Wednesday, July 14, 2021

Worst news since the Ice Age

Southeast Amazonia is no longer a carbon sink

"Atmospheric measurements show that deforestation and rapid local warming have reduced or eliminated the capacity of the eastern Amazonian forest to absorb carbon dioxide — with worrying implications for future global warming."

That's the heading to Scott Denning's article in Nature about the paper by Luciana V. Gatti et al. also in Nature (though this may be behind a paywall for you).

Other summaries are available from the Guardian, The New York Times, iNews and elsewhere.

Many folk have assumed that the vast tropical rainforests absorb at least some of our carbon emissions from burning fossil fuels but the latest research confirms what some have suspected, that we have damaged some areas of forest so much that they have become carbon emitters instead of sinks.

The IPCC emission scenarios have been widely criticised but the results from this Amazonia study keeps the outcome of the RCP8.5 forcing a possibility.

That may be the worst news humanity has received since the Last Ice Age. It's that bad.

 Carbon fluxes in different Amazonian regions. From 2010 to 2018, Gatti et al.2 measured vertical profiles of atmospheric concentrations of carbon dioxide and carbon monoxide above four regions in Amazonia (the two locations shown in northwestern Amazonia were counted as one region), and thereby calculated regional carbon fluxes upwind of each site, measured in grams of carbon per square metre per day. In the bar charts, net biome exchange (NBE) represents the average annual balance of CO2 absorbed by forests for photosynthesis compared with the amount of CO2 produced by the decay of organic matter (negative NBE values indicate that the forest acts as a carbon sink); ‘fire’ represents the average carbon emissions produced by fires; and ‘total’ represents the sum of NBE and fire emissions. The NBE values indicate that most regions of Amazonia are weak carbon sinks, but southeastern Amazonia is actually a carbon source.


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