As worry spreads through the nation about how global warming threatens the planet, some committed environmentalists find themselves afflicted by two new annoyances: “green noise” and “greenwashing.” Together, they are causing a certain green fatigue that could endanger the growing national determination to do something about climate change.

Green noise was described in a recent New York Times article as “static caused by urgent, sometimes vexing or even contradictory information played at too high a volume for too long.” The piece suggested that offering hemp-enriched shampoo and 100 percent organic tampons is a bit too much.

Greenwashing, according to a Newsweek article, has been described as “the unjustified appropriation of environmental virtue.” Lexus, for example, boasts about its hybrid SUV, but it uses who knows how much jet fuel to fly a car to Paul McCartney from Japan. And Maine’ s Poland Spring touts its thinner plastic bottles and carbon-saving caps and labels but still uses a lot of carbon-based plastics in pushing an alternative to plain tap water.

A Boston College survey found that only 47 percent of the public trusted corporate green claims. As the din goes on, skepticism can only increase.

Planners of the Democratic National Convention in Denver have gone overboard with a scheme to make their gathering the greenest ever. Caterers rebelled when told to make everything organic and ecofriendly to the point of supplying food in five colors and abandoning french fries. Balloons are a must at all conventions, but the Denver planners wanted to make sure that their balloons would be biodegradable. They buried a few balloons to see, but they refused to rot.

Al Gore’ s “Inconvenient Truth” book and movie certainly unleashed nationwide concern, and his recent prophetic speech urging us to stop burning coal, gas and oil in 10 years called for even greater urgency. But when advertisers and promoters grabbed the issue many of their products and claims have become trivial or even nutty. Has the nation really been in dire need of vegan sandals?

Mr. Gore may have overdone his warnings by choosing the worst scenarios from the wide range of possibilities agreed upon in an international scientific consensus, but that’ s another story.

What is needed is less ballyhoo and a focused national policy aimed squarely at the main producers of the carbon dioxide that is said to be responsible for a destructive warming trend. For starters, why not take advantage of $4-a-gallon gasoline and make a major push for alternative energy sources like wind and wave power and electric or hydrogen-powered cars while expensive gasoline makes them competitive? A national speed limit of 55 miles an hour would create immediate massive savings.

The American public is paying attention, but it needs leadership and a comprehensive plan rather than the present cacophony of confusing and often contradictory or hollow exhortations.