Summary: An eminent climate scientist gives her summary of the debate about the Climate Emergency. Sadly, much of this repeats the messages given us by the IPCC and the major climate agencies. Few people know this because the major news media misrepresent their messages, since claims by alarmists are more exciting and (to them) politically pleasing.
About climate ‘limits’ and timelines
By Judith Curry at Climate Etc., 16 October 2019.
I received the following questions today from a reporter, related to climate change and ‘timelines.’ These questions are good topics for discussion. My answers are provided below
Q: From your perspective, have the early warnings about how hot the Earth is getting turned out to be accurate? Have they been adjusted higher or lower than expected?
Early predictions of warming were 0.2 to 0.3°C/decade were too high relative to actual observations. Further, blaming all of the recent warming on carbon dioxide emissions is incorrect, in my opinion. Solar indirect effects and multi-decadal oscillations of large scale ocean circulations have been effectively ignored in interpreting the causes of the recent warming.
Q: What is the best figure that explains how we will know when things are really irrevocably bad? Is it the 2ºC limit, as some have reported?
‘Bad’ is a value judgment, and regions are affected differently by climate variations and change. Most of the so-called ‘bad effects’ of climate change relate to the natural variability of weather, and there is little to no evidence that extreme weather events have been worsening, against the large variations of natural climate variability.
The single adverse impact that is unambiguously associated with warming (whatever the cause) is a sea level rise. Since 1900, global sea level has risen about 8″. There are substantial temporal and spatial variations of sea level rise, associated with large scale ocean circulation patterns, glacial rebound, weather, and tides. Projections of a sea level rise by 2100 beyond several feet require: implausible scenarios of the amount of carbon dioxide in the atmosphere, climate models that have implausibly high warming sensitivity to the amount of CO2 in the atmosphere, and the collapse of the West Antarctic ice sheet (from speculative and poorly understood processes).
The 2°C limit relates to expectations for long-term (many many centuries) melting of the Greenland and Antarctic ice sheets. The issue of the 2°C limit is better described as ‘planetary diabetes’ rather than extinction or other dire characterizations. Another way of thinking about the so-called 2°C limit is analogous to a highway speed limit. If the speed limit is 65 mph, exceeding that by 10 or even 20 mph is not guaranteed to cause a crash. But if you exceed the limit by a lot, your risk of a fatal crash certainly increases.
Q: How do the actions (or inactions) of the Trump administration, such as withdrawing from the Paris climate agreement, affect that timeline? If Democrats win the government in 2020, would implementing the Green New Deal (if it even passed) be too little, too late?
The actions of President Trump have made no essential difference to this timeline. Most of the signatories to the Paris Agreement are falling far behind in their commitments {details here} – although the U.S. has been doing relatively well in terms of its emissions cuts. Any future success of the Green New Deal relies on both politics and technology. Overwhelming Democratic control of the U.S. government wouldn’t necessarily help with the needed technology developments.
Afterword
The bottom line: these timelines are meaningless. While we have confidence in the sign of the temperature change, we have no idea what its magnitude will be. Apart from uncertainties in emissions and the Earth’s carbon cycle, we are still facing a factor of 3 or more uncertainty in the sensitivity of the Earth’s climate to CO2, and we have no idea how natural climate variability (solar, volcanoes, ocean oscillations) will play out in the 21st century. Even if we did have significant confidence in the amount of global warming coming, we still do not have a handle on how this will change extreme weather events. With regards to species and ecosystems, land use and exploitation are bigger issues.
Cleaner sources of energy have several different kinds of justifications, but thinking that sending CO2 emissions to zero by 2050 or whenever is going to improve the weather and the environment by 2100 is a pipe dream. If such reductions come at the expense of economic development, then vulnerability to extreme weather events will increase.
There is a reason that the so-called climate change problem has been referred to as a ‘wicked mess.’
Reposted under her Creative Commons license.
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About Judith Curry
Judith Curry retired as a Professor of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. She is now President and co-owner of Climate Forecast Applications Network (CFAN). Prior to joining the faculty at Georgia Tech, she served on the faculties of the University of Colorado, Penn State University and Purdue University.
She has served on the NASA Advisory Council Earth Science Subcommittee, the DOE Biological and Environmental Science Advisory Committee, the National Academies Climate Research Committee, and Space Studies Board, and the NOAA Climate Working Group.
She is a Fellow of the American Meteorological Society, the American Association for the Advancement of Science, and the American Geophysical Union. Her views on climate change are best summarized by her Congressional testimony: Policy Relevant Climate Issues in Context, April 2013.
Follow Dr. Curry on Twitter at @curryja. Learn about her firm, CFAN, at their website.
For More Information
Ideas! See my recommended books and films at Amazon.
If you liked this post, like us on Facebook and follow us on Twitter. For more information about this vital issue see the keys to understanding climate change. Also, see all posts about uncertainties in climate science, about Judith Curry, and especially these …
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- Look at the trends in extreme weather & see the state of the world.
- Focusing on worst case climate futures doesn’t work. It shouldn’t work.
- The IPCC gives us good news about climate change, but we don’t listen.
- Roger Pielke Jr.: the politics of unlikely climate scenarios.
- A look at the workings of Climate Propaganda Inc.
- Scary but fake news about the National Climate Assessment.
- Did the IPCC predict a climate apocalypse? No.
Activists don’t want you to read these books
Some unexpected good news about polar bears: The Polar Bear Catastrophe That Never Happened
To learn more about the state of climate change see The Rightful Place of Science: Disasters & Climate Change
Love her skill at writing!
A “wicked mess” it is. I’ll venture a guess and say the energy market (without subsidies) will win out and cooler heads will prevail. In spite of the media, politicians and activists.
Nice work by LK and Dr. Curry.
In regard to “Early predictions of warming were 0.2 to 0.3°C/decade were too high relative to actual observations.”
In regard to the above incorrect claim by Judith, the prediction of 0.2 to 0.3 Deg. C/decade was wrong because warming over land areas in the Northern Hemisphere (where most of us live) has actually averaged 0.345 deg C/decade which is equal to 6.2 degrees F. per century. (Least squares linear rate for the 360 month (30 year) period ending with Sept. 2019.)
Graph: http://www.durangobill.com/GwdLiars/GwdNOAALandStopped.jpg (Red line)
Data source: https://www.ncdc.noaa.gov/monitoring-references/faq/anomalies.php
(Click on “Anomalies and Index Data”)
(Select “Northern Hemisphere” for Region and “Land” for Surface)
Bill,
Curry’s claim about global average warming is incorrect because warming was faster in a specific region? Biggest logic fail I’ve seen in a long time. Perhaps you are unclear about the meaning of “average.”
Follow-up to Bill,
Unlike Curry’s, your claim is false.
Comparing forecasts vs. observations for different areas tells us nothing. To prove the early models’ forecasts were correct, you have to compare predicted vs. actual forecasts for the same area. That is, global to global (as Curry does), or N. Hemisphere land to N. Hemisphere land.
The current 30 year least squares global (land & sea) warming rate via the GISS/NASA database is 0.2102 degrees per decade (and slowly accelerating). This is within the 0.2 to 0.3 range.
NOAA’s (land + sea) rate is slightly under 0.20 at 0.1945. If you take an average of the two, it’s still over 0.20.
Bill,
How fun that you’ve found a number that makes you happy.
The average change over the era in which over half of the warming is anthro (1950-2019) is 0.14°C/decade.
The average change from El Nino peak to El Nino peak (just as economists measure economic cycles), 1998 – 2016 is 0.16°/decade.
These are the numbers from NOAA’s Climate At A Glance website, thru September 2019.
Larry, engineers do that as well. Also, if you know the system well trough to trough can give you approximations to variance or indicate the presence of other factors. This is especially important to look at when there is something with a name like “natural variance.” True, that all these require assumptions, but that is pretty common.
Extinction Rebellion in the UK
https://www.telegraph.co.uk/news/2019/10/17/commuters-drag-extinction-rebellion-protester-roof-train-activists/?fbclid=IwAR3MbpIeUSgwFHP7vAGSVoVaEevqxVx7sDCECGsHj5cwWsNL_XvTdMPgMsY
Hoo boy. You remember your posts about the problem of how the military is the most trusted arm of society in America? Whelp, we’ve got another one of the Night of the Generals pieces. https://www.nytimes.com/2019/10/17/opinion/trump-mcraven-syria-military.html#click=https://t.co/Q0JjU64ck4
It’s probably just twaddle but still, it’s never good when upper brass military start talking about personel charge in the executive.
Ps I’ve guessed you’ve noticed, but isn’t it funny that Johnson, Nixon and Clinton and maybe soon trump we’re all impeached not for any real reason but because they pissed off other members of the ruling class? I mean, we’ve had presidents being celebrated and lauded for their crimes and atrocities and not a whiff of impeachment, but cross the other elites and the hammer drops.
I do know that those are not the reasons that Nixon and Clinton were impeached for, but that’s how the story gets told.
Isaac,
Chapter 3973 in There Is No Deep State Working Against Trump So Move Along.
That joke never gets old. The article is so derivative too.
1. Intro about mundane things with more sentimentality than hallmark crack.
2. Abrupt transition into serious and stern warnings of vaguly violated norms, complete with totally real person desperate for a resolution that just so happens to mirror the author.
3 impeach the orange twitter troll.
It would be funny if it wasn’t so pathetic. And the great part is? Everyone always accepts it, just like they accepted all the ones before it. Probably good money involved in writing these. Maybe should be planning for retirement by banging out a couple of these a day.
That last part was a joke.
PS Hubert Humphrey would be ashamed of the dems. At the last debate, the head of the dnc got up on national tv and thanking the intelligence networks and the freaking CIA for speaking “truth to power”