Wednesday is Earth Day, a day first celebrated 39 years ago to inspire awareness and appreciation of the environment. But, according to the latest Rasmussen Reports telephone survey, only 31% of American adults believe their fellow countrymen are environmentally aware.

Fifty-three percent (53%) say most Americans are not environmentally aware. Adults under the age of 40 believe this more strongly than their elders.

Seventy-two percent (72%) of Americans think individuals can improve the environment by their actions, and just 15% disagree.

Seventy-four percent (74%) of both Democrats and voters not affiliated with either major party say individuals can improve the environment, compared to 67% of Republicans.

In a separate survey, just 34% of U.S. voters now think global warming is caused by human activity, the lowest finding yet in Rasmussen Reports national surveying. The Obama administration's proposed anti-global warming efforts are predicated on reducing human causes for the problem.

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Fifty-seven percent (57%) of Americans rate Earth Day as at least somewhat important, including 28% for whom it is Very Important. Women (64%) deem the day more important than men (50%). Thirty-five percent (35%) of all adults say the day is not very or not at all important.

Yet while most Americans value Earth Day, just 21% plan to do something special to celebrate Earth Day. Sixty-eight percent (68%) have no such plans. Younger adults are more likely to celebrate it than older Americans.

The Earth Day findings are largely unchanged from a survey a year ago.

Most (51%) adults are aware that Earth Day takes place in April, although one third (34%) aren't sure when it is. Seven percent (7%) thought it was in July, five percent (5%) thought October and four percent (4%) said January.

Recycling is one way individuals can make a difference in the environment. A separate Rasmussen Reports survey found that 70% of American families now say they recycle.

President Obama has said he hopes to put a million energy-efficient hybrid cars on the road by 2015. In addition, he wants to implement an economy-wide cap-and-trade program to reduce greenhouse gas emissions 80 percent by 2050.

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