Assumptions are things we believe to be true, things we take for granted. We may make assumptions about the benefits that a project may bring, or about the percentage of credit customers who will actually pay us, and then there are assumptions that affect the planet itself. The problem with assumptions is that if not tested, they can actually conceal significant risks.
The Amazon rainforest has been assumed to be the great lung of the planet. It absorbs carbon dioxide and releases water into the atmosphere to such an extent that it influences the circulation of ocean currents and therefore global climate. There has long been concern about destruction of the rainforest but it has always been assumed that it is still an effective absorber of carbon dioxide, a major carbon sink.
Last week, the results of a nine-year study of the Brazilian part of the Amazon rainforest were released. The study involved fortnightly measurement of CO2 up to 4,500 metres above the forest using small planes to gather data over wide areas of the Amazon.
The results showed that the Brazilian Amazon has actually been releasing 20% more CO2 into the atmosphere than it has been absorbing. For at least a decade now, it has been an emitter not a sink, with net emissions equal to those of Japan.
Emissions of CO2 from the burning and destruction of the rainforest have exceeded the amount absorbed by the remaining forest, and in 2019, the rate of deforestation increased four-fold compared to the previous two years, i.e. the situation is worsening dramatically.
The destruction is principally to clear land for beef cattle and for soya production (mainly for animal feed). Each year’s deforestation makes the adjacent forest more susceptible. The trees produce most of the region’s rain, and having fewer trees leads to more severe droughts, heat waves, and more tree deaths and fires, in a dangerous feedback loop. Ironically, the droughts have caused the soya industry to lose billions through reduced productivity caused by their own forest clearances.
There are two shock realisations from our now defunct assumption: 1) the tipping point where complete destruction of the rainforest becomes irreversible is closer than we thought, and 2) the timeframe for containing global warming is a lot shorter than we thought.
Data sources: Nature Climate Change, Agence France Presse, The Guardian, WWF website