WASHINGTON
— Directly contradicting much of the Trump administration’s position on
climate change, 13 federal agencies unveiled an exhaustive scientific report
on Friday that says humans are the dominant cause of the global
temperature rise that has created 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. 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.”
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 Mr. 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 scrubbed references to climate change from its website and barred 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.
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Read the Full Climate Science Special Report
“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.
Their agencies referred questions to the National Oceanic and Atmospheric Administration, which oversaw the research.
The
report has provoked consternation in scientific circles for months.
Though the study has been in the works since 2015, several scientists
said the election of Mr. Trump, who has labeled climate change a “canard” and appointed cabinet members who disputed the scientific consensus, caused them to worry the report would be blocked or buried.
That
did not happen. Scientists who worked on the report said none of the 13
agencies that reviewed it tried to undermine its findings or change its
wording.
“I’m
quite confident to say there has been no political interference on the
message,” said David Fahey, a NOAA scientist and a lead author of the
report. “Whatever fears we had weren’t realized.”
Responsibility
for approving the report fell to Gary D. Cohn, director of the National
Economic Council, who generally believes in the validity of climate
science and thought the issue would have been a distraction from the tax
push, according to an administration official with knowledge of the
situation.
One
of Mr. Cohn’s top policy deputies, Michael Catanzaro, had the authority
to block, delay or change the report. But Mr. Catanzaro, a former
energy adviser to President George W. Bush and former Speaker John A.
Boehner, chose instead to follow the lead of the Obama administration by
referring the report back to more than a dozen federal agencies for
feedback.
That
review, according to two people familiar with the process, went
relatively smoothly, surprising some scientists who worked on the report
who had expected more resistance.
The
only significant turbulence, according to one person familiar with the
process, came from a midlevel political appointee at the Department of
Energy who grilled the report’s authors on changes that had been made to
temperature and other climate data over the years. The authors
responded by adding a more detailed explanation of their methodology and
all of the agencies then gave their approval, the person said.
Mr. Trump was barely aware of the report’s existence, several White House officials said.
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.
“I’m
saddened that they have decided they will let the permanent government,
the civil servants, continue down this road without supervision,” said
Myron Ebell, director of global warming policy at the Competitive
Enterprise Institute, a libertarian advocacy group.
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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 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.”
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.”
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.”
