CO2 already led to climate change 200 million years ago

Spektrum der Wissenschaft

20.4.2020

Translation: machine translated

Gigantic lava pulses 201 million years ago emitted carbon dioxide almost as fast as mankind. The event could reveal the future of our climate.

Gigantic volcanic eruptions around 200 million years ago could have had an impact comparable to that of man-made greenhouse gas emissions. This is the result of an analysis of gas inclusions in one of the largest flood basalts in the Earth's history. As a team led by Manfredo Capriolo from the University of Padua reports, during the break-up of the supercontinent Pangaea, enormous amounts of lava erupted in very short bursts. The team reports in "Nature Communications" that these bursts were so concentrated that they released as much carbon dioxide in just 500 years as humanity is expected to produce in the 21st century. This means that these episodes may be among the fastest carbon dioxide increases in the Earth's history before the current climate change.

Earth history is an important source of information about the future of the climate system, as computer models alone can only provide limited information. Particularly interesting for comparisons with the present are those episodes in which the carbon dioxide content of the atmosphere rose at a similar rate to today. However, these are rare in the recent past. Only 55 million years ago did greenhouse gases rise very quickly and cause a biological crisis known as the PETM, albeit still ten times slower than today. During the extinction of the dinosaurs 66 million years ago, greenhouse gases also rose very quickly, but the situation is difficult to compare with today due to the impact of a celestial body several kilometres in size.

Climate and environmental situation at the end of the Triassic as a vision of the future?

The previous great mass extinction 201.3 million years ago, on the other hand, could provide a much better model for today's climate situation, suggests the work of Capriolo and his team. The modern rise in carbon dioxide is only five times faster than the violent volcanic episodes at the end of the Triassic period, each of which emitted as much carbon dioxide as humanity is expected to emit by the end of this century. The working group concludes this from the unusual abundance of carbon dioxide with which the lava must have erupted, otherwise the number and type of gas inclusions could not be explained.

The team argues that a significant proportion of the carbon must have come from great depths and risen very quickly. Several of these volcanic episodes spanned the period of the associated mass extinction, during which around a third of all animal families in the sea and virtually all of the competition from dinosaurs on land died out. According to the group's calculations, each of them emitted comparable amounts of carbon dioxide over around 500 years as humanity will emit in the entire 21st century according to IPCC calculations. Therefore, the changes to the climate and environment at the end of the Triassic may have been roughly comparable to the situation today. There may have been more volcanic episodes back then, but humanity still has more centuries. Perhaps at any rate.

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