Meeting in Stockholm last week, the Intergovernmental Panel on Climate Change (IPCC) released new research from its Fifth Assessment Report – the culmination of six years of research and data analyses since the Fourth Assessment Report was issued in 2007. The IPCC Working Group concluded "… It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. The evidence for this has grown, thanks to more and better observations, an improved understanding of the climate system response and improved climate models."
Warming in the climate system is unequivocal and since 1950 many changes have been observed throughout the climate system that are unprecedented over decades to millennia. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850, reports the Summary for Policymakers of the IPCC Working Group I assessment report, Climate Change 2013: the Physical Science Basis, approved last Friday by member governments of the IPCC.
Thomas Stocker, the Co-Chair of Working Group I said: "Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions."
Projections of climate change are based on a new set of four scenarios of future greenhouse gas concentrations and aerosols, spanning a wide range of possible futures. The Working Group I report assessed global and regional-scale climate change for the early, mid-, and later 21st century.
The full report will not be released until next year. Part 1, generally the most anticipated part of the IPCC report, deals with scientific assessment. Part 2—on impacts, adaptations and vulnerability, and Part 3—on mitigation.
More information on the IPCC, its work and future meetings is available at http://www.ipcc.ch/.