Talking About Global Warming on the First Day of Winter

Dear Brenda,

I know our fingerprints are all over global climate change. I know the science is clear that it's happening now and that it's caused by all the human activities that emit heat-trapping gases. And I know that people, countries, and natural systems are at risk from global warming. But I don't know what to say to friends, family, or colleagues who question the existence of climate change when cold weather sets in.

I admit that sometimes, when my ears are freezing as I walk to the subway, I grumble to myself, "Where's global warming when you need it!" When it's cold, I just don't know how to explain to people that Earth has a fever. Just the other day I was talking to someone at a holiday party who said the blizzards we had last winter disproved global warming.

I'm not the kind of person who always has to set people straight even when I know they're wrong. I usually let people have their say, but I'm really appalled at the lack of understanding of basic science. If you have any suggestions, especially when it comes to winter weather, could you let me know? What can I say to people who pooh-pooh global warming? And why do they hold their tongues in summer when we're wilting in a record-high heat wave?

Cold in Winter

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Dear Cold in Winter,

The hallmark of winter is cold, at least in North America. Even with climate change, you're still going to wake up on a January morning and see snow falling. I walk to the bus stop, too, so I know about cold ears and fingers. As a climate scientist, I have plenty of compelling facts at hand about global warming, and trust me, it's hard to explain the overwhelming evidence of climate change when people are feeling winter's wind in their faces. I understand the problem you describe, for sure.

You may want to remind your friends that weather is different from climate. The day-to-day weather -- even a cold snap or a heat wave -- doesn't prove or disprove climate change. Climate is the prevailing condition--temperature, precipitation, humidity, and atmospheric pressure -- of a region over a long period of time. For example, in Wisconsin you expect cold, snowy winters. In Mexico you expect mild, sunny winter weather.

When you see the first snowfall of the season, a few details about climate projections might help you explain what's happening outside. I wasn't at all surprised by this past year's drenching rains and devastating blizzards in parts of the United States. In areas that typically get rain and snow, we've seen an increase in the intensity of the storms. It may seem counterintuitive, but we have strong evidence that heavier snows are actually one of many links scientists have uncovered between climate change and extreme weather. Rising ocean-surface temperatures have already raised the temperature and moisture content of the air passing over the United States. The heaviest precipitation events in the Northeast are typically more severe now compared with 50 years ago. And the Great Lakes region has had more lake-effect snow; that's because the lakes aren't covered by as much ice during the winter months, allowing the air to absorb more moisture, which then falls as snow. At the same time, most of the deserts are getting drier.

It's also helpful to put our local conditions into perspective. If you look only at our country, you're seeing only 2 percent of Earth's surface. That's like watching a football game and seeing only what's going on between the 48-yard line and the 50-yard line. Well-documented measurements all across the world over the past several decades show that Earth is definitely warming. Science takes a whole-world view, just like watching the football game in high definition on a wide-screen television.

So, Cold in Winter, there's no need to get into a confrontation over climate change. But I do want to give you a basic comeback to anyone who spouts false information. Just say, Hey, it's winter, snow happens, and a cold snap doesn't prove anything one way or another. And a warming planet generates more intense precipitation in areas that usually get rain or snow. You may also want to remind your friends about how winters are becoming shorter. A lot of people have noticed what scientists have been measuring for years -- spring is arriving about 10 days earlier than it has historically. You might want to keep this note handy.

At least, don't shy away from telling people it's winter. You just might need to remind them when winter comes next year.

Your friend,