16:00 〜 16:15
[ACC32-09] Projecting the evolution of the Northern Patagonian Ice Field until the year 2200
キーワード：Patagonia, Ice cap, Ice field, Northern Patagonian Ice Field, Climate change, Modelling
The Northern Patagonian Ice Field (NPI), Chile, is the second-largest ice body in the Southern Hemisphere outside Antarctica, and one of the two remnant parts of the Patagonian ice sheet that existed during the last glacial period. It is located in the Southern Andes, a region that was identified to have one of the most negative specific mass balances of the world's glacierized regions, thus making the highest contribution per area unit to sea-level rise. The NPI is a highly dynamic ice body, characterized by large accumulation/ablation rates, and also a large contribution of calving to the overall mass balance produced by both ocean- and lake-terminating glaciers.
We use the ice-sheet model SICOPOLIS to reproduce the dynamical state and observed changes of the NPI in the early 21st century and realize projections under different climate change scenarios. Calving is treated by implementing an additional specific mass loss for grid cells in contact with the ocean. We realize a spin-up run to generate an ice field similar to the state of the NPI in the year 2000. We then force the model with a present-day and projected surface mass balance to obtain the committed mass loss and projected evolution of the NPI under different climate change scenarios.
In the committed mass loss, the ice field stabilizes by the end of the 21st century at 75% of the current ice volume. In the climate change scenarios, mass loss rates are higher from the middle of the 21st century on, and mass loss continues until the end of the 22nd century, although the climate is assumed to be constant here. We conclude that the NPI exhibits a response time of around 100 years and call for caution when interpreting currently observed changes. The effect of the emission scenario on the remaining ice volume by the end of the 22nd century is very important (62±10% of the current volume for RCP2.6, 30±14% for RCP8.5) which indicates that the conclusions of global studies are also valid for Patagonia: every decimal degree matters!
We use the ice-sheet model SICOPOLIS to reproduce the dynamical state and observed changes of the NPI in the early 21st century and realize projections under different climate change scenarios. Calving is treated by implementing an additional specific mass loss for grid cells in contact with the ocean. We realize a spin-up run to generate an ice field similar to the state of the NPI in the year 2000. We then force the model with a present-day and projected surface mass balance to obtain the committed mass loss and projected evolution of the NPI under different climate change scenarios.
In the committed mass loss, the ice field stabilizes by the end of the 21st century at 75% of the current ice volume. In the climate change scenarios, mass loss rates are higher from the middle of the 21st century on, and mass loss continues until the end of the 22nd century, although the climate is assumed to be constant here. We conclude that the NPI exhibits a response time of around 100 years and call for caution when interpreting currently observed changes. The effect of the emission scenario on the remaining ice volume by the end of the 22nd century is very important (62±10% of the current volume for RCP2.6, 30±14% for RCP8.5) which indicates that the conclusions of global studies are also valid for Patagonia: every decimal degree matters!