Trump Admin Sees Grim Climate Outcome in Car Rule

by Zack Colman and Scott Waldman (E&E News) The last time carbon dioxide levels hit the mark the Trump administration envisions for the end of the century, crocodiles roamed the poles and palm trees existed where glaciers are today. In fact, there were no glaciers — not even in Antarctica.

Although the White House has avoided addressing climate change, it made a rare acknowledgement that its proposal to weaken vehicle fuel efficiency standards would contribute to a warmer planet. Its prediction for what the atmosphere will look like in 2100 startled climate scientists — a carbon dioxide concentration of 789.76 parts per million. That's nearly double current levels.

Scientists said reaching that mark would be devastating for the planet. Although humans would survive, much of that would depend on the ability to adapt to new conditions. Food and water scarcity would result from changing precipitation patterns and higher temperatures. Potentially billions of people would struggle. Some species and ecosystems would collapse.

The number used by the Trump administration assumes that fossil fuel consumption will continue to rise every year, said Ralph Keeling, head of the CO2 program at the University of California, San Diego's Scripps Institution of Oceanography. It does not account for competition from renewable energy, emissions reduction policies or the assumption that the market can support that rate of growth, he said. It also doesn't account for a significant global effort to curb emissions, such as the Paris climate agreement.

"That 700 range is accessible, but only if we continue to have a few-percent-per-year growth in emissions, all the way through to 2100," he said. "It's more than a doubling of emissions, so it's assuming that the world is going to be burning more than twice as much fossil fuel in 80 years than it is burning now, so not only are we not cutting emissions, we're just continuing to grow them."

Keeling said the current level of atmospheric carbon dioxide is likely equivalent to that of about 3 million or 4 million years ago. The number used by the Trump administration would put the planet at the same level of carbon dioxide it experienced during the Eocene Epoch, he said. In the early Eocene, when carbon dioxide levels topped 1,000 parts per million, there were crocodiles swimming in the Arctic.

The concentration of atmospheric CO2 has risen more than 35 percent since before the Industrial Revolution, when it was estimated to be 280 ppm, according to Scripps. When scientists first started recording CO2 about 60 years ago, it was 320 ppm. This year, that number hit 410.31, a record high in modern history and a sharp increase since 2013, when CO2 levels surpassed 400 ppm for the first time, according to Scripps.

Scientists said it's the rates of change, rather than the absolute value of carbon dioxide in the atmosphere, that will matter most.

EPA and the National Highway Traffic Safety Administration said its proposal to freeze vehicle fuel efficiency standards at 2020 levels, rather than keep tightening targets through 2026, would raise carbon dioxide concentrations 0.65 ppm relative to the Obama administration levels in 2100. READ MORE