Contrary to the IPCC's assessment, Lindzen said that climate models are inadequate. Despite accepted errors in their models, e.g., treatment of clouds, modelers still thought their climate predictions were valid. Lindzen has stated that due to the non-linear effects of carbon dioxide in the atmosphere, CO2 levels are now around 30% higher than pre-industrial levels but temperatures have responded by about 75% of the expected value for a doubling of CO2. The IPCC (2007) estimates that the expected rise in temperature due to a doubling of CO2 to be about , ± 1.5°. Lindzen has given estimates of the Earth's climate sensitivity to be 0.5 °C based on ERBE data. These estimates were criticized by Kevin E. Trenberth and others, and Lindzen accepted that his paper included "some stupid mistakes". When interviewed, he said "It was just embarrassing", and added that "The technical details of satellite measurements are really sort of grotesque." Lindzen and Choi revised their paper and submitted it to "PNAS". The four reviewers of the paper, two of whom had been selected by Lindzen, strongly criticized the paper and PNAS rejected it for publication. Lindzen and Choi then succeeded in getting a little known Korean journal to publish it as a 2011 paper. Andrew Dessler published a paper which found errors in Lindzen and Choi 2011, and concluded that the observations it had presented "are not in fundamental disagreement with mainstream climate models, nor do they provide evidence that clouds are causing climate change. Suggestions that significant revisions to mainstream climate science are required are therefore not supported."