On the basis of a unique global comparison of data from core samples extracted from the ocean floor and the polar ice sheets, AWI researchers have now demonstrated that, though climate changes have indeed decreased around the globe from glacial to interglacial periods, the difference is by no means as pronounced as previously assumed. Until now, it was believed that glacial periods were characterised by extreme temperature variability, while interglacial periods were relatively stable. The researchers publish their findings advanced online in the journal Nature.
Drilling an Antarctic ice core [Credit: Martin Leonhardt] |
Climate researchers from the Helmholtz Young Investigators Group ECUS at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) in Potsdam have now investigated how temperature variability changed as the Earth warmed from the last glacial period to the current interglacial period. To date it has been assumed that temperatures varied greatly during the last glacial, while the current interglacial was largely characterised by small temperature variations. This interpretation was based on water isotope data from central Greenland ice cores.
Sampling locations [Credit: Kira Rehfeld] |
The achievement of first author Kira Rehfeld and her colleagues: they have for the first time gathered and compared data from diverse climate archives and a total of 99 research sites. In the climate research community, ice cores are generally considered the gold standard, because their layers are highly consistent, unlike sediment layers from the seafloor, which are frequently marred by tectonic shifts, currents or marine organisms. The AWI researchers have devised mathematical methods that allow them to estimate the uncertainties and potential sources of error while assessing various paleoclimate archives, and to take these factors into account in their analyses. "As such, we can compare the sediment samples with the ice cores for various epochs in the planet's history," says Laepple.
Detail of an Antarctic ice core from 2668 meters depth [Credit: Sepp Kipfstuhl] |
Climate modellers had previously postulated the mechanism of reduced variability under warmer climatic conditions in 2014. Yet with their analysis, Rehfeld, Laepple and colleagues are the first to reinforce this theory with global climate data from the past. The AWI researchers describe their next endeavour as follows: "We plan to investigate in detail the changes in short-term variations in the past and their relation to long-term climate changes. To do so, we need reliable climate archives, and to improve our understanding of how they work." Increasing the accuracy to a level at which paleo-archives can also reflect extreme events will likely be one of the greatest challenges for the years to come.
Source: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research [February 05, 2018]