US report sounds climate-change alarm

A pickup truck drives along a highway threatened by flooding near Grand Isle, Louisiana in August. Climate change is affecting the United States more than ever, and the impacts on people and the economy are expected to increase, a draft of the National Climate Assessment says. (William Widmer/New York Times)

WASHINGTON: Directly contradicting much of the Trump administration’s position on climate change, 13 US government agencies have released an exhaustive scientific report that says humans are the dominant cause of climate change.

Human activity, the report says, is responsible for much of the global temperature rise that has created the warmest period in the history of civilisation.

Over the past 115 years, global average temperatures have increased 1 degree Celsius and sea levels have risen 20cm, leading to record-breaking weather events and temperature extremes, the report says.

The global, long-term warming trend is “unambiguous”, it says, and there is “no convincing alternative explanation” that anything other than humans — the cars we drive, the power plants we operate, the forests we destroy — are to blame.

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.

The report was approved for release by the White House, but the findings come as the Trump administration is defending its climate change policies. The United Nations convenes its annual climate change conference next week in Bonn, Germany, and the US delegation is expected to face harsh criticism over President Donald Trump’s decision to walk away from the 195-nation Paris climate accord and top administration officials’ stated doubts about the causes and impacts of a warming planet.

“This report has some very powerful, hard-hitting statements that are totally at odds with senior administration folks and at odds with their policies,” said Philip Duffy, president of the Woods Hole Research Center. “It begs the question, where are members of the administration getting their information from? They’re obviously not getting it from their own scientists.”

While there were pockets of resistance to the report in the Trump administration, according to climate scientists involved in drafting the report, there was little appetite for a knockdown fight over climate change among Trump’s top advisers, who are intensely focused on passing a tax reform bill — an effort they think could determine the fate of his presidency.

The climate science report is part of a congressionally mandated review conducted every four years known as the National Climate Assessment. The product of hundreds of experts within the government and academia and peer-reviewed by the National Academy of Sciences, it is considered the United States’ most definitive statement on climate change science.

The White House put out a statement Friday that seemed to undercut the high level of confidence of the report’s findings.

“The climate has changed and is always changing,” Raj Shah, a White House spokesman, said in the statement. “As the Climate Science Special Report states, the magnitude of future climate change depends significantly on ‘remaining uncertainty in the sensitivity of Earth’s climate’” to greenhouse gas emissions, he added.

Despite the scientific consensus presented in the report, the Environmental Protection Agency has deleted references to climate change from its website and barred its scientists from presenting scientific reports on the subject.

EPA administrator Scott Pruitt has said carbon dioxide is not a primary contributor to warming. Rick Perry, the energy secretary, asserted Wednesday that “the science is out” on whether humans cause climate change.

Their agencies referred questions to the National Oceanic and Atmospheric Administration, which oversaw the research.

Scientists said the report’s findings were clear.

“This new report simply confirms what we already knew. Human-caused climate change isn’t just a theory, it’s reality,” said Michael Mann, a professor of atmospheric science at Pennsylvania State University. “Whether we’re talking about unprecedented heat waves, increasingly destructive hurricanes, epic drought and inundation of our coastal cities, the impacts of climate change are no longer subtle. They are upon us. That’s the consensus of our best scientists, as laid bare by this latest report.”

The report says the Earth has set temperature highs for three years running, and six of the last 17 years are the warmest years on record for the globe. Weather catastrophes from floods to hurricanes to heat waves have cost the United States $1.1 trillion since 1980, and the report warns that such phenomena may become common.

“The frequency and intensity of extreme high temperature events are virtually certain to increase in the future as global temperature increases,” the report notes. “Extreme precipitation events will very likely continue to increase in frequency and intensity throughout most of the world.”

In the United States, the report finds that every part of the country has been touched by warming, from droughts in the Southeast to flooding in the Midwest to a worrying rise in air and ground temperatures in Alaska, and conditions will continue to worsen.

The findings, other researchers said, create an unusual situation in which the government’s policies are in direct opposition to the science it is producing.

“This profoundly affects our ability to be leaders in developing new technologies and understanding how to build successful communities and businesses in the 21st century,” said Christopher Field, director of the Stanford Woods Institute for the Environment. “Choosing to be dumb about our relationship with the natural world is choosing to be behind the eight ball.”