What can Earth‘s past tell us about future global warming?

11/09/2016 - A new analysis of more than 700,000 years climate history shows that with ongoing greenhouse gas emissions our planet might warm even more than previously predicted. In the past, Earth’s temperatures varied strongly, driven by a variety of factors including CO2 concentration in the atmosphere. This provides valuable information for assessing the climate effect of modern times’ burning of fossil fuels. A study now published in Science Advances indicates that human-caused warming might even exceed earlier projections by the Intergovernmental Panel on Climate Change (IPCC). This would mean that we can emit even less CO2 to meet the temperature target of the Paris Agreement: keep warming below 2 degrees.
What can Earth‘s past tell us about future global warming?

“Strong changes in past Earth’s temperatures show how sensitive our climate is and hence allow us to better understand future effects of the perturbation caused by anthropogenic greenhouse gas emissions,” says Andrey Ganopolski, co-author of the paper and senior scientist at the Potsdam Institute for Climate Impact Research. “Our new estimate for climate sensitivity does not imply that the goal to stay below 2 degrees of global warming cannot be achieved but, if our estimate for climate sensitivity  is correct,  this  would require even stronger reduction of CO2 emission." While the new findings overlap with the so-called CMIP5-scenarios  of the IPCC, they certainly are at the upper range and could even mean 5 instead of 4 degrees warming by the end of the century in a business-as-usual scenario of greenhouse-gas emissions.

Article: Friedrich, T., Timmermann, A., Tigchelaar, M., Timm, O.E., Ganopolski, A. (2016): Nonlinear climate sensitivity and its implications for future greenhouse warming. Science Advances [DOI:10.1126/sciadv.1501923]

Weblink to the article: http://advances.sciencemag.org/content/2/11/e1501923

Weblink to media publication on the study: http://www.independent.co.uk/news/science/climate-change-game-over-global-warming-climate-sensitivity-seven-degrees-a7407881.html