The greenhouse gases driving climate change have reached highs not seen in at least 3 million years, prompting UN scientists to warn the “window of opportunity” to tackle emissions is rapidly closing.

Carbon dioxide, nitrous oxide and methane are all still on the rise, the World Meteorological Organisation (WMO) has said, and there has been a resurgence in ozone-depleting CFCs.

“The last time the Earth experienced a comparable concentration of carbon dioxide was 3-5 million years ago, when the temperature was 2-3C warmer and sea level was 10-20 metres higher than now,” said WMO secretary general, Petteri Taalas.

In its annual bulletin on greenhouse gas levels, the WMO said there is no sign of a reversal in the trend in increasing emissions which are driving climate change, sea level rises, extreme weather and making oceans more acidic.

“The science is clear,” Mr Taalas said. “Without rapid cuts in carbon dioxide and other greenhouse gases, climate change will have increasingly destructive and irreversible impacts on life on Earth.

“The window of opportunity for action is almost closed.”

Average concentrations of carbon dioxide hit new highs of 405.5 parts per million (ppm) in 2017, up from 403.3 ppm in 2016 and 400.1 ppm in 2015 – 2.5 times the pre-industrial revolution concentration.

“CO2 remains in the atmosphere for hundreds of years and in the oceans for even longer. There is currently no magic wand to remove all the excess CO2 from the atmosphere,” said WMO deputy secretary-general Elena Manaenkova.

Heatwaves driven by climate change making insects infertile, study suggests

“Every fraction of a degree of global warming matters, and so does every part per million of greenhouse gases,” she said.

Levels of methane have soared to 3.5 times their pre-industrial levels, with emissions largely coming from cattle, rice paddy fields and oil and gas leaks.

Farming methods including use of fertilizers is largely behind the rise in nitrous oxide, which has doubled since the pre-industrial era.

The latest findings come after a report from the UN’s Intergovernmental Panel on Climate Change (IPCC) found net emissions of carbon dioxide must reach zero by around 2050 to keep temperature rises to 1.5C above pre-industrial levels and reduce the risks of climate change.

IPCC chairman Hoesung Lee said: “The new IPCC special report on global warming of 1.5C shows that deep and rapid reductions of emissions of carbon dioxide and other greenhouse gases will be needed in all sectors of society and the economy.

“The WMO greenhouse gas bulletin, showing a continuing rising trend in concentrations of greenhouse gases, underlines just how urgent these emissions reductions are.”

Professor Corinne Le Quere, director of the Tyndall Centre for Climate Change Research at the University of East Anglia, said she was “not surprised but I am very concerned” the major greenhouse gases are rising unabated.

Extinction rebellion: Climate change protesters block London bridges Show all 25 1 /25 Extinction rebellion: Climate change protesters block London bridges Extinction rebellion: Climate change protesters block London bridges Demonstrators block Westminster Bridge in central London to show anger at government inaction on climate and ecological issues AFP/Getty Extinction rebellion: Climate change protesters block London bridges A pro environment protester is arrested by police on Lambeth bridge in London EPA Extinction rebellion: Climate change protesters block London bridges Organised by Extinction Rebellion, the protest is part of many taking place this weekend to bring attention to political inaction on issues of pollution and climate change Reuters Extinction rebellion: Climate change protesters block London bridges A demonstrator puts tape on her mouth as she takes part in a pro-environment protest blocking Westminster Bridge in central London on November 17, 2018, calling on the British government to take action on climate and ecological issues. - Organized by Extinction Rebellion, the protest is part of many taking place this weekend to call for action on what they describe as a climate and ecological emergency. Extinction Rebellion demands that the UK government reduces to net zero greenhouse gas emissions by 2025 and creates a citizens assembly to oversee changes in environmental policies. (Photo by Tolga AKMEN / AFP)TOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Extinction rebellion: Climate change protesters block London bridges Organised by Extinction Rebellion, the protest is part of many taking place this weekend to bring attention to political inaction on issues of pollution and climate change PA Extinction rebellion: Climate change protesters block London bridges Demonstrators on Blackfriars Bridge PA Extinction rebellion: Climate change protesters block London bridges Police with demonstrators on Blackfriars Bridge PA Extinction rebellion: Climate change protesters block London bridges Demonstrators take part in a pro-environment protest as they block Westminster Bridge in central London on November 17, 2018, calling on the British government to take action on climate and ecological issues. - Organized by Extinction Rebellion, the protest is part of many taking place this weekend to call for action on what they describe as a climate and ecological emergency. Extinction Rebellion demands that the UK government reduces to net zero greenhouse gas emissions by 2025 and creates a citizens assembly to oversee changes in environmental policies. (Photo by Tolga AKMEN / AFP)TOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Extinction rebellion: Climate change protesters block London bridges epa07172610 Pro environment protesters block Westminster bridge in central London, Britain, 17 November 2018. Reports state that the protest organized by Extinction Rebellion group is planning to close five main bridges across the river Thames, seeking to bring attention to political inaction on issues of pollution and climate change. EPA/FACUNDO ARRIZABALAGA FACUNDO ARRIZABALAGA EPA Extinction rebellion: Climate change protesters block London bridges A demonstrator is led away by police on Blackfriars Bridge PA Extinction rebellion: Climate change protesters block London bridges Environmental campaigners from the direct action group Rebellion demonstrate on Westminster Bridge in central London, Britain, November 17, 2018. REUTERS/Peter Nicholls PETER NICHOLLS Reuters Extinction rebellion: Climate change protesters block London bridges Police with demonstrators on Westminster Bridge in London for a protest called by Extinction Rebellion to raise awareness of the dangers posed by climate change. PRESS ASSOCIATION Photo. Picture date: Saturday November 17, 2018. See PA story PROTEST Rebellion. Photo credit should read: John Stillwell/PA Wire John Stillwell PA Extinction rebellion: Climate change protesters block London bridges Environmental campaigners from the direct action group Rebellion demonstrate on Westminster Bridge in central London, Britain, November 17, 2018. REUTERS/Peter Nicholls PETER NICHOLLS Reuters Extinction rebellion: Climate change protesters block London bridges Demonstrators take part in a pro-environment protest as they block Westminster Bridge, near the Houses of Parliament in central London on November 17, 2018, to show anger at government inaction on climate and ecological issues. - Organised by Extinction Rebellion, the protest is part of many taking place this weekend to bring attention to political inaction on issues of pollution and climate change. (Photo by Tolga AKMEN / AFP)TOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Extinction rebellion: Climate change protesters block London bridges Demonstrators take part in a pro-environment protest as they block Westminster Bridge in central London on November 17, 2018, to show anger at government inaction on climate and ecological issues. - Organized by Extinction Rebellion, the protest is part of many taking place this weekend to bring attention to political inaction on issues of pollution and climate change. (Photo by Tolga AKMEN / AFP)TOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Extinction rebellion: Climate change protesters block London bridges Police with demonstrators on Westminster Bridge in London for a protest called by Extinction Rebellion to raise awareness of the dangers posed by climate change. PRESS ASSOCIATION Photo. Picture date: Saturday November 17, 2018. See PA story PROTEST Rebellion. Photo credit should read: John Stillwell/PA Wire John Stillwell PA Extinction rebellion: Climate change protesters block London bridges epa07173093 A pro environment protester infornt of police on Lambeth bridge in London, Britain, 17 November 2018. Reports state that the protest organized by Extinction Rebellion group is planning to close five main bridges across the river Thames, seeking to bring attention to political inaction on issues of pollution and climate change. EPA/FACUNDO ARRIZABALAGA FACUNDO ARRIZABALAGA EPA Extinction rebellion: Climate change protesters block London bridges epa07172601 Pro environment protesters block Westminster bridge in central London, Britain, 17 November 2018. Reports state that the protest organized by Extinction Rebellion group is planning to close five main bridges across the river Thames, seeking to bring attention to political inaction on issues of pollution and climate change. EPA/FACUNDO ARRIZABALAGA FACUNDO ARRIZABALAGA EPA Extinction rebellion: Climate change protesters block London bridges epa07172698 Pro environment protesters hold a placard as they block Westminster bridge in central London, Britain, 17 November 2018. Reports state that the protest organized by Extinction Rebellion group is planning to close five main bridges across the river Thames, seeking to bring attention to political inaction on issues of pollution and climate change. EPA/FACUNDO ARRIZABALAGA FACUNDO ARRIZABALAGA EPA Extinction rebellion: Climate change protesters block London bridges Demonstrators on Westminster Bridge in London for a protest called by Extinction Rebellion to raise awareness of the dangers posed by climate change. PRESS ASSOCIATION Photo. Picture date: Saturday November 17, 2018. See PA story PROTEST Rebellion. Photo credit should read: John Stillwell/PA Wire John Stillwell PA Extinction rebellion: Climate change protesters block London bridges Environmental campaigners from the direct action group Rebellion demonstrate on Westminster Bridge in central London, Britain, November 17, 2018. REUTERS/Peter Nicholls PETER NICHOLLS Reuters Extinction rebellion: Climate change protesters block London bridges epa07172703 Pro environment protesters hold a placard as they block Westminster bridge in central London, Britain, 17 November 2018. Reports state that the protest organized by Extinction Rebellion group is planning to close five main bridges across the river Thames, seeking to bring attention to political inaction on issues of pollution and climate change. EPA/FACUNDO ARRIZABALAGA FACUNDO ARRIZABALAGA EPA Extinction rebellion: Climate change protesters block London bridges Demonstrators take part in a pro-environment protest as they block Westminster Bridge in central London on November 17, 2018, to show anger at government inaction on climate and ecological issues. - Organized by Extinction Rebellion, the protest is part of many taking place this weekend to bring attention to political inaction on issues of pollution and climate change. (Photo by Tolga AKMEN / AFP)TOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Extinction rebellion: Climate change protesters block London bridges epa07172629 Pro environment protester holds a placard as they block Westminster bridge in central London, Britain, 17 November 2018. Reports state that the protest organized by Extinction Rebellion group is planning to close five main bridges across the river Thames, seeking to bring attention to political inaction on issues of pollution and climate change. EPA/FACUNDO ARRIZABALAGA FACUNDO ARRIZABALAGA EPA Extinction rebellion: Climate change protesters block London bridges Environmental campaigners from the direct action group Rebellion demonstrate on Westminster Bridge in central London, Britain, November 17, 2018. REUTERS/Peter Nicholls PETER NICHOLLS Reuters

“It seems the urgency and extent of the actions needed to address climate change have not sunk in.

“Low-carbon technologies like wind, solar, and electric transport need to become mainstream, with old-fashion polluting fossils pushed out rapidly,” she said.

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