Researchers eye global warming impacts to North Atlantic region
By Summit Voice
FRISCO — Some of the biggest potential global warming impacts could occur if major ocean currents change in strength or direction — a shift in the Gulf Stream, for example, would have major implications for parts of northwestern Europe, kept temperate by the transport of subtropical water.
Some research has suggested that increasing amounts of cold, fresh water in the North Atlantic could have a big impact on the Gulf Stream and other important currents, but there’s not a lot of detailed historic or baseline data against which to measure changes. But that could change in the next few years, as science agencies in the U.S. and the U.K. team up on a $70 million project to study North Atlantic currents.
In one five-year effort, the Overturning in the Subpolar North Atlantic Program, scientists from seven countries will set up an array of moored instruments and use autonomous gliders across the North Atlantic, along a line running from Scotland to Canada via Greenland. These will record ocean temperatures, salinity and the strength of currents in an area called the North Atlantic Subpolar Gyre.
The team is interested in this region because the currents here, which are part of the so-called ocean conveyor belt, are known to be important for the Earth’s climate.
The conveyor belt is a system of ocean currents, which move heat around in the world’s oceans. In the Atlantic Ocean, warm upper-ocean water travels north, to the high northern latitudes, where it loses heat to the atmosphere. It’s this process that keeps the UK relatively mild in winter compared to other countries at similar latitudes. This water cools then sinks and returns southwards at great depth.
Despite its name, the image of a conveyor belt is misleading, because the process isn’t smooth and continuous. Instead, the belt can stretch, rumple, fray or even stall. This means the strength of currents in the global conveyor belt can vary significantly. As these currents are strongly linked to our climate, the aim of the OSNAP array is to understand the connection between these variations and Britain’s weather.
“It is fitting that a project to better understand what affects the global climate, given the British fascination with weather conditions, has UK involvement,” said U.K. science minister David Willetts.
“Not only will this funding improve our understanding of the planet’s climate through innovative research, it will highlight the importance of one of the eight great technologies – autonomous and robotic equipment. The autonomous gliders being used for this project are helping to revolutionise climate research and are contributing to world class science.”
“In the high latitudes of the North Atlantic, and the Arctic Ocean that it connects to, the ocean can efficiently imprint its memory on the atmosphere by releasing the huge amounts of heat stored in it,” said Dr. Sheldon Bacon with NERC’s National Oceanography Centre.
“And with average global temperatures currently rising by 0.75°C every hundred years, we need to be able to forecast how the climate might change before our descendants face the consequences,” said Bacon, who will lead the UK component of OSNAP.
While the US will lead the measurement aspect of OSNAP with contributions from Canada, the Netherlands, Germany and the UK, Bacon and colleagues will also interpret data from OSNAP using computer models.
Scientists aim to start monitoring in July 2014, and will continue until 2018.
A second component involves continued monitoring of currents between the Canary Islands and Florida, where data goes back to 2004. This collection of instruments continuously monitors the strength of the North Atlantic portion of the global conveyor belt.
“The unexpected stalling of the conveyor in 2009-10 observed by the RAPID array, but not captured by state-of-the-art climate models, gives impetus to continuing the observations begun in 2004,” said National Oceanography Prof. Meric Srokosz. “The observations are unique and tell us about the role of the ocean in the climate system, as well as providing a means of testing and improving the models used for climate predictions, on which government policy is based.”
“The findings from OSNAP and RAPID will be crucial for helping us understand how changes in Atlantic currents affect both the climate and the weather, especially in Britain,” said Prof. Duncan Wingham, chief executive of NERC.