by Janet A. Ginsburg

It is hard to argue with global warming on a sunny, 50-degree, early January day in Chicago. It is hard to miss shivering, or excavating a car buried in snow, or walking with eyes cast downward to better navigate the icy patches. A year ago, I trudged up Michigan Avenue bundled three layers deep, a Polartec princess with frost-fogged sunglasses. Today my coat is open and my hat is in the closet.

Winter isn’t completely without its charms. But as glorious an arctic vision as Lake Michigan frozen to the horizon may be, or the city covered in a clean quiet blanket of white, or even soap bubbles shattering in wind-chilled below-zero air (a seasonal amusement for the truly desperate), this is so much…easier.

Whatever is behind the season’s oddly pleasant temperatures – a warming planet, an El Nino bonus, or a combination of the two -- it doesn’t take much to make a big difference.  Heat up surface waters in the Pacific by a few degrees and cherry blossoms bloom months early in Washington DC, while giddy New Yorkers celebrate in t-shirts on an unexpected 70-degree day. And yet in India, people are freezing to death, while drought threatens Australia and Canadian ski resorts are shutting their doors -- all from the same shifting weather patterns.

Other changes go beyond the simple measurements of thermometer and rain gauge. Polar bears are literally skating on thin ice, about to be listed as an endangered species in the Bush administration’s first admission that global warming -- in the form of rising arctic temperatures and melting sea ice -- is a serious problem right now. Without sea ice, bears can’t reach the seals they hunt to survive. While the bears are struggling, other species with more of a taste for warm weather are thriving and heading northward, expanding their ranges. Armadillos have marched from Texas to Illinois, while possums have crossed the border into Canada.

Insect-borne diseases are also catching a break. Adult mosquitoes, for example, can survive a mild winter in a hibernation-like state called diapause. So can any viruses they carry. All it takes is a few nice spring days and both are back in business. A mosquito infected with West Nile in the fall can reawaken a killer ready for business in the spring.

Although the ice age glaciers melted at the end of the Pleistocene, technically, the Holocene, the epoch we’re in now, is an interglacial period. Over the last nearly 2 million years glaciers have come and gone at least 20 times. Which means enjoy the warm up while it lasts. Only 20,000 years ago, my neighborhood was under a mile of ice, and winter was pretty much a year round event, The land is still recovering, rising a little bit each year. The pace of climate change has accelerated, spurred on by significant amounts of man-made greenhouse gases (GHGs) accumulating in the atmosphere, but the warming trend has actually been underway for quite some time.

Plants and insects were the first to chase the retreating glaciers’ northward, followed quickly by birds that evolved elaborate migration patterns to take advantage of new summer mating grounds.  

Some say you can even hear echoes of the glaciers’ last hurrah in the songs of 17-year cicadas, which are found only in North America and only in areas where once there were glaciers. Although no one knows exactly how the 17 year cycle got going (almost all cicada species are either biannual or annual), it is known that cicadas only emerge from their netherworld nurseries when the ground is about 70 degrees – which these days in the Midwest and Northeast means sometime in July. It is just possible that small populations of particularly patient cicadas found themselves waiting years longer than usual for the ground to warm up during a period of glacial retreat. And maybe, just maybe, the epic wait reset their developmental clocks in a way that could be passed down to their descendants – who have carried on the tradition of counting to 17 ever since. Other than that, there is not much difference between standard 2-year cicadas and their 17-year cousins. 

No question about it, change is in the air. Which is why no matter what time of year, I keep a snow shovel, ice scraper, jumper cables, beach chair and beach bag in the trunk of my car. You just never know.