WASHINGTON — No evidence exists that climate change has led to more tornadoes or stronger ones, experts said Wednesday at a House hearing exploring the links between global warming and severe weather events.
“Tornadoes in the United States have not increased in frequency, intensity or normalized damage since 1950,” said Roger Pielke Jr., the director of the Center of Science and Technology Policy Research at the University of Colorado.
“And based on research we've done, there's some evidence in fact that they've actually declined — the strongest tornadoes.”
Pielke was one of three researchers from U.S. universities who testified before a House Science, Space and Technology subcommittee about severe weather and climate change. The Republican-controlled subcommittee sought to debunk oft-cited claims that climate change has contributed to severe droughts and storms in recent years.
Two of the witnesses, Pielke and University of Alabama researcher John Christy, have been criticized by some environmentalists for their views on climate change. Both dismissed any link between climate change and hurricanes, droughts, tornadoes and floods.
“To label today's events as extreme usually fails the test of time,” said Christy.
The third witness, retired U.S. Navy Admiral David Titley, now at Penn State University, acknowledged that a direct link couldn't be made between climate change and any particular weather event. But, he said, the absence of evidence didn't mean a link doesn't exist.
“It's a little bit like playing with a loaded gun here,” he said. “Is it going to go off? Well maybe yes, maybe no. But you look at the typhoon that went into the Philippines — the strongest winds ever recorded on landfall. Is that climate change? I don't know. But the atmosphere lined up with the ocean to create one of the strongest storms we've ever seen.”
A precarious subject
Environmental groups frequently connect drought, wildfires and severe storms to climate change, and President Barack Obama has made those links a common theme in his efforts to put limits on U.S. greenhouse gas emissions.