Anthropogenic CO2 increase is unprecedented

Date:
August 20, 2020
Source:
University of Bern
Summary:
Even in earlier warm periods there were pulse-like releases of
CO2 to the atmosphere. Today's anthropogenic CO2 rise, however,
is more than six times larger and almost ten times faster than
previous jumps in the CO2 concentration.



FULL STORY ==========================================================================
A new measurement technology developed at the University of Bern provides unique insights into the climate of the past. Previous CO2 concentrations
in the atmosphere could be reconstructed more accurately than ever before, thanks to high-resolution measurements made on an Antarctic ice core. The study, which analyzed the Earth's atmospheric composition between 330,000
and 450,000 years ago, was made possible by the commitment of experts,
and their decades of experience, at the University of Bern. The results
of the study have been published in Science.


========================================================================== Melting ice masses disturbed the ocean circulation In 2008, the Bern ice
core specialists were able to show that the CO2 concentration in the
atmosphere during the last 800,000 years was consistently much lower
than today. Since then, the ice core experts have built upon those
findings enabling a much more detailed reconstruction of the 330,000
to 450,000 year time window. Until now, the maximum speed and frequency
of naturally occurring centennial scale jumps in the CO2 concentration
remained unknown.

This study shows that abrupt CO2 rises are a pervasive feature of
our climate system and that they can even occur during interglacial
periods. "Until now, it had been assumed that the climate was very stable during previous interglacial periods and that there were no abrupt changes
in the atmospheric CO2 concentration," explains Christoph Nehrbass-Ahles,
lead author of the study, who earned a doctorate from the University
of Bern and is now based at the University of Cambridge. According to Nehrbass-Ahles, the abrupt rises were always evident when melting ice
masses in Greenland or Antarctica considerably disturbed the ocean
circulation. If the CO2 in the atmosphere rose quickly, simultaneous
changes in the Atlantic Ocean's circulation could also be detected.

CO2 increase was ten times slower than today The fact that rapid CO2
jumps could be detected not only during glacial periods but also during
two previous interglacial periods surprised the researchers.

"We measured these events in the ice several times and always came to
the same conclusion," explains Nehrbass-Ahles. Why the CO2 concentration
in the atmosphere suddenly rose during previous interglacial periods
cannot be conclusively explained by the researchers. "We do not know why
this happened yet," explains Bernese climate researcher Thomas Stocker, co-author of the study: "This raises new research questions." However,
the CO2 jumps in previous interglacial periods are far exceeded by the
current development: "These natural jumps in the CO2 concentration in
the atmosphere happened almost ten times slower than the human-driven
increase over the last decade," Nehrbass- Ahles emphasizes.

The largest jump in the past corresponds to the current CO2 emissions
over only six years The researchers compared the CO2 jumps of the
past with the ongoing human- driven rise of CO2 concentration in the atmosphere. According to Stocker, the largest centennial CO2 jump in the
past was around 15 ppm (parts per million is the unit for atmospheric CO2 concentration), which is approximately equivalent to the increase caused
by humankind over the last of six years. "This may not seem significant
at first glance," says Stocker, "but in light of the quantities of CO2
that we are still allowed to emit in order to achieve the 1.5DEGC climate target agreed in Paris, such increases are definitely relevant." The
findings of this study put us under even greater pressure to protect
the climate.


========================================================================== Story Source: Materials provided by University_of_Bern. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Christoph Nehrbass-Ahles, Jinhwa Shin, Jochen Schmitt, Bernhard
Bereiter,
Fortunat Joos, Adrian Schilt, Loi"c Schmidely, Lucas Silva, Gregory
Teste, Roberto Grilli, Je'ro^me Chappellaz, David Hodell, Hubertus
Fischer, and Thomas F. Stocker. Abrupt CO2 release to the atmosphere
under glacial and early interglacial climate conditions. Science,
2020 DOI: 10.1126/science.aay8178 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200820151335.htm

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