The International Panel on Climate change undertook several surveys of the overall economic impacts of climate change in the Second through Fifth Assessment Reports. The IPCC stated that "the global mean losses could be 1 to 5 p.c. of GDP for 4* C of Warming." This study pursues several controversial issues e.g. methods and models for climate change, Stern Report, Kyoto Protocol and after, Global warming, Climate policy for 21st century.