Study: Drastic Temperature Jump Events (Dansgaard-Oeschger Events) The Result Of CO2 Tipping Points
Rapid jumps in the temperatures of the high latitudes of the Northern Hemisphere over just a few decades time have been a somewhat common event during the glacial periods of the last 100,000 years or so.
These events, known as Dansgaard-Oeschger events, have seemingly at least sometimes been the result of rising carbon dioxide levels surpassing invisible “tipping points” that result in atmospheric and oceanic changes relating to wind, moisture, and temperature, according to a new study published in the journal Nature Geoscience.
These findings of course hold modern relevance both because of the rapid speed at which the Arctic and West Antarctic regions have been warming in recent years and also because of the fact that atmospheric carbon dioxide levels keep rising.
Part of the reason that the new work is notable is because it was previously a common belief that these abrupt rises in temperature were the result of sudden meltwater floods into the North Atlantic.
Professor Stephen Barker, from Cardiff University’s School of Earth and Ocean Sciences, a co-author of the new study, commented on that: “Our results offer an alternative explanation to this phenomenon and show that a gradual rise of CO2 within the atmosphere can hit a tipping point, triggering abrupt temperature shifts that drastically affect the climate across the Northern Hemisphere in a relatively short space of time.
“These findings add to mounting evidence suggesting that there are sweet spots or ‘windows of opportunity’ within climate space where so-called boundary conditions, such as the level of atmospheric CO2 or the size of continental ice sheets, make abrupt change more likely to occur. Of course, our study looks back in time and the future will be a very different place in terms of ice sheets and CO2 but it remains to be seen whether or not Earth’s climate becomes more or less stable as we move forward from here.”
The press release provides more: “Using climate models to understand the physical processes that were at play during the glacial periods, the team were able to show that a gradual rise in CO2 strengthened the trade winds across Central America by inducing an El Nino-like warming pattern with stronger warming in the East Pacific than the Western Atlantic.
“As a result, there was an increase in moisture transport out of the Atlantic, which effectively increased the salinity and density, of the ocean surfaces, leading to an abrupt increase in circulation strength and temperature rise.”
The researchers involved in this work are now planning to create a detailed reconstruction of global ice volume across the last glacial cycle, which will be used to help them further test the theory.
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