By KEVIN O'CONNOR

A century and a half from now, historic-minded Vermonters may rewind to 2007 and recall a teen rap group with a prophetic ear for the future:

"Economy's hurting from a short ski season
If that's not enough, let me give you another reason.
Maple production is on the downfall
Vermont will soon experience a sugar withdrawal.
Increased spread of Lyme disease and malaria
If you have insurance you can still be a carrier.
Leaf-peepers visit for colorful trees
You mess with our cows and we'll break your knees."

So sing a current-day group of Montpelier High School seniors called X10 in their global warming rap "CO2." Colin Arisman, Kevin Hartmann, Pat Leene and Luke Martin wrote the lyrics this year after their first music video, the funny Vermont valentine "802," sparked a story in The New York Times and more than 150,000 plays by Internet users worldwide.

Since then, the group has rapped "CO2" (scientific shorthand for carbon dioxide, one of the gases that fuels global warming) at a Montpelier rally (log onto www.youtube.com for "X10 performs ‘CO2' at the Statehouse") and for U.S. Sen. Bernard Sanders, I-Vt. (whose Washington Web site carried the music video this past summer).

The idea of Vermont without winter sports or fall foliage might sound as farfetched as a hip-hop hit in a slowpoke state. But skiers, farmers and foresters already are reporting problems because of warmer weather, and scientists project more trouble if fossil-fuel exhaust from smokestacks and tailpipes keeps rising.

"New state-of-the-art research shows that if global warming emissions continue to grow unabated, Vermont can expect dramatic changes in climate over the course of this century, with substantial impacts on vital aspects of the state's economy and character," the Union of Concerned Scientists says in its most recent report, "Confronting Climate Change in the U.S. Northeast: Science, Impacts, and Solutions."

It wouldn't be the first such environmental shift in Vermont history. A century and a half ago, the state had more than 1.5 million sheep, and farmers made big money selling wool. Then the market price dropped by half as the Western frontier began to raise flocks. By the end of the Civil War, the state's sheep industry unraveled. Pastures deforested for grazing sat empty — and then sprouted with maple trees and tourists.

Today, people think of Vermont for syrup and snow. Is that image about to melt away?

Spring awakening

Several recent studies (including the federal government's New England Regional Assessment of the Potential Consequences of Climate Variability and Change) warn of the growing possibility of future environmental problems. But a variety of Vermonters already are reporting alarming shifts.

Vermont today is the nation's largest producer of maple syrup, with about $20 million in annual sales and more than 10 times that amount in related economic and employment impact. But earlier springs are cutting the number of cold nights and warm days needed for collecting sap, experts say.

The University of Vermont's Proctor Maple Research Center, the oldest and largest such facility in the world, has worked five years on the first regional study of the "Effects of Global Change on the Maple Sugaring Industry."

Scientists asked the state's sugarmakers for their production records over the last four decades and then culled the data for any significant changes. The findings, now undergoing peer review, could be published as soon as next spring. But researchers already have revealed the sugaring season is starting "significantly earlier" than it did 40 years ago, and its duration has decreased by an average of 10 percent.

That's affecting national numbers. Vermont makes one-third of the country's maple syrup, but the United States, which produced 80 percent of the world's supply 50 years ago, has seen its figure drop to less than 20 percent today. In comparison, southeastern Canada — where the climate is warming to that historically found in the Green Mountains — has leapt from 20 percent to more than 80 percent of the global market.

Experts fear the state's maple industry could evaporate in their lifetimes.

"It appears to be a rather dire situation for the maple industry in the Northeast if conditions continue to go toward the predictions that have been made," Timothy Perkins, director of the Maple Research Center in Underhill, was quoted last March on the front page of The New York Times.

Maple production isn't the only thing changing around March town meeting season. Road crews say warmer winters are mucking up Vermont's 8,643 miles of dirt road, which make up 55 percent of the state's vehicle routes. Mud season, which once limited itself to tax time, now is plaguing drivers, hikers and loggers months earlier and weeks longer.

"Mud season came and went several times due to the warmer weather," the road crew in Danville, population 2,340, noted in this year's town report, "making our efforts even more challenging."

Summer heat

Rising temperatures also are redrawing plant hardiness zone maps used by Vermont's $3-billion-a-year farming sector.

The last official U.S. Department of Agriculture map in 1990 labeled the Northeast Kingdom as zone 3 (with annual lows of -40 to -30 degrees), the bulk of the state as zone 4 (with lows of -30 to -20) and the southern tip as zone 5 (with lows of -20 to -10). But this past year, the National Arbor Day Foundation released a new map showing the lows have grown higher: Vermont has lost its colder zone 3 up north, while the entire southern half of the state now sits in the warmer zone 5.

That's stretching the state's growing season and ability to harvest new crops. Vermonters who traditionally didn't farm and garden until Memorial Day now can plant peas in mid-April and tomatoes as early as the first of May and harvest until the first frost, which has shifted from September to October.

"To me, being able to grow things, being able to eat the vegetables we grow, all those things are very satisfying," says Dr. Alan K. Betts, a scholar of meteorology and theoretical physics who has gardened outside his Pittsford home for 15 years.

But the atmospheric researcher knows warmer summers aren't all sweetness and light. He and his colleagues say changing weather patterns are sparking more damaging downpours and droughts — and freak events like the fresh Brussels sprouts Betts picked from his garden one spring-like day this past January.

The heat also is harming wildlife. Rising temperatures are threatening cold-water fish such as brook trout — the state's most widely distributed and only native stream-dwelling trout — which require the high levels of oxygen found only in clear water measuring 50 to 65 degrees.

While nearly 14 percent of Vermont's watershed is deemed healthy for brook trout, another 63 percent has degraded because of warmer temperatures and other changing conditions, according to a new government study. A report by the U.S. Environmental Protection Agency says a 5-degree rise in average temperature could devastate trout and salmon populations nationwide and eliminate brook trout entirely in Vermont.

Birders say global warming is spurring more Southern species to migrate to Vermont — and threatening to scare away native flyers such as flycatchers, swallows and warblers that feed on gypsy moths, tent caterpillars and other plant-eating pests.

And entomologists are observing new insects, including ticks spreading Lyme disease northward, mosquitoes flying up with West Nile virus and several forms of encephalitis and plant-eating pests such as the hemlock woolly adelgid, a tree-munching troublemaker recently discovered in the southeastern corner of the state.

Autumn's fall

An old saying claims Vermont has more cows than people. But the reality is that trees trump them both: Forests cover almost 80 percent of the Green Mountain State. One in every four trees is a maple, and almost half of the Northeast's commercial woodlands are made up of maple, beech and birch.

But global warming may ax those statistics. Foresters say rising temperatures are attracting more pests and diseases, heightening the possibility of drought and air pollution and cutting into the habitat of traditional trees.

UVM researchers have confirmed those findings in a four-decade study on Vermont's most celebrated mountain, Camel's Hump.

Exactly 25 years ago, Hubert Vogelmann, then chairman of UVM's botany department, made national news by citing the research in a Natural History magazine article that, for the first time in a mainstream publication, revealed the effects of acid rain on the environment. Today, Vogelmann's son Thomas, who now heads the department, is helping the university continue the study — this time to search for signs of global warming.

Students are mapping hardwoods such as sugar maples, yellow birch and beech in the lower elevations and conifers including spruce and balsam fir in the higher ones. Comparing past and present findings, they have discovered the conifer zone had retreated 100 meters upslope. That distance — about the length of a football field — equals 8 percent of the peak's elevation.

The USDA Forest Service projects that oaks and hickories, which thrive in temperate zones like Virginia and now comprise less than 15 percent of Vermont woodlands, will overshadow the state's maples by the end of the century. That means leaf-peepers accustomed to the red, yellow and orange foliage of maple, birch and beech eventually could see the landscape shift to blander browns.

The fall timetable may change, too. It takes at least one or two hard frosts to kill the chlorophyll that keep leaves green in the spring and summer. That traditionally has happened well before tourists descended each October for the long, lucrative Columbus Day weekend. Now, in southern parts of the state, the chill is coming later and later.

Such changes are unsettling not only for leaf-peepers, but also for loggers and other locals tied to the state's nearly $1.5 billion forest-related manufacturing, tourism and recreation economy.

"The surprising thing is we're already seeing changes in the distribution of trees," Thomas Vogelmann says. "If we're already seeing changes, there are probably other things going on that we haven't identified yet."

Winter's melt

Global warming also is hitting Vermont's ski slopes. Snowfall has decreased 15 percent in the state over the last 50 years, records show. Average winter temperatures, meanwhile, have risen 4.4 degrees since 1970, shrinking the season by more than two weeks in the past half century. Such changes are threatening skiing, snowmobiling and snowboarding, which plow more than $2 billion a year into the state.

Vermont ski areas are spending $30 million a year to power snowmaking guns against the plight. But such machines only work if the temperature is low, and that's no longer guaranteed:

— Lake Champlain, for example, is freezing less frequently than in the past. Records show it has iced over only three times between 1990 and 2000.

— Residents in the Northeast Kingdom town in Danville, population 2,287, have made a ritual of guessing when Joe's Pond will melt. Fifteen years ago, it was May 6. In 2000, it was April 30. Last year, it was April 16, the earliest in recorded history.

Scientists predict those patterns will continue. According to a recent study by the Union of Concerned Scientists, Vermont's winter temperatures could rise anywhere from 5 to 13 degrees by the end of the century, depending on future emissions of carbon dioxide and other gases that cause global warming.

Higher temperatures may sound good for winter-weary Vermonters tired of heating bills and snow shoveling. But the federal government's New England Regional Assessment says the shift will affect much more.

"If 6 degrees F were added to Boston's 30-year average annual temperature (an average of 51.3 F between 1961-1990), the resulting temperature would approximate the 30-year annual average for Richmond, Va.," the assessment says. "If 10 degrees F were added to Boston's 30-year average, the 30-year average for Atlanta, Ga., (61.3 F) would result."

Researchers caution it is difficult to predict local and regional impacts because computer simulations have yet to analyze small areas reliably. But the Union of Concerned Scientists says winter precipitation could rise as much as 30 percent — mostly in the form of rain — while days when the ground is covered by snow may drop as much as 50 percent by the end of the century.

The future, the union says, will be determined by what people do now.

"If the rate of emissions is lowered," its latest report says, "projections show that many of the changes will be far less dramatic."

What to do?

When people envision a quintessential Vermonter of the past, they often point to Robert Frost, the late farmer turned official poet laureate of the Green Mountain State who ended his 1923 Pulitzer Prize-winning poem "New Hampshire" with the words, "At present I am living in Vermont."

When people think of someone who personifies the state today, they often cite Bill McKibben, the author and activist who lives in a solar-powered home on a small Ripton plot once owned by Frost.

The environmental scholar at Middlebury College is author of "The End of Nature," a 1989 bestseller and the first book about global warming written for a general audience. He's asking individuals to try hybrid cars (his Honda Civic hybrid, powered by a gas engine and rechargeable electric battery, gets more than 50 miles per gallon), compact fluorescent light bulbs and better building insulation.

McKibben also is pushing collective efforts through a new book (Holt Paperbacks has just released his "Fight Global Warming Now: The Handbook for Taking Action in Your Community") and a series of nationwide public rallies (the most recent effort last weekend featured hundreds of events in all 50 states).

McKibben's call: Governments must set goals to reduce carbon emissions.

At the federal level, Sanders has introduced the Global Warming Pollution Reduction Act — initially offered last year by his predecessor, retired U.S. Sen. James Jeffords, I-Vt., that calls for an 80 percent reduction in carbon emissions by 2050.

At the state level, the Governor's Climate Change Commission just released a report that says "the time for debate over the realities of global climate change is over" and "the reduction of carbon dioxide and other greenhouse gases and the activities that cause their emission will be the major challenge facing Vermonters in the years to come."

In the courts, Vermont made national news in September when a federal judge upheld a state law that calls for a 30 percent reduction in motor vehicle emissions by 2016. The ruling, the first of its kind in the country, could force automakers to improve average fuel economy to as high as 43 miles per gallon.

And in a case yet to be decided, Arthur Berndt, owner of the Maverick Farm in Sharon — one of the state's largest maple producers — has joined several citizens and cities in suing two federal agencies in U.S. District Court in San Francisco.

The plaintiffs — represented by the Burlington law firm of Shems Dunkiel Kassel & Saunders — charge that the Export-Import Bank and the Overseas Private Investment Corp. have contributed to carbon emissions by financing overseas oilfields, pipelines and coal-fired power plants instead of investing in alternatives such as renewable energy and efficiency projects.

Looking forward

When Scottish-born researcher Hector Galbraith moved to Vermont a decade ago, he had just begun to look for links between global warming and the changing environment. Such work has led him around the world. But he need only stand in his Dummerston backyard to see shifts.

Galbraith and other Vermont birders are reporting an increase in Southern species such as Carolina wrens and a decrease in native birds such as the Bicknell's thrush, one of 57 birds on the state Department of Fish and Wildlife's "Species of Greatest Conservation Need" list.

Such changes touch everyone, Galbraith says, because the world is woven together like one big nest. Birds don't simply sing and fly. They also pollinate plants, disperse seeds and eat insects such as the gypsy moths, tent caterpillars and eastern spruce budworms that can threaten woodlots and orchards.

"I'd be very surprised if we're not experiencing changes in amphibians in Vermont right now," Galbraith says. "Yellow-spotted salamanders are very sensitive to climate change. Trouble is, no one is looking for those changes, so we're not going to notice them until some big catastrophic shift whops us on the side of the head."

Galbraith stresses it's imperative for people to cut their fossil fuel emissions so as not to exacerbate global warming. But Vermont produces the least amount of greenhouse gases of any state (437,000 tons of carbon dioxide annually, compared with Texas' 290 million tons, the group Carbon Monitoring for Action reports). As a result, Galbraith says it's also essential that Vermonters explore what's already shifting.

"One of my concerns right now is that people think if we just stick a bunch of fluorescent light bulbs in and all drive a hybrid, things will be fine and we'll go back to business as usual. We've got to reduce emissions, sure. But even if we switched off everything right now, we're still looking at major impacts over the next 50 years. Mitigation is not enough. We've got to adapt to this."

Galbraith wants the state to take stock of what's in danger.

"Let's call it a vulnerability analysis, a real thorough appraisal of what species, resources and habitats are likely to be most sensitive and vulnerable to climate change. Until we arrive at that list, we don't really have any idea what we're going to monitor and what we should spend a lot of money trying to protect."

He cites brook trout as an example.

"Are they all going to go, or are we going to have some left at the higher elevations? Do we have rivers with dams where there should be a source of cool water for spawning habitat?"

Galbraith poses similar questions for the rest of the state's natural resources.

"Some things we can't adapt to — we're going to lose resources and there's nothing we can do about it. But what are the things we can do something about? What's vulnerable, how do we monitor it, how do we protect it? A lot of big brains live in Vermont. We could do this. The real question now is what the hell are we going to do?"