地球温暖化懐疑主義者の原因は

アメリカで地球温暖化懐疑主義者が多いのは冬が暖かくなって住みやすくなっているからではないかという研究を今週のNatureが取り上げていました。誰でも思いつくようなことですがそれを実証する方法を論文としてまとめるのは大変ですよね。今回の研究者たちは何十年にも渡る温度変化と移住パターンから推論を導き出していました。Natureは有料記事だったので大学のプレスリリースを紹介します。

Recent warmer winters may be cooling climate change concern
NEW YORK UNIVERSITY
April 20, 2016

The vast majority of Americans have experienced more favorable weather conditions over the past 40 years, researchers from New York University and Duke University have found. The trend is projected to reverse over the course of the coming century, but that shift may come too late to spur demands for policy responses to address climate change.

The analysis, published in the journal Nature, found that 80 percent of Americans live in counties where the weather is more pleasant than four decades ago. Winter temperatures have risen substantially throughout the United States since the 1970s, but summers have not become markedly more uncomfortable. The result is that weather has shifted toward a temperate year-round climate that Americans have been demonstrated to prefer.

念のためNatureに発表されたものも抜粋します。PodcastにMegan Mullinさんが出てお話しされていました。14分くらいです。スカンジナビアでは気温は温厚になっているが環境問題の意識は高いというツッコミを受けていました。確かにこういう研究は結論ありきのものになりがちです。

Recent improvement and projected worsening of weather in the United States
• Patrick J. Egan & Megan Mullin
Nature 532, 357–360 (21 April 2016) doi:10.1038/nature17441
Received 30 March 2015 Accepted 16 February 2016 Published online 20 April 2016

Our results have implications for the public’s understanding of the climate change problem, which is shaped in part by experiences with local weather15, 16, 17, 18, 19, 20. Whereas weather patterns in recent decades have served as a poor source of motivation for Americans to demand a policy response to climate change, public concern may rise once people’s everyday experiences of climate change effects start to become less pleasant.




大学のプレスリリースに戻りますが、快適な気候がこれまで続いてくるが、今後といっても今世紀終わりなのでずっと先ですが夏の気温が上がったりして不快な気候を体験するようになると予測しているようです。

To quantify how Americans are evaluating these changes, Egan and Mullin drew upon research by economists examining weather’s role in growth of the Sun Belt and population declines in the Northeast and Midwest. Using these findings, they developed a metric of the average American’s preferences about weather. This “weather preference index” (WPI) reflects the U.S. public’s preferences for places with warmer temperatures in winter and cooler temperatures and lower humidity in summer. The index also takes into account preferences about precipitation. Egan and Mullin found that WPI scores have risen in counties accounting for 80 percent of the U.S. population since the 1970s.
But projections of future temperatures—and future WPI scores—offer a markedly different picture. Climate change models predict that under all potential levels of future warming, average summer temperatures will ultimately rise at a faster rate than winter temperatures. Using these projections, the researchers calculated that under a severe warming scenario, WPI scores will decline such that an estimated 88 percent of the U.S. public will experience less pleasant weather at the end of this century than it has in the past 40 years.

「未来を予知して予防的な対応を取れるか」地球温暖化問題の核心とも言える部分をこの研究は訴えているようです。