Global carbon dioxide emissions, 1850-2030 [CO2 Information Analysis Center, World Energy Outlook]
When the Environmental Protection Agency quietly issued its new four-year plan in mid-October, the phrase "climate change" did not appear anywhere in the 38-page document.
It is now clear the Trump Administration intends to delay, halt, or erase government efforts to limit U.S. emissions of carbon dioxide, the global-warming gas that is the main cause of climate change.
On Friday, a broad team of climate scientists released the fourth National Climate Assessment—and it clearly, bluntly underscored the scientific consensus: humans have caused that change.
“It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century,” the report (known as NCA4) says.
“For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”
As The Washington Post reports, "to the surprise of some scientists," the Trump White House did not attempt to prevent release of the study, which is required by law to be issued every four years.
Chrome exhaust pipe
A draft of the 545-page report compiled by 13 different federal agencies was leaked in August by scientists concerned that the Trump Administration would suppress it because it contradicted assertions by top officials.
Friday's release comes at a particularly awkward time for the administration, which is preparing to defend and promote fossil fuels at the annual United Nations climate-change conference, to be held this week in Bonn, Germany.
As The New York Times notes, "The American delegation is expected to face harsh criticism over President Trump's decision to walk away from the 195-nation Paris climate accord and top administration officials' stated doubts about the causes and impacts of a warming planet."
If the U.S. carries through on that pledge, it would join only Syria among all other nations in refusing to work toward limiting emissions of carbon dioxide.
President Donald Trump has called climate change a "hoax" created by China to hurt U.S. interests, and referred to it using a comparison to bovine excrement.
BYD e6 electric taxi in service in Shenzhen, China
EPA Administrator Scott Pruitt has acknowledged that climate change is taking place.
But he has questioned whether human activities are behind it—NCA4 leaves that in no doubt—and whether the agency has the authority to regulate carbon emissions, which the Supreme Court affirmed it did fully a decade ago.
He has moved to rescind the Obama-era Clean Power Program that lets each state create a plan to limits carbon-dioxide emissions from electric utilities, and has initiated a review of carbon emission limits from vehicles for model years 2022 through 2025.
Those limits, agreed to by the auto industry in 2012, could even be rolled back to earlier years' numbers, setting the U.S. auto industry on an increasingly divergent course from vehicles in every other region, including the crucial Chinese new-car market, the world's largest.
Globally, carbon emissions from transportation make up 15 percent of the world's total, according to the World Resources Institute's 2017 Climate Analysis Indicators Tool, largely from the combustion of fossil-fuel gasoline.
Electric-car wells-to-wheels emission equivalencies in MPG, May 2017 [Union of Concerned Scientists]
Battery-electric vehicles recharged from the electric grid have notably lower "wells-to-wheels" emissions of carbon dioxide per mile than do gasoline and diesel vehicles.
In some areas of the U.S. with relatively clean grids, a car powered by fossil fuels would have to achieve more than 100 miles per gallon to be as low in carbon emissions as an electric car.
Even in areas with the dirtiest, most coal-intensive grids, that equivalence is about 35 mpg. The average new vehicle sold in the U.S. today achieves about 25 mpg.
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