Global warming contributed to extreme heat waves in many parts of the world last year, but cannot be definitively linked to the California drought, according to a report released Monday.
The third annual analysis of extreme weather events underscored the continuing difficulty of teasing out the influence of human-caused climate change on precipitation patterns.
One of three studies examining the California drought in 2013 found that the kind of high-pressure systems that blocked winter storms last year have increased with global warming.
But another study concluded that a long-term rise in sea surface temperatures in the western Pacific did not contribute substantially to the drought. And researchers noted that California precipitation since 1895 has “exhibited no appreciable downward trend.”
Overall, the report editors concluded that the papers didn’t demonstrate that global warming clearly influenced the drought, which is one of the worst in the state record. …
Comparing the periods of 1871-1970 with 1980-2013, the authors wrote that there was “no appreciable long-term change in the risk for dry climate extremes over California since the late 19th century.”