By Amy Chapman

By the turn of the next century, Maine’s climate will approximate that of present-day New Jersey.

“We really can’t sit around waiting for a lifetime before we deal with this,” said Maine State Climatologist Dr. George Jacobson, in his presentation, The Changing Nature of Climate: Climate Variability and Maine Ecosystems. “I know we can solve these challenges, but we shouldn’t wait too long to get started.”

Jacobson delivered that message to a packed auditorium at Gould Academy’s McLaughlin Science Center last week. His presentation was the fourth in the Mahoosuc Land Trust’s Changing Nature series.

Jacobson is a Professor Emeritus of Biology, Ecology, and Climate Change. For 35 years, he has been affiliated with the University of Maine’s Climate Change Institute, the first climate research institute of its kind in North America.

Several years ago, the CCI was asked by then-governor John Baldacci to assess Maine’s climate in the twenty-first century and to predict the effects of climate change over the next hundred years on forests, lakes and streams, and the Gulf of Maine.

Maine is unique in terms of climate variability, Jacobson said, because it encompasses six different plant hardiness zones within just four degrees of latitude from north to south.

This is the same variation in zones that occurs between northern North Dakota and southern Kansas. Jacobson said the same climate gradient that exists in Maine’s four degrees of latitude occurs over 20 degrees of latitude in Europe, a distance equal to twice the length of California.

“This climate variability is one of the reasons we have such diversity of plants and animal life in the state. We can drive an hour or two and be in someplace so different.”

In response to Baldacci’s request, Jacobson assembled a group of about 75 volunteer colleagues who were willing to share their expertise. They included biologists, geologists, archaeologists, oceanographers, and computer scientists. Their report, “Maine’s Climate Future,” was released in 2009.

“We based our estimates of the changing climate on a conservative scenario,” he said. “We made a hopeful assumption that there would be some progress in reducing emissions. Even with that middle range set of emissions, [by 2100] the climate will be about seven to ten degrees warmer all over the state of Maine, in all parts of the year.”

That increase in average temperatures, Jacobson said, means that by the end of the twenty-first century, our climate in Maine will be similar to current conditions “well south of Connecticut.” Estimates are that sea levels will rise by at least one meter, and possibly by as much as two meters, over the same period.

Five hundred billion metric tons of carbon have been added to the earth’s atmosphere since 1850 as a result of the use of fossil fuels, and half of that amount has been added in just the past 25 years. Projections from recent studies show that carbon dioxide levels, which recently passed the 400 parts per million threshold, will rise to between 550 and 900 parts per million by 2100, depending on what steps are taken to counteract the rise.

“In my lifetime, I certainly have noticed changes, and I’m sure some of you have, too,” Jacobson said, citing earlier average dates for ice-out and peak spring run-off. He also noted that in the early twentieth century, it was not unusual for many of New England’s ocean harbors to freeze over in the winter, adding, “the last time Penobscot Bay froze over was in the winter of 1934-35.”

“Maine’s economy is strongly tied to the natural resource base,” he said. Warmer temperatures and a longer growing season will likely mean that some species of trees and other plants will no longer thrive in Maine, but will be replaced by other species.

Jacobson said the rapid increase in the world’s population has accelerated the rate of climate change. Every five days, the world population grows by a number equal to the population of Maine. Every year, 40 million people—the equivalent of two Californias, or two Canadas—is added.

“All of those people need to be fed, and have places to live, and of course, they all want to be able to plug in their iPads,” he said. “We can’t think about carbon, and fossil fuel, without realizing that the number of people using our resources has something to do with it.”

“I do not have an answer,” Jacobson said. “But I am optimistic, believe it or not. Humans are incredibly creative, and good at solving problems. We just need to apply ourselves, and figure it out.”

In October, the CCI will host a one-day workshop at the University of Maine on “Climate Adaptation and Sustainability.” The focus will be on planning for the inevitable changes to come and adapting to them.

The full CCI report, “Maine’s Climate Future,” which contains the information and graphs on which Jacobson based his presentation, can be downloaded from the Climate Change Institute’s website, http://climatechange.umaine.edu