State and timescale-dependency of surface climate variability from the last Glacial to present day (STACY2022)
Abstract
If the variability of our planet's climate systematically depends on its mean temperature, changes ahead may be to some extent predictable. Nonstationary distributions of temperature and precipitation lead to changes in the frequency of the occurrence of extreme climatic events. Climate projections rely on complex climate models and thus their ability to represent changes in climate variability needs to be assessed. The instrumental record is too short and limited to close-to-present day conditions to constrain modeled variability changes beyond the decadal scale. Benchmarking climate models against indirect paleoclimatic evidence derived from natural archives, such as ice cores, speleothems or fossil pollen preserved in lake sediments, is the only solution for this at present. We find that model simulations display in general far less temperature variability on all timescales beyond the interannual than paleoclimate proxy data. To improve our understanding of centennial climate variability, the STACY project investigates temperature and precipitation variability over the last 80,000 years.
This period extends back into the last Glacial, and covers the transition into the current warm period, the Holocene. The deglaciation was the last time Earth's global mean temperature underwent a large-scale climate shift by more than 3°C, comparable to that projected for the next 300 years. Within the ongoing project we quantify changes of climate variability between these cold and warm climate periods, and within the Glacial state, and link them, if possible, to underlying changes in climate dynamics. With systematic model-to-data-comparison we constrain the gap between modeled and reconstructed variability. We investigated changes in total centennial-scale variability, as well as the linkage between annual, centennial and millennial-scale climate variability, and evaluated, if and how the sensitivity of the climate system to volcanic eruptions is influenced global mean temperature. This has improved our understanding of the long-term predictability of the climate system, although many questions remain.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMNG25A..05R