Заседание семинара "Физика атмосферы и океана и охрана окружающей среды" 31.10.2019 в 15-00. "A Past-to-Future perspective on climate change and variability ", Kira Rehfeld

Changes in climate variability are as important for society as are changes in mean climate. Therefore, contrasting last Glacial and Holocene temperature variability can provide new insights into the relationship between the mean state of climate and its variability, as well as future climate stability. However, although glacial-interglacial changes in variability had been quantified in Greenland, a global view remained elusive. Here, I present the results of the recently published first quantitative reconstruction of changes in temperature variability between the Last Glacial Maximum (27 to 19 thousand years ago) and the Holocene (since 11 thousand years ago). The estimates, based on a global network of marine and terrestrial temperature proxies. Using statistically robust methods, I demonstrate that temperature variability decreased globally by a factor of 4 for the warming of 3-8C. The decrease displays a clear zonal pattern with little change in the tropics and greater change in the mid-latitudes of both hemispheres. In contrast, Greenland ice-core records show a reduction of a factor of 73. This much larger value suggests either a proxy-specific overprint or a decoupling of Greenland atmospheric from global surface temperature variability. Using an isotope-enabled model we find some evidence for the former. The overall pattern of variability reduction can be explained by changes in the meridional temperature gradient, a mechanism that points to further decreasing temperature variability in a warmer future.