Updated Science Report Provides Window Into Key Climate Trends
As the world prepares for the next round of international climate talks in Copenhagen, a new study has been released on the recent science. The Copenhagen Diagnosis, which was a year in the making, documents the key findings in climate change science since the publication of the landmark Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report in 2007.
One of the key findings that will impact our southeastern coast are the updates on the pace of sea-level rise. The report updates recent (2007) projections of 7-23 inches (18-59 cm) to “about double” the estimate reached two years ago. This means that projections in the 1 to 4 foot range are becoming the scientific norm. See excerpt below from page 40 of the report:
Sea level is likely to rise much more by 2100 than the often-cited range of 18-59 centimeters from the IPCC AR4. As noted in the IPCC AR4, the coupled models used in developing the 21st century sea level projections did not include representations of dynamic ice sheets. As such, the oft-cited 18-59 centimeters projected sea level rise only included simple mass balance estimates of the sea level contribution from the Greenland and Antarctic ice sheets. As a consequence of an assumed positive mass balance over the Antarctic ice sheet in the AR4, Antarctica was estimated to have contributed to global sea level decline during the 21st century in that report. However, the Antarctic Ice Sheet is currently losing mass as a consequence of dynamical processes (see Figure 10 in this report). Based on a number of new studies, the synthesis document of the 2009 Copenhagen Climate Congress (Richardson et al. 2009) concluded that “updated estimates of the future global mean sea level rise are about double the IPCC projections from 2007.”
As Eric Steig notes, everything in the Copenhagen Diagnosis is from the peer-reviewed literature, so there is nothing really new. Some of the key points summarized in this report are:
– Both the Greenland and Antarctic ice-sheets are losing mass and contributing to sea level rise at an increasing rate, according to satellite and direct measurement data.
– Arctic sea-ice has melted far beyond the expectations derived from climate models. For example, the area of summer sea-ice melt during 2007-2009 was about 40% greater than the average projection from the 2007 IPCC Fourth Assessment Report.
– Sea level has risen more than 5 centimeters over the past 15 years, about 80% higher than IPCC projections from 2001. As mentioned above, accounting for ice-sheets and glaciers, global sea-level rise may exceed 1 meter by 2100, with a rise of up to 2 meters considered an upper limit by this time. This is much higher than previously projected by the IPCC. Furthermore, beyond 2100, sea level rise of several meters must be expected over the next few centuries.
– In 2008, carbon dioxide emissions from fossil fuels were ~40% higher than those in 1990. Even if emissions do not grow beyond today’s levels, within just 20 years the world will have used up the allowable emissions to have a reasonable chance of limiting warming to less than 2 degrees Celsius.
This spells serious trouble on a number of fronts around the world. For the Southeast, it’s very bad news for some of our treasured places (Southern Alliance for Clean Energy video) such a the Outer Banks, Florida Keys, the Everglades and many of our beautiful beaches.
Check out some news coverage of the report’s release from other sources:
– ABC-Australia interviews one of the report’s authors, Professor Matthew England, in this podcast.
– “The Copenhagen Diagnosis: Sobering Update on the Science,” from Yale Environment 360 (a publication of the Yale School of Forestry & Environmental Studies).
– “The Best Reason to Ignore ‘Climategate: The Climate Really is Changing,” from The Washington Independent.
– “Copenhagen Diagnosis’ offers a grim update to the IPCC’s climate science,” from Grist.
