A climatic domino effect that began in Egypt 30 years ago could result in a new ice age by the 22nd century, concludes the research of University adjunct geology professor Robert Johnson.
Dams in Egypt, in addition to global warming trends, have contributed to a saltier Mediterranean Sea, which in turn could change the flow of Atlantic Ocean currents, chilling the entire Northern Hemisphere and plunging the planet into a glacial ice age.
The solution proposed by Johnson: a partial dam across the Strait of Gibraltar.
Johnson described his research, recently published in Earth and Planetary Science Letters, as a “conceptual model,” or synthesis of previous scientific work.
“The new thing about this (research) is the influence of the salinity of the Mediterranean on high-latitude climates,” Johnson said.
The Mediterranean is becoming saltier as a result of global warming and the diversion of water from the Nile River to irrigation projects.
Irrigation projects are currently diverting 90 percent of the Nile’s water. The Aswan High Dam, completed in 1968, is responsible for about half of that total. The proposed Abu Simbel diversion, an artificial branch of the Nile to be extended into the Western Desert, will take most of the Nile’s remaining water.
Ground was broken on the artificial river in January, and the project will be completed by 2015.
Because Mediterranean water is saltier, and therefore denser, than ocean water, it is pulled into the North Atlantic through the Strait of Gibraltar, where it sinks to the bottom, and moves north toward the Faeroe Islands off Scotland. There it encounters the Gulf Stream.
The current from the Mediterranean deflects some of the warm water of the Gulf Stream westward toward the Labrador Sea. The warmer the ocean surface, the more water is evaporated. This, in turn, could lead to greater precipitation in both Labrador and Baffin Island.
A saltier Mediterranean will result in more Gulf Stream deflection, less warm water reaching Scandinavia and greater snowfall on Baffin Island. This means lower temperatures for both sides of the Atlantic.
“Baffin Island is the cradle of new ice ages,” Johnson said. “It has, at the moment, a rather dry climate. It’s plenty cold enough up there to grow glacier and ice sheets, but it lacks the precipitation.”
Johnson said that Europe may already be experiencing the effects of increased Mediterranean salinity.
“The last two northern European winters were more severe than usual,” he said. “Canals in the Netherlands hadn’t frozen over in recent memory.” But since the early 1990s, Dutch waterways have frozen several times.
A peculiar two-directional current flow occurs at the Strait of Gibraltar. At the surface, lighter Atlantic water is flowing into the Mediterranean. Deeper down, dense Mediterranean water is flowing into the Atlantic.
A partial dam could block the flow of water out of the Mediterranean while allowing Atlantic water in, Johnson said.
“This project dwarfs any other project in the world,” he said. “The technology isn’t known. We don’t really know how to dump rock in a 600-foot channel and not have it roll off someplace 10 miles away where you don’t want it.”
Johnson estimates that it will take 30 to 40 years to build such a dam.
“If we wait until the Canadian and European climates have clearly deteriorated, then we’ll have lost a lot of valuable time,” he said.
The effect of such a dam would be extremely difficult to simulate.
The small size of the Strait of Gibraltar, compared with the seas on either side of it, makes any computer simulation difficult, said Matt O’Keefe, an assistant professor of electrical engineering who has worked on computer simulations of the oceans.
“If you take the very biggest computer and let it run for a couple of months on just this problem, you might be able to figure it out,” O’Keefe said.