Study: Actually, carbon dioxide might not warm the planet as much as thought

The climate may be less sensitive to carbon dioxide than we thought – and temperature rises this century could be smaller than expected. That’s the surprise result of a new analysis of the last ice age. However, the finding comes from considering just one climate model, and unless it can be replicated using other models, researchers are dubious that it is genuine…

Schmittner plugged the atmospheric greenhouse gas concentrations that existed during the Last Glacial Maximum into a climate model and tried to recreate the global temperature patterns. He found that he had to assume a relatively small climate sensitivity of 2.4 °C if the model was to give the best fit.

If climate sensitivity really is so low, global warming this century will be at the lower end of the IPCC’s estimates. Assuming we keep burning fossil fuels heavily, the IPCC estimates that temperatures will rise about 4 °C by 2100, compared with 1980 to 1999. Schmittner’s study suggests the warming would be closer to their minimum estimate for the “heavy burning” scenario, which is 2.4 °C.