The article: Has CO2 warmed the planet at all in the last 50 years? It’s harder to tell than you think explains the uncertainty regarding the Anthropogenic Global Warming proposition.
It seems clear that the perception of human caused "Global Warming" is a function of several factors:
1) Urban Heat Island Effect (UHI) - the effect of concentrated human technocratic infrastructure that raises local temperatures. The proximate causes of UHI range from placement of weather recording stations in areas of artificial heat generation (airports, near air conditioners r other industrial heat sources) to generalized heat bubbles surrounding major cities. Selection of recording sites is critical in evaluating temperature records. (See numerous articles on Watts Up With That?)
2) Temperature data and data source manipulation - selection of recording sites, start and end points of records analyzed, step increases in temperature masking trends, manipulation of raw data, work to create the impression of a warming climate.
sustainable development," and most, if not all of their policy documents are couched in terms of making the developed nations pay for continuing development in the "global South." Environmental organizations such as Greenpeace, The Sierra Club, and World Wildlife Fund have changed from grassroots advocacy and action to political lobbying organizations, requiring multi-million dollar budgets and a compromising presence in world seats of power and influence.
4) Natural climate change - Yes, the climate of the earth does change, all on its own. In fact, change is the norm. It is the expectation of a static, unchanging climate that is at odds with reality.
5) Media hysteria - Media mavins love a bold headline, even if it isn't true.
6) Anecdotal weather observations - heat, tornadoes, hurricanes, flooding. Individual, (aka anecdotal) weather observations of floods, tornadoes, hail, thunderstorms, hurricanes give a perception of weather "out of control," as if weather was ever in control. Today's weather extremes are no different than those of the past. Anecdotal weather observations do not take into account the history of weather and climate variation.