Facts versus opinions regarding global climate change

We are not entitled to our own facts when it comes to matters of science. This excellent point was made by climatologist Michael Mann.  He further stated the opinions and beliefs of a few climate change skeptics should not be given equal credibility to such credible sources as the US National Academy of Sciences and all the National Academies of Sciences from around the world.

A brief ScienceFriday audio clip with Dr. Mann is available for listeners, "The difference between facts and opinions".  Michael Mann has also written a book that goes into great more detail "The Hockey Stick and the Climate Wars: Dispatches from the Front Lines."

A group of 18 science related organizations within the US wrote a letter in 2009 to the US Senate stating the following consensus scientific view:

Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science. Moreover, there is strong evidence that ongoing climate change will have broad impacts on society, including the global economy and on the environment. For the United States, climate change impacts include sea level rise for coastal states, greater threats of extreme weather events, and increased risk of regional water scarcity, urban heat waves, western wildfires, and the disturbance of biological systems throughout the country. The severity of climate change impacts is expected to increase substantially in the coming decades.1

If we are to avoid the most severe impacts of climate change, emissions of greenhouse gases must be dramatically reduced. In addition, adaptation will be necessary to address those impacts that are already unavoidable. Adaptation efforts include improved infrastructure design, more sustainable management of water and other natural resources, modified agricultural practices, and improved emergency responses to storms, floods, fires and heat waves.

1 The conclusions in this paragraph reflect the scientific consensus represented by, for example, the Intergovernmental Panel on Climate Change and U.S. Global Change Research Program. Many scientific societies have endorsed these findings in their own statements, including the American Association for the Advancement of Science, American Chemical Society, American Geophysical Union, American Meteorological Society, and American Statistical Association.