Policy issues climate change impacts

Mankind s impact on the global climate and whether pollution from modern energy use is indeed warming the Earth have become important issues for national and international policy makers. Political pressure and public sentiment are based on complex data sets that, alone, cannot tell the whole story. The ultimate question is whether our climate is becoming warmer because of the slow build-up in atmospheric greenhouse gas concentrations (1). The answer is not clear, because much of what we know about global climate change is inferred from historical evidence of uncertain quality. 

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