Sun, Nov 05, 2017 - Page 5 News List

US climate report contradicts Trump

‘TIPPING POINTS’:Scientists highlighted potential events that could accelerate the pace of global warming, but did not give an estimate of how likely they would be


A massive US report concludes the evidence of global warming is stronger than ever, contradicting a favorite talking point of top officials of US President Donald Trump’s administration, who downplay humanity’s role in climate change.

The report released on Friday is one of two scientific assessments required every four years. A draft showing how warming affects the US was also published.

Despite fears by some scientists and environmental advocates, David Fahey of the National Oceanic and Atmospheric Administration and several authors said there was no political interference or censoring of the 477-page final report.

It is the most comprehensive summary of climate science since 2013, showing a warming, worsening world.

“A lot of what we’ve been learning over the last four year suggests the possibility that things may have been more serious than we think,” said Robert Kopp of Rutgers University, one of the dozens of scientists inside and outside the government who wrote the studies.

Since 1900, the Earth has warmed by 1°C and seas have risen by 20cm, while heat waves, downpours and wildfires have become frequent, the report said.

US Secretary of Energy Rick Perry and US Environmental Protection Agency Administrator Scott Pruitt have repeatedly said carbon dioxide is not the primary contributor to global warming.

It is “extremely likely” — meaning with 95 to 100 percent certainty — that global warming is of human origin, mostly from the spewing of carbon dioxide into the atmosphere from the burning of coal, oil and natural gas, scientists concluded.

“Over the last century, there are no convincing alternative explanations,” the report said.

Scientists calculated that human contribution to warming since 1950 is between 92 percent and 123 percent. It was more than 100 percent on one end, because some natural forces — such as volcanoes and the orbital cycle — are working to cool the Earth, but are being overwhelmed by the effects of greenhouse gases, said study coauthor Katharine Hayhoe of Texas Tech University.

“This period is now the warmest in the history of modern civilization,” she said.

For the first time, scientists highlighted a dozen “tipping points” of potential dangers that could happen from warming, things that Hayhoe said “keep me up at night.”

They include the slowing down of the giant Atlantic Ocean circulation system that could dramatically warp weather worldwide; much stronger El Ninos; major decreases in ice sheets in Greenland and Antarctica, which would spike sea level rise; and massive releases of methane and carbon dioxide from thawing permafrost that could turbocharge warming.

Researchers did not provide an estimate of how likely tipping points would occur, but “there is certainly some chance of some of these things happening,” Fahey said.

The report also documented how different climate change-caused events can interact in a complex way to make life worse, such as the California wildfires and Superstorm Sandy five years ago.

“It shows that if anything, the findings of scientists have become more dire” since 2013, said University of California, Berkeley climate scientist Zeke Hausfather, who was not part of the work.

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