Seeing is believing
Environmental signs of climate change
BY PETER B. BRACE

Third in a Series Embedded in Nantucket's muted autumn mosaic is the shiny red glow of the ubiquitous poison ivy plant, seemingly single snarled, snaking vine blanketing the understory of our entire island.

Eradication of this plant, which causes itchy red blistering rashes on the skin of those susceptible to its poisonous urushiol oil, is accomplished by digging out the entire plant, roots and all.

Get ready for the bad news: global warming is good news for this noxious weed.

Now in its sixth year, a study being done by a team of researchers led by Jacqueline E. Mohan, a postdoctoral scientist at the Ecosystems Center of the Marine Biological Laboratory in Woods Hole, revealed that this prolific vine thrives on carbon dioxide.

According to a story by National Geographic, Mohan and a team of researchers pumped CO2 out through a system of pipes in a forest near Chapel Hill, N.C., and built atmospheric CO2 to 200 parts per million higher than existing conditions. The researchers discovered that poison ivy grew 150 times faster and intensified the strength of its urushiol oil.

"That was a bit of a surprise," Mohan told National Geographic. "It was not actually producing more of the carbon compounds, but producing a more poisonous form."

THE CLIMATE GAME

The signs of climate change over traditional quirky weather events appear to be growing in frequency. Milder winters followed by delayed, drenching, colder springs, summer pushing well into fall and warm fall weather in November and December speak to potential climate change on Nantucket.

Tropical ocean species have washed into Nantucket waters, and water temperatures in the harbor approached the low eighties last summer.

Birds, ever the indicators of weather patterns, offer signs of climate change with several species staying longer than normal during the year and new species showing up.

"It's not really accurate to try to tie in the effect of any one day or season to the effects of climate change," said William Babcock, a meteorologist at the National Weather Service forecast office in Taunton, Mass. "Climate is a football game and this winter is just one possession. The fact that we had the very, very warm temperatures in the early part of this season is not a good indicator. What you have to do is look at, say, the last 30 years."

Less tangible is the prospect of rising sea levels. Anyone with a sense of island geography can imagine what Nantucket might look like if some estimates are correct and sea levels increase three to six feet by 2100, although a more conservative estimate puts the increase in 93 years at 2.3 to 4.6 feet, according Dr. Sarah Oktay, director of the UMass Boston Nantucket Field Station.

Weather on Nantucket directly affects tourism, recreational and commercial fishing, travel to and from the mainland, outdoor activities and heating costs, among many other aspects of island living.

It is only natural, then, to prognosticate and predict with our own cause-and-effect beliefs. Babcock said that all island meteorologist wannabes need to take a longer view before pointing their fingers at the tempting scapegoat of the moment - global warming - as the catchall for weird island weather.

"Some people are on the bandwagon, some people need a higher level of research to see it," said Babcock. "In the scientific community we want to see the result before starting to wave the flag and say this is happening. We want to be responsible and want to be able to be right when we say something, and to be right we need to have the data to back us up. Any one year, however anomalous, is not enough proof."

According to Beth Daley in a Jan. 28 story, "Winter warm-up costing N.E. region" in the Boston Sunday Globe, the average annual temperature in New England rose two degrees Fahrenheit in the last 100 years.

On Nantucket, despite Babcock's grounding statements, some strange stuff is going on.

In the last three years, June, typically a summery month, has been relatively cool and wet, with summer not making its appearance until early July. Summer now seems to last well into September and fall feels milder. Remember those 60-degree days near the end of November? On Christmas Stroll Saturday last year, Dec. 2, the mercury climbed to 59 degrees Fahrenheit, according to historical data compiled by Weather Underground. Little or no snow fell at Stroll in the last seven years over which time the average high temperature for Stroll Saturday has been 42 degrees Fahrenheit.

In Nantucket Harbor, water temperatures only recently dipped below 45 degrees Fahrenheit, said Town Biologist Keith Conant. A mere trace of snow has fallen on island thus far this winter.

"We're seeing a change in the growing season," said Oktay. "We're definitely getting more poison ivy on

the island." I

Next installment: Part 2 of environmental impacts