[ad_1]
Global warming will cause “catastrophic” biodiversity loss worldwide if greenhouse gas emissions are not reduced, and some ecosystems may collapse as early as 2030, according to new research on where and when extinctions can occur.
Earth has never warmed in human history as quickly or uniformly as it does today, but a variety of factors affect temperatures in individual regions, with significant seasonal and geographic variations.
Scientists predict that at the current level of human-made carbon emissions, Earth is on track to heat up to four degrees Celsius by 2100.
Rather than looking at global trends, researchers in Britain, the United States, and South Africa analyzed more than 150 years of climate data and crossed it with the spread of more than 30,000 species of birds, mammals, reptiles, and fish.
They then divided the globe into segments of 100 square kilometers (39 square miles) and modeled temperature trends and the effects this would have on wildlife in a given area.
Writing in the journal Nature, they concluded that under typical emissions, known as the RCP8.5 scenario, up to 73 percent of species will experience unprecedented warming with potentially disastrous effects on populations.
Alex Pigot, of the University College London Center for Biodiversity and the Environment, said the models showed that animal populations can collapse once they cross a temperature “horizon”, leaving them exposed to heat that they are not evolved to handle.
“By passing this threshold, we expect the risk of local extinction to increase substantially,” Pigot told AFP.
“It is not a slippery slope, but a series of cliff edges that hit different areas at different times,” he said.
The models change dramatically according to each emission path.
For example, at 4 ° C warming, 15 percent of all animals could see extreme heat that could cause “irreversible damage” to regional ecosystems.
But at 2 ° C warming, the limit set in the Paris climate agreement, that number fell to two percent, according to models.
The researchers predicted that such unprecedented temperature events will begin before 2030 in the tropical oceans.
Recent phenomena like the massive bleaching of the Great Barrier Reef suggest that this is already happening in some places, the team said, adding that higher latitudes would see similar events by 2050.
Coral reefs occupy a small percentage of the oceans but support up to a quarter of all marine life.
The Earth has already warmed more than 1 ° C since the Industrial Revolution and the emissions of greenhouse gases that heat the planet by burning fossil fuels are increasing annually.
The United Nations says humanity needs to cut emissions by 7.6 percent a year by 2030 to limit warming to 1.5C, the most ambitious goal of the Paris agreement.
“As we approach 2C from global warming, there is an alarming escalation in the risks of these abrupt losses of biodiversity, providing strong evidence of the need to keep warming below 2C,” said Pigot.
