Evidence for man-made global warming has reached a ‘gold standard’ level of certainty and that it is ‘extremely likely’ that humans are the cause, say scientists.
The new study, based on satellite measurements of rising temperatures over the last 40 years, claims that there is only a one-in-a-million chance that they are wrong.
This adds even more pressure on governments to take more urgent measures to cut greenhouse gases to limit rising temperatures.
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Evidence for man-made global warming has reached a ‘gold standard’ level of certainty and that it is ‘virtually certain’ that humans are the cause, say scientists. The new study, based on satellite measurements of rising temperatures over the last 40 years (file photo)
Confidence that human activities are raising the heat at the Earth’s surface have reached a ‘five-sigma’ level, a measurement of how certain scientists are of their results.
This statistical gauge means that there is only a one-in-a-million chance that the signal would appear if there was no warming.
‘Humanity cannot afford to ignore such clear signals,’ the U.S.-led team wrote in the journal Nature Climate Change of satellite measurements of rising temperatures.
The ‘gold standard’ was applied in 2012, for instance, to confirm the discovery of the Higgs boson subatomic particle, a basic building block of the universe.
Dr Benjamin Santer, lead author of the study at the Lawrence Livermore National Laboratory in California, said he hoped the findings would win over sceptics and spur action.
‘The narrative out there that scientists don’t know the cause of climate change is wrong, we do,’ he said.
Mainstream scientists say the burning of fossil fuels is causing more floods, droughts, heat waves and rising sea levels.
President Trump has cast doubt on global warming in the past and plans to pull out of the Paris climate agreement, which aims to combat climate change.
195 countries adopted the agreement which seeks to end the fossil fuel era this century by shifting to cleaner energies such as wind and solar power.
Sixty-two per cent of Americans polled in 2018 believed that climate change has a human cause, up from 47 per cent in 2013, according to the Yale Program on Climate Change Communication.
The ‘gold standard’ was applied in 2012 to confirm the discovery of the Higgs boson subatomic particle, a basic building block of the universe. Mainstream scientists say the burning of fossil fuels is causing more floods, droughts, heat waves and rising sea levels (stock image)
Monday’s findings, by researchers in the United States, Canada and Scotland, said evidence for global warming reached the five sigma level by 2005 in two of three sets of satellite data widely used by researchers, and in 2016 in the third.
Separately in 2013, the U.N.’s Intergovernmental Panel on Climate Change (IPCC) concluded that it is ‘extremely likely’, or at least 95 per cent probable, that human activities have been the main cause of climate change since the 1950s.
Peter Stott of the British Met Office, who was among the scientists drawing that conclusion and was not involved in Monday’s study, said he would favour raising the probability one notch to ‘virtually certain’, or 99-100 per cent.
‘The alternative explanation of natural factors dominating has got even less likely,’ he told Reuters.
The last four years have been the hottest since records began in the 19th century.
The IPCC will next publish a formal assessment of the probabilities in 2021.
‘I would be reluctant to raise to 99-100 per cent, but there is no doubt there is more evidence of change in the global signals over a wider suite of ocean indices and atmospheric indices,’ said Professor Nathan Bindoff, a climate scientist at the University of Tasmania.
WHAT IS CORAL BLEACHING?
Corals have a symbiotic relationship with a tiny marine algae called ‘zooxanthellae’ that live inside and nourish them.
When sea surface temperatures rise, corals expel the colourful algae. The loss of the algae causes them to bleach and turn white.
This bleached states can last for up to six weeks, and while corals can recover if the temperature drops and the algae return, severely bleached corals die, and become covered by algae.
In either case, this makes it hard to distinguish between healthy corals and dead corals from satellite images.
This bleaching recently killed up to 80 per cent of corals in some areas of the Great Barrier Reef.
Bleaching events of this nature are happening worldwide four times more frequently than they used to.
An aerial view of Australia’s Great Barrier Reef. The corals of the Great Barrier Reef have undergone two successive bleaching events, in 2016 and earlier this year, raising experts’ concerns about the capacity for reefs to survive under global-warming