Jacob Sebastian Haugaard Mernild (born 20 October 1972) is a Danish professor in climate change, glaciology and hydrology, who is the pro-vice-chancellor of the University of Southern Denmark. Mernild has been an Intergovernmental Panel on Climate Change (IPCC) author for the United Nations since 2010. Initially a contributing author on the IPCC Fifth Assessment Report, he was lead author on the IPCC Sixth Assessment Report.