As we celebrate the 40th anniversary of Earth Day, the most serious environmental problem that we face is not global warming or the pollution of our air, water, land and food. It is whether or not our country moves forward in developing public policy based on science or whether we make decisions based on politics and fear mongering.

When Americans walk into a doctor’s office to get treated, they usually don’t worry whether the physician’s politics is progressive or conservative, Democrat or Republican. They want to know that the doctor they are seeing has been well trained in a scientifically accredited institution. They want to know that their treatment is based on the latest and most effective peer-reviewed methodology.

When our highly-trained NASA scientists and engineers work on the exploration of Mars, nobody I know in Congress challenges their credibility or honesty as they study and draw conclusions about that planet’s surface and origin. That is also true with the work of our scientists at the National Institutes of Health, the Centers for Disease Control and Prevention, the National Oceanic and Atmospheric Administration, and other governmental research agencies.

Yet when it comes to global warming, the situation is very different. Here, radio and TV entertainers such as Rush Limbaugh, Glenn Beck, and a host of others in the right-wing echo chamber, with no scientific training in climate science, are spouting off to tens of millions of people every day about a subject they know little about.

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Let’s set the record straight. There is no serious dispute within the scientific community and in peer-reviewed journals that global warming is real and that it is significantly caused by anthropogenic greenhouse gas emissions. Virtually the only people who disagree with this conclusion are representatives of the oil and coal companies, their apologists in the media, and those on Capitol Hill who are stubborn defenders of their big polluter patrons.

As Congress debates global warming, it reminds me of those congressional hearings where tobacco company executives swore under oath that the nicotine they put in cigarettes was not addictive. Some people in Congress believed them. Despite overwhelming scientific evidence, the wealthy and powerful tobacco lobby had many allies in Congress toeing the company line.

Like the evidence that tobacco kills, the science on global warming is overwhelming. NASA just reported that the decade from 2000-2009 was the warmest on record. Carbon dioxide levels are increasing because we are burning fossil fuels and cutting down forests at a rate that is unsustainable. How do we know that carbon dioxide pollution causes global warming? Among the researchers who reached that conclusion are scientists at NASA, EPA, the National Science Foundation, and the departments of Energy, Commerce, Defense, Interior, State, Health, Transportation, and Agriculture. They say, through the U.S. Global Change Research Program, that “global warming is unequivocal and primarily human-induced.” The CIA and many military leaders have warned that climate change threatens our national security and international stability.

If anything, we have underestimated the problem. Our own National Academies of Science released findings last year that “climate change is happening even faster than previously estimated” and “the need for urgent action to address climate change is now indisputable.” U.S. average temperatures have already increased by 2 degrees Fahrenheit in the last 50 years, and a Massachusetts Institute of Technology report found a very high probability that unless we act now temperatures could rise by 9 degrees Fahrenheit by the end of this century. That would be catastrophic.

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We already have seen sea levels rise by as much as nine inches in some areas. As ice sheets and glaciers continue to melt, rising sea levels will put coastal cities at risk of increased flooding and island nations in danger of being submerged. Our top U.S. scientists tell us that unchecked global warming also means increased risks of regional flooding and drought, increased risk to human health and more extreme weather events.

Despite the scientific evidence, some of my colleagues in Congress still tell the public that global warming is a “hoax.” They recently grasped onto a series of stolen emails from a few climate scientists, which they say undermines the science. Well, according to exhaustive reviews throughout the world, the emails do no such thing.

The truth is that there is a real global warming scandal, but it has nothing to do with the emails of a few scientists. The real scandal is that the oil companies and the coal industry and others with an economic stake in the status quo are using the tobacco-industry playbook to confuse the public and prevent Congress from taking strong action. ExxonMobil, for example, has spent more than $24 million since 1998 to fund organizations that are willing to dispute the consensus on global warming. Oil and gas companies spent $154 million lobbying Congress in 2009 alone trying to block legislation to move our county away from fossil fuels and toward sustainable energy.

As we celebrate this Earth Day, we can make this the year when we stop arguing about the science, and start doing something truly significant about global warming. That would make 2010 a year to celebrate for generations to come.

U.S. Sen. Bernie Sanders, independent of Vermont, is chairman on the Senate Green Jobs and the New Economy Subcommittee. He is the only member of the Senate majority caucus to sit on both the energy and environment committees.