Climate change could cause the extinction of one in six global species by 2100
A new report in the journal, Science, says that even if international attempts to curb greenhouse gas emissions are successful by keeping the inevitable rise in global average temperatures to below the 2C “safe” threshold, over 5% of species in the world would face the risk of imminent extinction purely because of climatic factors. That is just the rate of extinction from temperature rise, not from habitat loss, over-exploitation, introduced species, environmental degradation or ocean acidification. On current climate projections, which would see global average temperatures reach about 4C higher than pre-industrial times by 2100, the study found that 16% of species would become extinct, due to climate factors alone. The study anticipates that if the world continues down the existing path of CO2 emissions, the rate of mass extinction will not just get worse for every 1C extra rise in global average temperatures, it will actually accelerate. The rates of extinction differ between continents, with endemic plants and animals of South America, Australia and New Zealand particularly at risk from higher temperatures, as many have nowhere else to move to. The study was a meta-analysis of 131 previous studies into the extinction risks due to climate change.
Climate change ‘could make one in six species extinct by end of the century’
By Steve Connor, (Science Editor, Independent)
30 April 2015
One in six species could face extinction by the end of the century as a direct result of increasing global temperatures, an analysis of the threat posed by climate change to wildlife has found.
If the world continues down the existing path of carbon dioxide emissions, the rate of mass extinction will not just get worse for every 1C extra rise in global average temperatures, it will actually accelerate, the study discovered.
The endemic plants and animals of South America, Australia and New Zealand are particularly at risk of rising temperatures because for many of these rare species there is nowhere else to go when their only homeland becomes uninhabitable, scientists found.
On current climate projections, which would see global average temperatures reach about 4C higher than pre-industrial times by 2100, the study found that 16 per cent of species in the world would face the risk of imminent extinction purely because of climatic factors, rather than from habitat loss, environmental degradation or ocean acidification.
Even if international attempts to curb greenhouse gas emissions are successful by keeping the inevitable rise in global average temperatures to below the 2C “safe” threshold, the global extinction risk would still increase from its current 2.8 per cent to 5.2 per cent, said Mark Urban of the University of Connecticut, the author of the new report in the journal Science.
“We don’t know how long these extinctions will take, but these species will be committed to extinction. They will be on the train towards extinction, but we don’t know when it will arrive,” Dr Urban told The Independent.
“This is purely the contribution to extinction risk from the changing climate. Today, the biggest threats are from habitat loss and environmental degradation, but in a warmer world the climate will become more and more important,” he said.
The study was a meta-analysis of 131 previous studies into the extinction risks posed by climate change. It was an attempt to build a global picture across a range of animals and plants living on all continents, and on both land and sea.
“We can look across all the studies and use the wisdom of many scientists. When we put it all together we can account for the uncertainty in each approach, and look for common patterns and understand how the moderators in each type of study affect outcomes,” Dr Urban said.
Stephen Cornelius, chief adviser on climate change at WWF-UK, said: “This study further highlights the urgency of taking strong action to address climate change and that ‘business as usual’ is no longer an option.”
The analysis revealed that the regions of the world where endemic species are most vulnerable to climate change, such as Australia and New Zealand, were actually the least studied in term of the threats posed by global warming, he said. Regions of North America and Europe showed up to have the lowest extinction risks.
The most studied regions of North America and Europe showed up to have the lowest extinction risks, at 5 per cent and 6 per cent respectively, while South America had the highest extinction risk of 23 per cent, with Australia and New Zealand following with a 14 per cent extinction risk each.
“One of the biggest contributions to risk in South America and New Zealand is that they have a relatively large number of endemic species with small distributions,” Dr Urban said.
“With Australia and New Zealand, we’re also looking at land masses that are relatively small and isolated, so that the possibility of a species shifting to a new habitat simply doesn’t exist,” Dr Urban said.
Raising temperatures will present particular problems for mountain animals and plants that have evolved to live within a certain range of climate extremes. As it gets warmer, they can move higher and higher but eventually there will run out of habitable space.
Some species will be able to disperse more easily than others at the local climate changes, while for others the habitat range will become smaller and smaller, leading to a point where breeding populations are no longer viable, the study said.
“Extinction risks from climate change are expected not only to increase but to accelerate for every degree rise in global temperature,” Dr Urban said.
“The signal of climate change-induced extinctions will become increasingly apparent if we do not act now to limit future climate change,” he said.
Planned curbs in greenhouse gas emissions won’t prevent global warming ‘danger limit’ being reached, warns report
Study says temperatures will still rise more than 2C despite planned reductions
By Steve Connor, Science Editor (Independent)
4 May 2015
The planned curbs in greenhouse gas emissions by the nations of the world fall well short of what is required to avoid global average temperatures exceeding the “danger limit” of 2C this century, a report has warned.
An analysis of the pledges made by countries attending the climate summit in Paris this December has found that the promised reductions as they stand will still exceed the amount of greenhouses gases widely considered to breach of the safe threshold, it says.
The authors of the report have called on nations to be more ambitious in their promises for reductions of the carbon dioxide and other greenhouse gases that scientists have found are largely responsible for the rise on global average temperatures over recent decades.
The analysis by the Grantham Research Institute and the Centre for Climate Change Economics and Policy at the London School of Economics found serious shortcomings in what countries have suggested for their future annual emissions, and what is actually needed as the basis of an international treaty in Paris – widely considered the most important climate summit yet.
Recent estimates by the United Nations Environment Programme have suggested that there is a 50 to 66 per chance of limiting the rise in global temperatures to within 2C if annual worldwide emissions of greenhouse gases stabilise at between 32bn and 44bn tonnes by 2030.
However, the Grantham report found that the European Union, the United States and China together are proposing annual emissions of between 20.9bn and 22.3bn tonnes of greenhouse gases by 2030.
This means that the pledges for emissions from the rest of the world should not exceed about 23bn tonnes in 2030. However, the current and planned policies of these nations suggest that their annual emissions alone will rise to about 35bn tonnes by 2030.
This would result in a combined total for the world’s emission of up to 57bn tonnes, and a gap of at least 13bn tonnes between what is pledged and what is needed.
It is unlikely that the pledges from all countries before the Paris summit will collectively be sufficient to bridge the gap to an emissions pathway that is consistent with the limit of 2C, say the report’s authors, who include Lord Stern, the chair of the Grantham Research Institute and leader of 2006 Stern Review on the economics of climate change.
“There is a gap between the emissions pathway that would result from current ambitions and plans, and a pathway that is consistent with the global warming limit of 2C. Consequently, countries should be considering opportunities to narrow the gap before and after the Paris summit,” the report says.
“The ambitions and plans agreed at the Paris summit in December 2015 should be regarded as a critical initial step. It is also important that countries make pledges that are credible,” it says.
“However, the magnitude of the gap between current intentions and the international target of limiting global warming to no more than 2C clearly shows that an international agreement in Paris will have to include dynamic mechanisms for assessment of progress and the raising of ambitions,” it adds.
“[Paris] should not be regarded as just a one-off opportunity to fix targets.”