Study 'finds climate models are unable to reproduce the temperatures of the mid-Miocene Climatic Optimum when CO2 levels were about the same as today [400 ppm]. The authors find the models simulate a global mean temperature 4°C less than determined from climate proxies, and 'an equator to pole temperature gradient which is at least ~ 10°C larger than the reconstruction from proxies.' The authors acknowledge "a major climate problem" between the model world and the real world reconstructions. The paper adds to hundreds of other peer reviewed publications indicating that there are fundamental flaws in the climate models, including sensitivity to CO2 and heat transfer assumptions. Prior papers have also found that climate models are unable to reproduce the Medieval Warming Period, or the 20th & 21st century climate, much less the future.'