"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. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.:
- from "Highlights of the Findings of the U.S. Global Change Research Program Climate Science Special Report", Nov. 3 2017
Surprising many "climate watchers", on Friday the Trump Administration allowed the release of a sweeping federal climate report that began under President Barack Obama and concludes that humans are the primary driver of climate change, causing higher temperatures, sea level rise, agriculture problems and more. The report - whose executive summary alone is 34 pages - found the Earth is undergoing its warmest period “in the history of modern civilization,” fueled primarily by rising levels of carbon dioxide. It was released by the U.S. Global Change Research Program, which is mandated by Congress to report every four years on the state of climate change.
The massive study - which is the first volume of the Fourth National Climate Assessment, was years in the making and involved contributions from more than a dozen federal agencies - is meant to be an authoritative assessment of the current state of climate change science.
However, what has caught pundits by surprise, is that many of the report’s conclusions directly contradict the Trump administration’s publicly held positions on climate change.
Case in point: Trump officials like EPA chief Scott Pruitt and Energy Secretary Rick Perry have said they can’t be sure whether human-caused greenhouse gases like carbon dioxide are the primary cause of climate change. And yet the Climate Assessment plainly states that is the case. “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,” it says. “For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”
"Globally averaged, annually averaged surface air temperature has increased by about 1.8 degrees Fahrenheit, or 1 degree Centigrade, over the last 115 years," David Fahey, an atmospheric scientist at the National Oceanic and Atmospheric Administration (NOAA) and one of the leading authors of the report, told reporters. "This period is now the warmest in the history of modern civilization."
While it concedes that greenhouse gas emission growth has slowed in recent years, it concludes it’s not enough to keep temperatures from rising more than 2 degrees Celsius, the limit at which scientists expect the worst effects of climate change to be irreversible.
The report also cites “thousands of studies conducted by researchers around the world” that show evidence of a warming globe, including “changes in surface, atmospheric, and oceanic temperatures; melting glaciers; diminishing snow cover; shrinking sea ice; rising sea levels; ocean acidification; and increasing atmospheric water vapor.” The study also includes dire warnings about the impact of climate change on human activities.
Heavy rainfall, which causes flooding, is expected to increase over the rest of the century, and heat waves will become more frequent. Severe weather events like forest fires and drought will grow more prevalent, and sea levels will rise “by at least several inches in the next 15 years and by 1–to-4 feet by 2100.”
Severe weather events like forest fires and drought will grow more prevalent, and sea levels will rise “by at least several inches in the next 15 years and by 1–to-4 feet by 2100.”
The study is the fourth time this century that federal scientists have put together a report on the impacts of climate change around the globe and in the United States.
What has perplexed analysts, is what was contained in the study, or rather what wasn't: this year’s assessment comes amid concerns that the White House would work to undermine the study’s conclusions. As we reported at the time, scientists shared a draft version of the study with The New York Times in August, seeking extra publicity for its findings in the hope of rebuffing any attempt to water it down.
"Of course there are perhaps fears. We’re all citizens and scientists at the same time. But I think whatever fears we had weren’t realized," NOAA scientist Fahey said. "The word ‘interference’ might have been a threat, but it never materialized. This report says what the scientists wanted it to say."
In an attempt to preserve some ambivalence, the White House issued a statement that “the climate has changed and is always changing” and pointed to a line in the report that concluded the future of climate change depends primarily on “remaining uncertainty in the sensitivity of Earth's climate to [greenhouse gas] emissions.”
The report said, with “very high confidence,” that the magnitude of climate change will also depend on the “amount of greenhouse gases emitted globally” over the next few decades.
“The administration supports rigorous scientific analysis and debate and encourages public comment on the draft documents being released today.To address climate change as well as other risks, the U.S. will continue to promote access to the affordable and reliable energy needed to grow economically, and to support technology, innovation and the development of modern and efficient infrastructure that will reduce emissions and enable us to add
The bottom line, and what may spark controversies among Trump supporters, is that the central premise of the report, that climate change is real and that humans are to blame, contradicts previous statements of President Donald Trump and many high-ranking members of his administration, who have questioned the scientific findings regarding climate change. The EPA had no immediate comment.