Can we rule out a worst case global warming scenario? These scientists sure think so

By Michael Bastasch

A new study is bolstering arguments that the United Nations’ worst case manmade global warming scenario is not likely to happen.

The study, published in the journal Nature, claims to have narrowed the likely range of how sensitive the climate is to a doubling of atmospheric greenhouse gas concentrations, or climate sensitivity.

Researchers used variations in past temperatures to get what they say is a more accurate range of future warming. Essentially, the study was able to rule out the very high end estimates of climate sensitivity, meaning the United Nations’ worst case scenario is less likely than climate models suggest.

On the other hand, the study also ruled out the low-end estimates of climate sensitivity, which researchers say means there is still enough projected warming to “demand action.”

“Our study all but rules-out very low or very high climate sensitivities, so we now know much better what we need to,” lead author Peter Cox from the University of Exeter said in a statement.

“Climate sensitivity is high enough to demand action, but not so high that it is too late to avoid dangerous global climate change,” Cox said.

Cox’s study shrinks the United Nations’ range of climate sensitivity 60 percent, from a range of 1.5 to 4.5 degrees Celsius to a range of 2.2 to 3.4 degrees. Cox’s central estimate of climate sensitivity is 2.8 degrees.

While scientists skeptical of catastrophic global warming may take issue with the low-end estimate, this is the second study in recent months to cast doubt on more alarming global warming scenarios.

Two University of British Columbia scientists published a study in December calling into question scientists’ use of the United Nations’ RCP 8.5 scenario — the “nightmare” scenario.

Researchers found that RCP 8.5 modeled a future where historical trends reverse, and the world switches to using more coal. Coal consumption is projectedto increase as poor countries develop, but it’s projected to become a declining share of global energy use.

This “indicates RCP8.5 and other ‘business-as-usual scenarios’ consistent with high CO2 forcing from vast future coal combustion are exceptionally unlikely,” the study found.

But this is really nothing new. Skeptics have been pointing out for years that the United Nations’ “business as usual” scenario is unlikely, and only served to make national pledges to comply with the Paris accord seem more ambitious than they actually were.

For example, former Cato Institute climate scientist Chip Knappenberger often pointed out that RCP 8.5 is not “business as usual.”

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Image courtesy of Wikimedia Commons/Ansgar Walk

2 thoughts on “Can we rule out a worst case global warming scenario? These scientists sure think so

  1. Funny how this article does not have one single scientific fact in it, yet it claims a “known result”. Every article I read on this topic is the same, zero facts and all opinion.

  2. The scientist can’t even agree. What will happen in the worst case scenario? Weather runs in cycles. Leave it alone and it will work itself out. What will happen if the volcanoes in Yellow Stone Park explode as I saw some projections in a documentary? If nukes start flying, life as we know it will be gone forever.

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