A decade ago, however, Richard Seager of Columbia University's Lamont-Doherty Earth Observatory and his colleagues produced an explanation for Europe's warmer winter that had nothing to do with the Gulf Stream. Seager's modeling study indicated that when the atmospheric jet stream, which flows around the earth from west to east, hits the Rocky Mountains, it begins to oscillate north and south. The oscillation produces winds that flow from the northwest over the western side of the Atlantic basin and from the southwest over the Atlantic's eastern side. The northwesterly winds bring cold continental air to the northeastern U.S., whereas the southwesterly ones bring warm maritime air to northwestern Europe.
In this view, it is not heat carried by the Gulf Stream that moderates the European climate. Instead heat that is stored off the shores of Europe, in the upper 100 meters of the ocean during the summer, is released to the atmosphere in winter when the southwesterly winds mix the surface ocean waters. In this scenario, the classic conjecture of Maury is incorrect: large-scale wind patterns directed by mountain ranges, plus local storage of heat by the ocean near Europe, set the temperature differences between the western and eastern sides of the Atlantic [see box on next two pages].
It is important to keep in mind that Seager's model simulations did not explicitly take into consideration the transport of heat by the ocean, a point addressed in a study released soon after Seager's by Peter Rhines of the University of Washington and Sirpa Häkkinen of the NASA Goddard Space Flight Center. They put forth a counterargument that offered some modern support for Maury's historical ideas. After examining archived sea-surface temperature data, the two oceanographers concluded that the amount of heat stored in the upper layer of the eastern Atlantic Ocean at the latitudes of northern Europe is enough to maintain mild air temperatures only through December of an average year. The additional heat required to moderate the climate over the remainder of the winter had to be imported from elsewhere. The most likely source: the northeastward-flowing Gulf Stream.
Measurements showed that at 35 degrees north latitude—roughly the latitude of North Carolina—the North Atlantic transports about 0.8 petawatt of heat northward, mostly by the Gulf Stream. Yet at 55 degrees north latitude—the latitude of Labrador in Canada—this poleward heat transport is negligibly small. Where does all the heat go? Rhines and Häkkinen suggested that it is released by the ocean into the atmosphere along the path of the Gulf Stream. The prevailing winds then carry the heat eastward, where it moderates the European climate. Rhines and Häkkinen essentially argued for Maury's Gulf Stream conjecture, and Seager argued against it, focusing on the role of the atmospheric jet stream.
In 2011 Yohai Kaspi, now at the Weizmann Institute of Science in Rehovot, Israel, and Tapio Schneider of the California Institute of Technology unveiled a third idea, based on novel numerical experiments of the atmosphere and the ocean. They suggested a degree of truth in both the Seager and Rhines scenarios but concentrated mostly on patterns of atmospheric pressure. Kaspi and Schneider's model indicated that the loss of heat from the ocean to the atmosphere along the path of the Gulf Stream where it leaves the U.S. East Coast generates a stationary, atmospheric low-pressure system to the east—on the European side of the Atlantic. It also creates a stationary high-pressure system to the west—over the eastern edge of the North American continent. For complex reasons, the net result of this pattern is that the stationary low-pressure system delivers warm air to western Europe via the jet stream's southwesterly winds, which pick up heat released all winter long by the Gulf Stream. The stationary high pulls in cold air from the Arctic, cooling eastern North America and increasing the contrast in temperature between North America and Europe.
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9 Comments
Add CommentThere are lots of palm trees in Scotland, and there seems to be a subtropical climate on some sections of the coast.
Reply | Report Abuse | Link to thisThe palm trees are apparently native or "wild" so it's not just an effect of people planting and nurturing them.
This has been attributed to the gulf stream's warming effect, and in this case, I think it's likely since the climate at least locally along the coast is subtropical, which is amazing at such high latitudes.
Just a general warming effect on the Atlantic would probably not generate a sub-tropical climate, although it would certainly have a moderating effect, so probably there is a combination, localized subtropical climates from the Gulf Stream, and a more generalized moderating effect on Western Europe as a whole from the generalized warming effect of the Atlantic with southwesterlies winds having a moderating effect. This would be responsible for the notorious London fogs, with fog developing from the southwesterlies humid winds off the western Atlantic, colliding with the cold continental air masses originating off the arctic and Siberia.
I lost interest in whose model said what, and don't care which model might be more correct (at least in some peculiar circumstances). Any wonder why there is little confidence in unvalidated climate models?
Reply | Report Abuse | Link to thisThe most obvious conjecture is that both the ocean and the atmosphere are dynamically involved in global thermal exchanges - effective climate models most likely must reasonably represent both (and any other contributing factors).
It is clear why the American public does not believe in climate warming and its effect: all science is in meters and centimeters, as well as in centigrade for the temperature. Since the American population can only think in archaic measurements, they are missing it.
Reply | Report Abuse | Link to thisIt is indeed an amazing event to hit the "North Wall" of the Gulfstream in your sailboat on an Atlantic Crossing. The boat makes odd popping noises as the hull and structure expand at differing moduli, the water changes from that North Atlantic black-blue to a more Pacific color, maybe with a bit of sargassum thrown in like an erstwhile Cajun stew; and wherein you suddenly find yourself sweating in the New England Sound jacket which was absolutely necessary even 2 hours prior. I would suppose that such an amount of thermal energy would have to step to Entropy somewhere. The Entropy of that Somewhere would also be changed.
Reply | Report Abuse | Link to thisThe “Old theory” as well as all of the “New Theory” explanations appear to involve the Gulf Stream in various ways and are not exclusionary. It seems likely that several of these effects will be found to apply and explain multiple mechanisms by which the original narrative remains essentially true.
Reply | Report Abuse | Link to thisSo true sir! When will the rest of the world come into the modernity of feet and inches, one wonders?
Reply | Report Abuse | Link to this(Truthfully, I have a heck of a time with the metric system, having lived in the US for 6 decades. Sure, I can do the conversions, but I don't have the same 'feel' for the length of an inch vs that of a centimeter).
I really enjoyed this very balanced article, and feel like I learned a lot.
Reply | Report Abuse | Link to thisIt was long enough to explain the theories and point out the pros and cons of each.
I am particularly happy to hear that the flow of the Gulf Stream is not in danger of disruption from the effects of global warming:
"Yet recent modeling studies with higher resolution of ocean currents suggest that fresh Arctic meltwater may pour mostly into currents that are more restricted to the coastlines and therefore have less influence on the open ocean, where downwelling primarily occurs. Even if freshwater significantly affected the amount of waters downwelled in the North Atlantic, it turns out to be highly unlikely that this change would effectively shut down the Gulf Stream. A shutdown is unlikely because the path and the strength of the Gulf Stream depend largely on the speed and direction of the large-scale midlatitude winds. In most climate change scenarios, the general direction of the large-scale winds does not change significantly as Arctic ice melts, so the general path and strength of the Gulf Stream do not change much either."
Ocean currents drive weather patterns. This is not the debate, the debate is over how big of role these currents will play in climate change. The effects of ice melt upon upwelling ocean currents is being examined here, but this article also states that data resources are lacking.
Reply | Report Abuse | Link to thisI feel it is critical to look at as many variables as we can to determine implications of Arctic and Antarctic thaw, or redistribution of ice in these regions. With more data in locally effected areas, areas where ice melt is impacting thermo-haline gradients in any measurable way, it would be easy to make vague statements about how Europe might change in climate because of the effected Gulf Stream.
It is much better to look at this in terms of atmospheric events along with ocean currents to model weather. It is also a big deal that the ocean, itself, is vastly unknown and the role of deep ocean currents for thing like nutrient turnover, salinity gradient, and climate stability may play a much larger part in all of this when compared to high and low pressure systems.
This is interesting. No doubt the specific heat of water is 4000 times larger than that of air, and 4 times larger than that of soil. The explanation assumes that water moves horizontally from one location of the earth to another. It overlooks the vertical movements up and down in the ocean. However, the ocean floor is not at the same temperature eveywhere. At locations where volcanic eruptions occur in the ocean bed, the warm water there could move upward (vertically), displacing the colder (denser) water mass above. It would be nice to consdier this geothermal effecct on top of the solar effect explanied in the ariticle. Just a thought. I could be wrong.
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