Trump admin sees grim climate outcome in car rule

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."By mid Century, food and especially water shortages will likely become so widespread that regional conflicts and environmental refugees will dwarf anything we see now, and hence it is not really livable for all humans," Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research, said in an email. "So the last time 800 ppm occurred is not really pertinent because there were not 10 billion people present."