Global Warming Feels Quite Pleasant
By PATRICK J. EGAN and MEGAN MULLIN
CHRISTMAS in New York was lovely this year — especially for those who prefer to spend the day working on their tans. It was the city’s warmest ever, with temperatures peaking at 66 degrees.
Record-breaking temperatures are occurring with alarming frequency in the United States, but Americans are reacting with a collective shrug. In a poll taken in January, after the country’s warmest December on record, the Pew Research Center found that climate change ranked close to last on a list of the public’s policy priorities. Why?
In a paper published on Wednesday in the journal Nature, we provide one possible explanation: For a vast majority of Americans, the weather is simply becoming more pleasant.
Over the past four decades, winter temperatures have risen substantially throughout the United States, but summers have not become markedly more uncomfortable.
Of course, people’s preferences about weather vary widely. Some want a snowfall every winter, while others would rather wear sandals year-round. So we sought to develop a measure of the average American’s weather preferences. To do this, we made use of research by economists who study local population growth in the United States. They have found that Americans have been moving to places with warm winters and cool, less humid summers. We made the inference (not true in every case, but reasonable to assume in general) that Americans prefer such conditions.
Then we evaluated the changes in weather conditions that Americans have experienced over the past four decades (i.e., roughly since climate change emerged as an issue in the public sphere).
Climatologists customarily report weather changes averaged over the land surface — an approach that counts changes in sparse Montana just as heavily as shifts in populous California. But because we were interested in the typical American’s exposure to weather, we took a different tack, calculating changes over time on a county-by-county basis, weighted by population.
Our findings are striking: 80 percent of Americans now find themselves living in counties where the weather is more pleasant than it was four decades ago. Although warming during this period has been considerable, it has not been evenly distributed across seasons. Virtually all Americans have experienced a rise in January maximum daily temperatures — an increase of 1.04 degrees Fahrenheit per decade on average — while changes in daily maximum temperatures in July have been much more variable across counties, rising by an average of just 0.13 degrees Fahrenheit per decade over all. Moreover, summer humidity has declined during this period.
To those of us who believe climate change is the most profound challenge of our age, our discovery is both illuminating and disheartening. In previous work, we’ve shown that Americans make sense of climate change in part through their personal experience of the weather. Our new findings suggest that the weather changes caused by global warming cannot be relied on to spur the public to demand policies that address the problem. By the time the weather changes for the worse later in this century, it may be too late.
And it will change for the worse. Under all likely scenarios, seasonal trends are projected to eventually reverse: Future warming in the United States will be more severe in summer than in winter. Should greenhouse gas emissions proceed unabated, we estimate that 88 percent of Americans will be exposed to less pleasant weather at the end of this century than they are today.
In order to more effectively raise awareness and increase public concern about climate change, our research suggests that we need to stop talking so much about rising temperatures. A focus on extreme weather events — which are easily understood by the public and have potentially much greater impact on human health and the economy — may be a better strategy.
And when we do discuss temperatures, we should acknowledge the temporarily pleasant side effects of global warming. But then we should stress that these agreeable conditions will one day vanish — like ice on a warm winter day.