The Changing Arctic: Recent Events & Global Implications Martin O. Jeffries National Science Foundation Office of Polar Programs Division of Arctic Sciences Presentation to the Seasons and Biomes Workshop Fairbanks, AK, 27 September 2007 Source: BBC Increasing Greenhouse Gas Concentrations in the Atmosphere CO 2 CH 4 Radiative effect 20:1 NO 2 Radiative effect 1:300 Source: BBC Greenhouse Gases and Increasing Global Temperature Computer models can not simulate the 20th Century global air temperature trend unless increased atmospheric greenhouse gas concentrations are included. Source: BBC Computer Simulation of Global Temperatures IPCC: Inter-governmental Panel on Climate Change Non-uniform geographic distribution of temperature increase. Arctic amplification of global warming. Why arctic amplification? Regional positive feedback processes. Albedo ( ) The ratio of reflected solar radiation to total incoming solar radiation. A black object has an albedo of 0 (zero). That is, all solar radiation is absorbed. A white object has an albedo of 1 (one). That is, all solar radiation is reflected. Source: National Snow and Ice Data Center (NSIDC) 16 August September 2005 Arctic Sea Ice Retreat: A Positive Feedback August ice extent, Extent (10 6 km 2 ) x 10 6 km 2 16 September 2007 Record minimum, 4.1 x 10 6 km 2 Sea Ice Loss: The Real World Outpaces the Virtual World Consequences of a Declining Sea Ice Cover On 7 September 2007, the US Geological Survey reported the results of a study that predicts that by 2050 the polar bear population will be reduced by 66%. The reduction will not be evenly distributed - polar bear populations in some regions will not survive the loss of sea ice - they will disappear completely. Changing polar bear populations are a very visible and emotional sign of ecosystem change. 279 species of migratory bird breed in significant numbers in the Arctic. Of those, 30 reach southern Africa, 26 reach Australia and New Zealand, 22 reach southern South America, and several species reach the Southern Ocean. Arctic Change has the potential to affect biodiversity far from the Arctic. Arctic tern Natural Resources, International Trade and Geopolitics Northern Sea Route Northwest Passage Source: NSIDC Source: BBC S.S.Manhattan, NW Passage, 1969 Source: BBC 2 August 2007 People & Communities Shishmaref, Alaska Arctic CoastCentral Alaska Rising Ground Temperatures Source: Vladimir Romanovsky Thawing Permafrost Thermokarst Landscape Change & Methane (CH 4 ) Methane gas Bacteria make methane (decomposition) Arctic methane & permafrost Methane Mobilized: Another Positive Feedback Source: MOJ Increased Melting on the Greenland Ice Sheet