Heidi Cullen on tornadoes, extreme weather and the "C"-Word
Our guest blogger is climate scientist Heidi Cullen. This was first published at HuffPost. My comments are inserted in brackets.
UPDATE: See the featured comment from Richard Brenne at the end. And Cullen herself has posted in the comments section.
My phone tends to ring a lot more when the weather is bad. I often get calls from reporters and producers who usually ask me the same question a bunch of different ways. “Is this global warming?” “Is climate change to blame?” “Is the weather getting worse?”
These are big — almost existential — questions. I suspect they are a polite way of asking, “Is this our fault?”
Climate scientists approach the question a little differently. We want to test how global warming shifts the odds of a severe weather event. Just like medical researchers do with cigarette smoking and lung cancer. In fact, this line of climate research comes straight out of epidemiology. In essence, we’re doing autopsies on extreme weather events to find out what made them so bad-ass.
Depending on the type of extreme weather event, my answer can be short or long, straightforward or complicated. Keep in mind, all weather is now born into an environment that is warmer and moister because of man-made greenhouse gas pollution. But we don’t always know what influences (man-made or natural) will win out on any given day.
Events like droughts, wildfires, heat waves and heavy downpours get my short answer. We know they are going to become more frequent, more intense, and last longer. In fact, we can already see this playing out in historical data. (For a complete overview, check out the “Global Climate Change Impacts in the US” as well as some newly published research summarized here.)
[Joe Romm: For a review of the recent scientific literature, see "Two seminal Nature papers join growing body of evidence that human emissions fuel extreme weather, flooding that harm humans and the environment."]
Tornadoes get the long answer. Will they become more frequent, more intense? Will Tornado Alley get bigger? Will the season last longer?
Jeff Masters and Andrew Freedman have both done a great job laying out the state of the research.
The bottom line is that two of the key ingredients that go into making a tornado are expected to change as a result of global warming — water vapor (moisture in the atmosphere) and wind shear (changing wind speed and direction with height). Thanks in part to warmer oceans, water vapor has already increased about 4% and it will continue to increase as the planet warms — providing more fuel for storms. But wind shear may decrease and that could mean fewer tornadoes. So which influence wins out — increasing water vapor or decreasing wind shear? We don’t know yet.
[Joe Romm: For a longer look at the climate-tornado science, see "Tornadoes, extreme weather, and climate change."]
But even though we don’t have all the answers — and maybe never will — we do know enough to act. And that is really the bigger point, the one I try to bring home when the phone rings. The recent National Research Council’s “America’s Climate Choices” report advised Congress that we know enough to get started on preparing for climate change and preventing the most severe consequences, and we need to get started right away. Almost anything we do to protect ourselves in the future from this hotter world we’re creating, will also protect us right now from many of the extremes Mother Nature throws at us. We can’t afford to wait.
Yet, despite this recent report, and despite all we do know about climate change, the topic has become the C-word in Washington, D.C. Just as the term “global warming” fell out of favor, the term “climate change” is now one that few in our nation’s capital dare bring up in conversation, much less in legislation. Budgets for climate research have been threatened, and now a nominee for Commerce Secretary is garnering opposition in large part because of his stance on environmental issues, including global climate change.
As the people of Joplin, Missouri, begin the slow, painful process of rebuilding their lives — a new wave of extremes is making headlines. A state of emergency was declared in Massachusetts on Wednesday after rare and powerful tornadoes ripped through the city of Springfield and smaller towns nearby. At the same time, long-standing temperature records fell as a wall of heat blanketed the eastern half of the country — Washington, D.C., set a new daily record high of 98 °F — busting the old record that dated back to 1895. Hurricane season also started this week and forecasters expect it to be busier than usual. And I’m here ready for the phone to ring again, so that I can tell you one more time that if we do nothing to adapt and reduce our greenhouse gas pollution, things will only get worse… and yes, it will be our fault.
Heidi Cullen is a climate scientist at Climate Central (www.climatecentral.org) — an independent, non-profit journalism and research organization. She is also a Visiting Lecturer at Princeton University and the author of "The Weather of the Future."
Related post:
- Joplin disaster spurs media whirlwind on link between climate change, extreme weather, and tornadoes
Featured comments:
Featured Comment from Richard Brenne, a leading climate communicator and long-time commenter:
Well done Heidi! I especially like your comment about tornadoes. We’ve discussed that quite a bit here beginning with the April 27 outbreak in Alabama, with Joe’s link the most complete discussion I’ve seen.Many of us try sample quotes here, and here’s mine: “Every weather event is now influenced by global warming in one way or another, and this trend is intensifying. In approximate order, record high temperatures of all kinds are increasing, as are heat waves, droughts and dramatic precipitation events of all kinds, including snow where and when it is cold enough to snow. Hurricanes and tornadoes are more complex, but when conditions are right higher sea surface temperatures alone are enough to intensify them. This combined with 4% additional water vapor in the atmosphere and far greater energy in the system has created storms like those we’ve seen within the last year in Pakistan and Australia that are unprecedented in the human written record. With 40% more water vapor in the atmosphere possible by 2100, this century would see storms no human can now imagine, dwarfing every storm of every kind we’ve seen so far.”
Brenne is an award-winning screenwriter who teaches a NASA-sponsored, on-line, Global Climate Change class, serves on the American Meteorological Society’s Committee to Improve Climate Change Communication, and produces documentaries and large-scale town meetings and panels about climate change that he moderates with humor and insight.
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