World temperatures hit a record high for the third year in a row in 2016, creeping closer to a ceiling set by the Paris climate change deal, with extremes including unprecedented heat in India and ice melt in the Arctic, scientists said on Wednesday.
The findings, providing new signs of the impact of greenhouse gases, were issued two days before the inauguration of US President-elect Donald Trump, who questions whether climate change has a human cause.
Average global surface temperatures in 2016 were 0.83 degree Celsius (1.5 Fahrenheit) above a long-term average of 14 degrees Celsius (57.2F) from 1961-1990, according to the UN-affiliated World Meteorological Organisation (WMO) in Geneva.
Temperatures, lifted mainly by man-made greenhouse gases and partly by a natural El Nino weather event that released heat from the Pacific Ocean, beat the previous record in 2015, when 200 nations agreed a plan to limit global warming.
That peak had in turn eclipsed 2014. "We don't expect record years every year, but the ongoing long-term warming trend is clear," said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.
The WMO data were based on records compiled by NASA, the US National Oceanic and Atmospheric Administration (NOAA) and Britain's Met Office.
Global temperature records date back to the 1880s. It was only the second run of three record-breaking years after 1939-41, said Deke Arndt of NOAA's National Centres for Environmental Information.
Temperatures this year are unlikely to set a new record after the fading of El Nino, scientists said. But heat-trapping gases from burning fossil fuels, especially from China and the United States, will keep building up in the atmosphere. "Unless we have a major volcanic eruption, I expect the record to be broken again within a few years," said Piers Forster, climate expert at the University of Leeds. Ash from big eruptions can dim sunlight.
Among last year's extreme weather events, wildfires in Alberta were the costliest natural disaster in Canada's history, while Phalodi in western India recorded a temperature of 51 degrees Celsius (123.8 Fahrenheit) on May 19, a national record.
North America also had its warmest year on record, the Great Barrier Reef off Australia suffered severe damage from rising temperatures, and sea ice in both the Arctic Ocean and around Antarctica is at record lows for mid-January.
At a summit in Paris in late 2015, governments agreed a plan to phase out fossil fuels this century and shift to renewable energies such as wind and solar power.
They agreed to limit warming to "well below" 2 degrees Celsius (3.6F) above pre-industrial times, while pursuing efforts for a 1.5C (2.7F) limit. By that yardstick, the WMO said temperatures in 2016 were 1.1C (2.0F) above pre-industrial ties. "Long-term indicators of human-caused climate change reached new heights in 2016," said Petteri Taalaas, head of the WMO, referring to rising levels of carbon dioxide and methane.
He also said that warming was having other knock-on effects, such as melting Greenland ice that is pushing up sea levels.
Trump, who has described climate change as a hoax, has threatened to cancel the Paris Agreement and shift to exploiting cheap domestic coal, oil and gas. At a meeting in Marrakesh days after Trump's victory, however, almost 200 nations said it was an "urgent duty" to combat climate change.
Trump's choice to lead the Environmental Protection Agency, Oklahoma Attorney General Scott Pruitt, was quizzed by Democratic senators at a confirmation hearing on Wednesday about his fossil fuel industry ties. "The hottest year on record is such a clear warning siren that even President-elect Trump cannot ignore," said Mark Maslin, Professor of Climatology at University College London.