Amazon rainforest is losing resilience: New evidence from satellite data analysis

Date:
March 7, 2022
Source:
Potsdam Institute for Climate Impact Research (PIK)
Summary:
The Amazon rainforest is likely losing resilience, data analysis
from high-resolution satellite images suggests. This is due to
stress from a combination of logging and burning -- the influence
of human-caused climate change is not clearly determinable so far,
but will likely matter greatly in the future. For about three
quarters of the forest, the ability to recover from perturbation
has been decreasing since the early 2000s, which the scientists
see as a warning sign. The new evidence is derived from advanced
statistical analysis of satellite data of changes in vegetation
biomass and productivity.



FULL STORY ========================================================================== [Amazon rainforest (stock | Credit: (c) Marcio Isensee e Sa' /
stock.adobe.com] Amazon rainforest (stock image).

Credit: (c) Marcio Isensee e Sa' / stock.adobe.com [Amazon rainforest
(stock | Credit: (c) Marcio Isensee e Sa' / stock.adobe.com] Amazon
rainforest (stock image).

Credit: (c) Marcio Isensee e Sa' / stock.adobe.com Close The Amazon
rainforest is likely losing resilience, data analysis from high-
resolution satellite images suggests. This is due to stress from a
combination of logging and burning -- the influence of human-caused
climate change is not clearly determinable so far, but will likely matter greatly in the future. For about three quarters of the forest, the ability
to recover from perturbation has been decreasing since the early 2000s,
which the scientists see as a warning sign. The new evidence is derived
from advanced statistical analysis of satellite data of changes in
vegetation biomass and productivity.


========================================================================== "Reduced resilience -- the ability to recover from perturbations like
droughts or fires -- can mean an increased risk of dieback of the Amazon rainforest.

That we see such a resilience loss in observations is worrying," says
Niklas Boers from the Potsdam Institute for Climate Impact Research and
the Technical University of Munich, who conducted the study jointly with researchers from the University of Exeter, UK.

"The Amazon rainforest is a home to a unique host of biodiversity,
strongly influences rainfall all over South America by way of its enormous evapotranspiration, and stores huge amounts of carbon that could be
released as greenhouse gases in the case of even partial dieback, in turn contributing to further global warming," Boers explains. "This is why
the rainforest is of global relevance." "When the tipping itself will
be observable, it would be too late" The Amazon is considered a potential tipping element in the Earth system and a number of studies revealed its vulnerability. "However, computer simulation studies of its future yield
quite a range of results," says Boers. "We've therefore been looking
into specific observational data for signs of resilience changes during
the last decades. We see continuously decreasing rainforest resilience
since the early 2000s, but we cannot tell when a potential transition
from rainforest to savanna might happen. When it will be observable,
it would likely be too late to stop it." The research is part of the
project 'Tipping Points in the Earth System' (TiPES) funded by European
Union's Horizon 2020 programme.

The team from the Potsdam Institute for Climate Impact Research and the
Global Systems Institute of the University of Exeter used stability
indicators that had previously already been applied to the Greenland
ice sheet and the Atlantic overturning circulation. These statistical indicators aim at predicting the approach of a system towards an abrupt
change by identifying a critical slowing down of the system's dynamics,
for instance its reaction to weather variability. The analysis of two
satellite data sets, representing biomass and the greenness of the
forest, revealed the critical slowing down. This critical slowing down
can be seen as a weakening of the restoring forces that usually bring
the system back to its equilibrium after perturbations.

"A system might seem stable if one is considering only its mean state"
While a system might seem stable if one is considering only its mean
state, taking a closer look at the data with innovative statistical
methods can reveal resilience loss," says Chris Boulton from the
University of Exeter's Global Systems Institute. "Previous studies based
on computer simulations indicated that large parts of the Amazon can be committed to dieback before showing a strong change in the mean state. Our observational analysis now shows that in many areas destabilization indeed seems to be underway already." To try and determine causes for the loss
of resilience that the scientists find in the data, they explored the
relation to rainfall in a given area in the Amazon, culminating in three
'once in a century' drought events in the region.

Drier areas turn out to be more at risk than wetter ones. "This is
alarming, as the IPCC models project an overall drying of the Amazon
region in response to anthropogenic global warming," says Boers. Another
factor is the distance of an area to roads and settlements from where
people can access the forest. The data confirms that areas close to
human land-use are more threatened.

"Our novel analysis of empirical data brings additional evidence to the
worries about the forest's resilience, especially in the near future,"
says Tim Lenton, Director of the Global Systems Institute. "It
confirms that strongly limiting the logging, but also limiting
global greenhouse gas emissions, is necessary to safeguard the Amazon." ========================================================================== Story Source: Materials provided by Potsdam_Institute_for_Climate_Impact_Research_(PIK).

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Boulton, C.A., Lenton, T.M. & Boers, N. Pronounced loss of Amazon
rainforest resilience since the early 2000s. Nat. Clim. Chang.,
2022 DOI: 10.1038/s41558-022-01287-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220307113004.htm

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