Mark Clifford Serreze is an American geographer and the director of the National Snow and Ice Data Center (NSIDC), a project of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. He officially became the NSIDC's director in August 2009. In 2019, he was named a Distinguished Professor in the Department of Geography. Serreze is primarily known for his expertise in the Arctic sea ice decline that has occurred over the last few decades due to global warming, a topic about which he has expressed serious concern.