Don't rule out severe global climate change yet

climate change
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A key metric of global warming is the Earth's "equilibrium climate sensitivity" (ECS), which represents the global surface warming that will accompany a doubling of atmospheric carbon dioxide. For nearly four decades, ECS was thought to be somewhere between 2.7 degrees Fahrenheit (F) and 8.1 degrees F, but a more precise estimate has eluded climate scientists.

That was until Peter Cox and colleagues published a paper in Nature earlier this year, which arrived at a more precise estimate, indicating a likely range for ECS of 4.0 degrees F to 6.1 degrees F. The finding was noteworthy because the study suggested that the true likely range for sensitivity could be reduced by more than 50 percent. The results were widely highlighted as ruling out the worst-case global warming scenarios.

Scientists at Lawrence Livermore National Laboratory (LLNL) and the University of Washington have concluded that it is too early to rule out such scenarios. "While the work of Peter Cox and his colleagues represents a novel and thought-provoking analysis, we find that large values of climate sensitivity are still in the cards," said Stephen Po-Chedley, lead author of the LLNL follow-up comment published in Nature.

In the original study, Cox et al. analyzed a set of 16 climate models, relating the models' natural year-to-year fluctuations in global temperature to their overall equilibrium climate sensitivity. They found that models with the most global temperature variability tend to exhibit greater climate sensitivity. On the other hand, models with the least global temperature variability tend to have small values of ECS. Cox et al. found that the real-world variability was somewhere in between these low and high variability extremes. Using a statistical approach, they were able to create an observationally constrained estimate of ECS.

When Po-Chedley and colleagues consider 11 additional climate models, the constraint on ECS is substantially weaker and encompasses large values of ECS. The expanded analysis also shows that the temperature metric that Cox et al. use is sensitive to the combined influence of solar, volcanic and greenhouse gas forcing in the latter half of the 20th century. When alternative analysis time periods are chosen, the risk of the worst-case global warming scenarios increases substantially. These results make it difficult to discount the possibility that the Earth's climate sensitivity is large.

Aside from the sensitivity of the estimated value of ECS to the included and the time period selected, Po-Chedley also noted that "the Cox et al. results represent one study among hundreds of publications attempting to estimate climate . Although the analysis is interesting and useful, it alone does not provide a definitive constraint on ."


Explore further

Future climate change revealed by current climate variations

More information: Peter M. Cox et al. Emergent constraint on equilibrium climate sensitivity from global temperature variability, Nature (2018). DOI: 10.1038/nature25450

Stephen Po-Chedley et al. Climate constraint reflects forced signal, Nature (2018). DOI: 10.1038/s41586-018-0640-y

Journal information: Nature

Citation: Don't rule out severe global climate change yet (2018, November 1) retrieved 20 May 2019 from https://phys.org/news/2018-11-dont-severe-global-climate.html
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Nov 04, 2018
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Nov 04, 2018
This one isn't the sky falling in the next second, it's the frog in the slowly boiled pot.

You've ignored it for forty years. Because it didn't suit your politics. You and your children (assuming you're not an incel) will pay the price. Do you suppose a couple billion people dying of starvation who have nuclear weapons will refrain from using them against you when they are dying of the policies you have supported? Glad I don't have kids and won't live long enough to pay for your idiocy.

Nov 05, 2018
"You've ignored it for forty years. Because it didn't suit your politics."

And we ignore it today because .00042% of the atmosphere cannot physically control the temperature of the entire body....and raising that concentration by .00008% cannot cause the laughably predicted 8% temperature increase. Simplest math in the world disproves CO2 as the driver of atmospheric temperature, and this is the math that they must explain in order to convince anyone capable of understanding what ratios mean. For all those not sucked in by a wonderful display of statistical gymnastics using tree rings, feedback loops, ocean uptake and the newly discovered sinks they forgot to model such as night time plant behaviour...I salute you.

To those with a science degree from "MEDIA INC"....keep on believing...


Nov 05, 2018
Yeah, . we know, . Fox, Breitbart, and Putin all told you.

Nov 05, 2018
And we ignore it today because .00042% of the atmosphere cannot physically control the temperature of the entire body....and raising that concentration by .00008% cannot cause the laughably predicted 8% temperature increase. Simplest math in the world disproves CO2 as the driver of atmospheric temperature, and this is the math that they must explain in order to convince anyone capable of understanding what ratios mean. For all those not sucked in by a wonderful display of statistical gymnastics using tree rings, feedback loops, ocean uptake and the newly discovered sinks they forgot to model such as night time plant behaviour...I salute you
And there it is - the dumdum argument from ignorance. Whole lotta zombie arguments rising from the dead in that harangue. I am surprised it didn't raise the zombie argument that its the sun!!

Nov 05, 2018
I love how people who are skeptical of global change are now being put into the same pool as "incels". If there weren't people challenging these theories about global change then we wouldn't be doing what science is all about. By definition science is about challenging our ideas about the world around us, we have been doing it for many years, this isn't something new. Please try to keep your politics away from these discussions if you can help it and let's not resort to name calling. Calling someone an "incel" because they think you are wrong is not how we should be debating these things. As far as the person who called themselves "theredpill", we should all see them for who they really are: a troll. Just ignore those people and eventually they'll go bother someone else.

Nov 05, 2018
@redpill:
for the average male (82kg per the interwebs), a 100mg dose of arsenic is enough to cause acute death. This equates to ~1.2ppm. Just like people can build up tolerances to some poisons over a long period of time through slowly increasing the dose over a long time frame, a single large dose or rapid upswing in their dosing can have a very negative effect.
True, the Earth has had higher CO2 concentrations in the past, but to the best of our knowledge, never changing at the current pace.

Nov 05, 2018
They made the term "incel" up themselves. Maybe you forgot.

What do you suppose their cure for being involuntary celibates is? Women should submit? Does this strike you as a particularly good idea?

Just askin'.

Nov 05, 2018
To answer questions:
Government-subsidized robots
No
It's worth it to keep the cranks happy.

Nov 05, 2018
To those with a science degree from "MEDIA INC"....keep on believing...


Aaaannnnddd.... another scientifically illiterate crank commenting on subjects in which it is not qualified, nor conversant.

Nov 05, 2018
I know it was just a headline but "Don't rule out severe global climate change yet" is just bizarre - who the hell is ruling out severe global climate change under the current circumstances?

Nov 05, 2018
I love how people who are skeptical of global change are now being put into the same pool as "incels"


Firstly, he didn't lump you together. He was implying that Incels won't have children because they will never breed - a fact we can only hope is true. Of course, this understanding does require the ability to read. And a lack of literacy is something you are being accused of - because it's the only thing that could explain climate change denial at this stage.

If there weren't people challenging these theories about global change then we wouldn't be doing what science is all about.


The problem is not people studying climate change and actually doing science. It's those, like you, who think yelling "NO IT'S NOT, YOU'RE LYING" is the same thing as skepticism. It's not. If you want to "challenge climate change" then spend the next 10 years doing the science and come back to us. Until then, respect people who've done that research.

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