The U.S. government on Friday released a report on climate change that said there was "no convincing alternative explanation" for global warming besides human causes.
The National Climate Assessment, which the government is mandated by law to publish every four years, said Friday that climate change is almost entirely driven by human action. It warns that sea levels could rise by nearly 2.5 meters by the year 2100. It lists a number of incidents of damage across the United States that it attributes to the rise of global temperature by 1 degree Celsius since 1900.
It said the U.S. was already experiencing increasing temperatures, precipitation levels and numbers of wildfires; that more than 25 U.S. coastal cities were already experiencing flooding; and that there was no precedent in history with which these meteorological changes could be compared.
But, it said, there is "very high confidence" that the rate of climate change will depend on the amount of greenhouse gases released globally over the next few decades.
The report from the U.S. Global Change Research Program, an interagency unit that coordinates and integrates research on environmental changes, runs counter to the position on climate change taken by the current U.S administration, including that of the head of the Environmental Protection Agency.
Trump, Perry, Pruitt have doubts
President Donald Trump, Energy Secretary Rick Perry and EPA head Scott Pruitt have all questioned how much human activity has contributed to climate change. The president has announced the United States will leave the Paris climate agreement that would obligate the U.S. to cut its overall greenhouse gas emissions by at least 26 percent by 2025, compared with 2005 levels.
One of the study authors, climate scientist Robert Kopp of Rutgers University, told The Washington Post he thought the report was "basically the most comprehensive climate science report in the world right now."
In response to Friday's release, White House principal deputy press secretary Raj Shah noted a line in the report that said there was "uncertainty in the sensitivity of Earth's climate to emissions. The climate has changed and is always changing."