Climate change is set to trigger catastrophic biodiversity losses in the coming decades, according to a new study led by University College London. Global warming is pushing many species to a tipping point, and these plants and animals will disappear abruptly if temperatures continue to rise.
The researchers predict that a large number of species will vanish simultaneously under the strain of climate change, and some regions will suffer extraordinary losses sooner than others. Unprecedented disasters, such as the mass coral bleaching events on the Great Barrier Reef, indicate that the first wave of destruction has already arrived.
“We found that climate change risks to biodiversity don’t increase gradually. 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,” explained study lead author Dr. Alex Pigot. “It’s not a slippery slope, but a series of cliff edges, hitting different areas at different times.”
The research team, including experts in South Africa and the United States, set out to analyze threats to biodiversity through the end of the century. The investigation was focused on climate model data from 1850 to 2005 and the geographic ranges of 30,652 species of plants and animals.
The experts used climate model projections for each year through 2100 to estimate when specific regions will begin experiencing unusually high temperatures that persist for at least five years.
“The historic temperature models, combined with species ranges, showed us the range of conditions that each organism can survive under, as far as we know,” said study first author Dr Christopher Trisos. “Once temperatures in a given area rise to levels that the species have never experienced, we would expect there to be extinctions, but not necessarily – we simply have no evidence of the ability of these species to persist after this point.”
The study showed that in most ecological communities, a large share of the species will be pushed outside of their comfort zone within the same decade. Across the globe, 73 percent of the species exposed to abnormally hot temperatures will cross this threshold simultaneously.
According to the research, if global temperatures rise by 4°C this century, at least 15 percent of communities across the globe will be facing severe ecological disruption. If warming is limited to 2°C or less, the number of communities impacted would drop to less than two percent.
“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction. Keeping global warming below 2°C effectively ‘flattens the curve’ of how this risk to biodiversity will accumulate over the century, providing more time for species and ecosystems to adapt to the changing climate – whether that’s by finding new habitats, changing their behavior, or with the help of human-led conservation efforts,” said Dr. Pigot.
The researchers warn that some of the most biodiverse ecological communities on the planet, such as coral reefs, will feel the first impacts. Across tropical oceans, harmful exposure to excessive heat is expected to begin by 2030.
“We hope that our findings could serve as an early warning system, predicting which areas will be most at risk and when, that could help target conservation efforts and improve future model projections,” said study co-author Dr. Cory Merow. “It may be valuable to develop a ten-year monitoring program – similar to what climate scientists do, but for biodiversity – which could be updated regularly based on what actually occurs.”
The study is published in the journal Nature.