to expect one of the next 5 years or so to throw us another record smashing Arctic/Greenland year?.... and a step closer to ice free or even a Blue Ocean event......
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Alexander555

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Re: Ice-free Arctic
« Reply #159 on: March 10, 2018, 09:44:51 PM »
Oh I am now worrying about low solar impacts esp. the high pressure over the basin/Greenland that we saw last time!

The 2012 HP over Greenland led to that melt at summit if was so well positioned and brought us our record smashing  year in the basin.

I know we would need sympathetic naturals as well but I am sure that Low solar is the key to the trick working?

Over the period from half way down the cycle, to half way back up the cycle, saw the naturals have a few bites at the cherry that have not been repeated since half way up the cycle , peak solar to half way back down.

Now we are in that 'danger zone' again so how many seasons before the naturals assist enough to let the 'magic key' work again?

Have we now altered that naturals so much that it would have to be an even rarer conflagration of of them for the solar 'magic key' to work or are we to expect one of the next 5 years or so to throw us another record smashing Arctic/Greenland year?.... and a step closer to ice free or even a Blue Ocean event......


That danger zone, low solar. How do you explain that ? If i understand it correct, it's a little warmer at the solar high. And a little colder at the solar low. So is it that little extra heat during the solar high that steps in , in some way. Does it build up a couple years maybe, before it cools down a little on his way to the solar high.

Archimid

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Re: Ice-free Arctic
« Reply #160 on: March 10, 2018, 11:40:11 PM »
Oren, thanks for the correction. You are right. The Northern Alaska is the Chukchi/Beaufort not the Bering Sea as I said. Maybe since it is still March and the Bering refuses to cooperate my claim will be correct on the opposite side (April/May). Nice animation BTW.

Gerontocrat I agree that it is unlikely to happen this year. In my way of seeing things, ice volume is higher than last year.  There is a mild la niña going, I think that helps in general terms.  The big thing to watch is the Bering. That little dip in the Chukchi when the Bering was really low had disaster written all over it. I'm glad it recovered. I think it will recover again and grow for a bit.  If it doesn't melt will start real early in the chukchi
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gerontocrat

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Re: Ice-free Arctic
« Reply #161 on: March 18, 2018, 02:46:06 PM »
There has been a lot of stuff about increased snowfall in the freezing thread, some about the season to come from this winter's large snow fall and some looking further ahead, all saying that the increased snow on the ground will inhibit sea ice melt. i.e. -ve feedback

I've been looking at another consequence of increased snowfall with potential longer-term impacts on AGW and therefore the potential for an ice-free Arctic. Increased snowfall may well accelerate breakdown of permafrost and release of methane and CO2. i.e. +ve feedback. Two examples below.

Example 1
https://www.sciencedaily.com/releases/2016/03/160302204625.htm

Quote
How permafrost thawing affects vegetation, carbon cycle
Study focuses on Toolik Lake area of Alaska's North Slope
Date: March 2, 2016
Source: University of Delaware
Summary:Scientists are exploring how the thawing of permafrost affects vegetation and the carbon cycle in the Toolik Lake area of Alaska's North Slope.

Climate models predict 25-50 percent more precipitation in the Arctic region by the end of the century, mostly as fall and winter snow. However, extra snow can also mean extra moisture during warmer seasons like spring and summer.

Snow fence experiment
During fieldwork, the scientists used an existing snow fence that had been in place for 18 years to explore what changes in average snow accumulation might mean for the Toolik Lake area.

Typical winter snowfall depth in the area is about one foot. The snow fence, which stands approximately 9 feet high by 200 feet long, was built perpendicular to the wind direction so that snowdrifts would form behind the fence. This allowed the researchers to mimic various snowfall accumulations for the region, from below normal to average to much higher levels of winter precipitation.

Snow blanket means longer growing season for plants
As they reviewed the data, the researchers discovered that in areas with increased winter precipitation, the ground didn't freeze as deeply because the snow acted like a blanket, keeping the ground warmer than normal.

Their findings showed that higher snow accumulations resulted in increased soil temperatures and a deeper thawing of the permafrost, which, in turn, resulted in increased microbial activity, increased melting depth and more water content in the soil that led to increased production of methane and more plant growth.

In areas with reduced snow accumulation, however, the soil acted as a methane sink because of enhanced activity of methane-oxidizing bacteria.

When the snow melted, scientists noted a longer growing season for plants and shrubs. In areas with higher snow, the soil also collapsed when the ice that was occupying the soil's pore space melted, causing depressions in the ground.

"It affected more than just the amount of methane produced, it changed the landscape and the types of plants that grew there. We started seeing woody plants -- dwarf trees like birch and other shrubs -- instead of just moss, lichens and grass."

Example 2
http://iopscience.iop.org/article/10.1088/1748-9326/11/9/091004/pdf

Quote
Abstract
The dramatic shrinkage of Arctic sea ice is one of the starkest symptoms of global warming, with
potentially severe and far-reaching impacts on arctic marine and terrestrial ecology (Postet al 2013 Science 341 519–24) and northern hemisphere climate (Screen et al 2015 Environ. Res. Lett. 10 084006).
In their recent article, Alexeev et al (2016 Environ. Res. Lett. 11 074022) highlight another,
and unexpected, consequence of Arctic sea ice retreat: the thinning of lake ice in northern Alaska. This is attributed to early winter‘ocean effect’snowfall which insulates lake surfaces and inhibits the formation of deep lake ice. Lake ice thinning has important consequences for Arctic lake hydrology, biology and permafrost degradation......

....they show that impacts from an open Arctic Ocean in autumn are both direct, through
increased air temperature and precipitation, and indirect, through inhibiting bedfast ice formation in lakes leading to localised permafrost degradation and talik formation
« Last Edit: March 18, 2018, 02:56:35 PM by gerontocrat »
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crandles

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Re: Ice-free Arctic
« Reply #162 on: March 18, 2018, 05:16:25 PM »
Rather late but in addition to
S. Tietsche et al 2011 Recovery mechanisms of Arctic summer sea ice

there was also
D. Schröder  & W. M. Connolley 2007
Impact of instantaneous sea ice removal in a coupled general circulation model

https://wmconnolley.wordpress.com/2015/10/18/sea-ice-the-triumph-of-the-william/

So as you see, the events we are just recently witnessing are not properly acknowledged in the models used in what you posted. Climate scientists were expecting unknown unknowns. This is one of them.

I accept that there are effects not properly acknowledged in the models. However that doesn't demonstrate that those effects are important. If you look at the bets I made in the stoat link and manage to follow it back you would see I used a gompertz shape decline in sea ice. I bet on there being less ice than the gompertz fit.


Thanks - yes.  Hmmm - 6 years old!

I'm not bothered much by their optimistic projection of first ice-free summer. 

Despite the gompertz shape suggesting declining rates of sea ice loss, and despite thinking I had good terms on those bets, I lost those bets.

I suggest the conclusion that should be drawn is that the data since 2011 does not suggest things  are proceeding worse than a linear trend. I also suggest almost all of the scientists have stuck to their maybe 2030-2050 sort of timetable in spite of all the alarmist projections here and elsewhere and they unlike some here appear correct to have stuck to that sort of timeframe. The alarmist projections have failed badly since 2011 / 2012.

So rather than saying
"I'm not bothered much by their optimistic projection of first ice-free summer.",

I think the data would suggest we should instead be saying something more like

"Their [model/scientists] projections seem to be holding up as we receive more data making them seem realistic."

oren

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Re: Ice-free Arctic
« Reply #163 on: March 18, 2018, 05:51:08 PM »
2012 was below the trend, and no wonder projections made at the time were overly pessimistic for sea ice loss. It still doesn't mean the models are correct. I would be highly surprised if first "ice free" arctic in its common definition will occur after 2030.
Note: I realize that the trend is subject to change as more data comes in, and that any projections based on the trend can easily fail. And I acknowledge I am not an ice scientist and have no qualifications in making my prediction above. So feel free to ignore.

crandles

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Re: Ice-free Arctic
« Reply #164 on: March 18, 2018, 06:51:19 PM »
I believe my bets were made after 2011, so after 2012 I thought I was in a really strong position.

But yes we can see that now. That why I wasn't claiming the gompertz shape was too pessimistic but just the data since 2011 didn't support an OMG it is going to be worse than trend/what scientist think/...
« Last Edit: March 18, 2018, 06:57:14 PM by crandles »

crandles

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Re: Ice-free Arctic
« Reply #165 on: March 18, 2018, 07:03:52 PM »
It still doesn't mean the models are correct. I would be highly surprised if first "ice free" arctic in its common definition will occur after 2030.

I suspect 12 years is a bit long a period to bet on. Would you be willing to bet (with William Connolley?) on whether ice extent would be half way down to 1m km^2 in 6 years time? if not that, some different figure?

oren

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Re: Ice-free Arctic
« Reply #166 on: March 18, 2018, 07:15:04 PM »
It still doesn't mean the models are correct. I would be highly surprised if first "ice free" arctic in its common definition will occur after 2030.

I suspect 12 years is a bit long a period to bet on. Would you be willing to bet (with William Connolley?) on whether ice extent would be half way down to 1m km^2 in 6 years time? if not that, some different figure?
As a trader by profession, I am not averse to risk taking  but I'd rather keep my head clear for incoming science. Being in a bet does strange things to your psychology.

Alexander555

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Re: Ice-free Arctic
« Reply #167 on: March 18, 2018, 07:17:24 PM »
I would take the bet.

crandles

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Re: Ice-free Arctic
« Reply #168 on: March 18, 2018, 07:45:17 PM »
As a trader by profession, I am not averse to risk taking  but I'd rather keep my head clear for incoming science. Being in a bet does strange things to your psychology.

Fair enough, it can do. On the other hand if you don't attempt to lay out a bet, 6 years later it is hard to remember what you thought and therefore struggle to know how situation has changed. Think there may be an argument there for a few £1 bets.  ;)

William Connolley seems more likely to offer to bet in excess of £1000 which I am not prepared to do. So asked over on Stoat.

If Alexander wants £10 to £50 pounds, I will take it (subject to agreeing terms and exchanging suitable info) for a bit of fun. If Alexander wants more then better agreeing terms with WC.

Alexander555

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Re: Ice-free Arctic
« Reply #169 on: March 18, 2018, 07:50:40 PM »
If you look at the pic, at the diffrences between the years close to each other.

1979 = 16 800 km3
1981 = 12 600 km3
difference = 4200 km3

1992 = 14 800 km3
1995 = 11 200 km3
difference = 3600 km3

2004 = 9800 km3
2007 = 6500 km3
difference = 3300 km3

2012 = 3600 km3
2014 = 6800 km3
difference = 3200 km3

In nominal terms it's going down a little. But as a % of it's total body, it's going up fast. And we are now a little above 4000 km3, at minimum. The temperature continued to go up. A lot of the ice is fractured. I would put it before 2025. 1 million km2 at 1 m thick

crandles

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Re: Ice-free Arctic
« Reply #170 on: March 18, 2018, 08:01:39 PM »
I'll wait to hear how much you want to bet before starting to suggest to much detail on terms.

Think WC and I would prefer it to be extent but I may be prepared to change to volume. I would also prefer to use average of 3 or so years.

Alexander555

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Re: Ice-free Arctic
« Reply #171 on: March 18, 2018, 08:11:04 PM »
You have a company where you can bet on it ?

crandles

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Re: Ice-free Arctic
« Reply #172 on: March 18, 2018, 08:23:16 PM »
For £100 bets William has paid up to me, and I have paid up to him. So for that level I think we should just trust each other. There are some sites where money goes to winners charity. Intrade closed down and other betting sites don't seem interested.

If you want a larger amount but only if there is some trusted third party, then I could take a look to see if I can find someone bet would likely be with WC not me. A contract could be drawn up if that provides any reassurance.

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Re: Ice-free Arctic
« Reply #173 on: March 18, 2018, 08:40:13 PM »
I would just do it for fun, small amounts.

Daniel B.

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Re: Ice-free Arctic
« Reply #174 on: March 19, 2018, 05:54:02 PM »
2012 was below the trend, and no wonder projections made at the time were overly pessimistic for sea ice loss. It still doesn't mean the models are correct. I would be highly surprised if first "ice free" arctic in its common definition will occur after 2030.
Note: I realize that the trend is subject to change as more data comes in, and that any projections based on the trend can easily fail. And I acknowledge I am not an ice scientist and have no qualifications in making my prediction above. So feel free to ignore.

Many of the projections at that time assumed a second order decline in sea ice, such that the 1 million sq km mark would be breached in 2018.  Using a simple linear trend, that would not occur to sometime around 2054.  After an additional five years, the data aligns more closely to a third order decline, which may or may not reach an ice-free condition.

Archimid

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Re: Ice-free Arctic
« Reply #175 on: March 19, 2018, 07:05:51 PM »
***Hit Post instead of Preview, my apologies. edit finished***

Let's try a different approach using Maximum volume.
Every year volume is lost during the melting season. These are the stats for yearly volume loss:

Avgerage Volume Loss   16.89
Median Volume Loss           16.613
Maximum Volume Loss   19.693
Minimum Volume  Loss   13.925
SD   1.263269588

If Maximum Volume ever reaches 16.89 chances are that year the Arctic will be ice free using the literal definition of ice free. When is that maximum number reached? The following table uses the linear trend of 1990 and every year since the year 2000 to predict when the maximum volume hits the average volume loss. Maximum volume loss intercept with maximum volume in the second column.

intercept   16.89   19.7
1990    2105    2081
2000    2068    2051
2001    2067    2050
2002    2064    2048
2003    2062    2047
2004    2057    2043
2005    2055    2041
2006    2051    2038
2007    2046    2034
2008    2045    2033
2009    2045    2033
2010    2044    2032
2011    2041    2030
2012    2040    2029
2013    2040    2029
2014    2039    2029
2015    2040    2029
2016    2040    2029
2017    2038    2028


Can anyone else see the trend of the trend lines?

Yet Daniel B. claims that this must be ignored because the trend will reverse and stabilize? Why should it?

There is no sign in the data that the maximum volume trend is stabilizing.

Then there is physics. Is the Arctic warming or cooling? It is warming of course. Do we expect it to keep warming or to cool?  It is expected to keep warming.  Then why an Arctic with less ice and more heat should stabilize?

Daniel B. what phenomena are you counting on to decrease the trend? Saying that there will be ice in the arctic in 50-100 years is a extraordinary claim which requires extraordinary evidence.
« Last Edit: March 19, 2018, 07:30:47 PM by Archimid »
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Daniel B.

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Re: Ice-free Arctic
« Reply #176 on: March 19, 2018, 07:56:15 PM »
No, you have the burden of proof backwards.  Yours is the extraordinary claim, and therefore requires extraordinary evidence.  A simple extrapolation beyond that which is known, does not meet that test.

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Re: Ice-free Arctic
« Reply #177 on: March 19, 2018, 08:43:37 PM »
Arctic ice is doomed. IMO there will be a BOE sometime in the next decade.... sooner or later
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Archimid

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Re: Ice-free Arctic
« Reply #178 on: March 19, 2018, 08:50:11 PM »
To Crandles:


See the first Image attached. The Volume Gain represents the gain from Volume Minimum to Volume Maximum since 2007. The Volume Gain for the last 11 years was above the average for the whole data set, so it represents the historical best case scenario.

At the start of the freezing season, after the first BOE the volume of ice in the Arctic is 0. If you take best case scenario past growth as an estimate of Maximum Volume at the end of the freezing season, then the average ice volume in the Arctic will be below the average ice loss.

AvgVolGain        17.68545455
MedVolGain       17.726
MaxVolGain       19.659
MinVolGain      14.872
Variance            1.723272273

AvgVolLoss               18.091
MedVolLoss                18.235
MaxVolLoss                19.693
MinVolLoss                 16.243
Variance               1.2755444

Using the historical record alone and removing all context, the year following the first BOE will also have a BOE. If we start talking about global warming, arctic amplification, the delay of the freezing season after a BOE, waves, things get real ugly real fast.
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Iceismylife

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Re: Ice-free Arctic
« Reply #179 on: March 19, 2018, 09:00:02 PM »
No, you have the burden of proof backwards.  Yours is the extraordinary claim, and therefore requires extraordinary evidence.  A simple extrapolation beyond that which is known, does not meet that test.
Put some ice in a pan on the stove.  Turn on the heat. Watch it melt.  A simple extraction of ice loss will get you a result that is reasonably accurate.

yearly ice loss is going up.  yearly maximum ice volume is going down.

Put a high loss year with a low volume year and we are ice free now.

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Re: Ice-free Arctic
« Reply #180 on: March 19, 2018, 09:23:04 PM »
Quote
Put a high loss year with a low volume year and we are ice free now.

The record low Maximum was last year at 20.782. The two record high loss years are 2010 at 16.962 and 2012 at 19.963.  That's a difference of .819.  The standard deviation for ice loss is 1.26. An ice free Arctic can happen any year now, with increasing probabilities every year that goes by.
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Re: Ice-free Arctic
« Reply #181 on: March 19, 2018, 09:40:05 PM »
No, you have the burden of proof backwards.  Yours is the extraordinary claim, and therefore requires extraordinary evidence.  A simple extrapolation beyond that which is known, does not meet that test.
Put some ice in a pan on the stove.  Turn on the heat. Watch it melt.  A simple extraction of ice loss will get you a result that is reasonably accurate.

yearly ice loss is going up.  yearly maximum ice volume is going down.

Put a high loss year with a low volume year and we are ice free now.

Sorry, but burden of proof requires more than boiling an ice cube on the stove and extrapolating that to the Arctic.

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Re: Ice-free Arctic
« Reply #182 on: March 19, 2018, 09:41:03 PM »
Quote
Yours is the extraordinary claim, and therefore requires extraordinary evidence.

Funny. You think that my claim is extraordinary because it is scary. I think your claim is extraordinary because it defies the data and the evidence.

Your claim requires a turn around of global temperatures, arctic temperatures, a turn around of ice content and ice content trends. Even then you have no physical mechanism for such turn around. None. Zero. Zilch. Nada. Only insults and pseudo skeptic statements.  You are right, because what I say is too scary to be true. LOL.
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Daniel B.

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Re: Ice-free Arctic
« Reply #183 on: March 19, 2018, 11:01:30 PM »
Quote
Yours is the extraordinary claim, and therefore requires extraordinary evidence.

Funny. You think that my claim is extraordinary because it is scary. I think your claim is extraordinary because it defies the data and the evidence.

Your claim requires a turn around of global temperatures, arctic temperatures, a turn around of ice content and ice content trends. Even then you have no physical mechanism for such turn around. None. Zero. Zilch. Nada. Only insults and pseudo skeptic statements.  You are right, because what I say is too scary to be true. LOL.

What are you talking about?  In the situation you describe, the ice would expand, not shrink.  No one (that I am aware) has many any such projections or described any physical mechanism for such an occurrence.  Scary is what people use, when they do not sufficient science to back their claims.  Please stick to science, and not insults. 

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Re: Ice-free Arctic
« Reply #184 on: March 19, 2018, 11:14:43 PM »
Quote
What are you talking about?
Sea ice volume is going down. The data is clear. Temperatures are going up. The data is clear. Ice conditions are deteriorating, that is also clear.  Yet you claim that the volume loss will stop and even reverse. You make that claim without any statistic or physics to justify a reversal of the trends. That's an extraordinary claim because it goes against all trends and it is not properly justified. You need extraordinary evidence to justify a trend reversal.

The only reason my claim is extraordinary is because it seems scary. My claim is that the trends that we have seen will continue.

Will there be a hiatus that may temporarily slow the trends? Maybe, if we are lucky. but after the hiatus we get the next jump step. I don't see how the ice will survive it.

That an alleged man of science can't even acknowledge the risk but instead plays down the risk at every possible turn says everything about your claim.
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oren

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Re: Ice-free Arctic
« Reply #185 on: March 19, 2018, 11:18:53 PM »
I recommend letting nature take its course, rather than feeding into this argument. Any bad year now can finish the ice off.  2012 wasn't forecasted using these "conservative/skeptic" methods, and neither will the next one. No way all years will be lucky until 2054, probabilities don't work like that.

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Re: Ice-free Arctic
« Reply #186 on: March 20, 2018, 12:19:22 AM »
I recommend letting nature take its course, rather than feeding into this argument. Any bad year now can finish the ice off.  2012 wasn't forecasted using these "conservative/skeptic" methods, and neither will the next one. No way all years will be lucky until 2054, probabilities don't work like that.

Sounds reasonable.  If we get more bad years, the ice has little chance of surviving until 2054.  Contrarily if we get more good years, then an ice-free Arctic would be pushed out further.  If we continue on our current trajectory, and nothing changes, then the target is 2054 +/- 5 years.  The probability of a new record low occurring in the near future are high.  But every new record, is followed by renewed growth.  The odds of back to back records are low.

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Re: Ice-free Arctic
« Reply #187 on: March 20, 2018, 12:49:20 AM »
1 Cal to warm 1cm cubed of water to 1c isn't it?
70 Cals to melt 1cm cubed of ice?

But how much to take it from minus 40c to freezing?

And how much to raise it from minus 20c to freezing?

If winter isn't 'chilling' the ice as much as it used to then 'normal' summer heat packs more of a punch insofar as normal amounts of energy to help with that '70 cal' state change?

One year soon we will see just how much that matters!
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oren

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Re: Ice-free Arctic
« Reply #188 on: March 20, 2018, 01:12:20 AM »
I recommend letting nature take its course, rather than feeding into this argument. Any bad year now can finish the ice off.  2012 wasn't forecasted using these "conservative/skeptic" methods, and neither will the next one. No way all years will be lucky until 2054, probabilities don't work like that.
Sounds reasonable.  If we get more bad years, the ice has little chance of surviving until 2054.  Contrarily if we get more good years, then an ice-free Arctic would be pushed out further.  If we continue on our current trajectory, and nothing changes, then the target is 2054 +/- 5 years.  The probability of a new record low occurring in the near future are high.  But every new record, is followed by renewed growth.  The odds of back to back records are low.
Please don't try to twist my words as if we agree on this. I believe an "ice-free" arctic minimum will first occur before 2030.

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Re: Ice-free Arctic
« Reply #189 on: March 20, 2018, 01:43:23 AM »
I recommend letting nature take its course, rather than feeding into this argument. Any bad year now can finish the ice off.  2012 wasn't forecasted using these "conservative/skeptic" methods, and neither will the next one. No way all years will be lucky until 2054, probabilities don't work like that.
Sounds reasonable.  If we get more bad years, the ice has little chance of surviving until 2054.  Contrarily if we get more good years, then an ice-free Arctic would be pushed out further.  If we continue on our current trajectory, and nothing changes, then the target is 2054 +/- 5 years.  The probability of a new record low occurring in the near future are high.  But every new record, is followed by renewed growth.  The odds of back to back records are low.
Please don't try to twist my words as if we agree on this. I believe an "ice-free" arctic minimum will first occur before 2030.

I only get to read this guys comments when someone quotes him as I set him on ignore a while ago.

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Re: Ice-free Arctic
« Reply #190 on: March 20, 2018, 02:33:44 PM »
I recommend letting nature take its course, rather than feeding into this argument. Any bad year now can finish the ice off.  2012 wasn't forecasted using these "conservative/skeptic" methods, and neither will the next one. No way all years will be lucky until 2054, probabilities don't work like that.
Sounds reasonable.  If we get more bad years, the ice has little chance of surviving until 2054.  Contrarily if we get more good years, then an ice-free Arctic would be pushed out further.  If we continue on our current trajectory, and nothing changes, then the target is 2054 +/- 5 years.  The probability of a new record low occurring in the near future are high.  But every new record, is followed by renewed growth.  The odds of back to back records are low.
Please don't try to twist my words as if we agree on this. I believe an "ice-free" arctic minimum will first occur before 2030.

Sorry, but that was not evident from your post.  I still content that fewer scientists support an ice-free state before 2030, and will attach documentation:

https://www.amap.no/documents/doc/Snow-Water-Ice-and-Permafrost.-Summary-for-Policy-makers/1532

http://www.pnas.org/content/early/2013/07/10/1219716110

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL070067

Any predictions of when an ice-free Arctic will occur is largely guesswork.  The chaotic nature of the system precludes any such determination.  Could it occur before 2030?  Sure.  Might it takes decades long?  yes.  As Yogi Berra once said, "it's tough making predictions, especially about the future."

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Re: Ice-free Arctic
« Reply #191 on: March 20, 2018, 03:41:16 PM »
Quote
Sorry, but that was not evident from your post.  I still content that fewer scientists support an ice-free state before 2030, and will attach documentation:

Your contention went from 50-100 years to 2054 +-5 to the late 30's.  Welcome to reality. Please re-assess your risk accordingly. 

BTW

The notion that there is some sort of recovery going on is false.  The first attachment shows the annual Volume Gains and Losses from 1980  to 2017. In 2007 there was a change in behavior. Both Losses and Gains increased significant. See the second attachment.

After 2007 both Gains and Losses increased but the losses increased more than the Gains. For years I have been hearing the speculation that when the volume is very low there will be extra gains that will compensate for the losses. That is not what is happening. What is happening instead is that winter temperatures are going up.

 The third attachment is Gains vs Losses but zoomed in after 2007 to examine the behavior closely.

Of the two worst years for Volume Loss, 2010 and 2012 only the later is followed by record Gain. After 2012, the Volume Loss for every year remained above average but the Gains didn't respond with record increases. Instead it responded with a freezing season much hotter than average at N80. The periphery is also showing signs of decrease freezing momentum. This highly discredits the case that volume gains will improve enough to over take volume losses.


EDIT: SOrry for the hard to read table. It didn't look like that in the preview.
« Last Edit: March 20, 2018, 04:08:32 PM by Archimid »
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Daniel B.

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Re: Ice-free Arctic
« Reply #192 on: March 20, 2018, 05:59:06 PM »
I am not saying the late 2030s.  That was another poster.  I am sticking with the 2050s timeframe.

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Re: Ice-free Arctic
« Reply #193 on: March 20, 2018, 08:26:29 PM »
Since 2 of your 3 links point towards late 30's I thought you changed your mind.
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Re: Ice-free Arctic
« Reply #194 on: March 20, 2018, 08:58:29 PM »
No.  I was simply showing the range of opinions, and to show Oren that a multitude of scientists do not agree with his outcome.  There are more references, but I felt that those were sufficient, especially since they pointed to a more dire situation.

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Re: Ice-free Arctic
« Reply #195 on: March 21, 2018, 03:00:03 AM »
No.  I was simply showing the range of opinions, and to show Oren that a multitude of scientists do not agree with his outcome.  There are more references, but I felt that those were sufficient, especially since they pointed to a more dire situation.

I think this is a more accurate assessment,

When Will the Summer Arctic Be Nearly Sea Ice-Free? 

https://www.researchgate.net/publication/267541077_When_Will_the_Summer_Arctic_Be_Nearly_Sea_Ice-Free

Quote
Observations and citations in this article support the conclusion that current rapid Arctic change, especially loss of multiyear sea ice, is likely out of sample for most CMIP5 models. Thus, time horizons for summer sea ice loss of these three approaches turns out to be roughly 2020, 2030, and 2040 respectively for trendsetters, stochasters, and modelers. Predictions depend on the weight given to data, understanding of Arctic change processes, and the use of model projections.It is reasonable to conclude that Arctic sea ice loss is very likely to occur in the first rather than the second half of the 21st century, with a possibility of loss within a decade or two.

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Daniel B.

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Re: Ice-free Arctic
« Reply #196 on: March 21, 2018, 01:43:09 PM »
The abstract from this previously cited publication describes the difficulty of ice-free Arctic predictions.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL070067

"Climate model simulations give a large range of over 100 years for predictions of when the Arctic could first become ice free in the summer, and many studies have attempted to narrow this uncertainty range. However, given the chaotic nature of the climate system, what amount of spread in the prediction of an ice‐free summer Arctic is inevitable? Based on results from large ensemble simulations with the Community Earth System Model, we show that internal variability alone leads to a prediction uncertainty of about two decades, while scenario uncertainty between the strong (Representative Concentration Pathway (RCP) 8.5) and medium (RCP4.5) forcing scenarios adds at least another 5 years. Common metrics of the past and present mean sea ice state (such as ice extent, volume, and thickness) as well as global mean temperatures do not allow a reduction of the prediction uncertainty from internal variability."

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Re: Ice-free Arctic
« Reply #197 on: March 21, 2018, 04:35:00 PM »
So because the date of the first ice free Arctic is uncertain, we can just ignore it? No reason to be concerned? That could literally be the worst risk assessment in the history of the world.

In fact, given the vital role of the Arctic in NH weather, the rapid pace of collapse and the serial underestimation of current ice trends by models, the uncertainties are reason for alarm. We can't let the Arctic reach an ice free state.

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Re: Ice-free Arctic
« Reply #198 on: March 21, 2018, 05:02:11 PM »
Why would you not be concerned?  Worst?  It is not like this has never happened before.  It will be an adjustment, but not a catastrophe.

I am equally concerned about the overestimation, and feel that accuracy is important. 

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Re: Ice-free Arctic
« Reply #199 on: March 21, 2018, 05:16:52 PM »
Quote
Why would you not be concerned?


That's what you advocate at every chance possible in this forum.  There is no reason for concern. Or maybe you now accept there are significant risks associated with the collapse of the Arctic.

Quote
It is not like this has never happened before

For the times frames relevant to humanity, it has never happened before.
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