Is the earth warming? Is human activity the cause? Is there anything we can do about it?

While many believe there is a consensus in the scientific community that humans are causing the earth to heat and that serious action must be taken immediately, that's not what most Americans believe, according to a Pew Poll taken May 8.

The poll did find that 71 percent of Americans say there is solid evidence that the earth is warming. But only 47 percent said they believed the earth was warming because of human activities, such as burning fossil fuels.

That clear majority of Americans who believe the earth is warming has decreased slightly since January 2007, however. Pew found 77 percent of Americans believed global warming was a fact in January 2007: the same percentage as in August 2006.

But in July 2006, 79 percent of Americans said yes when asked if the earth was getting warmer. That percentage, however, was just 70 percent a month earlier in June 2006.

Pew doesn't attempt to explain the increase or decrease in the percentages it polls. But Al Gore's documentary, "An Inconvenient Truth" opened May 24, 2006, in Los Angeles and New York. The companion book was listed as No. 1 on the New York Times Best Seller list on July 2, 2006. And the DVD of the Oscar-winning movie went on sale in November 2006.

But while most Americans believe the atmosphere is getting warmer, less than half, 47 percent, blame it on human society. That percentage has held steady in Pew polls since July 2006 when 50 percent of Americans said humans were the cause. Only 41 percent believed that in June 2006 before "An Inconvenient Truth" was widely shown.

A smaller percentage of Americans are undecided on the issue or believe the warming is because of natural causes from that July 2006 peak.

Twenty-three percent of the people polled in July 2006 said environmental causes were behind global warming, while 17 percent didn't believe there was any warming at all.

By April 2008, only 18 percent still attributed global warming to the natural causes, while the percentage who doubted global warming altogether, had grown to 21 percent.

That may reflect politics.

In January of this year, 62 percent of poll respondents who identified themselves as Republicans said there was solid evidence that the earth was warming. Eighty-six percent of Democrats agreed, as did 78 percent of independents.

But three months later in the April 2008 poll, Republican agreement had dropped 13 percentage points to 49, Democrat support slipped two percent to 84 and the Independent tally slid three points to 75 percent.

Your political party affiliation, age, sex, race, education and where you live also seem to be involved.

Pew says 58 percent of Democrats believe human activity is causing global warming. Fifty percent of Independents agree, but 27 percent of the Republicans are convinced.

Slightly more women (48 percent) than men (45 percent) believe humans are the cause.

But if you're 18-29 years of age, 54 percent believe global warming is man-made, wuth 50 percent agreeing in the 30-49 year range. Only 44 percent of Americans 50-64 believe humans are at fault, and just 37 percent of seniors over 65 hold that opinion.

The level of education also seems to have an influence: 51 percent of college grads believe fossil fuel use causes global warming. Forty-nine percent of people with some college credits blame mankind, but only 43 percent of people with high school diplomas or less see humans as the cause.

Fifty-three percent of city dwellers believe global warming is human-caused, as do 46 percent of people living in suburbia. But only 37 percent of people living in the rurals were willing to lay the blame on humans.

But you can't play the race card on this issue. Pew found that 46 percent of white respondents believed global warming is caused by human activity, the same percentage as among black people.

Of those people who said they believed global warming is human caused, a resounding 82 percent said it's possible to reduce its effects, with 54 percent saying mayor sacrifices are needed.

Conversely, only 57 percent of those who believe global warming to be a natural occurence said it's possible to reduce its effects, with just 32 percent saying society must make major sacrifices.

Almost three-quarters of Americans beleive global warming is a serious problem, with just under a quarter saying the problem isn't serious at all. Pew said that's largely unchanged the past few years. And again, politics seems an influence: six in 10 Democrats, and almost half of Independents believe the problem is serious. Only 22 percent of Republicans agree.

But although an overwhelming percentage of Americans say global warming is a vary or somewhat serious problem, it ranks at the bottom of the public's list of priorities for Congress and the White House to deal with.

Only 35 percent of Americans polled in January 2008, said global warming should be a top priority of the federal government this year. That's down from 38 percent in January 2007.

Given a list of 21 priorities for the Administration and Congress to address, global warming ranked last, 21, with Republicans. It ranked 15 out of 21 with Democrats, and 18 out of 21 with Independents.

Pew has found that strengthening the economy is by far more important with Americans than any political differences. Possibly that's why the Warner-Lieberman Climate Protection Act met such an early end last week in the U.S. Senate.

Both Barack Obama and John McCain are committed to addressing climate change. McCain wholeheartedly supports nuclear energy, as well as developing renewable sources of power. Obama tends to advocate renewable energy more than nuclear, although he has said nuclear could play a role with proper safety.

Both oppose drilling for oil in Alaska. Obama opposes off-shore drilling; McCain says leave it up to the states, which is the same as opposing it. Both support the cap-and-trade system, an environmental three card monte.

But lest environmentalists become too complacent, both McCain and Obama also support development of clean coal as fundamental to breaking the United States' dependence on oil from foreign sources.