Atlantic Warming Turbocharges Pacific Trade Winds
Rapid warming of the Atlantic Ocean, likely caused by global warming, has turbocharged Pacific Equatorial trade winds to a level never-before-seen, according to new research.
The increase in these winds has caused eastern tropical Pacific cooling, amplified the Californian drought, accelerated sea level rise three times faster than the global average in the Western Pacific and has slowed the rise of global average surface temperatures since 2001.
"We were surprised to find the main cause of the Pacific climate trends of the past 20 years had its origin in the Atlantic Ocean," co-author Dr. Shayne McGregor, from the ARC Centre of Excellence for Climate System Science (ARCCSS) at the University of New South Wales, said in a statement.
"It highlights how changes in the climate in one part of the world can have extensive impacts around the globe."
This phenomenon had previously stumped scientists. Originally, they considered this trade wind intensification to be a response to Pacific variability over the last 20 years. However, this reasoning cannot explain the extreme strength of these winds.
Also, previous research indicated that under global warming scenarios Pacific Equatorial Trade winds would slow down over the coming century, not speed up.
This study found that warming of the Atlantic Ocean was at the heart of the matter, creating unexpected pressure differences between the Atlantic and Pacific.
"The enormous pressure see-saw with high pressure in the Pacific and low pressure in the Atlantic gave the Pacific trade winds an extra kick, amplifying their strength. It's like giving a playground roundabout an extra push as it spins past," explained co-author Axel Timmermann of the University of Hawaii.
The stronger Equatorial trade winds have caused far greater overturning of ocean water in the West Pacific, pushing more atmospheric heat into the ocean, the research shows. This increased overturning reportedly explains much of the recent slowdown in the rise of global average surface temperatures.
However, the researchers note that they don't expect the current pressure difference between the two ocean basins to last. Eventually, they expect to see some rapid changes, including a sudden acceleration of global average surface temperatures.
The findings were published in the journal Nature Climate Change.