Sustainability Climate Change

Risks to biodiversity remain even if a global temperature peak is achieved: study

“Urgent action is needed to ensure we never approach, let alone exceed, the 2 degree celsius limit.”
fish swimming near coral reef.
The Associated Press/Jacob Asher

Story at a glance

  • Reducing carbon emissions to ensure the planet does not warm over 2 degrees celsius compared with pre-industrial levels has been a global goal since the 2015 Paris climate summit.

  • But new research outlines the toll even approaching this threshold could take on the natural environment.

  • According to authors, even a rapid decline after a peak temperature is reached could have negative effects on the planet’s biodiversity. 

If global temperatures peak at just above the threshold of 2 degrees Celsius outlined by the 2015 Paris climate agreement, that may not be enough to curb the long-term implications of climate change, according to experts.

New research published today found biodiversity may continue to suffer decades after that point is reached and that de-exposure of species will lag behind any rapid temperature decline. 

Biodiversity encompasses both animal and plant species across the planet. The more biodiversity an ecosystem has, the healthier it is. 

Investigators from The University of Cape Town and University College London modeled temperature overshoot scenarios whereby the global warming exceeded a certain determined threshold, then rapidly declined via carbon dioxide removal from the atmosphere. 

More than 30,000 species were included in the 2-degrees model simulation, which predicted outcomes for the year 2040, should emissions keep increasing. Under the model, negative carbon emissions were achieved by 2070.

“While the global overshoot period lasts around 60 years, the duration of elevated exposure of marine and terrestrial biodiversity is substantially longer (around 100 and 130 years, respectively), with some ecological communities never returning to pre-overshoot exposure levels,” researchers wrote. 

For more than 25 percent of the 30,000 species assessed, the chance of returning to pre-overshoot conditions are nonexistent or uncertain, authors found.

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Furthermore, relying on carbon dioxide removal efforts once the threshold warming has been reached could further set back ecological health, as land use will be altered to achieve this goal. 

Reductions in biodiversity have already been recorded around the world in recent years as species extinction rates are accelerating.

According to the researchers, tropical regions will bear the brunt of global warming’s effect on biodiversity, specifically the Indo-Pacific, Central Indian Ocean, Northern Sub-Saharan Africa and Northern Australia areas.

“Our findings are stark. They should act as a wake-up call that delaying emissions cuts will mean a temperature overshoot that comes at an astronomical cost to nature and humans that unproven negative emission technologies cannot simply reverse,” said co-author Christopher Trisos in a press release. 

“Urgent action is needed to ensure we never approach, let alone exceed, the 2 degree celsius limit,” added co-author Alex Pigot.