Changes in the Arctic will hit home
Researchers say conditions up north may affect rising sea levels and what we eat
We often hear that climate change is radically reshaping the Arctic, a place many of us have never visited. As a result, it can be pretty hard to feel directly affected by what’s happening up in a distant land of polar bears, ice floes and something odd called permafrost.
A new booklet from the National Academy of Sciences’ National Research Council (NRC) in the U.S. wants to change that. Synthesizing much past academy work on the Arctic region, the booklet blazons this message: “What Happens in the Arctic Doesn’t Stay in the Arctic.”
Here are four potential ways, drawing both upon the new report and much reporting by the Washington Post, that changes in the Arctic will reverberate well beyond it and, in some cases, have planet-wide consequences. 1. Changing your weather This is controversial, but there is growing scientific research backing the still-contested conclusion that changes to the Arctic are leading to changes in weather in the mid-latitudes. The basic idea is that a warmer Arctic plays games with the jet stream, the stream of air high above us in the stratosphere that carries our weather and that is driven by temperature contrasts between the mid and high latitudes.
If the Arctic warms faster than the mid-latitudes do, then the jet stream could slow down, goes the theory. It could develop a more elongated and loopier path, leading to a persistence of particular weather conditions such as intense snow, heat or rain.
A recent study published in the journal Science found that a more wavy and elongated jet stream in the summer “has made weather more persistent and hence favoured the occurrence of prolonged heat extremes.” 2. Changing what you eat The NRC booklet notes that warming oceans could have a substantial effect on the fishing industry, which prowls the Arctic and sub-Arctic for a crucial part of its catch. “About half of the U.S. fish catch comes from subarctic waters,” notes the report.
A less-icy Arctic may open new routes to fishermen and fishing boats, but, at the same time, the composition and distribution of species could change with warming waters. “In the North Atlantic, for example, scientists project that ocean warming will cause shifts in the spawning and feeding grounds of several economically important fish populations, including Arctic cod, herring and capelin.” 3. Rising sea levels The melting of ice on land in the Arctic — whether from glaciers and ice caps in the Arctic, or the Greenland ice sheet — contributes to sealevel rise that does not stay in the Arctic, but rather spreads around the world. Greenland is of course the biggest potential contributor, because if it were to melt entirely, it would cause six metres of sea-level rise.
And there’s also a less-known Arctic contributor to sea-level changes: the way polar melting could weaken the great overturning circulation of the oceans.
There is suggestive evidence that the melting of Greenland is already contributing to a freshening of the waters of the North Atlantic. This, in turn, may be slowing down the socalled Atlantic meridional overturning circulation, which carries a tremendous amount of warm water northward in the Atlantic.
If the circulation weakens, then it affects sea level on either side of it. That’s for two reasons: Warmer waters lie to the east of the Gulf Stream, and warm water expands and takes up more area, leaving the sea level lower on the U.S. coast side of the circulation. A weakening would thus raise our sea level. 4. Worsening global warming itself Finally, changes in the Arctic are expected to amplify global warming itself. The principal way this could happen is through the thawing of frozen ground or permafrost, which covers much of the Arctic.
Recent scientific analysis has affirmed that Arctic permafrost is packed with carbon — some 1,330 gigatons worth, and that may be a low estimate — and that over the course of the century, a substantial fraction will get released to the atmosphere.