Why has it been so difficult to achieve meaningful solutions to global warming? Media pundits, partisan think tanks, and special interest groups raise doubts about the truth of global warming. This barrage of misinformation misleads and confuses the public — and makes it more difficult to implement effective solutions.
Some critics of the scientific consensus on global warming have argued that these issues should not be linked and that reference to them constitutes an unjustified ad hominem attack.  Political scientist Roger Pielke, Jr. , responding to Mooney, has argued that science is inevitably intertwined with politics. 
NASA’s Goddard Institute of Space Studies (GISS) tracks atmospheric global temperature climate trends. As environmental engineer, D Kelly O’Day, explained on (link no longer available): To facilitate assessments of long term trends, climatologists compare the mean for a base period with the annual mean. Differences between the annual mean and baseline mean are called anomalies. GISS uses the 1951 - 1980 period for their baseline period. They use the difference between the annual mean and the baseline mean to determine the global temperature anomaly for the year.
The term attached to the notion that the Earth 's temperature is increasing due to the greenhouse effect .