Last Friday in Stockholm, Sweden the Intergovernmental Panel on Climate Change (IPCC) presented the findings of its physical science working group as the first segment of their 5th Assessment Report (AR5) on global warming and climate change. Later in this post I’ve summarized those findings. But first here are some important links to this important report.
The IPCC website (including the AR5 report) is here. The AR5 headline summary is here. Always valuable on all environmental topics are the comments and discussion in Andrew Revkin’s NY Times column, Dot Earth, which is here.
Ok, now for my summary of the major points from this first IPCC segment of AR5. Important to remember that these finds are the consensus of over 250 climate scientists from 39 different countries after review ALL climate science research produced in the last 2 years:
• Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades and millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.
• Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.
• Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent
• The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia
• The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years.
• CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions.
•The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification.
• Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system.