Elevated Snowfall Will Compensate For Sea Degree Rise As The Antarctic Ice Sheet Melts – Watts Up With That?
from University of Bristol
A new study predicts that any rise in sea level on the world’s southernmost continent will be countered by an increase in snowfall associated with a warmer polar atmosphere. Using modern methods of calculating the predicted changes in sea level, researchers discovered that the two ice sheets in Greenland and Antarctica react differently, reflecting their very different local climates.
The paper published today in Geophysical Research Letters is based on the new generation of climate models used in the newly published Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which reviews scientific, technical and socio-economic information on climate change.
The project brought together over 60 researchers from 44 institutions to create, for the first time, process-based community projections of sea level rise through the ice sheets. This particular paper focuses on one aspect of the overall project, namely how the new generation of climate model projections used in the current IPCC assessments differ from the earlier generation in their impact on the ice sheets.
Professor Tony Payne, director of Bristol’s School of Geographical Sciences, said the team was trying to find out if the projected sea level rise of the new generation of climate models is different from the previous generation. “The new models generally predict more warming than the previous generation, but we wanted to understand what that means for the ice sheets,” he said. “The increased warming of the new models leads to a stronger melting of the Greenland ice sheet and a rise in sea level by a factor of 1.5 by 2100.
“The projected sea level rise from the Antarctic ice sheet changes little, however. This is because an increased mass loss caused by warmer oceans counteracts a mass gain due to increased snowfall, which is associated with the warmer polar atmosphere. “
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Link to the paper
Projections of the sea level contribution of the Greenland and Antarctic ice sheets (GrIS and AIS) are based on atmospheric and oceanic factors obtained from climate models. The Earth system models participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6) generally predict greater future warming compared to previous efforts of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Here we use four CMIP6 models and a selection of CMIP5 models to enforce multiple ice sheet models as part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We find that the projected sea level contribution around 2100 from the ice sheet model ensemble falls into the CMIP5 range under the CMIP6 scenarios for the Antarctic ice sheet, but is significantly increased for Greenland. A warmer atmosphere in CMIP6 models leads to a higher mass loss in Greenland due to surface melting. For Antarctica, CMIP6 propulsion is similar to that of CMIP5, and the mass gain from increased snowfall counteracts increased loss due to ocean warming.
Summary in simple language
The melting of the Greenland and Antarctic ice sheets (GrIS and AIS) will lead to higher sea levels in the future. How sea levels change depends in part on how the atmosphere and ocean warm and how this affects the ice sheets. We use multiple ice sheet models to estimate possible future sea levels under climate scenarios from the models of the new Phase 6 of the Coupled Model Intercomparison Project (CMIP6), which generally indicate a warmer world than the previous effort (CMIP5). Our results show that the possible future sea level change due to Antarctica is similar for CMIP5 and CMIP6, but the warmer atmosphere in CMIP6 models will result in higher sea level contributions from Greenland by the end of the century.