Sunday, January 16, 2011

Climate Change Atlantic Ocean Current Wind Change Portends Cold NE and Europe

Tags: Climate Change Gulf Stream Slowing Down Antarctic Currents Cold Arctic Winds Melting Glaciers Cold Europe

Most weather forecasts on television are explained by journalists who took a two week course in meteorology and passed a test. A local ABC station in Eugene has three BS degreed meteorologists who tell us that weather forecasts beyond three days is dangerous. Then we have the farmer’s almanac specifying the exact date of weather events. We only hear about the ones where their predictions came true.

Seasonal weather experts predict weather for profit. One was a weather forecaster for CBS and then he went into the profitable business of making forecasts for farmers and hedge funds. Dr. Judah Cohen, PhD, with impressive credentials at MIT and Columbia where he got his PhD in Atmospheric Science, penned a very popular explanation for a cold East Coast and Europe after it happened. He is one of these seasonal predictors of the weather for profit.

Judah Cohen, NY Times, Dec 25, 2010,… In winter, this change in flow sends warm air north from the subtropical oceans into Alaska and Greenland, but it also pushes cold air south from the Arctic on the east side of the Rockies. Meanwhile, across Eurasia, cold air from Siberia spills south into East Asia and even southwestward into Europe.

That is why the Eastern United States, Northern Europe and East Asia have experienced extraordinarily snowy and cold winters since the turn of this century. Most forecasts have failed to predict these colder winters, however, because the primary drivers in their models are the oceans, which have been warming even as winters have grown chillier. They have ignored the snow in Siberia.

Below are several research papers which go beyond Cohen’s guesses about things already published so his explanations are not novel and my guess is inaccurate base on the articles below. I wrote a much more complex explanation based on La Nina effects which I decided not to put it in my blog because it is hard to understand.

Jim Kawakami, Jan 16, 2011, for more blogs on other topics.

Climate Change Why Cooler in Europe and East Coast Fits Warming Model or Not

The North Atlantic Current (North Atlantic Drift and the North Atlantic Sea Movement) is a powerful warm ocean current that continues the Gulf Stream northeast. West of Ireland it splits in two. One branch (the Canary Current) goes south while the other continues north along the coast of northwestern Europe. It is thought to have a considerable warming influence on the climate, although a minority have disputed this.[1] Other branches include the Irminger Current and the Norwegian Current. Driven by the global thermohaline circulation (THC), the North Atlantic Current is also often considered part of the wind-driven Gulf Stream which goes further east and north from the North American coast, across the Atlantic and into the Arctic Ocean.

It is suspected that global warming might have a significant effect on the current; see Shutdown of thermohaline circulation for details. …

Global Warming Cools Down Northern Atlantic Ocean Temperatures.

ScienceDaily (Nov. 17, 2010) — The overall warming of Earth's northern half could result in cold winters, new research shows. The shrinking of sea-ice in the eastern Arctic causes some regional heating of the lower levels of air -- which may lead to strong anomalies in atmospheric airstreams, triggering an overall cooling of the northern continents, according to a study recently published in the Journal of Geophysical Research.

"These anomalies could triple the probability of cold winter extremes in Europe and northern Asia," says Vladimir Petoukhov, lead author of the study and climate scientist at the Potsdam Institute for Climate Impact Research. "Recent severe winters like last year's or the one of 2005-06 do not conflict with the global warming picture, but rather supplement it." …

ScienceDaily (Jan. 15, 2011) — The unusually cold weather this winter has been caused by a change in the winds. Instead of the typical westerly winds warmed by Atlantic surface ocean currents, cold northerly Arctic winds are influencing much of Europe.

However, scientists have long suspected that far more severe and longer-lasting cold intervals have been caused by changes to the circulation of the warm Atlantic ocean currents themselves.

Now new research led by Cardiff University, with scientists in the UK and US, reveals that these ocean circulation changes may have been more dramatic than previously thought.

The findings, published January 14, 2011 in the journal Science, show that as the last Ice Age came to an end (10,000 -- 20,000 years ago) the formation of deep water in the North-East Atlantic repeatedly switched on and off. This caused the climate to warm and cool for centuries at a time.

The circulation of the world's ocean helps to regulate the global climate. One way it does this is through the transport of heat carried by vast ocean currents, which together form the 'Great ocean conveyor'. Key to this conveyor is the sinking of water in the North-East Atlantic, a process that causes warm tropical waters to flow northwards in order to replace the sinking water. Europe is kept warmer by this circulation, so that a strong reduction in the rate at which deep water forms can cause widespread cooling of up to 10 degrees Celsius.

Lead author Dr David Thornalley, Cardiff School of Earth and Ocean Sciences, explains how the scientists studied changes in ocean circulation: "We retrieved ocean sediment cores from the seafloor of the Northeast Atlantic which contained the shells of small organisms. We used these shells to examine the past distribution of radiocarbon in the ocean.

Radiocarbon is a radioactive form of carbon that acts like a natural stopwatch, timing how long it has been since water was last at the sea surface. This allows us to determine how quickly deep water was forming in the Northeast Atlantic at different times in the past."

The team of scientists found that each time deep water formation switched off, the Northeast Atlantic did not fill with water that sank locally. Instead it became inundated with water that had originally formed near Antarctica and then spread rapidly northwards. The new results suggest that the Atlantic ocean is capable of radical changes in how it circulates on timescales as short as a few decades. (Not mentioned is that current from the Gulf Stream has slowed by two-thirds off the UK. Jim)

Dr Thornalley said: "These insights highlight just how dynamic and sensitive ocean circulation can be. Whilst the circulation of the modern ocean is probably much more stable than it was at the end of the last Ice Age, and therefore much less likely to undergo such dramatic changes, it is important that we keep developing our understanding of the climate system and how it responds when given a push."

The research is funded through the Natural Environment Research Council's Rapid Climate Change programme and the National Science Foundation (USA). The Science paper The Deglacial Evolution of North Atlantic Deep.

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