Cold weather poses special challenges to climate communicators. It’s laughably easy for climate contrarians to point to cold and snow in an attempt to dismiss climate science. Admittedly, when I put on snowboarding pants and a ski mask to bike to a job where I talk and write about global warming all day, I find a little bit of humor in it, too.
The good news is it’s easy to debunk these arguments and put the focus back on what scientists really know. Cold weather and snow also provide some important lessons about staying credible when it comes to extreme weather.
Coming in From the Cold
First, we need to put cold weather in context. If there were no climate change, we’d expect to see just as many record highs as record lows. But as the Earth has warmed, we now have twice as many record highs as record lows in the United States.
[UCAR graph from “The relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S.” by Gerald A. Meehl et al. in Geophysical Research Letters.]
So climate change, at least in the near term, is not the end of cold weather. And while it might be cold today, winter is getting milder and spring is arriving, on average, 10 days sooner. That’s expanding wildfire season and disrupting many animal species that live on tight, annual clocks.
Cold also has concrete benefits, especially for apple, blueberry and maple syrup farmers, whose crops depend on a base number of chill days to thrive. Cold snaps also kill insect larvae and keep insect populations in check. In the West, milder winters are helping lead to larger beetle populations that are decimating forests.
And if you’re from Wisconsin, New England or other areas where pond hockey and cross-country skiing are childhood hallmarks, it’s important to note the squeeze warmer weather will have on winter recreation.
Extreme snowfall is an ephemeral beast and climate communicators should tread carefully with it. Many of us remember the 2010 blizzard that blanketed the Northeast and shut down Washington, DC. I helped two friends move during the storm, so my memories are perhaps slightly more visceral. I also remember Senator James Inhofe having some fun with his family by erecting an igloo on the Mall and sticking an “Al Gore’s Home” sign on it.
Misleading and mean? Sure. That’s politics for you. But it was effective communication, too.
[The Inhofe family and their igloo. Image from ThinkProgress.]
In the wake of “Snowmageddon,” we convened six leading snow and climate researchers to ask them what they thought scientists could fairly say about snowfall and climate change.
Like most scientists, they said they first wanted to emphasize the bigger picture: Climate change is altering the character of our seasons, as noted above.
The snowfall story, they said, can be complicated. Snow can only form when temperatures are below 32 degrees and when there is enough water vapor in the air. While climate change makes it less likely that any given day will fall below the 32 degree threshold, it also causes the air to hold more moisture.
Due to increasing temperatures, scientists see a shift away from snow and toward rain. When they look at the overall picture for precipitation – including rain and snow – there has been a measurable concentration of precipitation in the heaviest events.
[Draft National Climate Assessment map showing the percent increases in the amount of precipitation falling in the heaviest 1 percent of all events.]
They also see that snow cover, which measures the extent and length to which snow stays on the ground, is shrinking. At the same time, the United States’ historic “Snow Belt” is shifting, and the region that receives heavy snow is moving northward.
Snow pack – which refers to the snow that builds up in mountain regions – is also declining. This is especially troubling for the U.S. Southwest, where mountain snow is a vital water source. When that snow melts rapidly, water managers struggle to deliver it to homes, businesses and farms.
[Draft National Climate Assessment map showing averaged projections for a shift toward less snowpack in the U.S. Southwest.]
At the same time, the researchers told us, more moisture in the air can lead to heavier snowfall, but only when other conditions are favorable. Therefore, it isn’t clear that climate change can be linked to heavy snowfalls in a straightforward way.
For climate communicators, it’s much better to lead with what scientists definitely know – and the consequences those findings will have for us – than to get into more speculative findings about heavy snowfall and climate change. And it’s always worth pointing out that a heavy snowfall does not negate the multiple lines of evidence pointing to global warming, including evidence of warmer conditions in winter.
Going to Extremes and Staying Credible
It’s tempting to point to every instance of extreme weather and say, “See, that’s climate change for you.” But scientists’ confidence in climate change’s link to various sorts of extremes varies. When it comes to tornadoes, for instance, scientists don’t have a long, consistent record from which they can work. By contrast, increasing intensity and frequency for heat waves is well documented in more than 100 years of temperature data. Scientists have also been making strides with “attribution studies” that can help them determine how much impact human-induced climate change had on specific weather events.
[Graphical representation of an Intergovernmental Panel on Climate Change report regarding climate change and extreme weather.]
Clearly, extreme weather is one of the most obvious ways climate change is connected to events we experience in our everyday lives. It’s something climate communicators should absolutely talk about. But it’s also an area where it’s easy to overstate the links and jeopardize your credibility.
I recently attended a talk at the World Wildlife Federation where one of my favorite climate communicators, scientist Katharine Hayhoe, delivered a lecture. When she talked about her home state of Texas, she was careful to point out that the extreme drought it had recently experienced actually wasn’t unprecedented in the region’s history. But, she noted, the sort of hot, dry summer the state has recently experienced could be an average summer in the future as climate change continues.
The effect on the audience was interesting. Heads nodded more emphatically than usual and there were more than a few murmurs of approval. Hayhoe had challenged the audience’s expectations then followed through with what scientists do know. It was honest, credible and effective.
As a scientist, Dr. Hayhoe is someone who thinks a lot about her credibility. It’s the currency of a scientific career.
Credibility is also the currency of public trust. The effects of climate change, especially if left unchecked, will no doubt be terrible. It doesn’t need to be overstated or given the appearance of being overstated. A look at storm surge maps for various levels of sea-level rise in the United States is sobering enough, as is Bill McKibben’s artful “Do the Math” translation of a somewhat dense scientific paper on our future heat-trapping emissions trajectory.
Given the polarization we face on climate change, as well as the varying levels of certainty we have to deal with on the underlying science, keeping credibility top of mind should be important for every climate communicator, especially when it comes to extreme weather. This is doubly true during winter, when it’s easier for people to see their own breath condensing in the cold air in front of them than it is to see the troubling nature of long-term climate change.
Aaron Huertas is a press secretary at the Union of Concerned Scientists, where he helps scientists communicate their research. Previously, he worked for Congressman Jim Saxton (R, NJ-3) This post was helpfully reviewed by UCS climate scientist Todd Sanford and UCS press secretary Lisa Nurnberger.