the last in a series of lectures. When he boarded the Louis in Resolute, he’d brought with him, in addition to Erin Freeland-Ballantyne, a number of supernumeraries whom he referred to as VIPs—luminaries of oceanography, all dressed, like him, in matching fleece cardigan vests onto which was embroidered the logo of this expedition—the C30 project, Carmack had called it, for Canada’s Three Oceans. His idea for the second leg of our voyage was to turn the Louis into a kind of icebreaking, traveling oceanographic lyceum.
During the lectures the VIPs delivered, I learned many interesting facts—for instance, that in the “microbiome” of the human body, only a portion of our cells, genetically speaking, are human in origin. The rest are bacterial. (While learning this, I found myself looking down, examining my midriff, into which, in the main mess, I’d recently deposited some potatoes, carrots, and buttery cod. The cloth between the buttons of my quick-dry adventure shirt was puckering over the waistband of my quick-dry adventure pants in an unflattering way, and I tried to smooth the puckers flat.) I learned that herring are shrinking but also that eighty-two “jumbo squids” had recently been caught in Canadian waters, and that these squids were members of an invasive, southern species. (To my mind this didn’t sound so bad—less herring, more calamari.) I learned that approximately every ten years the prevailing winds of the Arctic shift, a phenomenon known as the Arctic Oscillation, and that this wind regime plays a role in the movement of ice.
In the main lounge of the Louis, Carmack stood before a screen onto which a computer projected various slides. The computer also projected slides onto Carmack. As he paced back and forth over the carpeting, rocking in his mocassins, knitting and unknitting his fingers, smiling his sphynxlike smile, maps and diagrams played across his plaid shirt and jeans and cardigan vest, and made the lenses of his little spectacles shine.
Around five million years ago, Carmack told us, the Isthmus of Panama, without the efforts of Teddy Roosevelt, had been a strait, conducting equatorial currents freely between the Pacific and the Atlantic. Only after the Isthmus of Panama closed, and deflected the currents in both the Pacific and the Atlantic, did the oceans come to resemble the oceans of today, “with high-pressure centers in the subtropics and low-pressure centers in the subarctic, and clockwise currents traveling around the subtropical gyres and counterclockwise gyres flowing around the high latitudes north of the subtropical front.” Over the past five million years, two distinctly different kinds of oceans had formed.
There is on the one hand the ocean most of us have heard of and thought about. The one we like to go bathing in, on the beaches of Coney Island or Costa Rica or the Côte d’Azur. This is the “thermally stratified ocean,” where variations in temperature and salinity and therefore in density make layers of water mingle and move. Then, on the other hand, there’s the northern ocean, which is “permanently stratified by the accumulation of freshwater.” Much of the freshwater—sixteen thousand cubic kilometers of it or so per year—comes from the comparatively fresh currents that flow into the Arctic from the Pacific through the Bering Strait. Another thirty to forty thousand cubic meters or so come from the northerly rivers of Canada and Siberia and Europe. It was thanks to the freshwater as much as to the low temperatures (1.7 degrees Celsius, last I checked) that right now, in the middle of July, through the closed curtains of the Louis’s main lounge, the creaky thunder of crumbling ice—six feet thick and stretching from shore to shore and riddled with seal holes and stalked by bears—could be heard.
The northern ocean, Carmack emphasized, is connected to the “global ocean” by subtle currents and winds. In fact, the climate as we know it depends on those currents and winds, which transport excess heat away from the equator, to be released back into space at the poles. And the subpolar front, the boundary between “these two counterrotating gyres”—the boundary along which sixteen years ago twelve containers tumbled overboard, along which bath toys had traveled to Sitka—“acts as a bit of a wave guide for storm tracks.” The weather in Myanmar as in Manhattan is the consequence, in other words, of the Isthmus of Panama and of those currents circling and spiraling through time and space, currents that with alarming swiftness, as the Arctic warms, are changing in measurable if not always visible ways.