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Seven in 10 U.S. citizens believe climate change is real and happening now. Yet most have never even contacted a government official about the issue, let alone volunteered with an environmental organization or taken other action.

These findings are part of an exploration of Climate Change in the American Mind issued by the Yale Project on Climate Change Communication.

“They think it’s about polar bears or developing countries, not the United States  not my community, not my friends and family,” Anthony Leiserowitz, director of the Yale Project, told IPS.

Researchers divided the U.S. population into “six Americas” that share similar beliefs about climate change. Seventy percent belong to three major “Americas” that believe, to a more or less strong degree, that climate change is happening, is harmful and is caused by humans.

After falling between 2008 and 2010, public awareness on the topic here has been rising again, probably because of the number and severity of extreme weather events in the last two years. The trend was confirmed by an opinion poll released in April by the Gallup Institute.

The latest dire warning came just this week, when the executive secretary of the U.N. Framework Convention on Climate Change, Christiana Figueres, announced that the concentration of carbon dioxide in the atmosphere had passed the critical threshold of 400 parts per million.

To put this number in perspective, the last time the Earth had a similar concentration of CO2 was three million years ago during the Pliocene era, when sea levels were up to 80 feet higher.

“The main way people know about this issue is through media reporting,” Leiserowitz explained. “And when the media don’t report it, it’s literally out of sight and out of mind.”