By Will Dunham
WASHINGTON (Reuters) - Researchers have a message for Americans who like the milder winters and agreeable summers experienced in most of the United States since the 1970s thanks to global climate change: enjoy it while you can.
Eighty percent of Americans live in areas experiencing weather that is more pleasant than four decades ago, with balmier winters along with summers that are no more humid and only marginally warmer, researchers said on Wednesday.
By 2100, however, 88 percent of Americans will face weather considerably less comfortable, with summers eventually heating up at a much faster rate than the winters over the course of the 21st century, they found.
The researchers studied weather conditions from 1974 to 2013 in the continental United States, which excludes Alaska and Hawaii, and then examined projections to the end of the century.
"For those of us who are deeply concerned about climate change, our findings are disheartening," New York University politics and public policy professor Patrick Egan said.
"This is because improvements in year-round weather are giving Americans the wrong signal about the dangers of global warming. Rather than catalyzing a demand for policy response, daily weather may be another cause for apathy about this critically important problem."
Scientists predict effects from global climate change including rising sea levels, increasing temperatures, more droughts and heat waves, stronger hurricanes, different precipitation patterns, glacial melting and sea ice loss.
So far, U.S. temperatures have risen primarily during times of the year when many people would welcome warmer days.
Americans on average have encountered a significant increase in January daily maximum temperatures, which have risen 1.04 degrees Fahrenheit (0.58 degrees Celsius) per decade. July daily maximum temperatures increased by just 0.13 degrees Fahrenheit (0.07 degrees Celsius) per decade and summertime humidity has fallen slightly since the mid-1990s, the study found.
"In terms of large population centers where people have not experienced improved conditions, they are clustered in Massachusetts, Rhode Island and parts of southern California and Arizona," Duke University environmental politics professor Megan Mullin said.
With temperate year-round conditions prevalent, scientists must recognize that the U.S. public may not receive messages of a gradually warming planet with much concern, Mullin said.
"To capture public attention and concern, it may be more fruitful to talk about extreme events that have potentially much more serious effects on the economy and human health," Mullin added.
The research was published in the journal Nature.
(Reporting by Will Dunham; Editing by Sandra Maler)