THE BIG CHILL

IMAGINE AN ENVIRONMENTAL challenge to the Adirondacks harsher than acid rain, invasive species and global warming combined. Imagine something that would not merely damage every lake, forest and meadow but completely crush them, then grind and bury their remains under a mile-thick slab of sealant. Imagine the entire region looking as flat and featureless as a parking lot for tens of thousands of years, then like a gritty demolition site for centuries more. Incredibly, it actually happened here, not just once but dozens of times in the not too distant past

I’m referring, of course, to an ice age.

The global warming we are experiencing today is unusual not only because we are its main cause, but also because it runs counter to a general cooling trend over the last 50 million years or so. By two or three million years ago, the Arctic was occasionally cool enough to allow leftovers from each winter’s snowpack to persist through summer. Slow cycles in the tilt, wobble and orbit of the Earth amplified that summer cooling over millennia until the lingering drifts grew into two gigantic mounds that covered Baffin Island and Labrador.

Gradually thickening to hundreds, then thousands