A Closer Look at the Ipcc Report

In the future, Arctic warming and the melting of polar glaciers will be considerable, but the magnitude of both is uncertain. We used a global climate model, a dynamic ice sheet model, and paleolithic data to evaluate Northern Hemisphere high-latitude warming and its impact on Arctic ice fields during the Last Inter glaciation. Our simulated climate matches paleolithic observations of past warming, and the combination of physically based climate and ice sheet modeling with ice core constraints indicate that the Greenland Ice Sheet (GUYS) and other circumstantial ice fields likely contributed 2.2 to 3.4 m of sea level rise during the Last Interrelation. 

Determining the sensitivity of the Arctic climate system to anomalous forcing and understanding how well climate models can simulate the future state of the Arctic are critical priorities. Over the past 3 years, Arctic surface temperatures have increased o.3°C per decade (0); September Arctic sea-ice extent has decreased 7.7% per decade (2); and the seasonal ablation area for Greenland has increased, on average, by 16% (3-3). The global climate models being used to estimate future scenarios of Arctic warmth give polar warming of o.7°C to 4.4°Ca large ranges well as a reduction of Arctic sea ice of up to 65% at the time of the doubling of atmospheric CO (6). The Last Inter glaciation (LUG, about 130,000 to 116,000 years ago) is the last time that the Arctic experienced summer temperatures markedly warmer than those in the 20th century and the late Holocene, and it also featured a significantly reduced GUYS. Climate models need to be able to current event science articles. reproduce this large. warm climate change in the Arctic if they are to lie trusted in their representation of Arctic processes and their prediction for the future. Prerecords indicate much warmer Arctic summers during the LUG. Storm beaches and ancient barrier islands with mollusks of LUG age indicate that the open water north of Alaska was more extensive and Listed seasonally longer (7) Arboreal forest communities expanded pollard by as much as boo to moo km in Russia (8). reaching the coast everywhere crept in Alaska (9) and central Canada. Total gas evidence from L ice in the Greenland Ice Core Proctor (GRIP) ice (Orr indicates that the Summit region remained ice centered. although possibly up to about Soto m lower than the we level at per', rm. at sonic tune m the LING (soy In contrast. basal ice at Dye-3 (southern Greenland); in the Agassi Demon. and Meighen ice caps in the Canadian Arctic; and possibly in Camp Century (northwest Greenland) suggest that these doll sites were Refine during the LING (so. 1). The increased presence of vegetation over southern Greenland is reconstructed from plant macro. fossils 07) and fern spores (0). Elsewhere. pol• lens. Insects. marine plankton. and other pros ices document the magnitude of LUG summer warmth across the Arctic (14). We conducted climate simulations for the LUG with a global coupled ocean-atmosphere-land sea ice general circulation model National Center for Atmospheric Research (N CAR) Community Climate System Model (COSMIC) Dem. We also used we sheet simulations with a three-dimensional. coupled kindhearted-flow model 06). which spans the entire western