UNIVERSITY OF FLORIDA
Glaciers in tropical mountain ranges are suffering the same effects from climate change triggers as in the polar regions of Antarctica and the Northern Hemisphere, according to a study published today in Nature.
Paper by an international team of scientists, including Robert Hatfield, an assistant professor at the University of Florida Department of Geology, is the first study to show that the effects of greenhouse gases and other agents of Earth’s temperature are impacting glaciers in the Southern Hemisphere at a similar rate to those in the north. To make their discovery, the researchers used sediment from Lake Junín, high in the Peruvian Andes, to create a record of glacial changes spanning 700,000 years.
Hatfield explains that much of what scientists know about past glacial changes comes from records of ice growth and decay that occurred in the Northern Hemisphere.
“As we try to understand how climate works globally, we need more than just profiles that are influenced and biased towards the Northern Hemisphere,” Hatfield said.
The land-based records collected by Hatfield and his colleagues match the time period recorded for ice cores from Antarctica and span the longest time frame ever collected from the Southern Hemisphere.
“What makes our finding unique is that for the first time we have been able to obtain a continuous and independently dated record of tropical alpine cavities in the Alps,” he said. speak. “The bottom line is that the tropics follow the same rhythm and the same rhythm as what is happening in the Northern Hemisphere.”
Despite the difference in solar radiation between the two hemispheres, the study found that glacial changes in both regions occurred at the same time. This suggests that increasing concentrations of greenhouse gases in the atmosphere associated with changes in the volume of the northern ice sheets are affecting the entire planet simultaneously.
As glaciers expand in the high Andes, they erode the surrounding mountains, bringing the sediment contained in the meltwater to Lake Junín. During warmer times when glaciers are absent, carbonates are deposited in lakes instead.
To collect their data, geologists launched a large drilling mission at the lake in 2015, funded by National Science Foundation and International Continental Science Drilling Program. Working continuously for seven weeks, the team retrieved 100 meters of sediment from the lake’s basin. With the sediment recovery, the researchers spent the next few years developing a solid age model.
Christine Y. Chen, a Lawrence Livermore National Laboratory Scientist and co-author of the paper, analyzed the uranium and thorium content in the sedimentary layers to determine the time represented by the sediment core.
“Scientists have known for nearly a century that increased greenhouse gas emissions will affect climate everywhere in the world, but we are less certain about the rapid change in ice mass. at the poles will spread to the rest of the world.” Chen said. “The high mountains in the tropics are basically as far from the poles as one can get. We have now shown that the ice in both regions is growing and decaying in synchrony with each other for nearly a million years, which further highlights the interconnectedness of our planet. “
In 2020, the team published findings on the age of the sediments and began studying its climate record. Using a combination of mineral magnetism and sediment geochemistry, geologists reconstructed the timing and magnitude of glacial changes over a 700,000-year time frame.
According to Hatfield, the original plan for the study was conceived during a conference in 2009 and included 27 authors in the final paper to be published, including its lead author, Donald T. Rodbell, of University Union in Schenectady, New York.
###
JOURNEYS
Nature
DOI
Related
