The recent projections, which are based on new computer models and an analysis of the increased number of extreme heatwaves in the past decade, are more troubling than the findings of the UN panel of climate scientists last year. The report from the Intergovernmental Panel on Climate Change stated that it is very likely that heatwaves will become longer, more frequent, and more intense over most land areas this century. The study also revealed that monthly heat extremes in summer now affect five percent of the world's land area, a number projected to double by 2020 and quadruple by 2040. The most affected regions by increased heatwaves will be the tropics, the Mediterranean, the Middle East, parts of western Europe, central Asia, and the United States. According to Dim Coumou of the Potsdam Institute for Climate Impact Research, in many areas, the coldest summer months by the end of the century will be hotter than the hottest experienced today unless greenhouse gas emissions are reduced. The IPCC has warned that heat-trapping gases, primarily from burning fossil fuels, are causing temperatures to rise, leading to more severe downpours, heatwaves, floods, and rising sea levels. Nearly 200 governments have agreed to limit global warming to less than 2 degrees Celsius above pre-industrial times and are working towards a deal to reduce greenhouse gas emissions by the end of 2015. Global average surface temperatures have increased by 0.8C since the Industrial Revolution.