Land temperature variability driven by oceans at millennial timescales
Abstract
Variations in regional temperature have widespread implications for society, but our understanding of the amplitude and origin of long-term natural variability is insufficient. This is especially the case for terrestrial temperature variability which is currently thought to be weak over long timescales. Here, we provide the first comprehensive estimate of regional temperature variability from annual to millennial timescales based on sedimentary pollen records and instrumental data from the Northern Hemisphere. We show that the short-term random variations are overprinted by strong ocean-driven climate variability on multi-decadal and longer timescales. This may cause substantial climate change at the regional scale in the coming century, contrasting the rather monotonous warming projected by climate models. Due to the marine influence, regions characterized by stable oceanic climate at sub-decadal timescales experience stronger long-term variability while continental regions with higher sub-decadal variability show weaker long-term variability. This fundamental relationship between the timescales provides unique insight into the mechanisms governing slow terrestrial climate variability and sets the basis to project its amplitude.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMNG45A0534H