Today is Wednesday, May 22, 2024.
The team of international researchers undertook a detailed chemical analysis of ancient Antarctic ice, revealing more about the impact of human emissions.
Samples of Antarctic ice built over hundreds of thousands of years was collected by drilling cores up to 3.2km deep.
As the ice includes atmospheric gasses trapped in air bubbles inside it, scientists could trace elements to build a record of what the climate was like in the past.
Carbon dioxide, or CO2, is a gas that occurs naturally in the atmosphere and is also know as a greenhouse gas, as it contributes to warming of the climate. In the past, the levels have fluctuated in cycles.
Indeed the general pattern observed showed these jumps happened alongside cold intervals in the North Atlantic known as Heinrich events.
A Heinrich event is a natural phenomenon in which large groups of icebergs break off from the North American (Laurentide) ice sheet and end up in the North Atlantic. First described by marine geologist Hartmut Heinrich, they occurred during five of the last glacial periods over the past 640,000 years (source Wikipedia).
Each Heinrich event coincided with an abrupt increase in atmospheric CO2 and warming in Antarctica. Climate wise, likely due to shifting westerly winds driving increased release of CO2 from the Southern Ocean.
According to this new research, during the largest of the natural rises, CO2 increased by about 14 parts per million in 55 years cycles, besides jumps about once every 7,000 years or so.
But at today’s rates, a similar increase is happening in only 5 to 6 years. And this is serious.
Here a summary - and future alert - taken from the Discussion chapter of the research:
Ice core reveals periodic jumps in atmospheric CO2 levels that are synchronous with jumps in atmospheric CH4 concentrations
The synchronism of these jumps can be explained by a southward displacement of the Intertropical Convergence Zone in response to North Atlantic ice rafting events, which ultimately led to a poleward enhancement of the Southern Hemisphere westerlies.
Enhanced wind stress drove increased vertical transport and ventilation of deep waters in the Southern Ocean, resulting in rapid CO2 outgassing that drove a pulse of atmospheric CO2 rise of up to 14 ppm within half a century.
Other potential mechanisms, including a multiple decades scale release of CO2 from a terrestrial carbon pool, cannot be excluded and may have occurred in parallel to Southern Ocean changes.
The rate and magnitude of atmospheric CO2 rises resolved in this study provide critical constraints on carbon-cycle variability during abrupt climate shifts and urge caution that the modern-day Southern Ocean carbon sink has the potential to weaken in response to continued poleward enhancement of the Southern Hemisphere westerlies.
Click here for the press release by the University of St Andrews in Scotland, founded in 1413.
And at the image below for the research itself by Kathleen Wendt et al. titled “Southern Ocean drives multidecadal atmospheric CO2 rise during Heinrich Stadials” and published at the May 21, 2024 edition of the PNAS Proceedings of the National Academy of Sciences.
