Major report by government agencies goes against senior members of Trump administration and finds evidence of global warming stronger than ever
A comprehensive review by 13 US federal agencies concludes that evidence of global warming is stronger than ever and that more than 90% of it has been caused by humans.
The conclusion contradicts a favorite talking point of senior members of the Trump administration.
From Miami to Shanghai: 3C of warming will leave world cities below sea level Read more
A 477-page report released on Friday said it was “extremely likely” – meaning with 95 to 100% certainty – that global warming is manmade, mostly from carbon dioxide through the burning of coal, oil and natural gas.
The energy secretary, Rick Perry, and Environmental Protection Agency chief, Scott Pruitt, have said carbon dioxide is not the primary contributor to global warming.
Despite fears by some scientists and environmental advocates, David Fahey of the National Oceanic and Atmospheric Administration (Noaa) and several authors said there was no political interference or censoring. It’s 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 report says Earth has warmed by 1C and seas have risen by 8in. Heatwaves, downpours and wildfires have become more frequent.
Scientists calculated that human contribution to warming since 1950 is between 92% and 123%. It’s more than 100% on one end, because some natural forces such as volcanoes and orbital cycle are working to cool Earth, but are being overwhelmed by the effects of greenhouse gases, said study co-author Katharine Hayhoe of Texas Tech.
“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 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, 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 wasn’t part of the work.
On Friday, thirteen agencies within the United States government jointly issued the Climate Science Special Report, declaring that roughly 90% of climate change is caused by human activity, most notably the production of  by the burning of .  This directly contradicts assertions made by politicians within the administration of the current president, Donald Trump.

The report notes, "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century... For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence."

Officially, the report was submitted through the Trump Administration's Office of Science and Technology Policy, to which President Trump has not appointed a head. The official response from the rest of the White House, given to the press by White House spokesperson Raj Shah, reads as follows: "The climate has changed and is always changing. 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  emissions... In the United States, energy related carbon dioxide emissions have been declining, are expected to remain flat through 2040, and will also continue to decline as a share of world emissions."

The report clocks in at roughly 500 pages and places the human contribution to the increase in the Earth's temperature at 92–123% since 1950.  As explained by co-author Katherine Hayhoe, the space over 100% indicates counteraction of forces that have a cooling effect, like sun-blocking dust kicked into the upper atmosphere by .  Overall, the report calls the past 115 years "the warmest in the history of modern civilization."

The study cites several factors, called "tipping points," that might make global climate change more intense, such as changes in  and other major patterns in ocean currents, the loss of arctic and antarctic ice sheets, and the release of methane, a greenhouse gas, from rotting material as previously  ground begins to thaw and cites both the wildfires in California and  for effects due to global climate change.  It predicts one scenario in which ocean levels rise as much as 8  (2.4 ) by the year 2100.

Unlike with previous studies on climate change released by U.S. government agencies, said one lead author, David Fahey of the , the Trump Administration does not appear to have made an effort to block publication of the report or alter the wording describing its scientific findings, though there were some alterations to the description of U.S. policy with respect to the . Fahey remarked, "I'm quite confident to say there has been no political interference in the scientific messages from this report... Whatever fears we had weren't realized."

Head of the   and Secretary of Energy Rick Perry have both said publicly that carbon dioxide does not cause much global warming.

Phil Duffy of the  noted, "This is a federal government report whose contents completely undercut the Trump Administration's policies, completely undercut the statements made by senior members of the administration." President Trump has announced plans to withdraw the United States form the Paris Climate Accords, in which participating countries pledge to reduce carbon emissions, and to loosen federal laws regulating fossil fuels.

The Climate Science Special Report is part of the fourth National Climate Assessment, the last of which was in 2014. The National Climate Assessments are required by a law passed by the United States Congress in 1990.



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