The Climate System Tipping Points Race: Risk of Amazon Rainforest Collapse Takes the Lead: 1 of 3 // Mar 26, 2021

In my last few videos I chatted about how our terrestrial biosphere sink is failing. Presently, land vegetation absorbs about 30% of anthropogenic carbon emissions, but with BAU (Business-as-Usual) this number is expected to halve by 2040. The terrestrial biosphere will tip over from a net carbon sink to a net carbon source. CO2 concentrations in the atmosphere will skyrocket as we head there within a mere two decades. The reason is that further warming increases plant respiration while decreasing plant photosynthesis. Sources dominate sinks.

Of course the Amazon Rainforest is the largest swath of tropical rainforest on the planet. This forest drives a partially self-sustaining regional climate and hydrological system, whereby falling rainwater is taken up by rainforest, a lot of the water is put back into the atmosphere by evapotranspiration, and the cycle repeats over and over again. Thus, water is distributed over the entire rainforest, but if the cycle is cut off at the start then the entire rainforest can suffer severe drought. Thus, with slightly more warming from climate system change, we are at great risk of the sudden complete collapse of the entire rainforest.

In this video series (3 parts) I focus on the Amazon Rainforest. I chat about a new scientific review paper called “Carbon and Beyond: The Biogeochemistry of Climate in a Rapidly Changing Amazon”. Most discussions of the Amazon Rainforest focus solely on carbon cycles and storage. This is incomplete; they need to consider the overall Amazon system, and also examine CH4, N2O, black carbon, biogenic volatile organic compounds, aerosols, evapotranspiration, and albedo changes. The dynamic responses of all of the above to localized stresses (fires, land-use changes, extreme weather events) and to global stresses (warming, drying, El Niño Southern Oscillation) must be examined to get a more complete understanding of the Amazon System.

When the overall system is studied, it becomes quite clear that the CH4 and N2O changes are large enough to offset, and even actually exceed the carbon sink of the Amazon Rainforest. This is actually terrible news for the vitality of our planetary ecosystems and human societies.

Second video, of three, here:

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On Thin Ice

On Monday March 22 I hiked along the Ottawa River in Fitzroy Harbour with a friend. We hugged the shoreline where the river was shallow, to stay on the safe side. Feeling down into the cracks, the ice was over a foot thick. A few days later, after 20C temperatures and rain, the ice was all gone. Timing in life is everything:)
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