There is almost no ecosystem on Earth left untouched by human activity, according to new research that suggests widespread change from pollution, wildlife extinctions and disruption to plant life is pushing the planet into uncharted territory.
“We have shifted the system to conditions that we have not seen before,” says at Aarhus University in Denmark.
Ordonez and his colleagues have mapped the land’s exposure to three key drivers of ecosystem “novelty” around the world, spanning from the deep past to the present day. The first metric of novelty was climate change, which the team measured using data stretching back 21,000 years. The second metric was animal loss, particularly the extinction of large mammals, compared with a world without human pressures, while the third was “floristic disruption” – in other words, exotic plant introductions, and a decline in native plant abundance.
Advertisement
Previous research on ecological novelty has tended to focus on only one driver, such as climate change, notes Ordonez. “So far everyone has been thinking about this idea of novelty from one lens. So what ɱ’r trying to do here is think about it more holistically,” he says.
The team broke the world’s land mass down into 10-kilometre square segments and scored each against the three metrics. For a location to be rated as experiencing a high level of novelty, it must have scored highly across all three metrics, or else reached the maximum possible score in two of three metrics.
Across the world, the team concluded that 58 per cent of the total land area is exposed to a high level of novelty. But almost every ecosystem has been changed to some extent, says team member also at Aarhus University. “Nowhere in the world scored zero in our metric,” he says. Perhaps unsurprisingly, “our largest contributor to novelty globally was climate”, he says.
The Amazon rainforest, parts of the eastern Mediterranean, and New Zealand are experiencing some of the highest levels of novelty, the team found. Protected areas, such as national parks or other conservation zones, were just as likely to be exposed to unprecedented conditions as anywhere else, says Kerr. “It’s almost completely dispassionate where novelty is emerging. It’s not just near where humans are living,” he says.
at the University of Wisconsin-Madison in the US says the research “goes beyond prior work by really thinking about multiple dimensions of biological novelty”, rather than just one aspect, such as climate. “Their analyses provide the first global assessment of the relative importance of these factors at different places, including in biodiversity hotspots,” he says.
Kerr says the next step for the research is to examine how different ecosystems are responding to the new conditions. “We’re mapping the exposure of the ecosystem, but ɱ’r not testing the response of the ecosystem itself,” he says.
The research also does not account for the influence different metrics could have on each other – for example, the role of climate change in driving wildlife extinctions. That likely makes the headline conclusions an underestimate, says Kerr.
Nevertheless, he argues the findings underscore the scale of change humanity has wrought on the natural world, and cautions that it is no longer viable to restore ecosystems to their original state. “The instability has already set in; we can’t change these drivers now,” he says. Instead, he argues, conservation work must focus on where the pace of change can be slowed or managed.
from the conservation organisation WWF says the findings should act as a reminder to tackle the causes of ecosystem disruption, including taking urgent action to reduce fossil fuel emissions. “There’s no corner of the planet which is not being impacted,” he says. “If we keep down that road without addressing the root causes, then we are on a journey towards tipping points which will be catastrophic to the Earth.”
Nature Ecology and Evolution
