Naila Moreira: A world overheating not just in temperature, but in its very structure



Last modified: Wednesday, January 13, 2016

NORTHAMPTON — About a year ago, I saw three deer running across the Connecticut River. They weren’t walking on water: the river had frozen, thick enough to support their lightly tripping hooves. Last winter, Bostonians got so much snow they called it the Snowpocalypse.

This December, I saw a deer again, but it stood on the Connecticut’s bank, its head dipped, drinking. Three kayakers paddled slowly towards it. I stood with my bicycle on the bike trail, clad only in a sweater. Outside my office, that morning, I’d seen a cherry tree putting out hesitant, puzzled white flowers – flowers that wilted and turned a wrinkled brown with the New Year’s cold snap that finally plunged us into the winter weather we’d been expecting.

We live in New England. Things change here. “If you don’t like the weather in New England,” Mark Twain wrote, “just wait a few minutes.”

I tell my students at Smith College that I’m not surprised that many people struggle to believe in climate change. But everyone knows flowers in late December are, to put it mildly, not normal.

Each spring, I teach a course called “This Overheating World.” Officially, it’s a course on climate change, named after a Granta magazine issue of the same name. But I also talk with my students about the many different ways the world is heating up around us, building pressure like a corked, shaken bottle.

Overdevelopment.

Species extinction.

Increasing population.

Growing inequality.

And most of all, the temperature, that keeps rising, and rising.

But as global temperature goes up, not every region will see consistently warmer weather. In New England, both this year’s steamy December and last year’s icy blasts, perhaps surprisingly, can be attributed at least in part to climate change.

One key lies in the jet stream – fast-moving, west-to-east currents of air that form between warmer and colder zones. The polar jet stream separates Arctic air from more southern climes, and, in winter, usually approaches New England, shifting sometimes north, sometimes south of us.

Climate change has warmed the Arctic faster than southern latitudes. Because jet streams are fueled by temperature differences between north and south, as that difference declines, the polar jet stream slows down.

A slower jet stream makes for a weaker boundary between air masses, allowing cold Arctic air to seep south more easily. It also lets storm systems linger in one place for longer, dumping copious snow.

That was last year.

This winter, a strong El Niño was largely responsible for the crazy-warm Christmas. El Niño, a weather pattern driven by the Pacific Ocean, happens every two to seven years, and isn’t created by climate change.

During El Niño, the eastern Pacific Ocean experiences unusual warming at its surface, heating the overlying atmosphere. The moisture-laden air rises, changing atmospheric circulation patterns. These changes shoved the polar jet stream well into Canada, helping bottle cold air farther north.

Climate change doesn’t cause El Niño, but it made the air south of the jet stream much hotter than it used to be. Worldwide, 2015 was so much warmer than previous years that scientists announced the global record broken weeks before the year’s end.

Also, some research suggests a warmer world will intensify El Niño, though scientists still disagree on whether this will occur. The last 20 years have seen stronger El Niños. And while only circumstantial evidence links the strengthening to climate change, this winter’s El Niño has been the strongest ever recorded, according to Michael E. Mann, climatologist at Pennsylvania State University.

“What global warming does in general is make extremes more extreme,” says Stephen Gregory, a weather risk consultant with WeatherIntel Services. While no single event can be blamed on climate change rather than chance, he said, “personally, it’s hard for me to believe this isn’t reflective of global warming,”

The latest cold snap, Gregory explains, is due to a new large weather system moving across the Pacific, disrupting El Niño — possibly only temporarily — and pushing an S-shape into the jet stream that pulls cold air over our region.

But in the end, it hardly matters. Too warm or too cold — for me the upshot is the same. This is no longer the New England of my memory.

Over Christmas, like many people, I traveled to visit my parents. At my childhood home in New Hampshire, I went walking down by the old forested patch I used to love, where as a girl I wandered at my leisure under the trees. I remember bounding through knee-deep snow as blobs of white fell from the pine boughs overhead.

This year, everything had changed.

Now, the forest is mostly gone. Several huge condo complexes have gone up, and an office park, and a new motel. Bike trails wind through what scraps of woodland remain beside asphalt parking lots. Torn-up soil betrays where more buildings will soon rise.

And then there was the heat. “I’ve never seen it like this,” said a lady I met walking her dog. “Not in 25 years of living here.”

The world of my childhood, with its winters, its woodlands, its slower pace, has gone. No Paris climate-change summit will bring it back to me.

I teach my students, who never knew New England as I knew it. I try to convince myself I’m making a difference by helping them understand the ways their world is changing.

A world overheating not just in temperature, but in its very structure: our society, our development,our growth, our fears; and their future.

Their overheating world.

Naila Moreira is a writer and poet who often focuses on science, nature and the environment. She teaches science writing at Smith College and is the writer in residence at Forbes Library. She’s on Twitter @nailamoreira.




 


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