U.S. Report Says Humans Cause Climate Change, Contradicting Top Trump Officials
By LISA FRIEDMAN
NOV. 3, 2017
The New York Times
WASHINGTON — Directly contradicting much of the Trump administration’s position on climate change, 13 federal agencies unveiled anexhaustive scientific report on Friday that says humans are the dominant cause of the global temperature rise that has occurred since the start of the 20th century, creating the warmest period in the history of civilization.
Over the past 115 years global average temperatures have increased 1.8 degrees Fahrenheit, 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.
The report was approved for release by the White House, but the findings come as the Trump administration is defending its climate change policies on several fronts. The United Nations convenes its annual climate change conference next week in Bonn, Germany, and the American delegation is expected to face harsh criticism over President 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 B. 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.”
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.
That has not stopped the Environmental Protection Agency from wiping references to climate change from its website and barring its scientists from presenting scientific reports on the subject.
The E.P.A. 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.
Jim Bridenstine, the Oklahoma congressman whom President Trump nominated to lead NASA, came under fire this week from multiple lawmakers demanding to know his position on climate change. “Carbon dioxide is in fact a greenhouse gas,” Mr. Bridenstine allowed, but declined to say if he accepted it as the primary cause of climate change. He did pledge that scientists would not be punished or reassigned for working on or speaking about global warming.
Yet none of those agencies nor the White House moved to stop the report’s publication, and the White House Office of Science and Technology Policy signed off on the final release, despite fear among some scientists involved in the research that the Trump administration would block it or seek to water it down.
“I’m quite confident to say there has been no political interference on the messages of this report,” said David Fahey, a scientist at the National Oceanic and Atmospheric Administration and a lead author of the report.
The E.P.A. and other agencies involved in the report referred questions to NOAA, which oversaw the research.
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.
“This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century,” the report states. “For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”
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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.”
Some critics of climate change science attacked the report as the product of holdovers from the Obama administration and chastised the Trump administration for allowing it to be published. Others said the science may be valid but the findings did not justify new regulations to address the rise of emissions.
“I really don’t think that determines policy at all,” said Marlo Lewis Jr., a senior fellow at the Competitive Enterprise Institute, a libertarian advocacy group. Mr. Lewis said he does not deny that the majority of warming is caused by emissions. “The thing is, I’m also going to affirm that there are risks of climate policy as well as climate change,” he said. “To me the real issue is, where do the risks lie? Suppressing your economy is never a good solution.”
The report finds with very high confidence that the average annual temperature over the contiguous United States has increased by 1.2 degrees Fahrenheit (0.7 degrees Celsius) since 1986, relative to the previous century. It is projected to rise, scientists said with an equally high degree of confidence, about 2.5 degrees Fahrenheit (1.4 degrees Celsius) by midcentury. That will mean hotter days and nights, particularly in urban and densely populated areas.
The report finds with high confidence that if greenhouse gas concentrations were stabilized at their current level, the world would still see at least an additional 1.1 degree Fahrenheit (0.6 degree Celsius) of warming over this century.
“This new report simply confirms what we already knew. Human-caused climate change isn’t just a theory, it’s reality,” said Michael E. 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.”
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