It is indisputable, however, that past changes in temperature correspond with changes in atmospheric carbon dioxide concentrations. Rising temperatures corresponding to increasing atmospheric carbon dioxide concentrations are consistent with the laws of physics. Despite the uncertainties associated with the timing and extent of global climate change, there is scientific consensus that it is happening. Over 2,500 scientists support the key findings of the United Nation's 1996 Intergovernmental Panel on Climate Change report. Members of professional, scientific societies, such as the Ecological Society of America, have signed a statement supporting as solid science the fact that human-generated greenhouse gas emissions, mainly carbon dioxide, are trapping the Earth's heat like a greenhouse.
Greenhouse gases trap the heat of the sun, impacting the temperature on Earth.
The four major greenhouse gases are carbon dioxide, methane, nitrous oxide, and fluoro-carbons. Changing land-use patterns through agriculture and deforestation also contribute to emissions of CO2. Fluorocarbon emissions result from human-made chemicals used primarily for refrigeration and insulation. Increased greenhouse gases may or may not increase local land temperatures, depending on the degree to which local and regional climate is modified by other human actions. But a warmer atmosphere will influence other Earth properties.