Another Life Michael VineySome landscapes are better than others for contemplating the apocalypse. Or, rather, seascapes, since it's on the whim of the ocean that an awesome paradox of climate change could depend - snowstorms where we thought we would get grapevines; icicles draped down the Dublin Spire.
All this is more easily imagined on a glaciated hillside in January, looking out over snow-white surf to bleak islands and chill Atlantic swells. It doesn't take too much post-New Year angst to see icebergs nudging past Inishturk, just as they were doing 12,000 years ago.
How seriously do I take the possibility that global warming, now flooding the Arctic with fresh water from melted ice, could switch off the saline oceanic "pump" that draws the warm Gulf Stream north? The very idea of Western Europe freezing hard in winter while the planet as a whole is warming up seems one bizarre scenario too far - even part of what the good senator from Oklahoma, at last month's climate conference in Milan, called "the greatest hoax ever perpetrated by science." In the senator's view, scientists have invented the perils of global warming to boost their research budgets. He might be especially sceptical, then, about support for the prospect of a "little ice age" that emanates from the Woods Hole Oceanographic Institution on the coast of Massachusetts.
Established in 1930 with a few million dollars from the Rockefeller Foundation, Woods Hole has become the world's biggest independent oceanographic institution and a byword for research across the Atlantic basin. The Woods Hole director, Dr Robert Gagosian, backed by his senior scientists, decided a year ago to "throw a curveball" into theories of a gradual global warming. There is already enough evidence of abrupt, dramatic shifts in climate in the thawing of the last ice age (this from fossils in ocean sediments and the ancient Greenland ice-cores).
The swings back to cold were caused when meltwater overwhelmed the dense saltiness of the Gulf Stream and stopped its crucial sinking to the ocean floor, part of the great conveyor belt of ocean circulation.
Now, says Gagosian, we know that all this could be happening again, as man-made global warming melts the Arctic ice. In the past 40 years, the saltiness of the North Atlantic has been steadily declining, and especially within the past decade. This, he says, is "the largest and most dramatic oceanic change ever measured in the era of modern instruments". He fits it into a scenario that threatens abrupt climate change, perhaps in the space of a decade, in which average winter temperatures could drop by five degrees in the north-eastern US and in Europe.
That's enough, as he says, "to freeze rivers and harbours and bind North Atlantic shipping lanes in ice". So far, the influx of fresh water has been mixed through the ocean, down to 4,000 metres. When it begins to pile up at the surface, the pump could slow down or switch off. But just what the critical threshold is, Woods Hole has no idea. The ocean's role in storing heat and influencing climate is clearly profound, but only lately has it begun to receive proper study.
Atlantic weather, too, is heavily influenced by changes in atmospheric pressure linked to a cycle of warm and cold currents. But there are only three sites in the whole North Atlantic which keep a regular record of deep-sea temperatures, and there has been no continuous monitoring of crucial salinity in this, the saltiest ocean of the world.
All this is changing, if somewhat late in the day. I shall be watching the shore for any long yellow cylinder cast up at the tideline. If it has an aerial on top, I shall know it as one of the 1,200 "Argo" floats now set adrift in the oceans, and notably in the Atlantic, as part of the Global Ocean Observing System. They are like weather balloons for the ocean, drifting for 10 days at up to 2,000 metres deep and then rising to the surface to report profiles of temperature and salinity to a satellite - a cycle repeated 150 times or more.
Among scientists using the data will be those of the new Environmental Research Unit at NUI Cork. As Prof John Davenport told students last autumn, trying to decide if Ireland is more likely to freeze than to bask in a Mediterranean warmth "is an example of environmental science at its most global, difficult and intellectually exciting". You can see where the Argo floats are now at www.argo.ucsd.edu.
For the Woods Hole papers, see www.whoi.edu and search for "abrupt climate change". Gagosian also figures among articles offered at an Irish site, www.winterolympics2026.com/globalwarming.htm.