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2020 SkS Weekly Climate Change & Global Warming Digest #30

Posted on 26 July 2020 by John Hartz

Story of the Week... Toon of the Week... John Cook in the News... Coming Soon on SkS... Climate Feedback Claim Review... SkS Week in Review... Poster of the Week...

Story of the Week...

Major new climate study rules out less severe global warming scenarios

An analysis finds the most likely range of warming from doubling carbon dioxide to be between 4.1 to 8.1 degrees Fahrenheit

Hog Fire near Susanville, CA

Flames ripped through trees as the Hog Fire jumped Highway 36 about five miles from Susanville, Calif., on Monday. (Josh Edelson/AFP/Getty Images).

The current pace of human-caused carbon emissions is increasingly likely to trigger irreversible damage to the planet, according to a comprehensive international study released Wednesday. Researchers studying one of the most important and vexing topics in climate science — how sensitive the Earth’s climate is to a doubling of the amount of carbon dioxide in the atmosphere — found that warming is extremely unlikely to be on the low end of estimates.

These scientists now say it is likely that if human activities — such as burning oil, gas and coal along with deforestation — push carbon dioxide to such levels, the Earth’s global average temperature will most likely increase between 4.1 and 8.1 degrees Fahrenheit (2.3 and 4.5 degrees Celsius). The previous and long-standing estimated range of climate sensitivity, as first laid out in a 1979 report, was 2.7 to 8.1 degrees Fahrenheit (1.5 to 4.5 Celsius).

If the warming reaches the midpoint of this new range, it would be extremely damaging, said Kate Marvel, a physicist at NASA’s Goddard Institute of Space Studies and Columbia University, who called it the equivalent of a “five-alarm fire” for the planet. 

Click here to access the entire article originally posted on The Washington Post website. 

Major new climate study rules out less severe global warming scenarios by Andrew Freedman & Chris Mooney, Capital Weather Gang, Washington Post, July 22, 2020

Toon of the Week...

2020 Toon 30 

Hat tip to the Stop Climate Science Denial Facebook page.

John Cook in the News...

John Cook is quoted extensively in this article:

Everybody’s entitled to their opinion - but not their own facts': The spread of climate denial on Facebook.

'The arguments are that people can't trust scientists, models, climate data. It's all about building doubt and undermining public trust in climate science'

by Louise Boyle, The Independent (UK). July 24, 2020

Coming Soon on SkS...

  • Wildfires off to slow start in much of the West, but trouble expected starting in mid-July (Jeff Masters)
  • Announcing a new partnership between SkS and (Baerbel)
  • SkS New Research for Week #30 (Doug Bostrom)
  • The Trump EPA is vastly underestimating the cost of carbon dioxide pollution to society, new research finds (Dana)
  • Guest Post: Why low-end ‘climate sensitivity’ can now be ruled out (Piers Forster, Zeke Hausfather, Gabi Hegerl, Steven Sherwood & Kyle Armour,)
  • 2020 SkS Weekly Climate Change & Global Warming News Roundup #31 (John Hartz)
  • 2020 SkS Weekly Climate Change & Global Warming Digest #31 (John Hartz)

Climate Feedback Claim Review...

Greenhouse gases cause global warming by trapping infra-red radiations, not by “causing more holes in the ozone layer”

CLAIM: Greenhouse gases emitted into the ocean are causing more holes in the ozone layer … “the ozone layer has holes in it causing global temperature to rise”

VERDICT: Incorrect

SOURCE: Otis Holland, Instagram, July 11, 2020

KEY TAKE AWAY: It is a common misconception that Global Warming would be due to holes in the ozone layer caused by Greenhouse gases (GHG). Instead, GHGs warm the Earth’s surface by trapping infra-red radiations, limiting the natural process by which the Earth’s surface cools. Holes in the stratospheric ozone layer are caused by anthropogenic emissions of chlorofluorocarbons (CFC), halons, and other ozone-depleting substances. Reductions in ozone-depleting substances due to the Montreal Protocol have prevented the formation of more and deeper ozone holes.

Greenhouse gases cause global warming by trapping infra-red radiations, not by “causing more holes in the ozone layer” by Nikki Forrester, Climate Feedback Review, July 21, 2020

SkS Week in Review... 

Poster of the Week...

2020 Poster 30 

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Comments 1 to 7:

  1. I admit I haven't read the article on climate sensitivity, but I'm confused. I read two other articles about the new study and they said 2.6-4.1 C was the new range.  

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  2. sailrick,

    I also have not bought the article to read it. But the available abstract includes the following statement to indicate that several different, but similar ranges for S could be presented.

    "The 66% range is 2.6‐3.9 K for our Baseline calculation, and remains within 2.3‐4.5 K under the robustness tests; corresponding 5‐95% ranges are 2.3‐4.7 K, bounded by 2.0‐5.7 K (although such high‐confidence ranges should be regarded more cautiously)."

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  3. Some free details and opinions on the new climate sensitivity study here.

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  4. nigelj @3,

    And that RealClimate OP thread does contain this link accessing the full paper.

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  5. The most definitive article about the reserch findings is most likely the one writen by the paper's authors and posted on Carbon Brief. Here's the introduction to the article...

    After four years of labour and detailed discussions by an international team of scientists, we are able to quantify better than ever before how the world’s surface temperature responds to increasing CO2 levels.

    Our findings, published in Reviews of Geophysics, narrow the likely range in “equilibrium climate sensitivity” (ECS) – a measure of how much the world can be expected to warm for a doubling of CO2 above pre-industrial levels.

    Constraining ECS has remained a holy grail in climate science ever since US meteorologist Jules Charney suggested a possible range of 1.5C to 4.5C in his 1979 report. His estimate was largely based on the world’s first two global climate models, which gave different estimates of 2C and 4C when they performed a simple experiment where atmospheric CO2 levels were doubled.

    Since then, despite more than 40 years of research, much improved understanding of atmospheric processes, as well as many more detailed observations, this range has stubbornly persisted.

    Now, bringing together evidence from observed warming, Earth’s distant past and climate models, as well as advances in our scientific understanding of the climate, our findings suggest that the range of ECS is likely to be between 2.6C and 4.1C.

    This narrowed range indicates that human society will not be able to rely on a low sensitivity to give us more time to tackle climate change. But the silver lining to this cloud is that our findings also suggest that very high ECS estimates are unlikely.

    Guest post: Why low-end ‘climate sensitivity’ can now be ruled out by Piers Forster, Zeke Hausfather, Gabi Hegerl, Steven Sherwood & Kyle Armour, Carbon Brief, June 22, 2020

    Note: This article will be reposted in its entirety on this website later this week.

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  6. Thanks for the clarifications. The Carbon Brief article was one the two I had read.

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  7. Sailrick, I kind of agree with you. It's more a ruling out of low end then high end states. Personally I will place more importance on the paleontological evidence. If we're 1C+/- now

    + 0.2C for the pre-preindustrial warming 

    + 0.5C for aerosols

    plus you have a 30year/66% lag meaning the temperatures were experiencing now are more indicative of 350ppm than 420ppm. So I see your point on how a +40% increase in CO2 has in all probability commited us to +2C rise in 150yrs. This doesn't address what the end state will be in 1000yrs or more. Now instead of a 40% increase imagine an actual doubling its obvious that a 2C warming shouldn't even be in the equation

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