Mark C. Urban, University of Connecticut (image) University of Connecticut Caption University of Connecticut Assistant Professor Mark Urban stands under a sheet of aufeis in Alaska. These ice sheets form over Arctic underground springs but have become less prevalent with global warming. Urban, a professor of ecology and evolutionary biology, fears that current climate change models may grossly underestimate future extinctions because they fail to account for species competition and movement. Credit Mark Urban Usage Restrictions Image and caption information cannot be used until 7 p.m. (EST) Jan. 3, 2012 due to embargo. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.