The future climate of Amazonia

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The cover of Antonio Nobre’s report, a copy of which in English, Spanish or Portuguese can be obtained by clicking on the image above


At the Intergovernmental Panel on Climate Change (IPCC) conference in Lima this December, Brazilian researcher, Antonio Donato Nobre published a synthesis on the most recent scientific data about the Amazon’s climate accompanied by an explanation of the the profound impact that the Amazon has on South America and how this is changing as a consequence of climate change and deforestation. Antonio Donato Nobre, a well-respected Brazilian scientist and brilliant science communicator (click here to see his Ted Talk) has been researching the Amazon’s climate for decades.

The synthesis introduces two concepts that were new to me: the first was the notion of the Amazon as a ‘Green Ocean’, the second that the Amazon functions as a biotic pump pushing ca 20 billion tonnes of water into the atmosphere every day and in doing so drawing water vapour in from the Atlantic Ocean. The first idea of the Amazon as a Green Ocean is an important one as it gives a scale to the impact the Amazon has on the global climate, equivalent to one of the World’s Oceans. Conversely it also suggests the enormity of what we are doing to an ecosystem that is probably critical for our welfare. The second concept, not proven but for which there is mounting evidence, presents the Amazon as a vast community of ca 385 billion trees mutually interdependent with trillions of micro-organisms, insects and vertebrates functioning in concert as a water pump, extracting water from the ground, catalyzing its conversion to rain in the lower atmosphere and in doing so drawing water vapour in from the Atlantic Ocean and sending moisture to the grain belt of South America creating one of the most productive agricultural landscapes in the World.

Diagram from Makarieva et al.’s article in the Journal of Hydrometeorology, 15, 411-426 (2014) summarizing the biotic pump, the product of the action of ca 385 billion trees. Precipitation in the lower atmosphere catalysed by volatile secondary plant chemicals released by leaves results in a drying of the air above which when rehydrated over the moist ocean carries water inland


The main points of Antonio’s report are that 1) the Amazon generates a climate that supports agriculture to its south, 2) deforestation will result in a climate that does no longer supports agriculture in southern South America, 3) that the nature of the Amazon’s impact on climate means that there is a point of no-return with respect to deforestation which once passed will lead irreversibly to desertification for much of southern South America, 4) that deforestation in the Amazon is already having an impact on the regions climate and that this could accelerate the impact of climate change on the Amazon, and lastly 5) it is not too late to reverse these impacts and that muscular actions to outlaw forest fires and deforestation coupled with a popularization of the scientific research on the Amazon cold avert the destruction of the Green Ocean. I can not recommend reading the report enough, it is engagingly and precisely written and will make you amazed at the impact forest have on our World.


2 thoughts on “The future climate of Amazonia”

  1. Dear Alex, thanks for your post and good review of the report. This is just a quick note of correction: it is 20 “billion” tons of water transpired daily in the Amazon (you wrote 200 million). Or, if you prefer, 20 trillion liters of water. Cheers, Antonio

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