Amazon collapse is closer than thought – 06/29/2023 – Environment

Computer simulations conducted by British scientists have just drawn a worrying picture about the risk of ecosystem collapse in the future, such as the feared transformation of the Amazon into an open and impoverished environment. According to the study, the greater the complexity of the simulation — that is, the closer to reality — the greater the chance that these collapses will happen more quickly.

“Our work shows that ecosystems can collapse sooner than we would expect if they are experiencing multiple stresses at the same time,” he explained to Sheet the first author of the study, Simon Willcock, linked to the Rothamsted Research Center and the University of Bangor (Wales).

“There could be, for example, a combination of climate change, deforestation and loss of biodiversity caused by hunting, as well as extreme weather events. All these factors reflect relatively well the stresses that are affecting the Amazon recently and will affect it in the near future “, sums up Willcock.

Published in the specialized magazine Nature Sustainability, the British team’s work included other real and theoretical examples of environmental collapse, all simulated in computational models with different degrees of complexity.

In addition to modeling the future of Amazonian vegetation, Willcock and company evaluated a simulation of fishing activity in the Chilika Lagoon, on the east coast of India; the human population growth and environmental degradation that affected Easter Island in the Pacific before the arrival of Europeans; and, finally, the so-called Phosphorus Lake, a generic simulacrum of a pond affected by an excess of this nutrient (which can come, for example, from industrial fertilizers and often leads to the uncontrolled multiplication of microorganisms in the water).

These very different scenarios have in common the fact that they can all be subject to a qualitative “turning point”, in which these environments can assume a completely different aspect if a certain threshold is exceeded. Roughly speaking, it is something similar to what happens in the transition of states of matter, when a block of ice turns into liquid water or when a glass of water turns into vapour, say.

This is one of the most feared effects of climate change, because this type of collapse would be capable of completely altering the environmental conditions that today allow obtaining water, agriculture and animal husbandry in a given ecosystem, for example, triggering repercussions very dangerous for the survival of the human population.

Until now, many simulations had studied what happens to these systems with the gradual transformation provoked by a single disturbance factor (or stress, as the researchers say). In the case of the Amazon, this factor would be the loss of forest cover; on Easter Island, the increase in the human population; and so on.

In the models studied by the team, the addition of one more stressor causes the environmental collapse to happen sooner, which, of course, is to be expected. But, in addition, the combination of factors means that the disaster can happen even when the level of the main negative factor, if isolated, could be supported by the ecosystem.

And it gets even worse with what researchers call “noise.” The term refers to occurrences that are essentially random —unluckily, there is a drought or a flood much higher than expected, for example—, but that can once and for all weaken an environment that was already undermined by the most constant factors. Modeling indicates that the addition of these factors makes environmental collapses between 40% and 80% closer to happening in the near future.

The so-called savannization of the Amazon —that is, the possibility of a drastic reduction in humid and closed forests, replaced by drier and more open vegetation— falls into this category, and other studies also point to a very worrying situation, according to the British researcher.

“Recent work has shown that the Amazon is already losing resilience, while another has indicated that, once the collapse begins, it will be quick. According to that work, if the process starts in 2030, for example, it could be completed in 2080. The main uncertainty is when this critical threshold will be crossed,” he says. “Much of this will depend on how people across the planet change their behavior to reduce emissions. [de gases causadores da mudança climática].”