Support the Arctic Sea Ice Forum and Blog

Author Topic: ECS is 2.5  (Read 10661 times)

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #50 on: November 03, 2018, 10:53:43 PM »
https://www.nature.com/articles/s41586-018-0651-8

Quote
Abstract

The ocean is the main source of thermal inertia in the climate system1. During recent decades, ocean heat uptake has been quantified by using hydrographic temperature measurements and data from the Argo float program, which expanded its coverage after 20072,3. However, these estimates all use the same imperfect ocean dataset and share additional uncertainties resulting from sparse coverage, especially before 20074,5. Here we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2)—levels of which increase as the ocean warms and releases gases—as a whole-ocean thermometer. We show that the ocean gained 1.33 ± 0.20  × 1022 joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.83 ± 0.11 watts per square metre of Earth’s surface. We also find that the ocean-warming effect that led to the outgassing of O2 and CO2 can be isolated from the direct effects of anthropogenic emissions and CO2 sinks. Our result—which relies on high-precision O2 measurements dating back to 19916—suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases7 and the thermal component of sea-level rise8

your forcing parameters are AFU.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

AbruptSLR

  • Multi-year ice
  • Posts: 17535
    • View Profile
  • Liked: 734
  • Likes Given: 236
Re: ECS is 2.5
« Reply #51 on: November 06, 2018, 04:56:39 PM »
I would not take comfort in the uncertainties in estimating climate sensitivity:

Title: "Climate sensitivity uncertainties leading to more concern"

https://www.skepticalscience.com/climate-sensitivity-uncertainties-concern.html

Extract: "Dessler said his “best guess” currently, based on the evidence he’s seen, calls for an increase of 3 to 4 degrees C from a doubling of CO2 concentrations over pre-industrial levels.

“The idea that climate sensitivity from observations is a lot lower than the models, that the models are ‘running hot'” and showing more warming and not less … “that idea is headed for the junkyard,” Dessler concludes."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Ned W

  • Guest
Re: ECS is 2.5
« Reply #52 on: November 11, 2018, 01:23:26 AM »
https://www.nature.com/articles/s41586-018-0651-8

Yes indeed.  James Annan uses those new values of OHC to calculate an implied probability distribution for ECS (climate sensitivity):


The median value for ECS from that is 2.57 C.  So it fits nicely with this thread title.

http://julesandjames.blogspot.com/2018/11/blueskiesresearchorguk-that-new-ocean.html

AbruptSLR

  • Multi-year ice
  • Posts: 17535
    • View Profile
  • Liked: 734
  • Likes Given: 236
Re: ECS is 2.5
« Reply #53 on: November 11, 2018, 04:05:57 AM »
https://www.nature.com/articles/s41586-018-0651-8

Yes indeed.  James Annan uses those new values of OHC to calculate an implied probability distribution for ECS (climate sensitivity):


The median value for ECS from that is 2.57 C.  So it fits nicely with this thread title.

http://julesandjames.blogspot.com/2018/11/blueskiesresearchorguk-that-new-ocean.html

First, per James Annan's article, Annan states that estimates of ECS based on standard energy balance calculations (which he presents in his plot that you show) is biased to result in low estimates of ECS due to the "pattern effect" discussed in the second linked reference by Andrews et al. (2018).

Second, per Annan's calculations only consider heat absorbed by the ocean for a relatively short period, while the oceans have been absorbing anthropogenic heat since around 1750.

Title: "That new ocean heat content estimate"

https://bskiesresearch.wordpress.com/2018/11/01/that-new-ocean-heat-content-estimate/

Extract: "Plugging the numbers in to a standard energy balance approximation we get the following estimates for the equilibrium sensitivity:

This simple calculation has a (now) well-known flaw that tends to bias the results low, though how low is up for debate (it’s the so-called “pattern effect” or you might know it as the difference between effective and equilibrium sensitivity).

Another caveat in my calculation is that the new paper’s main result is based on a longer time interval going back to 1991, if the ocean heat uptake has been accelerating then that would imply a larger increment to the Johnson et al figure (which relates to a more recent period) and thus a larger effect."


Timothy Andrews et al. (30 July 2018), "Accounting for changing temperature patterns increases historical estimates of climate sensitivity; Geophysical Research Letters, https://doi.org/10.1029/2018GL078887

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078887

Abstract

Eight Atmospheric General Circulation Models (AGCMs) are forced with observed historical (1871‐2010) monthly sea‐surface‐temperature (SST) and sea‐ice variations using the AMIP II dataset. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a ‘pattern effect’ whereby the pattern of observed historical SST change gives rise to more negative cloud and LW clear‐sky feedbacks. Assuming the patterns of long‐term temperature change simulated by models, and the radiative response to them, are credible, this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the long‐term Otto et al. (2013) EffCS median and 5‐95% confidence interval from 1.9K (0.9‐5.0K) to 3.2K (1.5‐8.1K).

Third, Andrews et al (2018)'s findings taken together with Brown & Caldeira 2017 https://www.nature.com/articles/nature24672 and Caldwell 2018 https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0631.1 should firmly place ECS at 3.5 or greater.
« Last Edit: November 11, 2018, 04:25:55 AM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • Multi-year ice
  • Posts: 17535
    • View Profile
  • Liked: 734
  • Likes Given: 236
Re: ECS is 2.5
« Reply #54 on: November 11, 2018, 04:25:07 AM »
I think that it is important to note that Dessler & Forster (2018)'s recommended likely range for the current value of ECS to be 2.4 to 4.6C:

A. E. Dessler and P.M. Forster (07 August 2018), "An estimate of equilibrium climate sensitivity from interannual variability', Journal of Geophysical Research Atmospheres, https://doi.org/10.1029/2018JD028481

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD028481?campaign=wolacceptedarticle
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Richard Rathbone

  • Grease ice
  • Posts: 531
    • View Profile
  • Liked: 38
  • Likes Given: 7
Re: ECS is 2.5
« Reply #55 on: November 15, 2018, 11:40:17 PM »
https://www.nature.com/articles/s41586-018-0651-8

Quote
Abstract

Our result—which relies on high-precision O2 measurements dating back to 19916—suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases7 and the thermal component of sea-level rise8

your forcing parameters are AFU.

The authors of this paper have admitted a serious error in their calculations.

http://www.realclimate.org/index.php/archives/2018/11/resplandy-et-al-correction-and-response/

Quote
The revised uncertainties preclude drawing any strong conclusions with respect to climate sensitivity ...


jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #56 on: November 23, 2018, 08:14:17 PM »

Third, Andrews et al (2018)'s findings taken together with Brown & Caldeira 2017 https://www.nature.com/articles/nature24672 and Caldwell 2018 https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0631.1 should firmly place ECS at 3.5 or greater.


Brown & Caldeira 2017 inferred a best fit ECS of 3.7C  This OHC adjustment would produce a best fit of ~3.95C
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #57 on: November 23, 2018, 08:19:26 PM »
https://www.nature.com/articles/s41586-018-0651-8

Quote
Abstract

Our result—which relies on high-precision O2 measurements dating back to 19916—suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases7 and the thermal component of sea-level rise8

your forcing parameters are AFU.

The authors of this paper have admitted a serious error in their calculations.

http://www.realclimate.org/index.php/archives/2018/11/resplandy-et-al-correction-and-response/

Quote
The revised uncertainties preclude drawing any strong conclusions with respect to climate sensitivity ...

Yeah, you need to leave in the full quote, otherwise you are just being deceitful.

Quote
The revised uncertainties preclude drawing any strong conclusions with respect to climate sensitivity or carbon budgets based on the APO method alone, but they still lend support for the implications of the recent upwards revisions in OHC relative to IPCC AR5 based on hydrographic and Argo measurements.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Richard Rathbone

  • Grease ice
  • Posts: 531
    • View Profile
  • Liked: 38
  • Likes Given: 7
Re: ECS is 2.5
« Reply #58 on: November 24, 2018, 10:29:18 AM »
You are cited a flawed paper, that the authors admit is flawed, in support of something that the authors admit it doesn't support. After correction it confirms other recent work and because its a less accurate method it shouldn't be used as support for any changes. The full article condemns your position just as strongly as my quote, and you are being deceitful in pretending otherwise.

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #59 on: November 25, 2018, 08:49:02 PM »
Richard,

Once again, your 'english as a second language' handicap rears its ugly head. . .

the article states that the revision to the ocean heat content analysis (and more specifically the increased uncertainty) prevents it from being used to draw a 'strong conclusion' independently of other studies.

It then states that the value of the paper is now in support of multiple lines of evidence that supports a higher level of ocean heat content absorption and top-of-atmosphere radiative energy imbalance.

in other words. . .

they said,

Quote
they still lend support for the implications of the recent upwards revisions in OHC relative to IPCC AR5 based on hydrographic and Argo measurements.

you said,

Quote
it shouldn't be used as support for any changes.

perhaps you should read the article again???

here it is:  http://www.realclimate.org/index.php/archives/2018/11/resplandy-et-al-correction-and-response/

cheers!
 8)

Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #60 on: December 01, 2018, 03:02:21 PM »
Let me play devil's advocate for a minute:

What are the odds that we'll actually double co2? It seems unlikely to me given the transition off of fossils is well underway. Many countries will not be selling ICE cars after 2030-2035.

Pmt111500

  • Nilas ice
  • Posts: 1882
  • Yes, I do not always bicycle
    • View Profile
  • Liked: 90
  • Likes Given: 24
Re: ECS is 2.5
« Reply #61 on: December 01, 2018, 03:14:53 PM »
Let me play devil's advocate for a minute:

What are the odds that we'll actually double co2? It seems unlikely to me given the transition off of fossils is well underway. Many countries will not be selling ICE cars after 2030-2035.

Do you have a specific starting point for doubling in mind? 260, 280, 350 ppm? It might be decisive.
Cooling the outside by heat pump.

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #62 on: December 01, 2018, 03:21:22 PM »
Was thinking 280, but even 260 seems unlikely.

Sebastian Jones

  • Frazil ice
  • Posts: 314
    • View Profile
  • Liked: 52
  • Likes Given: 40
Re: ECS is 2.5
« Reply #63 on: December 01, 2018, 04:19:03 PM »
A doubling from pre-industrial levels of 260ppm is 520ppm.
Our current level is about 405ppm.
We are adding about 2.5ppm/yr.
That works out to 40 years at current rates to reach 520ppm.
2060 give or take a few years.
However our emissions have been trending upwards, so it is reasonable to suggest 30 years before we hit 520.
Yes, we are aspiring to eliminating CO2 emissions by 2050 across much of the world...with some luck we shall be able to reduce the rate at which CO2 concentrations are trending upwards and extend the doubling time to as much as 60 or 70 years.
It will help if civilization collapses of course.

Qce

  • New ice
  • Posts: 6
    • View Profile
  • Liked: 2
  • Likes Given: 0
Re: ECS is 2.5
« Reply #64 on: December 01, 2018, 04:49:58 PM »
Quote
What are the odds that we'll actually double co2?
IPCC estimates for 2100 CO2 levels range from 478 to 1099ppm.
Current policies take us to ~670ppm.

Quote
...transition off of fossils is well underway
The previous transition took something like 80 years.
This one will also take many decades if left to market forces alone.

Check out Vaclav Smil's eye-opening on energy transitions.

Or one of his books on the subject.

Oil companies plan to extract everything they've got the licence to extract.
USA, China, Russia and others can't wait to exploit the arctic for fossil resources as it thaws.

Quote
Many countries will not be selling ICE cars after 2030-2035
Citation needed.
Maybe Norway? Who at the same time the world's third largest exporter natural gas and oil, at 50% of their total export value.

oren

  • Young ice
  • Posts: 4488
    • View Profile
  • Liked: 878
  • Likes Given: 1287
Re: ECS is 2.5
« Reply #65 on: December 01, 2018, 05:32:18 PM »
I believe the only thing that can prevent a doubling of CO2 is civilizational collapse.
I am hopeful market forces will make a sizeable dent, but there is no way they can win in time without a global "Marshall Plan" or a WWII-like effort with the public sacrificing quality of life in order to fight off a common enemy. And I don't expect that to happen unfortunately.

mitch

  • New ice
  • Posts: 87
    • View Profile
  • Liked: 16
  • Likes Given: 0
Re: ECS is 2.5
« Reply #66 on: December 01, 2018, 05:46:37 PM »
When worrying about heating it is important to remember the other greenhouse gases. If you go to NOAA:

"...In terms of CO2 equivalents, the atmosphere in 2017 contained 493 ppm, of which 405 is CO2 alone. The rest comes from other gases..."
https://www.esrl.noaa.gov/gmd/aggi/

Another factor is that coal-burning in China and India is partly blocking solar insolation, so that there will be a warming associated with control of sulfate emissions in Asia. 

gerontocrat

  • First-year ice
  • Posts: 6601
    • View Profile
  • Liked: 1541
  • Likes Given: 21
Re: ECS is 2.5
« Reply #67 on: December 01, 2018, 06:36:24 PM »
A doubling from pre-industrial levels of 260ppm is 520ppm.
Our current level is about 405ppm.
We are adding about 2.5ppm/yr.
That works out to 40 years at current rates to reach 520ppm.
2060 give or take a few years.
However our emissions have been trending upwards, so it is reasonable to suggest 30 years before we hit 520.
A figure often quoted  is that 46% of CO2 emissions end up in the atmosphere, 28% is absorbed by the oceans, 26% rest by plants.
The sinks are under threat. Deforestation can not only remove a fraction of the sinks, but change where the forest was into a source.
Increasing acidification of the oceans can reduce its effectiveness, especially if emissions increase (certainly very possible until the late 2020s even with Paris Accord implemented?)

If the percentage going into the atmosphere increased from 46% to 50%, at current levels of emissions CO2 ppm would increase by 2.7 ppm per annum instead of 2.5. If emissions increase, and carbon sinks decline a double multiplier occurs.

Getting to 560 ppm happens a lot earlier. 450 ppm, still used as the upper limit, becomes much closer to today. Does it matter what the ECS is if we are going to fry before stability is reached?

https://scripps.ucsd.edu/programs/keelingcurve/2013/07/03/how-much-co2-can-the-oceans-take-up/
Quote
although the oceans presently take up about one-fourth of the excess CO2 human activities put into the air, that fraction was significantly larger at the beginning of the Industrial Revolution. That’s for a number of reasons, starting with the simple one that as one dissolves CO2 into a given volume of seawater, there is a growing resistance to adding still more CO2.

"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #68 on: December 01, 2018, 11:40:51 PM »
A doubling from pre-industrial levels of 260ppm is 520ppm.
Our current level is about 405ppm.
We are adding about 2.5ppm/yr.
That works out to 40 years at current rates to reach 520ppm.
2060 give or take a few years.
However our emissions have been trending upwards, so it is reasonable to suggest 30 years before we hit 520.
Yes, we are aspiring to eliminating CO2 emissions by 2050 across much of the world...with some luck we shall be able to reduce the rate at which CO2 concentrations are trending upwards and extend the doubling time to as much as 60 or 70 years.
It will help if civilization collapses of course.

Thank you, I had done the math  ::) Our emissions were mostly steady for three years before going up last year. But there has also been substantial work done changing infrastructure, and costs seem to be coming down for new tech. It's difficult to turn the titanic, as the saying goes, but we have been turning the wheel... we should expect significant drops in emissions beginning by the mid 2020s.

Quote
Many countries will not be selling ICE cars after 2030-2035
Citation needed.
Maybe Norway? Who at the same time the world's third largest exporter natural gas and oil, at 50% of their total export value.

2030 (or before): Costa Rica, Denmark, India, Ireland, Israel, Japan, Netherlands, Norway, Portugal and South Korea. Also some cities.

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


Remember all, I'm playing devil's advocate, so don't go easy on me.
« Last Edit: December 01, 2018, 11:48:15 PM by wdmn »

oren

  • Young ice
  • Posts: 4488
    • View Profile
  • Liked: 878
  • Likes Given: 1287
Re: ECS is 2.5
« Reply #69 on: December 01, 2018, 11:56:12 PM »
Israel (and some other countries in that list) only banned gasoline and diesel. I know that the (stupid) plan in Israel is to have lots of nat-gas cars, following the discovery in the past decade of extensive gas fields offshore.

I also note that future promises are easily broken or delayed when the future becomes the present.

TerryM

  • First-year ice
  • Posts: 5299
    • View Profile
  • Liked: 457
  • Likes Given: 5
Re: ECS is 2.5
« Reply #70 on: December 02, 2018, 10:48:09 PM »
Israel (and some other countries in that list) only banned gasoline and diesel. I know that the (stupid) plan in Israel is to have lots of nat-gas cars, following the discovery in the past decade of extensive gas fields offshore.

I also note that future promises are easily broken or delayed when the future becomes the present.


Last year Putin asked to convert all Russian autos to CNG, and all Russian trucks, including the military to LNG. It's a damn shame that he doesn't have dictatorial powers.
Terry

crandles

  • Young ice
  • Posts: 2512
    • View Profile
  • Liked: 94
  • Likes Given: 47
Re: ECS is 2.5
« Reply #71 on: April 20, 2019, 11:30:19 PM »
International climate scientists discuss first results from a new set of climate model simulations at the CMIP6 Model Analysis Workshop in Barcelona, Spain

https://www.wcrp-climate.org/news/wcrp-news/1478-cmip6-first-results

Quote
One commonly-used measure of a climate model’s response to greenhouse gas forcing is the ‘Equilibrium Climate Sensitivity’ (ECS), which approximates the change in global mean surface air temperature associated with doubling of CO2 concentration in the atmosphere. Initial results show that while for several CMIP6 models the ECS is similar to their CMIP5 counterpart (from about 6 years ago), some have a higher ECS.


Tom_Mazanec

  • Nilas ice
  • Posts: 1555
    • View Profile
    • Planet Mazanec
  • Liked: 346
  • Likes Given: 63
Re: ECS is 2.5
« Reply #72 on: April 23, 2019, 06:13:34 PM »
Even if the ECS is low (I don't think so, but saying) it is still easy to double CO2 because we are starting from such a low level. If humanity and fossil fuels had evolved in the Ediacaran, or if the Earth orbited farther from the sun, CO2 levels would start at a higher level and we could add a couple teratons of it without significant warming. Of course we could not just keep growing exponentially much longer, because something else would limit us, such as resource depletion. That is one thing I remember from Limits to Growth - if you solve one problem one decade, another gets you the next.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

Tom_Mazanec

  • Nilas ice
  • Posts: 1555
    • View Profile
    • Planet Mazanec
  • Liked: 346
  • Likes Given: 63
Re: ECS is 2.5
« Reply #73 on: May 29, 2019, 08:10:41 PM »
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

Shared Humanity

  • Young ice
  • Posts: 3971
    • View Profile
  • Liked: 422
  • Likes Given: 49
Re: ECS is 2.5
« Reply #74 on: May 29, 2019, 08:29:20 PM »
ECS is almost twice what was previously thought, it seems:
https://truthout.org/articles/we-may-have-much-less-than-12-years-to-reverse-climate-change/

If ECS is 5C instead of 3C, we are in more trouble than we realized but what we need to do has not changed. We need to stop using fossil fuels and become carbon neutral as quickly as possible.

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #75 on: May 29, 2019, 09:08:49 PM »
What we need to accomplish has not changed, but how we do it (and how we talk about it), may look quite different, since all of the pathways to 1.5 or 2C of warming are basically junk, as a massive analysis from earlier this year concluded:

“The massive analysis shows that meeting the 2C target is exceptionally difficult
in all but the most optimistic climate scenarios. One pathway is to immediately and
aggressively pursue carbon-neutral energy production by 2030 and hope that the
atmosphere’s sensitivity to carbon emissions is relatively low, according to the study.
If climate sensitivity is not low, the window to a tolerable future narrows and in some
scenarios, may already be closed.

... If the climate sensitivity is greater than 3 Kelvin (median of assumed
distribution), the pathway to a tolerable future is likely already closed.”

source: https://phys.org/news/2019-03-pathways-climate-future-action.htm

rboyd

  • Nilas ice
  • Posts: 1163
    • View Profile
  • Liked: 165
  • Likes Given: 44
Re: ECS is 2.5
« Reply #76 on: May 30, 2019, 12:10:12 AM »
We wont be cutting emissions significantly any time soon given the rapid growth in China, India and the Rest of the World (e.g. Indonesia and South East Asia etc.), together with the US administrations rejection of climate change science. The China-US struggle only makes things worse, as they will focus even more on growth as a security issue (the relative economic size tends to drive relative geopolitical power).

So attempted geo-engineering and increasing climate chaos will be in our futures. If ECS is really 5 it may be pretty much game over. Lets hope that the negative feedbacks in the Arctic (e.g. increased cloud cover during the summer months) hold off a BOE otherwise it will be game over.

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #77 on: May 30, 2019, 05:17:34 AM »
What we need to accomplish has not changed, but how we do it (and how we talk about it), may look quite different, since all of the pathways to 1.5 or 2C of warming are basically junk, as a massive analysis from earlier this year concluded:

“The massive analysis shows that meeting the 2C target is exceptionally difficult
in all but the most optimistic climate scenarios. One pathway is to immediately and
aggressively pursue carbon-neutral energy production by 2030 and hope that the
atmosphere’s sensitivity to carbon emissions is relatively low, according to the study.
If climate sensitivity is not low, the window to a tolerable future narrows and in some
scenarios, may already be closed.

... If the climate sensitivity is greater than 3 Kelvin (median of assumed
distribution), the pathway to a tolerable future is likely already closed.”

source: https://phys.org/news/2019-03-pathways-climate-future-action.htm

https://forum.arctic-sea-ice.net/index.php/topic,1269.msg53513.html#msg53513
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #78 on: May 30, 2019, 07:41:44 AM »
Thanks for the link JM.

So you believed geo-engineering would be required even four years ago...

Geo-engineering will be a disaster without the right leadership in place. Can you imagine how it will go if nationalist populist movements gain further ground?

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #79 on: May 31, 2019, 04:22:36 AM »
Thanks for the link JM.

So you believed geo-engineering would be required even four years ago...

Geo-engineering will be a disaster without the right leadership in place. Can you imagine how it will go if nationalist populist movements gain further ground?

I never said it wouldn't be a disaster.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #80 on: May 31, 2019, 04:28:01 AM »
I didn't mean to imply you didn't! I was just thinking out loud.

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #81 on: June 06, 2019, 05:34:27 PM »
FYI
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

wdmn

  • Frazil ice
  • Posts: 350
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: ECS is 2.5
« Reply #82 on: June 06, 2019, 06:29:43 PM »
Thanks JM,

How come it says 4xCO2? I thought ECS was for 2x?

jai mitchell

  • Nilas ice
  • Posts: 2042
    • View Profile
  • Liked: 82
  • Likes Given: 20
Re: ECS is 2.5
« Reply #83 on: June 07, 2019, 10:42:18 PM »
https://www.carbonbrief.org/qa-how-do-climate-models-work

Quote
Abrupt 4x CO2 runs

Climate models comparison projects, such as CMIP5, generally request that all models undertake a set of “diagnostic” scenarios to test performance across various criteria.

One of these tests is an “abrupt” increase in CO2 from pre-industrial levels to four times higher – from 280 parts per million (ppm) to 1,120ppm – holding all other factors that influence the climate constant. (For context, current CO2 concentrations are around 400ppm.) This allows scientists to see how quickly the Earth’s temperature responds to changes in CO2 in their model compared to others.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Ken Feldman

  • Grease ice
  • Posts: 767
    • View Profile
  • Liked: 79
  • Likes Given: 100
Re: ECS is 2.5
« Reply #84 on: November 06, 2019, 09:05:49 PM »
An update on the CMIP6 model intercomparison study has been posted at Real Climate.

http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/#more-22857


Quote
The results from climate models that are being run for CMIP6 have been talked about for a few months as the papers describing them have made it in to the literature, and the first assessments of the multi-model ensemble have been done. For those of you not familiar with the CMIP process, it is a periodic exercise for any climate model groups who want to have their results compared with other models and observations in a consistent manner. CMIP6 is the 5th iteration of this exercise (we skipped CMIP4 for reasons that remain a little obscure) that has been going since the 1990s.
The main focus has been on the climate sensitivity of these models – not necessarily because it’s the most important diagnostic, but it is an easily calculated short-hand to encapsulate the total feedbacks that occur as you increase CO2.

Quote
As more models have been put into the database (all of which is publically available), more consistent estimates are possible, for instance:



Quote
So what should people make of this? Here are some options:

These new higher numbers might be correct. As cloud micro-physical understanding has improved and models better match the real climate, they will converge on a higher ECS.

These new numbers are not correct. There are however many ways in which this might have manifest:
- The high ECS models have all included something new and wrong.
- They have all neglected a key process that should have been included with the package they did implement.
- There has been some overfitting to imperfect observations.
- The experimental set-up from which the ECS numbers are calculated is flawed.

There are arguments pro and con for each of these possibilities, and it is premature to decide which of them are relevant. It isn’t even clear that there is one answer that will explain all the high values – it might all be a coincidence – a catalogue of unfortunate choices that give this emergent pattern. We probably won’t find out for a while – though many people are now looking at this.