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ktonine

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #450 on: April 17, 2017, 03:39:10 AM »
I would suggest that Ding et al publish a public apology for their careless research which, frankly, makes no sense to my eyes.

Cant this crap stop?  I suggest you apologize - now.

jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #451 on: April 17, 2017, 05:58:30 AM »
This thread is dead

The top two authors on this paper both believe that the FIRST < 1X10^6 km^2 SIE September minimum will happen around 2065.  Or, this is what they have said publicly.  Whether they ACTUALLY believe this is not clear.

The difference between SIE effectively ice free in 2020-ish vs. 2060-ish is measured in the balance of millions of human lives.

There is no excuse for being this far removed from reality.  Either they are completely incompetent, unaware, overconfident in their supposed knowledge, don't care or are a fifth column element working against the greater good intentionally.

In any case these errors will soon be written in stone as one of the greatest failures in human history.

if there is anyone left to remember.

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ktonine

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #452 on: April 17, 2017, 06:09:59 AM »
There is no excuse for being this far removed from reality.  Either they are completely incompetent, unaware, overconfident in their supposed knowledge, don't care or are a fifth column element working against the greater good intentionally.

Go hang out at WUWT - you make about as much sense.

I'm very sad for this forum.  I never thought it would degenerate to name-calling respected scientists. It's embarassing. 

I guess I'll just join A-Team and Chris Reynolds and stay away.


bbr2314

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #453 on: April 17, 2017, 06:16:29 AM »
This thread is dead

The top two authors on this paper both believe that the FIRST < 1X10^6 km^2 SIE September minimum will happen around 2065.  Or, this is what they have said publicly.  Whether they ACTUALLY believe this is not clear.

The difference between SIE effectively ice free in 2020-ish vs. 2060-ish is measured in the balance of millions of human lives.

There is no excuse for being this far removed from reality.  Either they are completely incompetent, unaware, overconfident in their supposed knowledge, don't care or are a fifth column element working against the greater good intentionally.

In any case these errors will soon be written in stone as one of the greatest failures in human history.

if there is anyone left to remember.


I deleted my earlier comment but I am 100% in agreement with you on this. I think that discussion for discussion's sake does nothing to improve actual discourse if it lacks substance or meaning. I also wonder if any groups backing fossil fuels may be funding the "research" presented in this thread.

sidd

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #454 on: April 17, 2017, 07:18:14 AM »
Prof. Ding there are many on this forum who greatly value your participation and wish you to continue. You have certainly sharpened my thinking on the state of the arctic. If you can, please disregard the personal attacks. If you cannot, I would love to continue this discussion on a mailing list which I would be glad to set up if our host Neven cannot.

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #455 on: April 17, 2017, 07:29:45 AM »
Less heat, more light, everyone.  Prof. Ding has engaged us in a lively and productive scientific exchange to both explain the paper and hear our questions and criticism.

If you wish to convince him to abandon his findings, you must present compelling fact and arguments.  This requires patience and careful thought.  if you sought rapid results and gratification, I suggest you discard that expectation.

Your arguments will require:

1) work as thorough and compelling as his own and
2) time for everyone one (including the good professor) to digest it.
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Qinghua ding

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #456 on: April 17, 2017, 08:01:11 AM »
I don't really mind too much if someone don't like our stuff.

For the tipping point question, I think this paper is pretty informative.

Have a great week!

http://eisenman.ucsd.edu/papers/Armour-Eisenman-Blanchard-McCusker-Bitz-2011.pdf

The reversibility of sea ice loss in a state‐of‐the‐art climate model K. C. Armour,1 I. Eisenman,2,3 E. Blanchard‐Wrigglesworth,3 K. E. McCusker,3 and C. M. Bitz3 Received 29 June 2011; accepted 15 July 2011; published 20 August 2011.

 [1] Rapid Arctic sea ice retreat has fueled speculation about the possibility of threshold (or ‘tipping point’) behavior and irreversible loss of the sea ice cover. We test sea ice reversibility within a state‐of‐the‐art atmosphere– ocean global climate model by increasing atmospheric carbon dioxide until the Arctic Ocean becomes ice‐free throughout the year and subsequently decreasing it until the initial ice cover returns. Evidence for irreversibility in the form of hysteresis outside the envelope of natural variability is explored for the loss of summer and winter ice in both hemispheres. We find no evidence of irreversibility or multiple ice‐cover states over the full range of simulated sea ice conditions between the modern climate and that with an annually ice‐free Arctic Ocean. Summer sea ice area recovers as hemispheric temperature cools along a trajectory that is indistinguishable from the trajectory of summer sea ice loss, while the recovery of winter ice area appears to be slowed due to the long response times of the ocean near the modern winter ice edge. The results are discussed in the context of previous studies that assess the plausibility of sea ice tipping points by other methods. The findings serve as evidence against the existence of threshold behavior in the summer or winter ice cover in either hemisphere. Citation: Armour, K. C., I. Eisenman, E. Blanchard‐Wrigglesworth, K. E. McCusker, and C. M. Bitz (2011), The reversibility of sea ice loss in a stateof‐the‐art climate model, Geophys. Res. Lett., 38, L16705, doi:10.1029/2011GL048739.

Qinghua ding

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #457 on: April 17, 2017, 08:05:56 AM »
To Darvince
I don't know the answer. I don't think our models have a good skill to predict either the PDO or IPO.   

Neven

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #458 on: April 17, 2017, 10:52:12 AM »
As I've written in another thread that sidd has opened with regards to setting up a private mailing list:

Quote
Ever since Qinghua Ding engaged here, the 'abuse' has become even less. On the other hand he does say (based on his research) that the Arctic won't go ice-free for another 50-100 years, so some push-back is to be expected on a forum for people who are worried about AGW.

Okay, so I wrote this before reading the last couple of comments.  ;)

I'm also not sure if there is a lot of value for society (now and in the future) to state that there is some 70-year cycle that will cause the Arctic to go ice-free many decades later than most experts currently think, especially if there is no way of projecting or monitoring the cycle, let alone determining how AGW has influenced this cycle itself. What if this gets a lot of traction, but it turns out to be wrong? At face value, it gives a false sense of security (also caused by the misleading character of the word 'ice-free', which implies that the consequences won't kick into action before then).

But scientifically it's interesting, and we'll have to wait and see whether more groups will continue to build on this research.

Either way, I want to thank Qinghua again for engaging here, being a good sport and realizing that this is the Internet where it's easier to vent frustrations, etc. I would kindly like to ask everyone to refrain from posting, unless there is something new to be said/asked about the science. There is no use in going through the same motions again, and ending with disparaging remarks.
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Lennart van der Linde

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #459 on: April 17, 2017, 01:55:20 PM »
Qinghua,

Thank you for referring to Armour et al 2011.

They say:
“Although we find that CCSM3 does not show evidence of a summer sea ice tipping point, the variance in summer Arctic sea ice area increases in the model as the climate warms [Holland et al., 2008; Goosse et al., 2009]. The increase in variance may plausibly be related to a reduction in stability, or alternatively it may be driven by other factors such as reduced geographic muting of ice edge variability [Goosse et al., 2009; Eisenman, 2010] or an overall thinning of the ice pack [Notz, 2009]. However, in light of the present findings, it does not appear to be associated with a loss of stability altogether. Given that these same processes are expected to be at work in nature, variance in the observed sea ice cover may similarly be an unreliable indicator of an approaching threshold.”

Livina & Lenton 2013 say on potential Arctic sea ice tipping points:
http://www.the-cryosphere.net/7/275/2013/tc-7-275-2013.pdf

"there has been an abrupt and persistent jump in the amplitude of the seasonal cycle of Arctic sea-ice cover in 2007 (Ditlevsen, 2012), but the underlying causal mechanism remains uncertain. We describe this as a (non-bifurcation) “tipping point”, because it involved an abrupt, qualitative change in the sea-ice dynamics, without any evidence for a large forcing perturbation; i.e. the abruptness resides in the internal dynamics of the Arctic climate system."

And Serreze 2011 says:
http://www.nature.com.sci-hub.cc/nature/journal/v471/n7336/full/471047a.html

"with ice-free summers, the ocean picks up a great deal of extra heat, delaying autumn ice growth. If there was a tipping point, this summer heat gain would lead to ice cover the following spring being thin enough to completely melt out over the following summer. Instead, so much ocean heat is lost during the darkness of the polar winter that enough ice grows to survive the next summer’s melt."

The question seems to be: will it? Or will Arctic amplification feedbacks cause much of this extra heat uptake to stay in the Arctic? If so, how large will this amplification be? Even if there is no irreversibility, there still could maybe be an acceleration in ice loss. It seems a risk we can't ignore yet.

Also if we look again at fig 8 of Walsh et al 2016 (attached):
http://onlinelibrary.wiley.com/doi/10.1111/j.1931-0846.2016.12195.x/full

It shows maybe 0.5 million km2 decadal variability from 1850-1925 and about 1 million km2 from 1925-2000. Why has this decadal variability apparently grown? Could it be due to AGW? In that case maybe part of the 1.05 million km2 loss from 1979-1988 to 2007-2016 is not fully due to natural variability, but also partly to AGW, say 50% of it? In that case natural variability would have caused about 20% of ice loss since 1979 instead of 40%. Or how would this argument be mistaken?

Rob Dekker

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #460 on: April 18, 2017, 04:06:43 AM »
Hi Rob,
Please see this plot. The sea ice extent in 1938/sep is even larger than that in 1938/aug.

I cannot reproduce that.
https://nsidc.org/data/g10010

From the Walsh data, I obtain for ice 'extent' :

1938 8 : 8.45
1938 9 : 7.95

That's a 500 k km^2 drop between August and September, which is typical.
« Last Edit: April 18, 2017, 06:32:17 AM by Rob Dekker »
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Rob Dekker

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #461 on: April 18, 2017, 04:25:28 AM »
Qinghua Ding said
Quote
I also checked all these old sea ice reconstruction data from month to month before 1950s. I think they used a climatology of September from some periods later for all September sea ice before 1950s or 60s. As I know, old sea ice data/charts only recorded sea ice information from April to Aug.  I can plot some old ice data later. you will see what I mean here.

Actually, Walsh et al did not use a 'climatology'.
They used a spacial/temporal 'analog' method, using regional matches to obtain ice concentration in locations where there were no observations.

Also, September is a very hard month to reconstruct, since especially before 1953 there are very few ice (edge) observations in September.

August has more observations, and thus is easier to reconstruct for the earlier record :



Here you see the reconstruction from Walsh et al for August, and the reconstruction that I compiled with Diablo (from this thread) :
http://neven1.typepad.com/blog/2016/01/september-arctic-sea-ice-extent-1935-2014

Both Walsh and my methods are 'analog' based and Diablo's own method is 'climatology' based, but all 3 reconstructions show a 'dip' in the 30's and 40's, which is likely caused by the higher Arctic temperatures prevalent at the time, which appears to be pan-Arctic.

Yet it should be clear that the magnitude of the 'dip' around the 30's and 40's is minor compared to the decline in Arctic sea ice that we observe from the satellite era (80's to present).
« Last Edit: April 18, 2017, 06:34:38 AM by Rob Dekker »
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Lennart van der Linde

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #462 on: April 18, 2017, 08:51:45 AM »
Yet it should be clear that the magnitude of the 'dip' around the 30's and 40's is minor compared to the decline in Arctic sea ice that we observe from the satellite era (80's to present).

Yes, and the question seems to be: how big was this dip in the 30s-40s, and what part of it was natural variability and what part antropogenic (including possibly aerosols)?

Walsh et al say:
"Figure 8 provides further temporal context by showing the March and September ice extents for every year in the database. The time series for both months contain considerable interannual variability (variances of approximately a million km2 about a 10-year running mean), in contrast to earlier depictions such as HadISST1 (Rayner et al. 2003) that contained climatological fields in earlier decades. Except for the recent (post-1970) decrease of ice cover in both seasons, there is little indication of decadal or multidecadal variability in the pan-Arctic ice extent. However, there are indications of a decrease in September extent from the 1920s to the 1940s, followed by an increase to a relative maximum by the 1970s."

Looking at their Sept extent interannual variability seems closer to 0.5 million km2 for the first half of the time-period (1850-1930), and much larger for the second half (1930-2010). Is that due to a combination of say a 70-yr natural cycle and AGW, and if so, what combination?

My guestimate based on the discussion so far would be about 20% natural at the most, if at all (aerosols?), and at least 80% AGW, but if others have better estimates, let us hear them. Part of the decrease that Ding et al ascribe to natural variability should possibly/probably be ascribed to AGW, it seems to me. And potentially aerosols have prevented even faster extent decreases. I think Ding et al have not responded convincingly to these arguments yet, or if they have, I've missed it.

Random_Weather

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #463 on: April 18, 2017, 09:49:47 PM »

In my opinion this is overconfidence in models, on global scale i would agree but in arctic i would be carefully (...)

This was very fast, that my opinion about using Model Mean becomes a Paper: http://onlinelibrary.wiley.com/doi/10.1002/2016GL072342/abstract?utm_content=buffer4dd3e&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

"The multi-model ensemble mean is hence not representative of a consensus across the models in Arctic climate projections."

This is why i told before, that mean of models must not represent the forced response
« Last Edit: April 18, 2017, 09:56:48 PM by Random_Weather »

Rob Dekker

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #464 on: April 19, 2017, 04:34:38 AM »
Lennart
Quote
Yes, and the question seems to be: how big was this dip in the 30s-40s, and what part of it was natural variability and what part antropogenic (including possibly aerosols)?

From the reconstructions of pre-satellite Arctic sea ice, we know that the 30s-40s dip was there, but here is a lot of annual 'noise' in the August data, which makes it hard to say exactly how much decline there was. The 20% (of satellite era decline) that you mention looks reasonable.

As for the cause of the 30s-40s dip, I think the prime suspect is the AMO.
We know that high latitude Northern Atlantic SST's went up fast in the 20's and peaked in the 30's and 40's :



Note this is the REAL AMO, not the AMO index, which is tainted by anthropogenic signals (warming and aerosol cooling). More about that from Michael Mann himself here :
http://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/
and in the scientific paper about 'teasing' out the REAL AMO from the climate data :
http://onlinelibrary.wiley.com/doi/10.1002/2014GL059233/abstract

All this suggests that, yes, there is decadal natural variability in the (Arctic) climate, but it is limited in amplitude, and we need to be very careful when attributing any change in the climate to anthropogenic or natural causes.
« Last Edit: April 19, 2017, 05:05:26 AM by Rob Dekker »
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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #465 on: April 19, 2017, 05:39:44 AM »
There is no excuse for being this far removed from reality.  Either they are completely incompetent, unaware, overconfident in their supposed knowledge, don't care or are a fifth column element working against the greater good intentionally.

Go hang out at WUWT - you make about as much sense.

I'm very sad for this forum.  I never thought it would degenerate to name-calling respected scientists. It's embarassing. 

I guess I'll just join A-Team and Chris Reynolds and stay away.

(Off-topic, sorry)

I have checked Chris Reynolds' last posts here on ASIF and on his blog. Apparently he is just too busy with personal matters to continue posting about Arctic sea ice. So if he is "staying away", it's for personal reasons, and not because of anything anybody posted here on ASIF.

jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #466 on: April 19, 2017, 07:24:56 AM »
There is also a PDO and AMOC pattern that follows the AMO and -NAO.

I know of only one variable that could possibly produce impacts to all of these. 


Aerosols

1st image AMO and NAO
2nd image AMOC
3rd image PDO

the All metrics show a systemic change beginning in the early 1920s.   

These graphs clearly show (to me) that the GHG forcing driver was present, significant and starting the shift toward +PDO, Stronger Trades (AMO) and positive NAO. 
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jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #467 on: April 19, 2017, 07:43:19 AM »
indeed it does appear that the collapse in Coal consumption began pre-1920.
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Andreas T

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #468 on: April 19, 2017, 10:04:01 AM »
since this graph shows percentages, you would need to show how the total is changing (increasing) for this to illustrate how much coal burning has taken place. You also don't make clear what the graph represents. From the large decrease in oil consumption in WW2 I deduce that it shows a limited region of the world, Europe? Italy?
What can you tell from it?

RoxTheGeologist

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #469 on: April 19, 2017, 05:51:27 PM »

US consumption increased continually until 2008.

https://www.eia.gov/coal/review/coal_consumption.php

jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #470 on: April 19, 2017, 06:11:17 PM »
the spike in global wood fuel in the post world war I recession and 1920 depression indicates that, from an energy use perspective, its effects was much greater than the great depression from an aerosols perspective.  The sudden change of aerosol emissions driven by economic cycles is the only variable that has the potential to impact the global circulation patterns on such a short time scale.  I made a hypothesis that the shifts happened before the great depression (in the 1920's) and I was able to find out that indeed, the aerosol emission shift actually happened during that time - as opposed to what I had believed previously.

Also that the shift in PDO to positive indicated that there was significant forcing pent up in the system, which causes a sudden shift in atmospheric and ocean circulations when the cork is released by suddenly cutting aerosol emissions.  In a Dynamic Fluid system when this happens there is always an impact that swings far beyond equilibrium.  Hence a definitive signal can be derived from the period.  AND since recent studies all indicate aerosol impacts to these circulation metrics (AMO, AMOC, PDO, NAO) it can be reasonably deduced that a significant part of what was considered 'natural variability' at the time was actually driven by regional SO2 emissions reductions and GHG forcing -- contrary to the current assumption that we cannot determine the cause of early period warming by the IPCC.
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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #471 on: April 19, 2017, 06:28:45 PM »
I wonder if the proliferation of underground nuclear weapons testing after ww2 produced enough aerosols to make a difference in global temperatures.
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jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #472 on: April 19, 2017, 06:43:11 PM »
do you mean above ground nuclear testing? the purpose of below ground is to prevent atmospheric impacts.  I would have to look at it but my sense is that the amount is insignificant compared to global coal emissions at that time.
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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #473 on: April 19, 2017, 06:46:49 PM »
do you mean above ground nuclear testing? the purpose of below ground is to prevent atmospheric impacts.  I would have to look at it but my sense is that the amount is insignificant compared to global coal emissions at that time.

My thinking is that if  many nuclear weapons cause nuclear winter, a few may slow down global warming. I get the feeling that nuclear weapons had at least at small part in the cooling after 1945.
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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #474 on: April 19, 2017, 07:07:22 PM »
the spike in global wood fuel in the post world war I recession and 1920 depression indicates that, from an energy use perspective, its effects was much greater than the great depression from an aerosols perspective.  The sudden change of aerosol emissions driven by economic cycles is the only variable that has the potential to impact the global circulation patterns on such a short time scale.  I made a hypothesis that the shifts happened before the great depression (in the 1920's) and I was able to find out that indeed, the aerosol emission shift actually happened during that time - as opposed to what I had believed previously.
......
global wood fuel use (or coal use) is not shown in the graph you posted, do you have another source?
the graph seems to come from a paper which states in its abstract:
Quote
This article examines energy consumption in Sweden, Holland, Italy and Spain over 200 years, including both traditional and modern energy carriers.
and is labelled "The Italian energy transition, 1861-2000"

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #475 on: April 19, 2017, 07:08:38 PM »
do you mean above ground nuclear testing? the purpose of below ground is to prevent atmospheric impacts.  I would have to look at it but my sense is that the amount is insignificant compared to global coal emissions at that time.

My thinking is that if  many nuclear weapons cause nuclear winter, a few may slow down global warming. I get the feeling that nuclear weapons had at least at small part in the cooling after 1945.

Depends how high will the dust cloud go. Some volcanoes are more efficient in doing so. What percentage of nuclear tests were surface vs underground?

jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #476 on: April 19, 2017, 07:19:02 PM »
it is still a good indication,

U.S. and UK consumption patters also follow the similar trend shown here:  https://ourworldindata.org/energy-production-and-changing-energy-sources/

In addition, the real powerhouse of the time was Germany who in post WWI the Versailles Treaty had a massive hyperinflation and collapsed economy.



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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #477 on: April 19, 2017, 07:21:17 PM »
From wikipedia:

Quote
As of 1993, worldwide, 520 atmospheric nuclear explosions (including 8 underwater) have been conducted with a total yield of 545 megaton (Mt): 217 Mt from fission and 328 Mt from fusion, while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 is 1,352 explosions with a total yield of 90 Mt.[4]

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

Then on the Nuclear weapons testing page they say this about atmospheric weapons testing (my emphasis)

Quote
Atmospheric testing designates explosions that take place in the atmosphere. Generally these have occurred as devices detonated on towers, balloons, barges, islands, or dropped from airplanes, and also those only buried far enough to intentionally create a surface-breaking crater. Nuclear explosions close enough to the ground to draw dirt and debris into their mushroom cloud can generate large amounts of nuclear fallout due to irradiation of the debris. This definition of atmospheric is used in the Limited Test Ban Treaty, which banned this class of testing along with exoatmospheric and underwater.

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

I imagine the bolded type of testing had the potential for the most cooling because it ejects the most particles.

How does a nuclear weapons test compares to large volcano eruptions? If they are similar on matter ejected and height of ejection then Nuclear weapons might have played a significant role.
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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #478 on: April 19, 2017, 07:32:47 PM »
From wikipedia:

Quote
As of 1993, worldwide, 520 atmospheric nuclear explosions (including 8 underwater) have been conducted with a total yield of 545 megaton (Mt): 217 Mt from fission and 328 Mt from fusion, while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 is 1,352 explosions with a total yield of 90 Mt.[4]

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

Then on the Nuclear weapons testing page they say this about atmospheric weapons testing (my emphasis)

Quote
Atmospheric testing designates explosions that take place in the atmosphere. Generally these have occurred as devices detonated on towers, balloons, barges, islands, or dropped from airplanes, and also those only buried far enough to intentionally create a surface-breaking crater. Nuclear explosions close enough to the ground to draw dirt and debris into their mushroom cloud can generate large amounts of nuclear fallout due to irradiation of the debris. This definition of atmospheric is used in the Limited Test Ban Treaty, which banned this class of testing along with exoatmospheric and underwater.

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

I imagine the bolded type of testing had the potential for the most cooling because it ejects the most particles.

How does a nuclear weapons test compares to large volcano eruptions? If they are similar on matter ejected and height of ejection then Nuclear weapons might have played a significant role.

I think they were a blip re cooling

DrTskoul

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #479 on: April 19, 2017, 07:41:38 PM »
From Sceptical Science: http://www.skepticalscience.com/nuclear.html

The majority of large yield tests were in the early sixties..most of cooling in a war would be from the resulting fires and their smoke and ash. Not from the nuclear explosion themselves...

Archimid

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #480 on: April 19, 2017, 07:52:52 PM »
https://www.wunderground.com/resources/climate/nuke.asp

Quote
Their most recent paper, a December 2008 study titled, "Environmental Consequences of Nuclear War", concludes that "1980s predictions of nuclear winter effects were, if anything, underestimates". Furthermore, they assert that even a limited nuclear war poses a significant threat to Earth's climate. The scientists used a sophisticated atmospheric/oceanic climate model that had a good track record simulating the cooling effects of past major volcanic eruptions, such as the Philippines' Mt. Pinatubo in 1991. The scientists injected five terragrams (Tg) of soot particles into the model atmosphere over Pakistan in May of 2006. This amount of smoke, they argued, would be the likely result of the cities burned up by a limited nuclear war involving 100 Hiroshima-sized bombs in the region. India and Pakistan are thought to have 109 to 172 nuclear weapons of unknown yield.

The intense heat generated by the burning cities in the models' simulations lofted black smoke high into the stratosphere, where there is no rain to rain out the particles. The black smoke absorbed far more solar radiation than the brighter sulfuric acid aerosol particles emitted by volcanic eruptions. This caused the smoke to heat the surrounding stratospheric air by 30°C, resulting in stronger upward motion of the smoke particles higher into the stratosphere. As a result, the smoke stayed at significant levels for over a decade (by contrast, highly reflective volcanic aerosol particles do not absorb solar radiation and create such circulations, and only stay in the stratosphere 1-2 years). The black soot blocked sunlight, resulting in global cooling of over 1.2°C (2.2°F) at the surface for two years, and 0.5°C (0.9°F) for more than a decade (Figures 1 and 2). Precipitation fell up to 9% globally, and was reduced by 40% in the Asian monsoon regions. 


The scenario is different because it is talking about 100 nuclear weapon over a very small time and local frame . Nuclear testing were staggered over a few decades, but maybe each testing was a blip, and the accumulation of blips, had a measurable impact on global temps.
 

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DrTskoul

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #481 on: April 19, 2017, 08:18:23 PM »
Might be getting OT :)

Blizzard92

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #482 on: April 19, 2017, 08:27:27 PM »
On the discrepancy between observed and CMIP5 multi-model simulated Barents Sea winter sea ice decline [Li et al., 2017]

https://www.nature.com/articles/ncomms14991
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magnamentis

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #484 on: April 19, 2017, 08:53:47 PM »
There is no excuse for being this far removed from reality.  Either they are completely incompetent, unaware, overconfident in their supposed knowledge, don't care or are a fifth column element working against the greater good intentionally.

Go hang out at WUWT - you make about as much sense.

I'm very sad for this forum.  I never thought it would degenerate to name-calling respected scientists. It's embarassing. 

I guess I'll just join A-Team and Chris Reynolds and stay away.

IMHO to give those who strongly disagree and IMO are even right the feeling that they destroy a forum is at least as bad as throwing in thoughts about unbelievable things for consideration.

and then to press on the tear glands is typical female behavior, first yell then cry.

however anything that is far from "how it currently looks like" may well be questioned no matter who stands behind the theory, which is how mankind came that far ( far not only equals good but still )

scientist themselves work after the "negative principle" lives from permanent doubts and questioning that hopefully will end up with proof one day before it's too late.

however to take a clear stance, i would bet almost anything that we shall be more or less ice free in summer way before 2060-ies, can't proof but is my personal opinion and a valid one as per my best knowledge. can't see why opposing people with a "name" should not be allowed or do you prefer your surgeon to use a hammer to knock you out for operation LOL. beside the fact that we all make mistakes and at times loose temper or oversight this should never be a lasting and general habit. those who could not deal with things that way are the ones you mentioned, hence no problem here if you join them and rant over there [pun intended]

Archimid

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #485 on: April 19, 2017, 09:11:27 PM »
Might be getting OT :)

Yeah. To try bring it back on topic and tie it with coal emissions, 1930's warming and the natural or anthropogenic nature of the loses in sea ice, humans are a force of nature. Our impact on the planet is very significant. We are probably the main driver of variability of the climate system. Human impact on the climate system was insignificant more than 10k years ago. Our impact was similar to any other invasive species. It was slight but significant during the past 10k years. Mass agriculture and deforestation started to become global. About 200 years ago, with the dawn of the industrial revolution, our impact on the planet increased  to the point that we are the primary drivers of the variability of the climate system.

Attributing any cycle to "natural variation" requires very clear evidence of the forcings causing the variation. Random variation, internal variation, unknown variations, noise, sure that exists but is almost impossible that they have not been affected by human interference.

We are driving the climate, except we are driving blind.
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Jim Williams

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #486 on: April 19, 2017, 09:21:22 PM »
We are driving the climate, except we are driving blind.

To put it another way.  We are the Unknown Unknowns.

Andreas T

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #487 on: April 19, 2017, 10:13:32 PM »
it is still a good indication,

U.S. and UK consumption patters also follow the similar trend shown here:  https://ourworldindata.org/energy-production-and-changing-energy-sources/

In addition, the real powerhouse of the time was Germany who in post WWI the Versailles Treaty had a massive hyperinflation and collapsed economy.




At the risk of stretching this into OT territory, but since we are talking about the quality of evidence as well, I'll make another comment.
The short but very deep drop in Germany's coal production is most likely the effect of the 1923 occupation of the Ruhr, its main coal producing area. Again not representative of global consumption.
But you seem to be saying that to match the pattern of global temperatures, there needs to be an early 1920s dip in albedo increasing aerosols if I understand correctly?

bbr2314

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #488 on: April 19, 2017, 10:38:32 PM »
the spike in global wood fuel in the post world war I recession and 1920 depression indicates that, from an energy use perspective, its effects was much greater than the great depression from an aerosols perspective.  The sudden change of aerosol emissions driven by economic cycles is the only variable that has the potential to impact the global circulation patterns on such a short time scale.  I made a hypothesis that the shifts happened before the great depression (in the 1920's) and I was able to find out that indeed, the aerosol emission shift actually happened during that time - as opposed to what I had believed previously.

Also that the shift in PDO to positive indicated that there was significant forcing pent up in the system, which causes a sudden shift in atmospheric and ocean circulations when the cork is released by suddenly cutting aerosol emissions.  In a Dynamic Fluid system when this happens there is always an impact that swings far beyond equilibrium.  Hence a definitive signal can be derived from the period.  AND since recent studies all indicate aerosol impacts to these circulation metrics (AMO, AMOC, PDO, NAO) it can be reasonably deduced that a significant part of what was considered 'natural variability' at the time was actually driven by regional SO2 emissions reductions and GHG forcing -- contrary to the current assumption that we cannot determine the cause of early period warming by the IPCC.
the more we delve into this the more sense it makes (IMO) and I *highly hugely wish* that we had actual funding to explore this area of research further.

re: nuclear weapons testing, i would think that if there was any primary effect it would've been on ozone? besides that, the weapons being tested were being detonated in regions remote/barren enough to avoid substantial fallout in the vast majority of cases. i'm sure a Siberian forest or two went up in smoke thanks to the Russians, but beyond that, the "nuclear winter" aspect following any war is due to the cities/etc burning and being thrown into the atmosphere. with testing, this was not a goal or an outcome.

ktonine

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #489 on: April 19, 2017, 10:44:53 PM »

and then to press on the tear glands is typical female behavior, first yell then cry.


Stupid and sexist - what a freaking combo.   You're lower than the typical WUWT commenter.

jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #490 on: April 19, 2017, 10:56:26 PM »

But you seem to be saying that to match the pattern of global temperatures, there needs to be an early 1920s dip in albedo increasing aerosols if I understand correctly?

No, I am saying that the global circulation impacts pointed to a significant reduction at this time, I looked at the available data and it shows a post WWI recession that was global in nature and, including a massive drop in the most productive economy at that time (Germany) showed that I was reading the PDO, AMO, AMOC and NAO transition correctly.
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Archimid

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #491 on: April 19, 2017, 11:09:03 PM »
In the simulation they run 100 nuclear detonations and obtain the first image attached. If 100 nuclear weapons can lower the global temperature 1.2C for almost a decade then a naive calculation results that 1 nuclear weapon would lower the temps for .012 for probably much less time.

There where 520 atmospheric nuclear weapons test in the time period in question. Lets say that only 10% of those were in simulated cities, forests or other environments were enough particulates were present. Then that's 52 tests at .012 degrees each that's .624 degrees. Of course they didn't happen at the same time but that very back of the envelope calculation gives a good idea of the total forcing.
« Last Edit: April 19, 2017, 11:56:05 PM by Archimid »
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DrTskoul

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #492 on: April 20, 2017, 01:00:36 AM »
In the simulation they run 100 nuclear detonations and obtain the first image attached. If 100 nuclear weapons can lower the global temperature 1.2C for almost a decade then a naive calculation results that 1 nuclear weapon would lower the temps for .012 for probably much less time.

There where 520 atmospheric nuclear weapons test in the time period in question. Lets say that only 10% of those were in simulated cities, forests or other environments were enough particulates were present. Then that's 52 tests at .012 degrees each that's .624 degrees. Of course they didn't happen at the same time but that very back of the envelope calculation gives a good idea of the total forcing.

Getting to be OT.  However their sims assumed lots of fires due to nuclear weapons. No significan fires from testing.

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #493 on: April 20, 2017, 02:37:01 AM »
I wonder if the proliferation of underground nuclear weapons testing after ww2 produced enough aerosols to make a difference in global temperatures.
(Off-topic, sorry)
Underground nuclear weapons tests produced essentially zero airborne particles. Above ground nuclear weapons tests produced a specific kind of airborne particles that didn't stay long enough in the atmosphere (too heavy, falling quickly enough to the ground) and didn't reach high enough layers to cause any measurable global dimming effect.
Nuclear winter is a theory (untested, thankfully, and let's hope it remains so) that if enough thermonuclear (hydrogen) bombs are exploded over cities, the resulting fires would raise an enormous amount of ashes and these particles would then result in enough NH dimming for some 5~10 years to kill most trees and plants, hence starving whatever population would be left.

Takeaway from all this: past nuclear weapons tests are irrelevant to any serious discussion about climate change, past or present.

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

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #494 on: April 20, 2017, 02:46:12 AM »
Quick off the cuff thought - I'm piqued by the idea the 30s/early 40s temperature bump could be a result of decreased aerosols (SO2 in particular) tied to the reduction in industrial zctivity and fossil fuel consumption during the depression.
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DrTskoul

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #495 on: April 20, 2017, 02:51:58 AM »
Quick off the cuff thought - I'm piqued by the idea the 30s/early 40s temperature bump could be a result of decreased aerosols (SO2 in particular) tied to the reduction in industrial zctivity and fossil fuel consumption during the depression.

Too small of contribution. If climate is that sensitive we are 100% irrevocably screwed....

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #496 on: April 20, 2017, 03:40:20 AM »
Ok then. I'll assume most nuclear weapons test were not done on the surface near forests or cities so no firestorm formed, except at Hiroshima. There a firestorm formed. It's effect on global temperatures is unknown but probably small. Just one more negative force. Curiosity satisfied. Thanks.
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Rob Dekker

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #497 on: April 20, 2017, 05:05:23 AM »
Quick off the cuff thought - I'm piqued by the idea the 30s/early 40s temperature bump could be a result of decreased aerosols (SO2 in particular) tied to the reduction in industrial zctivity and fossil fuel consumption during the depression.

I doubt that the 30s-40s temperature bump had much to do with aerosols.
The AMO is a much more likely candidate.
After all, Delworth and Mann 2000 extracted (approx. 70 year) AMO cycles back 400 years from climate proxy data, including this one from the 30s-40s :


[edit: if for some reason that picture does not come through, then please check Figure 3a in the paper]

Full paper here :
http://www.meteo.psu.edu/holocene/public_html/shared/articles/delworthmann.pdf

Also Kinnard et al 20011 shows a small amplitude multi-decadal cycle pattern in their Arctic sea ice reconstructions :

« Last Edit: April 20, 2017, 06:14:29 AM by Rob Dekker »
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jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #498 on: April 20, 2017, 06:13:47 AM »

I doubt that the 30s-40s temperature bump had much to do with aerosols.
The AMO is a much more likely candidate.


http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.652.3232&rep=rep1&type=pdf

Quote
Here we use a state-  of-the-art earth system climate model, to show that aerosol emissions and periods of volcanic activity explains 76% of the simulated multidecadal variance in
detrended 1860 to 2005 North Atlantic SST. After 1950 simulated variability is
within observational estimates; from 1910-1940 our estimates capture twice the
warming of previous generation models, but do not explain the entire observed
trend. Other processes, such as ocean circulation, may also have contributed to
early 20th century variability. Mechanistically, we find that inclusion of aerosol cloud
microphysical effects, rarely included within previous multi-models
ensembles, dominates the magnitude (80%) and spatial pattern of the total
surface aerosol forcing in the North Atlantic.
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jai mitchell

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Re: Arctic sea ice changes: Natural variation vs human influence
« Reply #499 on: April 20, 2017, 06:18:19 AM »
https://pdfs.semanticscholar.org/821e/f923d31e8eb3db38ce6c961d23cf4e297815.pdf

Quote
In summary, our results are supportive of the hypothesis that cloud feedbacks favor the persistence of SST anomalies in the tropics via the WES feedback. By detrending the cloud observations, we roughly removed the influence of greenhouse gases. However, we have not examined the possible role of aerosol-cloud interactions on driving phase shifts of the AMO [Booth et al., 2012], which remains an open question.
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