Every day, it seems, there is another news story or reports of yet more evidence that the global climate is changing, either as we have predicted for years—or worse and faster. The climate system is incredibly complex, and climatologists, climate modelers and paleoclimatologists are furiously working to reduce the uncertainty. Despite the uncertainties and complexities, at this point it is clear that:
•Global mean temperatures are rising.
•Ocean heat content is increasing.
•Sea ice cover is, on average, decreasing (both in areal extent and thickness).

Arctic sea ice cover is in serious long-term decline (photo: Huffpost Canada)
•Ice sheets and glaciers are shrinking.
•Permafrost is thawing.
•Sea level is rising.
•Changes in climate-sensitive biota, ecosystems, and landforms are all consistent with a warming climate.
•The major driving force is a dramatic increase in heat-trapping greenhouse gases such as carbon dioxide and methane.
