McClatchy D.C. Bureau
US report contradicts Trump team: Warming mostly man-made
AP Science Writer November 03, 2017
FILE – In this Saturday, Sept. 3, 2016 file photo, water from Roanoke Sound pounds the Virginia Dare Trail in Manteo, N.C., as Tropical Storm Hermine passes the Outer Banks. A massive U.S. report released Friday, Nov. 3, 2017, concludes the evidence of global warming is stronger than ever and that more than 90 percent of it has been caused by humans. Since 1900, the reports said Earth has warmed by 1.8 degrees 1 degree Celsius) and seas have risen by 8 inches.
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 humans’ role 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. was also 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 (1 degree Celsius) 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 have repeatedly 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.
Scientists calculated that human contribution to warming since 1950 is between 92 percent and 123 percent. It’s more than 100 percent 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 Ninos, 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.
The world’s oceans are under a “triple threat” — the water is getting warmer, more acidic and seeing a drop in oxygen levels, Hayhoe said.
In a 1,504-page draft report on the impacts of climate change, scientists detailed dozens of ways global warming is already affecting parts of the U.S.
Scientists said global warming is already sickening, injuring and killing Americans with changes to weather, food, air, water and diseases. And it’s expected to get worse, hurting the economy, wildlife and energy supply.
“Risks range from the inconvenient, such as increasing high tide flooding along the East Coast related to sea level rise, to … the forced relocation of coastal communities in Alaska and along the Gulf Coast,” the draft report said.
Outside experts said the reports are the most up-to-date summary of climate science.
“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.
Related:
Engadget: Federal report says humans are the cause of climate change
Mallory Locklear, Engadget November 4, 2017
Today, over a dozen federal agencies released the Climate Science Special Report, which is a product of the National Climate Assessment — a Congressionally mandated review that takes place every four years. In it, hundreds of scientists from dozens of government agencies and academic institutions present evidence that supports the existence of a human-caused warming planet and all of the consequences that come with it. “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 stated. “For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”
The special report notes that each of the last three years have set temperature highs and that global temperature averages have risen by 1.8 degrees Fahrenheit over the last 115 years. It also warns that weather disasters like hurricanes and floods that have cost the US $1.1 trillion since 1980 could become more commonplace if action isn’t taken to reduce our emissions. “The frequency and intensity of extreme high temperature events are virtually certain to increase in the future as global temperature increases (high confidence). Extreme precipitation events will very likely continue to increase in frequency and intensity throughout most of the world (high confidence),” said the report.
Also noted, was the importance of reducing emissions for any hope of curtailing the negative outcomes of climate change. “The magnitude of climate change beyond the next few decades will depend primarily on the amount of greenhouse gases (especially carbon dioxide) emitted globally. Without major reductions in emissions, the increase in annual average global temperature relative to pre-industrial times could reach 9°F (5°C) or more by the end of this century,” the report stated.
The report released today — an exhaustive compilation of research totaling over 600 pages and peer reviewed by the National Academy of Sciences — is just the first of two. A second, longer volume detailing the regional impacts of climate change is not yet finalized, but is open for public comment and will soon undergo peer review. Somewhat surprisingly, today’s report was approved by the White House even though the Trump administration has repeatedly worked against efforts to combat climate change including removing the US from the Paris Accord, placing a climate change denier at the helm of the Environmental Protection Agency (EPA), and nominating one to lead NASA. Under the Trump presidency, the EPA has stopped researchers from speaking about climate change and deleted climate change information from its website while the Department of Agriculture has pressed its staff to not refer to climate change in their communications.
In regards to the report released today, Penn State University geo-scientist Richard Alley told NPR, “This is good, solid climate science. This has been reviewed so many times in so many ways, and it’s taking what we know from … a couple of centuries of climate science and applying it to the U.S.” Michael Mann, director of the Earth System Science Center at Penn State University told the New York Times, “This new report simply confirms what we already knew. Human-caused climate change isn’t just a theory, it’s reality. 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.”
Read the full Climate Science Special Report here. Climate Change Special Report