Wanda Shelton, 51, of Ham Lake, is highly skeptical when it comes to climate change. Even if the climate is changing, she said, it's not because of human behavior.

"That takes a lot upon ourselves to think that we could change this climate by that much," she said. "I think that that's putting us above God, and I don't think we could do that."

When told that according to the Proceedings of the National Academy of Science, 97 percent of U.S. climate scientists believe climate change is real and is largely man-made, she remained skeptical: "I think data can be manipulated to whatever you want to believe."

It can be difficult to find solid ground in a topic awash in misconception from political slants and conflicting media coverage. While climate scientists agree that the Earth is warming unnaturally fast and that human behavior -- particularly in the release of gases like carbon dioxide from industry and cars -- is largely responsible, Americans grow increasingly skeptical.

A study conducted this spring by Yale University researchers found that, since 2008, the percent of people who believe that climate change is occurring dropped from 71 percent to 64 percent. Of the people who do believe that climate change is happening, 47 percent believe it's because of human behavior, compared to 57 percent three years ago.

The reasons for skepticism range from psychology to economics. An overlong winter makes it more difficult to believe the Earth is warming. Many people don't want to acknowledge serious effects -- like reduced crop yields and increased flooding -- that scientists say may result from climate change. But scientists insist the problem is there.

John Abraham, associate professor of engineering at the University of St. Thomas, is one such scientist.

"Climate changes for two reasons: Natural and man-made," he said. "Right now, the man-made is overriding the natural."

Greenhouse gas levels are the highest they have been in 800,000 years, Abraham said. Since those gases are a primary cause of climate change, he finds it no wonder that the Earth is the warmest it's been in the last 400 years.

Greenhouse gases include carbon dioxide, methane and even water vapor. The gases are part of Earth's natural climate cycle. Without their presence, the atmosphere wouldn't retain enough warmth to support life.

So why would their presence affect climate in a negative way? And can individuals influence the climate?

Scientists explain it this way: The atmosphere that surrounds Earth acts as a barrier between us and our major supplier of energy, the sun. The atmosphere absorbs, reflects and re-emits the sun's rays as a natural process of maintaining temperatures on Earth. Carbon dioxide and water vapor are natural components of the atmosphere, but also prevent energy from leaving. This is typically a good thing; Earth needs this energy to remain warm. But when human behavior adds an unnatural amount of these gases -- particularly carbon dioxide -- to the atmosphere, the amount of energy retained begins to exceed what is healthy for the planet.

Dan Sweeny, 45, of St. Francis, believes the climate is changing but isn't sure that he can do anything about it.

"I don't know if there's much we can do individually."

Abraham said having a government energy policy is most important. But individual action is a close second.

"If people realize that everything you do involves energy, [they'll see] that you can make a tremendous impact. I think that every person in the U.S. could reduce their energy use by a third and not know it. If I leave something on all night, I know it's using energy unproductively. So making personal choices does matter."

Samantha Fredricks will be a senior at Anoka High School.

Teaching climate change upsets some students, she said. "But it brings up conversation. I think [we should talk] more about global warming and keep it as an open issue so it's obvious that, hey, this affects you."

Meanwhile, she's determined to convince her mom that she needs an electric car.

CALCULATE YOUR EMISSIONS

The Environmental Protection Agency highlights power plants, factories and transportation as some of the largest contributors to the United States' overall emissions.

But individual behavior also has an effect, the EPA says. When we leave lights on, run our water and drive our cars, it adds up. The EPA offers an easy way of calculating our impact with a "Household Emissions Calculator" offered on its website: www.epa.gov/climatechange/emissions/ind_calculator.html.

Your results may surprise you: The average American household is estimated to emit anywhere from 11 to 20 tons of carbon dioxide a year.