For generations, the red spruce stood tall against the rumpled hills of Vermont. Today, near the timber line of Camel's Hump, gray skeletons of dead trees spike the clouds that drift over the mountaintop.
The killer is acid rain.
It has eaten away at Northeast forests for decades, but researchers thought they finally had the problem licked after Congress amended the Clean Air Act in 1990. It called for dramatic reductions in sulfur dioxide (SO2) emissions that help create the acidity.
And the program has been a great success. Industry, especially utility companies, has already reduced SO2 emissions far beyond what the law calls for to date - and at much less than the estimated cost.
But the red spruce die-off continues in Vermont. Clouds surrounding the peak of Mt. Washington in New Hampshire are still as acidic as lemon juice. Streams that run through the Hubbard Brook Research Foundation in Hanover, N.H., can still pickle the leaves that fall from the trees.
"The good news is that acid rain isn't getting worse. The bad news is, it may not be getting better, at least, not fast enough," says Bruce Hill, senior staff scientist of the Appalachian Mountain Club in Gorham, N.H.
While the national environmental spotlight has shifted to more global concerns, like climate change and stratospheric ozone depletion, acid rain quietly continues to fall on the Northeast's forests. The realization has prompted new legislation and calls for more dramatic reductions in emissions.
Industry is adamantly opposed, arguing that good progress has already been made and the full force of the current Clean Air Act requirements are yet to be felt.
But researchers contend there's no time to delay. The problem, according to Mr. Hill and other researchers, is that the Clean Air Act didn't go far enough.
The law targeted and has significantly reduced the amount of acids in the rain caused by SO2 emissions, which come mainly from Midwest power plants. But it was far less aggressive in ordering reductions in nitrogen oxides (NOX), produced not only by utilities but also by cars and trucks. Although Detroit was reducing auto emissions at the same time industry was cleaning its smokestacks, the average American is driving more miles now than ever before.
As a result, NOX emissions have dropped by a fraction compared with reduced emissions of sulfur dioxides. In each acidic raindrop today, sulfuric acids are down, but the percentage of nitric acids is up, in some cases significantly. So, in much of the Northeast it's a wash: Acidity levels remain about the same.
A fight on many fronts
Within the month, the Environmental Protection Agency is expected to announce new NOX emissions targets for industry as part of the phase-in of the Clean Air Act. This summer, the EPA proposed tough new regulations for soot, which are also expected to eventually limit even more NOX emissions. And the Northeast states have tapped a separate mechanism in the Clean Air Act that could force the EPA to mandate even more NOX reductions if the proposed reductions are not deemed sufficient.
But critics say none of these will come soon enough to slow the damage to nature.
"According to the EPA, 45 percent of the lakes in the Adirondacks will be too acidic to support most aquatic life by the year 2040," says Sen. Daniel Patrick Moynihan (D) of New York. "That is not the inheritance we want to leave to our progeny."
The senator has introduced a bill that calls for reductions in sulfur dioxides by 50 percent beyond those required by current law, and cuts of more than 70 percent in power-plant NOX emissions from 1990 levels.
Many industry officials think that's ridiculous.
"We believe that we're making some great progress in reducing SO2 and NOX emissions already," says John Kinsman, manager of atmospheric science for the Edison Electric Institute, a power utility trade group based in Washington. "We don't see the scientific evidence as mandating the further reductions they seek."
Mr. Kinsman argues that the EPA's new regulations and its soon-to-be-issued standards should be left to do their work, before any Draconian new measures are undertaken. He notes that when a utility burns a ton of coal today, it releases only a third of the SO2 emissions that it did in 1970. Under the Clean Air Act, that number will be required to drop even further by 2000.
Reason for optimism
The EPA, too, is optimistic about the success of the acid rain portions of the Clean Air Act. One study showed reductions in acidity of the rain ranging from 10 to 25 percent in various research sites throughout the Northeast and Midwest.
"We're ... reducing the nitrogen-oxide emissions into the atmosphere by a large amount, and so we're going to be able to monitor that and see how successful that is," says Richard Wilson, acting assistant EPA administrator for air and radiation.
That optimism is welcome on Camel's Hump in Vermont, where acidity levels in the rain have remained about the same for the past 10 years. But there's also a sense of urgency that more needs to be done.
"There's a much bigger list of questions than answers in the way that ecosystems interact with air pollutants and climate change," says Tim Sherbatskoy, research director of the Vermont Monitoring Cooperative, a joint scientific program between the University of Vermont at Burlington and the Vermont Agency of Natural Resources. "That's why it's essential we keep monitoring it and studying it."