Report blames humans for warming
US climate study at odds with Trump administration claims
Climate change is real, it’s here, and we’re the cause, according to the nation’s most comprehensive climate science report, which was released Friday by the federal government.
Noting that the planet is now the warmest it’s been in the history of modern civilization, the report said that “it’s 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,” the report said.
The Climate Science Special Report serves as the first volume of the federally mandated National Climate Assessment, which is prepared by the nation’s top scientists every four years for the president, Congress and the public.
The contents of the report contradict claims by President Donald Trump and his team, who have continually downplayed the human contribution to climate change and questioned the ability of scientists to predict its effects.
Earlier this year, Trump said he planned to withdraw the U.S. from the Paris climate agreement, which requires countries to establish ambitious targets to reduce the greenhouse gases that cause global warming.
There are no policy recommendations in the report, only scientific information, according to coordinating lead author David Fahey of NOAA. There was also no interference from policymakers, he said.
Hundreds of scientists assessed more than 1,500 scientific studies and reports to write the report. Some of its findings:
Global average sea level has risen by about 7-8 inches since 1900, with almost half (about 3 inches) of that rise occurring since 1993.
Global average sea levels are expected to continue to rise — by at least several inches in the next 15 years and by 1-4 feet by 2100. A rise of as much as 8 feet by 2100 cannot be ruled out.
Heavy rainfall is increasing in intensity and frequency globally and is expected to continue to increase.
The incidence of daily tidal flooding is accelerating in more than 25 Atlantic and Gulf Coast cities.
Heatwaves have become more frequent
A global average sea level rise of as much as 8 feet by 2100 cannot be ruled out.
in the U.S. since the 1960s, while extreme cold temperatures and cold waves are less frequent.
The incidence of large forest fires in the western U.S. and Alaska has increased since the early 1980s and is projected to further increase.
Annual trends toward earlier spring melt and reduced snowpack are already affecting water resources in the western United States.
The report noted that the global atmospheric carbon dioxide concentration has now passed 400 parts per million, a level that last occurred about 3 million years ago, when global average temperature and sea level were significantly higher than today.
The only solution to the problem is to reduce the amount of greenhouse gases (especially carbon dioxide) that are emitted globally, the report says.