Climate variability

Global warming is accelerating climate variability, study finds •


The Earth has gone through many warming and cooling periods where temperatures were drastically different from what they are today.

What makes today’s climate change so noticeable compared to other warm interglacial periods of the past is that rates of warming and carbon build-up in the atmosphere are occurring at unprecedented levels. .

But examining past interglacial periods can help researchers predict the impacts of future climate change and understand how the globe as a whole has been affected by drastic temperature changes.

An international team of researchers led by University College London took an in-depth look at climate change during the last interglacial period (129-116,000 years ago) and found that global warming accelerates climate variability.

The results, published in the journal Nature Communication, show how century-wide climate change is driven by interglacial temperatures, which can help climatologists make future projections.

“The last interglacial is particularly relevant because it provides insight into climatic processes during a period of excessive heat,” said Chronis Tzedakis, lead author of the study.

During this latest period of warming, surface air temperatures were three to eleven degrees above pre-industrial levels.

Global sea level at the time is estimated to have risen six to nine meters above current levels.

Earlier climate records show changes in temperature and precipitation that took place over the course of a century during the last interglacial, but exactly where and when those changes took place have remained unknown.

For this study, the researchers created a detailed chronology of the ocean and atmospheric changes in southern Europe and the North Atlantic during the last interglacial period.

To develop this complete timeline, the researchers used marine and terrestrial geological archive data and climate model experiments. Taking data from different records and environments can produce uncertainties in forming a complete picture of the climate at any given time.

The researchers were able to overcome the gaps in the timeline by analyzing fossils from sediment samples and creating a sort of stratigraphic “Rosetta Stone”.

Once researchers got a better picture of the climate in southern Europe, it was easier to relate certain weather events in different environments.

For example, changes in vegetation caused by variations in precipitation were linked to chemical changes in stalagmites in Corchia Cave in northern Italy.

“Corchia’s case is particularly important as it is supported by very detailed radiometric dating using the decay of uranium isotopes, producing one of the best chronologies available for this period,” said Russell Drysdale, a chief of the research team responsible for studying Italy. Cave.

Next, the researchers were able to use climate model experiments to show that these generalized changes in precipitation aligned with disruptions in the Atlantic overturning meridian circulation.

The study shows how climate change over the course of a century can be fueled by warmer temperatures causing the sea ice to melt.

“Although not a strict analogue of future anthropogenic changes, the profile of the last interglacial that emerges is one of increased climate instability on a century-wide scale, with implications for the dynamics of the ice cap and the oceans, ”Tzedakis said. “Future research efforts should focus on limiting the extent of the Greenland ice sheet melt and runoff and its effects on ocean circulation during the last interglacial. “

Through Kay vandette, Editor-in-chief

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