Climate Models

A study by Patrick Brown and Ken Caldeira published in Nature uses statistical analysis to show that the climate models that most accurately simulate the recent past tend to predict greater future warming. The effort tries to reduce the uncertainty of climate projections. Caldeira:

Our study indicates that if emissions follow a commonly used business-as-usual scenario, there is a 93 percent chance that global warming will exceed 4C by the end of this century.

Update (December 15):  Any revision on climate estimates (even if there is some good news) is used by the right-wing media to say, "Oh, well, it was all wrong before then!"

Update (May 29, 2019):  Revised climate models will be incorporated into the next IPCC report. The models now indicate a climate sensitivity (doubled carbon dioxide concentration) of around 5 degrees Celsius rather the previous estimate of around 3 degrees.

Update (July 21, 2019):  It's interesting how a non-peer-reviewed paper is seized by rightwing sites as a major blow to anthopogenic climate change. Zeke Hausfather shows how to explain climate models:

Update (July 28, 2019):  Jaclyn Jeffrey-Wilensky reports on papers published in Nature and Nature Geoscience that drive a "stake through heart of skeptics' argument". New global temperature reconstructions find that previous cooling or warming trends had been more localized than present.

[T]he rise in global temperatures over the past 150 years has been far more rapid and widespread than any warming period in the past 2,000 years — a finding that undercuts claims that today’s global warming isn’t necessarily the result of human activity.

Update (August 25, 2019):  The CO2 Coalition is hard at work trying to discredit climate models. I'd like to see a response to specific claims, but my initial thought is that the projections might just as easily be too low as they could be too high. The actual data show a clear trend and we're already seeing significant consequences. Uncertainty about just how bad off we'll be in the future is no reason not to treat climate instability as a major problem.