One of the most visually compelling examples of recent climate change is the retreat of glaciers in mountain regions. In the U.S. this is perhaps most famously observed in Glacier National Park, where the terminus of glaciers have retreated by several kilometers in the past century, and could be gone before the next century (see e.g. the USGS web site, here, and here). In Europe, where there is abundant historical information (in the form of paintings, photographs, as well as more formal record-keeping), retreat has been virtually monotonic since the mid 19th century (see e.g. images of the glaciers at Chamonix). These changes are extremely well documented, and no serious person questions that they demonstrate long term warming of climate in these regions. New work published in Science (“Extracting a Climate Signal from 169 Glacier Records”) highlights these results, and uses them to make a new estimate of global temperature history since about 1600 A.D., which agrees rather well with previous, independent temperature reconstructions.
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Guest commentary from David Archer (U. Chicago)
The notion is pervasive in the popular and scientific literature that the lifetime of anthropogenic CO2 released to the atmosphere is some fuzzy number measured most conveniently in decades or centuries. The reality is that the CO2 from a gallon out of every tank of gas will continue to affect climate for tens and even hundreds of thousands of years into the future.
The primary purpose of the Intergovernmental Panel for Climate Change (IPCC) is to assess the available scientific knowledge about climate change, not to initiate new research. The next IPCC report (Assessment Report 4, or AR4) is due in 2007, and in order to update of the state of knowledge it will only consider papers published in peer-review scientific journals between 2000 and papers submitted by May 1st 2005 (must be accepted before December 2005). It is essential that the papers be published in scientific quality journals in order to ensure the credibility of the results. Nevertheless the IPCC reports undergo several additional reviews and revisions involving a large number of independent referees. Thus, the IPCC reports undergo a more stringent review process than common papers in the scientific literature.
This is the first of two pieces on the recent IPCC workshop in Hawaii, This brought together independent researchers from all over the world to analyse computer model simulations of the last 150 years and to assess whether they are actually any good.
Guest commentary from Natassa Romanou (Columbia University)
During the first 3 days of March 2005, balmy downtown Honolulu in Hawaii was buzzing with agile scientists conversing, chatting, announcing, briefing and informing about IPCC assessment reports, climate models, model evaluations, climate sensitivities and feedbacks. These were the participants of the Climate Model Evaluation Project workshop (CMEP) and came here from most (if not all) the major, most prestigious climate research laboratories of the world, including; The US labs National Center for Atmospheric Research, the Geophysical Fluid Dynamics Laboratory and the Goddard Institute for Space Studies, the British Hadley Centre for Climate Prediction, the German Max Planck Institute for Meteorology, the Canadian Centre for Climate Modelling and Analysis, the French Centre National de Recherches Meteorologiques and the IPSL/LMD/LSCE, the Australian CSIRO Atmospheric Research, the Chinese Institute of Atmospheric Physics, the Russian Institute for Numerical Mathematics and the Japanese Meteorological Research Institute. This meeting was sponsored by the benevolent NSF, NOAA, NASA and DOE.
Guest Commentary by Drew Shindell (NASA GISS)
The current winter and early spring have been extremely cold in the Arctic stratosphere, leading to the potential for substantial ozone depletion there. This has been alluded to recently in the press (Sitnews, Seattle Post Intelligencer), but what’s the likely outcome, and why is it happening?