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The UN launches a trumpet cry on the “irreversible” climate impacts of man

  • Human activities “unequivocally” cause climate change
  • World expected to reach 1.5 ° C warming limit within 20 years

Aug. 9 (Reuters) – The United Nations climate panel issued a terrible warning on Monday, saying the world is dangerously close to uncontrollable warming – and that humans are “unequivocally” to blame.

Already, levels of greenhouse gases in the atmosphere are high enough to guarantee climate change for decades, if not centuries, scientists warn in a report from the United States. Intergovernmental Panel on Climate Change (IPCC).

This is in addition to the deadly heat waves, powerful hurricanes and other extreme weather events that are happening now and are likely to get worse.

Describing the report as a “code red for humanity,” UN Secretary-General António Guterres called for an immediate end to power from coal and other highly polluting fossil fuels. Read more

“The alarm bells are deafening,” Guterres said in a statement. “This report must spell the end of coal and fossil fuels, before they destroy our planet.”

The IPCC report comes just three months before a major United Nations climate conference in Glasgow, Scotland, where nations will be under pressure to pledge ambitious climate action and substantial funding.

Drawing on more than 14,000 scientific studies, the report provides the most comprehensive and detailed picture yet of how climate change is altering the natural world – and what may still be to come.

Unless immediate, rapid and large-scale action is taken to reduce emissions, the report says, the average global temperature is likely to exceed the warming threshold of 1.5 degrees Celsius over the next 20 years.

So far, the commitments of nations to reduce emissions were insufficient to bring down the level of greenhouse gases accumulated in the atmosphere. Read more

Reacting to the findings, governments and activists have expressed concern.

“The IPCC report underscores the overwhelming urgency of this moment,” US climate envoy John Kerry said in a statement. “The world must come together before the ability to limit global warming to 1.5 degrees Celsius is out of reach. “


Emissions “unequivocally caused by human activities” have pushed the current global average temperature 1.1 ° C above the pre-industrial average – and would have pushed it 0.5 ° C further without the tempering effect pollution in the atmosphere, according to the report.

This means that, as societies move away from fossil fuels, much of the aerosols in the air would disappear – and temperatures could soar.

Scientists warn that a warming of more than 1.5 ° C above the pre-industrial average could trigger uncontrollable climate change with catastrophic impacts, such as heat so intense that crops fail or people simply die because they are outside.

Each additional 0.5 ° C of warming will also increase the intensity and frequency of extreme heat and heavy rainfall, as well as droughts in some areas. Because temperatures fluctuate from year to year, scientists measure global warming in terms of 20-year averages.

“We have all the evidence we need to show that we are in a climate crisis,” said Sonia Seneviratne, three-time IPCC co-author and climate scientist at ETH Zurich, who doubts she will sign for one. fourth report. “Policymakers have enough information. You may ask: is this a significant use of scientists’ time if left unchecked? “

The 1.1 ° C warming already recorded was enough to trigger disastrous weather. This year, heat waves killed hundreds of people in the Pacific Northwest and broke records around the world. Heat and drought-fueled wildfires are sweeping entire cities across the western United States, releasing record emissions from Siberian forests and causing Greeks to flee their lands by ferry. (Global warming graph)

“Every element of warming matters,” said IPCC co-author Ed Hawkins, a climatologist at the University of Reading in Britain. “The consequences are getting worse as we warm up.”

The Greenland ice sheet is “virtually certain” to continue to melt. The oceans will continue to warm and surface levels will rise for centuries to come. (Graphic on Greenland)

It is too late to prevent these particular changes. The best the world can do is slow them down so that countries have more time to prepare and adapt.

“We are now engaged in some aspects of climate change, some of which are irreversible for hundreds to thousands of years,” said Tamsin Edwards, co-author of the IPCC, climatologist at King’s College London. “But the more we limit warming, the more we can avoid or slow down these changes.”


But even to slow climate change, the report says, the world is running out of time.

If the world significantly reduces its emissions over the next decade, average temperatures could rise another 1.5 ° C by 2040 and possibly 1.6 ° C by 2060 before stabilizing.

If the world does not significantly reduce emissions and instead continue on the current trajectory, the planet could see a warming of 2.0 ° C by 2060 and 2.7 ° C by the end of the century.

The land has not been this hot since the Pliocene epoch, around 3 million years ago, when the earliest ancestors of man appeared and the oceans were 25 meters (82 feet) higher than today.

It could be even worse if warming triggers feedback loops that release even more climate-warming carbon emissions, like melting arctic permafrost or dying out of global forests. In these high emission scenarios, the Earth could roast at temperatures 4.4 ° C above the pre-industrial average by 2081 to 2100.

“We have already changed our planet, and some of those changes that we will have to live with for centuries and millennia to come,” said Joeri Rogelj, IPCC co-author, climatologist at Imperial College London.

The question now, he said, is how many irreversible changes we avoid: “We still have choices to make.

Reporting by Nina Chestney in London and Andrea Januta in Guerneville, California; Additional reporting by Jake Spring in Brasilia, Valerie Volcovici in Washington and Emma Farge in Geneva; Editing by Katy Daigle and Lisa Shumaker

Our standards: Thomson Reuters Trust Principles.

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