"there is room for debate about the overall impact of mankind’s contribution to global warming"

Actually there is none, the scientific consensus is "It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period."

http://www.realclimate.org/index.php/archives/2013/10/the-ipcc-ar5-attribution-statement/

The current scientific debate wrt climate is how future warming will play out at a local level.