By Maureen Kelly

Across the Northeast, nature is changing in subtle ways. In Long Island Sound, for instance, blue crabs—a warm-water species—are now appearing where cold-water lobsters were once more abundant. It is a shift of habitat range, which some scientists attribute partly to warming waters in the Sound. In New Hampshire, the maple-tapping season is starting earlier because of the overall trend toward warmer and shorter winters. At the same time, the weather is becoming more volatile. This past year, the northeastern seaboard experienced record-breaking cold snaps and snowfalls, severe ice storms, flash flooding and a Category 2 hurricane that left disaster in its wake. Many experts, who attended a symposium in Boston this spring, believe these signs are precursors to more dramatic alterations in the natural environment and more extreme weather to come.