The Intergovernmental Panel on Climate Change (a.k.a. the IPCC) stated in its most recent report (AR4, 2007) that, “it is extremely unlikely that global climate change of the past 50 years can be explained without external forcing, and very likely that it is not due to known natural causes alone.”
What this means is that scientists are now very confident in stating that observed climate change has been caused by humans and in particular, their release of greenhouse gases, namely carbon dioxide.
The consensus in the scientific community is that climate change is real, and occurring now. The evidence is overwhelming that humans are having a negative impact on the Earth’s climate, and something needs to be done. Now.
Understanding Climate Change
Skeptical science – a website that answers every objection you have heard to the science of climate change
CO2 now – provides up-to-date information on the current concentration of CO2