Climate report points to humans

Scientists say no alternative cause truly convincing

WASHINGTON — A massive U.S. report concludes the evidence of global warming is stronger than ever, contradicting a favorite talking point of top Trump administration officials, who downplay the role of humans in climate change.

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

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

Since 1900, Earth has warmed by 1.8 degrees and seas have risen by 8 inches.

Heat waves, downpours and wildfires have become frequent.

Energy Secretary Rick Perry and Environmental Protection Agency chief Scott Pruitt repeatedly have said carbon dioxide isn’t the primary contributor to global warming.

It’s “extremely likely” — meaning with 95 to 100 percent certainty — that global warming is man-made, 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.

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 Niños, major decreases in ice sheets in Greenland and Antarctica, which would spike sea level rise, and massive release of methane and carbon dioxide from thawing permafrost that could turbo-charge warming.

Researchers did not provide an estimate of how likely tipping points would occur.