Does the Amazon rainforest slow down man-made climate change?
A new study published in Nature Geosciences highlights a very important feedback in the Amazon rainforest that current climate models are not considering, but may, in fact, accelerate climate change. The article was written by an international team of 27 scientists, including Daniel Goll from the Department of Geography, and lead by Katrin Fleischer from the Technical University of Munich (TUM).
Current climate change projections assume that the Amazon rainforest removes large amounts of carbon dioxide from the atmosphere storing it in biomass, thereby dampening man-made climate change. The models is used for climate change projections assume that elevated carbon dioxide concentration have a stimulating effect on plant growth.
There is evidence that this fertilization effect operates in temperate forests, however, it is not clear if tropical forest respond in similar ways. To test how tropical vegetation response to elevated carbon dioxide an ecosystem-scale experiment is needed. Currently, such an experiment, the first of its kind, is being established in Brazil (AmazonFACE: http://amazonface.inpa.gov.br/), but because ecosystems respond slowly it will take many years before we will know it’s outcome.
In the new study in Nature Geosciences an ensemble of state-of-the-art ecosystem models was used to simulate this experiment before-hand. The results indicate that the commonly low soil phosphorus availability in the Amazon region can lead to a much more dampened response of tropical vegetation to elevated carbon dioxide than currently assumed.
This finding has still to be confirmed by the real life experiment, but it shows that current climate models which omit phosphorus effects on plant growth are likely overestimating the carbon dioxide removal by tropical forests. The findings also suggest that the Amazon forest could be even more threatened by climate change than currently thought – adding further pressure on of the most rapidly diminishing ecosystems on Earth.
Dr. Daniel Goll
Lehrstuhl für Physische Geographie mit Schwerpunkt Klimaforschung
Katrin Fleischer et. al., Amazon forest response to CO2 fertilization dependent on plant phosphorus acquisition, Nature Geoscience, 05 August 2019, http://www.nature.com/articles/s41561-019-0404-9, DOI 10.1038/s41561-019-0404-9