Prof. Hagit Afek from Yale University: "Antarctica was once warm and even today, like 50 million years ago, the warming at the poles is faster"

In an interview with the Hidan site, Prof. Hagit Afek from Yale University says that an accurate measurement of the temperature in the past will make it possible to calibrate the climate prediction models * The research, which focuses on the Eocene period, when there were much greater concentrations of carbon dioxide than today, shows a similarity to today when the polar regions are warming at a rate Faster than the rest of the planet

Antarctica was once warm, according to the research of Prof. Hagit Afek, professor of geology and geophysics at Yale University, whose group developed a method for measuring historical temperatures.

The findings, published in the April 21 issue of the journal PNAS of the American National Academy of Sciences, highlight the potential of the increasing warming of the polar regions and the risk of melting ice and rising sea levels. The research combined geochemists, paleontologists and climate physicists.
"Quantifying past temperatures helps us understand that ancient Antarctica was as hot as the California coast today and the polar regions in the South Pacific recorded temperatures similar to California's heat waves.

The researchers examined rare oyster fossils from the Oocene period, a warm period of 21 million years (which lasted from 56.5 million years to 35.5 million years ago), in which the seas flooded large parts of the continents.

In response to a question from the knowledge website, Afek explains that in the last sixty million years the continents were more or less where they are today, although not all of them: "India was much further south, the region of the Arabian Peninsula was not connected to Asia but to Africa, the Red Sea did not exist and the Mediterranean Sea was connected to the Indian Ocean but Antarctica was where it is today. All 20 million years of the Eocene were warm, but the beginning period was the warmest. Our study dealt with samples from 48 million to 36 million years old."

"During the period we are talking about, the Eocene, the amount of carbon dioxide in the atmosphere was significantly higher than in our time. If today the concentrations are on the order of 400 parts per million then the atmosphere contained DTP concentrations of 1,000-1,500. The whole world was warm accordingly. From non-geochemical methods but simply from observing fossils we know that the poles were extremely hot. You can see it in fossilized pollens that indicate that there was a forest in the Antarctic, fossils of animals that lived in warm areas such as crocodiles or large turtles were also discovered in the Arctic region in Canada and Alaska. You can see from biology that it was hot, the question is how hot. The common geochemical methods for studying climate change are mainly isotopic methods, but they have a large error range and heavy assumptions have to be made in order to extract heat measurements from them."

"The method we work with - clumped isotope or in Hebrew, conjugated isotopes - examines calcium carbonate and measures the temperature at which calcium carbonate is formed through a chemical bond between two heavy rare isotopes. In the study in question, we extracted the calcium carbonate from fossilized oysters of oysters that lived in the Antarctic region on the Antarctic Peninsula, which is a northern extension on the Atlantic side of Antarctica. "

"In addition, we measured fat molecules preserved in the sediment that fills these oysters - a fairly common method for measuring temperature, but it suffers from methodological problems mainly because we do not know the biology associated with these fatty substances. However, by measuring with two different methods instead of one, we can retroactively examine and calibrate the data in the literature on the tests that have already been done in the past for oyster fat. From these measurements it appears that the Atlantic side of the Antarctic Peninsula and the Pacific side (facing the Pacific Ocean) are not the same, as are the fossils from New Zealand which was much further south at the time and relatively close to Antarctica.

This is how the members of Afek's group discovered that parts of the Antarctic Peninsula experienced a temperature of 17 degrees Celsius during the Eocene period when the average was 14 degrees, like the average temperature of the coast of California today (temperature from Council - day, winter night and summer AB). On the other hand, the parts of Antakatekia facing the Pacific Ocean recorded temperatures of 22 degrees, like tropical Florida nowadays, and a difference of 7 degrees compared to the Atlantic side. Today the average temperature of the South Pacific near Antarctica is zero degrees Celsius. The researchers estimate that the difference is due to changes in ocean currents.

However, both in the article and in the interview with the science website Afek emphasizes that it is not just about researching the past, but that these data have implications for the present. "The study confirms that, similar to today's climate changes, the poles are the ones that are more enclosed than the global average and this of course has consequences for the melting of the glaciers and the rise in sea level."

According to Afek, the combination of the methods used by its staff members will make it possible to improve the models that try to predict the current rate of warming: "When you want to predict what will happen in the future, the only way to do it is to use models. The climate models we use are calibrated to the present but when you look at ten different models they have the same present but their futures are different. This means that there is something missing in the models and part of this is due to the fact that each model's way of describing the present is a little different, because there are things we don't know, when we go to the past and try to use the same models to understand the past or to compare with geochemical data from the past we can get more A point of reference that allows us to say which models are good and reliable in their predictions for the future and which models are bad."

Afek completed her three degrees in Israel, with her first degree completed at the Technion Faculty of Chemistry in 1994. In 1997 she completed her master's degree in chemistry at the Weizmann Institute, also in the field of geochemistry as her master's thesis supervised by Prof. Dan Yakir and Prof. Daniel Ronan. Dan Yakir was also her supervisor for her doctorate in environmental and energy studies at Weizmann, which she completed in 2003. She then went on to do a post-doctorate at Caltech, and after its completion in 2007, she moved to Yale University.

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