BRETTON WOODS, N.H. – Thick, hazy air and sweltering heat Friday at a conference for leading air quality and climate change experts bluntly hammered home their overall message: If global warming emissions are allowed to grow unabated, the Northeast can expect significant temperature shifts and other climate changes this century.

It was the first day of the two-day Mount Washington Symposium for Air and Climate inside the Mount Washington Hotel at Bretton Woods. The quality of information was such that minds were enlightened and eyes opened after only three of the event’s first 20 speakers shared what they came to say.

“Just because there may be some disagreement over whether or not global warming is real, that doesn’t mean we should do nothing,” Gary Newfield of Randolph, N.H., said after participating in a preconference field trip with two geologists and listening to Ronald G. Prinn’s PowerPoint presentation “Global Climate Change: Science, Economics and Policy.”

“The science is irrefutable – the earth is warming. It behooves us to do something about our carbon dioxide footprint. Even though there may be seeds of doubt, we still need to go toward energy independence,” Newfield added.

Using studies of natural heating and cooling cycles in New England from thousands of years ago and glacial evidence in the White Mountains, geologists Brian Fowler and Woody Thompson painted a different portrait of climate change than did Prinn, who dealt with it in decades and centuries.

Fowler is a geologist with the Mount Washington Observatory and Thompson is a geologist with the Maine Geological Survey in Augusta. They led a half-day trip to several places in nearby towns to examine geological features that have led to new interpretations of glacial events in the White Mountains, and how these features relate to climate fluctuations in the North Atlantic region.

Prinn is the professor of atmospheric science with the Department of Earth, Atmospheric and Planetary Sciences and director of the Center for Global Change Science, both at Massachusetts Institute of Technology in Cambridge, Mass.

Whereas the geologists’ talks dealt with natural climate change, Prinn said today’s greater-than-normal climate change is predominantly driven by humans.

“Temperatures today are at the highest they’ve been in the last 1,200 years,” Prinn said to about 100 people. “Growing concentrations of greenhouse gases like carbon dioxide is the significant cause of climate change. 1998 and 2005 had the highest temperatures ever recorded. If the North Pole warms by 12 degrees Centigrade, I assure you, Greenland is gone.”

He was talking about the dangerous buildup of ozone, aerosols, methane and other gases that are causing scientists to worry about the stability of the West Antarctic ice sheet, melting glaciers and rising sea levels. If Greenland goes under, he said that means the sea level has risen by 38 feet.

“It’s not going to happen, ‘Bang!’ instantaneously, but maybe over 30 or 40 years,” he said, if nothing is done to lower the demand for energy or better manage energy use.

“The Northern Hemisphere snow cover is starting to decrease. Less snow cover means more sunlight being absorbed by the earth rather than reflected. Sea ice, once it melts, you replace a reflector with an absorber and that accelerates heat, which depletes the Arctic of summer sea ice,” Prinn said.

That’s why the world is facing a growing conflict between environment and development, he stated in an abstract of his talk.

“The climate issue exemplifies the challenge. Climate change is a century-scale threat requiring a centurylong effort in science and policy analysis, and institutions that can sustain this effort over generations,” he said.