Livelihoods at risk as entire ecosystems could be under threat
A warming global climate could cause sudden and potentially catastrophic losses of biodiversity in regions across the planet throughout the 21st century, warns a new study, which suggests that the first waves could already be under way.
“If we continue on our high emissions pathway, then absolutely abrupt collapses might happen much earlier than we thought,” said the study's first author Christopher Trisos, a senior researcher at the African Climate and Development Initiative at the University of Cape Town, in a statement.
“Generally, people think it’s going to be bad in 2100, but this study showed it could be as soon as 2030.”
The study - the Projected Timing of Abrupt Ecological Disruption from Climate Change - published in the journal Nature this week warns how under a scenario of high greenhouse gas emissions, such abrupt exposure events are forecast to begin before 2030 in tropical oceans, spreading to tropical forests and temperate regions by the 2050s. The mass bleaching of corals on the Great Barrier Reef suggests this is already under way.
The study by Trisos, co-author Dr Cory Merow, of the University of Connecticut, and lead author Dr Alex Pigot, of University College London, shows how biodiversity is at risk in the first half of this century and the risk of collapse at a single location doesn’t accumulate gradually but can go from low risk to high risk within a decade.
"Instead, as the climate warms, within a certain area most species will be able to cope for a while, before crossing a temperature threshold, when a large proportion of the species will suddenly face conditions they've never experienced before," said Pigot. "It's not a slippery slope, but a series of cliff edges, hitting different areas at different times."
The team used annual projections from climate models of temperature and precipitation - including rain, snow and sleet - from 1850 to 2100 across the ranges of more than 30000 species of birds, mammals, reptiles, amphibians, fish and other mammals, to estimate the timing of their exposure to potentially dangerous climate conditions.
If global warming is limited to below 2ºC, less than 2% of animal communities will experience abrupt exposure. But the risk accelerates with the magnitude of warming in species in protected and unprotected areas.
Entire ecosystems could be under threat, putting people’s livelihoods at risk.
The research found the tropical Indian and Pacific oceans are most at risk for abrupt collapse of coral and fish communities. On land, animal communities in Indonesia, northern Australia, India and the Amazon are at high risk.
For Africa, extreme biodiversity loss could be seen earliest in the Sahel region, the Congolese rainforests and the tropical Indian and Atlantic oceans.
In SA, in a high-emissions scenario, the coast from Cape Agulhas to Mozambique, inland areas on the western side of the Western Cape up to the Namibian border, the entire Northern Cape and part of the Free State, are all at risk.
“Billions of people depend on ecosystems for their livelihood and vital nutrition,” said Trisos. “If there is a sudden collapse of these ecosystems in a single decade, you could lose most or all of these services. Your income is at risk. Your food security is at risk. Your mental and spiritual well-being could be at risk if those ecosystems are important for you culturally.”
Cutting emissions and delaying the onset of exposure to dangerous climate conditions, even by a few decades, could buy valuable time for species to adapt, “potentially reducing the magnitude of ecological disruption and catastrophic extinction of local biodiversity”.