Global warming is bringing moderate temperatures to most of North America, but this may not be a good thing, according to a new study.

The northeastern United States, for instance, experienced an extremely mild winter during 2015 and 2016. However, some environmentalists are concerned that mild weather, an enjoyment to most people, could reduce public concern about the environmental effects of global climate change.

Over the last four decades, winter weather has become more mild in 80 percent of the counties around the U.S., researchers report.

Meanwhile summers have not grown significantly hotter than they were in the 1940s. This combination has resulted in a more moderate, temperate climate year-round across much of the U.S.

These conditions are preferred by a majority of Americans, investigators found, which could reduce concern over climate change around the world.

"Rising temperatures are ominous symptoms of global climate change, but Americans are experiencing them at times of the year when warmer days are welcomed," said Patrick Egan of New York University.

Although conditions today are more pleasurable, on the whole, than climate in the 1970s, investigators warn pleasant times will soon be drawing to an end. Computer climate models show conditions could be significantly less comfortable by the end of the century than they are today.

If Americans grow passe about the rise in global temperatures until conditions become uncomfortable, it may be too late to stop the environmental degradation, researchers fear.

New York and Duke University researchers examined data showing temperatures from 1974 to 2013, recorded in counties around the nation.

Investigators showed January temperatures around the U.S. increased by an average of 1.04 degrees Fahrenheit per decade. July temperatures rose much more slowly than that during the same time period – just 0.13 degrees Fahrenheit per decade.

This data was then compared to records of human migrations from the northeastern states and midwest to the sun belt region. Data was analyzed and used to create a weather preference index to gauge public attitudes toward climate.

The same team of researchers who carried out this study found, as part of a 2012 investigation, that locale affects attitudes toward global warming. People living in areas experiencing warmer-than-normal conditions were more likely than others to support the idea that average temperatures are rising around the globe.

Analysis of the public attitude of Americans toward global warming in light of moderate temperatures was published in the journal Nature.