Far in the NE Atlantic halfway between Iceland and Scotland sits a small group of islands known as the Faroes or Faroe Islands. The islands have been inhabited for over 1000 years since Vikings from the west coast of Norway first settled down there. For centuries sheep farming was a major source of livelihood, supplemented by grain and other supplies through trade with Norway. In the last hundred years or so, fishing has steadily grown in importance and comprises today by far the greatest source of activity and income to the islands. Indeed, the waters around the Faroes are immensely productive because they are both warm and nutrient-rich thanks to the warm waters flowing past the islands from the North Atlantic into the Norwegian and Greenland Seas, more generally known as the Nordic Seas.
The Faroes, along with Iceland, straddle a major underwater ridge between Greenland and Scotland that traps the deep waters of the Nordic Seas from the larger North Atlantic and the rest of the global ocean. This geological feature plays a key role to the mild climate of Europe and by extension the high latitudes of the Northern Hemisphere. The reason is that when the warm and salty North Atlantic waters lose their heat to the atmosphere while remaining saline, they sink to great depths in the Nordic Seas and become amongst the densest waters in the world. These deep waters fill the Nordic Seas up to the level of the deep sills of the Greenland-Scotland ridge, across which they spill and flow out into the deep North Atlantic and beyond. This overflow of dense waters continues year after year thanks to the production of new deep waters through cooling in the Nordic Seas each winter. It is this continual overflow or spill that maintains the demand for more warm saline water into the Nordic Seas from the North Atlantic. The high salinity of the North Atlantic Waters plays a central role here. Were they not sufficiently saline, the waters spilling into the Atlantic would not sink to great depths and would instead remain in the North Atlantic south of the ridge resulting in a local instead of global exchange. Unless these waters flow out into the deep global ocean, there would be no demand for warm, salty waters from low latitudes, leading almost certainly in a much cooler climate for northern and central Europe.
In recent years we have read much discussion about the possibility that global warming could disrupt this deepwater production through increased ice melt in the Arctic Ocean and from run-off from the Greenland ice-mass. The threat is easy to understand: the added fresh water would reduce the salinity of the waters such that they would no longer sink no matter how much cooling (they would freeze instead). If they don’t sink, there will be no demand for more water from the North Atlantic leading to falling surface temperatures and a cooler climate as a result. This shutdown of what oceanographers refer to as the ‘thermohaline’ circulation was the basis for the dramatic climate-change film ‘The Day after Tomorrow’. While the above scenario is conceptually simple, it is by no means clear whether and how such a shutdown might take place, indeed whether the supply of fresh water is large enough and can be delivered to the right place to cause a significant change. We can speculate about these things as much as we like, but in order to establish some certainty to these concerns, it would help to have an early warning system, some means of detecting a possible change or decrease in the strength of flow of warm waters into the Nordic Seas.
The location of the Faroes on the ridge is propitious in this context because almost all warm waters flowing north into the Nordic Seas flow past the Faroes, some between the Faroes and Scotland and the remainder between the Faroes and Iceland. Further, a large fraction of the waters spilling back into the North Atlantic do so in the deep sills around the Faroes. It comes therefore as no surprise that oceanographers from the Faroes, Norway, Sweden and other countries have been collaborating to monitor the deep outflows for any change that might foresage a change in climate over northern Europe and Scandinavia. If any decrease in inflow into the Nordic Seas were to develop, the waters around the Faroes will be the ones to watch for such change. This is why some of us like to think of the Faroes as the ‘Canary of North Atlantic Climate Change’.
(This was originally published as a letter to the editor of the Providence Journal.)