What if the gulf stream turned off

As it melts, it adds more fresh water into the sea making the water in the North Atlantic less dense. The global ocean conveyor belt will stop circulating. This would be the end of the Gulf Stream and the beginning of something else. A new Ice Age. You heard it right. The Gulf Stream is a warm current. What would happen if this warmth-bearing current was cut off? Well, it would stop bringing warm waters to those areas.

Western Europe would get plunged into a deep freeze. And so would North America. London, among other cities, would be covered in snow for weeks. Something is telling me, Londoners would never stop complaining about the weather. The east coast of the U. But, more dramatically, rainfall during the growing season is expected to drop by mm. That drop is enough to reduce the UK's percentage of arable land from 32 percent to just seven percent.

Obviously, this would cause a big hit to the UK's agricultural productivity. Irrigation could again offset this, but the scale of the changes needed would be far larger; the authors estimate adding this irrigation at ten times the value of the crops that would be produced. But they note that it's not clear if the UK would have enough water to spare to fully reverse the loss of rain. The underlying scenario here—the complete shutdown of the AMOC and thereby the Gulf Stream by midcentury—is likely to be science fiction.

But the work indicates that one of the ideas about what would happen isn't: Europe really would cool down enough to more than offset the warming climate by the end of the century.

But, in terms of food production, this is almost an afterthought—the changes in rainfall are far more significant. What's needed next is an analysis of what would happen if, instead of a complete shutdown, the expected gradual reduction took place.

Nature Food , DOI: You must login or create an account to comment. Further Reading Barents Sea seems to have crossed a climate tipping point. John Timmer John became Ars Technica's science editor in after spending 15 years doing biology research at places like Berkeley and Cornell. Both of these factors dump ever greater amounts of freshwater into the ocean, reducing the density and salinity of the surface water at the northern end of the Gulf Stream conveyor belt. According to the researchers, this freshwater inhibits how quickly the water can sink and begin its journey back south, weakening the overall flow of the AMOC.

If the flow continues to weaken or collapse entirely , the effects could be severe. Images of melt: Earth's vanishing ice. The reality of climate change: 10 myths busted. Top 10 ways to destroy Earth. Other studies have linked severe heat waves and storm patterns in northern Europe and the eastern United States to the weakened current.

The precise impacts could be "even more severe," Caesar said, though scientists won't know for sure until we cross that bridge. Its warm water provides a ready supply of fuel to hurricanes crossing its path. The role of climate change in hurricanes is the subject of extensive scientific inquiry, with some research suggesting we may see fewer hurricanes, with the ones that do form tending to be stronger and rainier. A weaker Gulf Stream system could weigh in as a factor that reduces the number of hurricanes because it would tend to produce cooler water along the storms' Atlantic path.

Counteracting the cooling influence on the Atlantic, in a warmer world, would be the tendency of oceans to be warmer in general. A weaker Gulf Stream could lead to higher sea levels along the Florida coast. Sea level worldwide is currently rising at a rate of about one inch every eight years, partly because of melting ice sheets and partly because water expands as it warms.

But for local sea level, an important role is played by currents. And if the Gulf Stream weakens, just the opposite happens. It's not sweeping away the water as much, and so sea level rises. If the Gulf Stream weakens, it will exacerbate sea level rise. Research into the fate of the Gulf Stream system, known as the Atlantic meridional overturning circulation, illustrates a broad truth about climate science.

While there's a consensus that the climate is warming and that this is happening largely because of human activities, scientists disagree on the likely impacts.

No one knows how fast glaciers will melt or how much sea level will rise and how quickly this will happen. There's intense research into the potential impact on the frequency and strength of hurricanes and into the possible impact on plants, wildlife and human health. With the Gulf Stream, scientists attempting to determine the role of climate change have to separate out natural factors, such as multi-decade temperature cycles in the Atlantic Ocean, that have strengthened or weakened the system for thousands of years.

There's a lot of debate about it. I think the scientific consensus is that the jury's still out. A key piece of evidence for a possible weakening of the current is a strange patch of cold water—dubbed by scientists the "cold blob"—south of Greenland.

While other parts of the earth have warmed, this area has cooled, and many scientists have concluded that this reflects a decline in the quantity of warm water reaching the area from the Gulf Stream. Normally, the current is driven by the cooling of water as it travels to the northern part of the Atlantic. As water cools, it becomes denser and sinks. This pulls warm water from the south to replace it. But with climate change, melting glaciers and Arctic sea ice are overwhelming the system with fresh water, which is less dense and therefore less heavy than salt water, so less water sinks and less warm water is drawn from the south, disrupting the entire system.

Another study, published last year in the journal Nature, found the system to have reached its weakest point in 1, years, although it says the loss of strength probably began from natural factors. The Fourth National Climate Assessment, published last November by a group of federal agencies, says there's insufficient data to conclude that the system has lost strength but says weakening over the next few decades is "very likely.

Whatever the causes, the possibility of a slowdown has caused concern on both sides of the Atlantic.