The Feature

Emails reveal squabble among scientists over how to talk to media about climate change

May 2, 2017
Image via Pixabay

Hurricane Alex arrived early. Just a category-one storm, it wasn’t very powerful as hurricanes go. When it made landfall in the Azores, a spatter of islands about 900 miles west of Portugal, its winds had already dwindled to 63 mph, which meant that technically, it was no longer even a hurricane. What made Alex unusual was not its speed, but its timing: The storm formed in January of last year, long before the official start of hurricane season, which is June 1. You’d have to wind back the clocks to 1955 to find another named hurricane—its name was Alice—swirling in the Atlantic in January.

Timing may have been the most remarkable quality Alex possessed. But sometimes, timing is everything.

National outlets made note of the storm, and stories on Alex ran in The New York Times, The Washington Post, and the Christian Science Monitor, among other high-profile publications. To handle that hot question of whether climate change was a factor with the rare storm, some news outlets did what they are programmed to do: They quoted an expert, linking back to a post published on Weather Underground that mentioned higher-than-normal sea surface temperatures at the time. In the post, Jeff Masters, director of meteorology at Weather Underground, wrote that “Global warming made Alex’s formation much more likely to occur.”

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Rare events like Alex pose a challenge for the media and for scientists: When can climate change be mentioned as a contributing factor to an event? While scientists do conduct formal attribution studies, those analyses take time and aren’t any help for a reporter on deadline. The questions of how scientists should talk to the media about Alex and whether climate change should be blamed sparked a heated online discussion among scientists, according to emails acquired by CJR through the Freedom of Information Act.

The request focused on the use of the terms “global warming” and “climate change” in emails sent from or received by six hurricane researchers or forecasters. Hurricane Alex and the emails that scientists exchanged about it also point to what can be a disconnect between scientists and the general public: namely, that the media and the public are primed to seek direct causes-and-effects, and scientists speak in probabilities.

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Climate scientists predict that in a warming world, hurricane behavior will intensify. Hurricanes will blow with stronger winds and shed heavier rainfalls, and because of rising sea levels, they will produce more dangerous storm surges.

“We’ve seen these sorts of hurricanes naturally in the past,” Masters tells CJR, referring to Alex. “So these things do occur without global warming. But we’ve increased the probability of it occurring, with global warming.”


Of heat and hurricanes

On January 18, four days after Alex earned hurricane status, Chris Landsea, the science and operations officer at the National Hurricane Center in Miami, sent an email to a slew of other researchers and forecasters who follow tropical storms.

“With the unusual occurrence of Hurricane Alex as an out-of-season hurricane, there have been a couple of meteorologists stating to the media that manmade global warming helped to cause the hurricane,” he wrote. “Such statements are not, in my opinion, factual.”

Landsea’s lengthy email touched on the research regarding what effect climate change will have on hurricanes, and as for Alex, he said it would be “an exceeding stretch of imagination to make a significant linkage of global warming to this event.” He concluded by saying that “such hyperbole” detracts from a more important problem—the multitude of people living in cities at risk of storm surges—as well as global-warming-fueled sea-level rise.

Landsea saw something in the media that “provoked” him, he recalls to CJR, and he felt “frustrated.”

“There was at least a couple stories, that I saw coming out, right after or during Hurricane Alex, that I did not agree with,” he says.

In Landsea’s opinion, “hurricanes aren’t a real good poster child for global warming impacts.” He says global warming is likely to produce mildly stronger storms over the next century, and that the uptick in strength we see now would be too small to measure; he says there may also be fewer hurricanes. His biggest concern is sea-level rise, which could exacerbate storm surges from hurricanes.

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He adds that he attended an event where he heard Al Gore talking about Hurricane Matthew, and the way Gore spoke about the connection between Matthew and global warming made him “cringe, because there’s some links, but it’s much much more subtle than he is insinuating,” Landsea recalls.

James Kossin, an atmospheric research scientist at NOAA’s National Centers for Environmental Information, replied to the email thread. “I think that one of the issues, among many, is that we can’t easily disentangle the factors leading to an event, so it’s just as difficult to support saying it had no connection to climate change as it is to say it was caused (or, perhaps better to say amplified) by climate change,” he wrote.

“I completely agree with Chris Landsea,” Kossin tells CJR. “I think we do a great disservice to everybody, when some singular, short-term event like a hurricane happens, or a very hot day, or an ice storm, and we immediately say, well, this was caused by global warming. That’s fundamentally unsupportable.” That’s not to say that you can’t make a connection between events and climate change, he says, but the process behind making that connection is a “tempered, cautious, time-consuming methodology.”

Hurricanes are especially challenging because they’re so dynamic, shifting track and intensity, he says. A cyclone is “a much much more complicated thing to attribute cause to than a heat wave,” he tells CJR. (For example, one study found that manmade global warming was a “major factor” in the European heat wave of 2015.)

Ultimately, Kossin says, scientists should stop saying that climate change caused an event—unless there’s been a careful analysis of the data, and that statement then becomes supportable.

“One of things I’m torn about in all this, is that on the other hand,” he adds, “I do like the idea that when something extreme happens, the public says, ‘Wow, I wonder if this is related to climate change.’ I think that’s okay. I think weather events and reminders of the kind of things we think climate change will affect, I think those are good connections for the public to make.”

In the email thread, Kossin also wrote about speaking to the press about specific events and climate change. The kind of question he thinks is the right one, he tells CJR, is along the lines of: “Is this event the sort of thing we might expect more of in a warming world?” Questions like that, in his opinion, are better than ones that ask about direct causation.


The brief life of Alex

The tempest that eventually became Alex first geared up into a strong storm near the Bahamas, around January 7, 2016. It took an unusual route, shaped vaguely like a hook on its side: traveling east and north from the Bahamas area, then south again, then north towards the Azores, and then curving back westward. On January 14, it officially graduated to hurricane status, a title it lost the following day. Like all hurricanes in the northern hemisphere, Alex spun counterclockwise. When its winds were strongest, they blew at about 86 mph. That’s mild compared to other hurricanes, like Hurricane Patricia of 2015, which boasted winds of a whopping 215 mph.

Kerry Emanuel, a professor of atmospheric science at MIT and an expert on how climate change will affect hurricanes, tells CJR there’s a “thermodynamic speed limit” on hurricane winds that will increase in a warming world.

“That speed limit definitely goes up when you warm the climate,” he says. “What that means for actual hurricanes is that they have the potential to become more intense in the future climate than they are able to in this climate.”

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The real connection between hurricanes and a warming world

Emanuel says because of global warming, scientists predict there will be an increased frequency of the strongest storms. That’s an important prediction, since the strongest storms account for the most damage. (The science is less settled around whether the total number of storms will increase or decrease, but he says that doesn’t matter much, since the total count of hurricanes is dominated by weaker storms. In other words, the number of strong hurricanes is the most important factor.)

Practically speaking, he says, there might be an increased frequency of the strongest hurricanes: categories five, four, and maybe three. “There is some evidence,” he adds, “mostly from satellite observations, that we’re already beginning to see an uptick in the frequency of these very high-category events.”

In short, a warming world could produce stronger storms more often; and thanks to sea-level rise and more people living on coasts, those storms will be more dangerous. Hurricanes will also bring more rain. Plus, he says, upticks in wind speeds produce exponentially more destruction—it’s not a linear relationship.

Under one global warming scenario, thanks to sea-level rise and an increase in hurricane intensity on the coasts, by the year 2100, hurricanes will cause an estimated $75 billion of damage annually in the US, compared to around $10 billion today, according to Emanuel.

Emanuel thinks the way Landsea characterizes the effect of global warming on hurricanes is misleading and a bit of a lowball. “The risk of hurricane damage [and] mortality is increased substantially with global warming,” he says. “That’s the true story.”


The eye of the storm: How to report on hurricanes

The best way to think about whether climate change was a factor with Alex—a weak, category-one storm—is to ask about probability, Emanuel says: In a warming world, is there a greater chance of a hurricane forming in the Atlantic in January?

But the attribution question points to the disconnect between science and the public when it comes to questions like: How did climate change affect this hurricane? “It’s tricky, because we have to talk in probabilistic terminology, and yet that’s not something that always sits well with the public. They just want to know the answer. The fact is, we can’t fall into the temptation of giving them a concrete answer,” Emanuel says, with a laugh, “when it is unscientific to do so.”

Eric Blake, a hurricane specialist at the National Hurricane Center in Miami, weighed in on the same email thread in which Landsea, Kossin, and others shared their thoughts about Alex and global warming, calling the storm a “thought-provoking case.” In the email, he remarked that sea-surface temperatures were “at record levels all over the western Atlantic Ocean.”

“I think it’s a fair thing to mention,” Blake tells CJR in an interview, referring to climate change and Alex. “It just shouldn’t be listed in a primary sort of way. If you wanted to know more definitively, you’d have to do a long study of it.”

He adds that what he was getting across in his email was that “Alex may have formed over water temperatures that were near normal, but the system that eventually became Alex formed a week earlier, and the whole time it moved over the warmest waters that we’ve ever seen.”

Ultimately, he’d like to see someone model what effect those warm waters had.

Formal attribution studies between weather events and climate change take time. But Heidi Cullen, the chief scientist at Climate Central, is part of a World Weather Attribution team that seeks to turn around results within about a week of weather like a heat wave or cold wave, which are two of the easiest events to tie to climate change. She says over the past decade or more, the science of attribution has matured, allowing scientists to make those connections publicly where they couldn’t before.

Noted climate scientist Michael Mann, who directs the Earth System Science Center at Penn State University, says he felt “disappointed” by Landsea’s missive to the other scientists. “It removes all nuance from the discussion,” he says. “The idea that you can reject any role of climate change at all is not scientifically defensible. It’s just as bad as saying it was totally caused by climate change.”

He said hurricane season may be lengthening due to warmer sea-surface temperatures. And Landsea and others, Mann argues, have a history of incorrectly pointing at natural variability as the cause of these warming temperatures, instead of manmade climate change.

On a deeper level, climate scientists may feel safer saying that an event had no connection to climate change than saying there is one, especially when pointing to a tangible example like a hurricane—an event that resonates with the public.

“Just because the attribution study hasn’t been published that shows the connection, does not mean the connection doesn’t exist,” he says. Assuming a connection only exists after a formal attribution study has been done, Mann said, is a “dangerous precedent to set.”

As for Alex, that rare, out-of-season storm, Mann says it was consistent with warming sea-surface temperatures, which can widen the window in the Atlantic for hurricane activity. “Climate change provides a context for interpreting what we’re seeing.”

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Rob Verger is the assistant tech editor at Popular Science. His work has also appeared in Newsweek, Vice News, The Daily Beast, and The Boston Globe. Follow him on Twitter @robverger