There is much to be said about the Obama administration’s linkage of California’s extreme drought and global warming. For starters, President Obama and John Holdren, his chief science advisor, should spend a little time in the United States Global Change Research Program’s library. There they will find the U.S. government’s recently updated 2008 study on the issue, “Weather and Climate Extremes in a Changing Climate.”

The study notes that the 1930s and 1950s were drier than the current decade and concludes that “droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the U. S. over the last century … The trends averaged over all of North America since 1950 are similar to U.S. trends for the same period, indicating no overall trend.”