Recent evidence has revealed that the Antarctic and Greenland ice sheets are not as static as once thought. Accelerated ice loss from the Greenland Ice Sheet, disintegrating ice shelves around Antarctica, and signs that several marine-terminating glaciers in Antarctica have begun an irreversible retreat all signal that changes are taking place faster than was thought possible. Ice sheets are projected to contribute significantly to global sea-level rise, which poses dramatic risks for coastal communities and island nations worldwide. In response to these rapid changes, several USGCRP agencies are funding efforts to improve representation of ice-sheet behavior in Earth System Models (ESMs), aiming to better estimate the potential future impacts of climate change on communities around the world.

International model intercomparison efforts such as the Marine Ice Sheet-Ocean Model Intercomparison Project, with participation from DOE, NASA, NOAA, and NSF, test and validate techniques to allow ice sheets and ice shelves to interact with other components of the Earth system. The newest generation of ESMs is making strides in allowing model ice sheets to respond dynamically to forcings from the ocean, atmosphere, and land components of the system and feeding those changes back into the climate system. Led by NASA, models like these are now gearing up for a head-to-head comparison in the context of the Ice Sheet Model Intercomparison Project, a component of the Coupled Model Intercomparison Project Phase 6 that has officially been sanctioned by the World Climate Research Programme.