More news about the 400 ppm world

In Carbon Dioxide at Miocene levels, I wrote, "If the 10-15 million year figure is right, the last time CO2 was this high, Antarctica still had forests."  Even if it isn't, and the last time was about 3 million years ago, the world was still a very different place, as Erin Wayman of Science News reported in The Arctic was once warmer, covered by trees

Pliocene epoch featured greenhouse gas levels similar to today's but with higher average temperatures

The Arctic wasn’t always frozen tundra. About 3.6 million years ago, the far north was blanketed in boreal forests, and summers were 8 degrees Celsius warmer than they are today, geologists report May 9 in Science.

Researchers pieced together that picture from sediments buried beneath Lake El’gygytgyn (pronounced EL-gih-git-gin), about 100 kilometers north of the Arctic Circle in northeastern Russia (SN: 11/20/10, p. 13). The sediments preserve the most complete history of Arctic climate on land over the last 3.6 million years. 

“It’s an unprecedented record,” says study coauthor Julie Brigham-Grette, a geologist at the University of Massachusetts Amherst. “It gives us a way of envisioning what the future may hold.”

That was then.  What about the effects now?

Science News: Southwest's monsoon season may heat up with the climate
Warmer temperatures may bring stronger rainy seasons over the long term, study finds
By Erin Wayman
Web edition: May 28, 2013

The summer monsoon that dumps rain on an otherwise-arid American Southwest may grow stronger as the climate warms, suggests a study of the region’s monsoon patterns of the last millennium. 

Across the Northern Hemisphere, monsoons — winds that change directions seasonally, altering rainfall — could intensify, the team reports May 27 in the Proceedings of the National Academy of Sciences.

The results complement recent observations and simulations of monsoon activity, says Pang-chi Hsu, a climate scientist at the University of Hawaii at Manoa, who was not involved in the work. “We do see enhanced Northern Hemisphere monsoons over the recent decades, from the 1970s.”

My friend Nebris will appreciate this prediction for reasons that will take too long to explain here now.