Pollution Playing A Major Role In Sea Temperatures by CHRISTOPHER JOYCE

The Atlantic Ocean, especially the North Atlantic, is peculiar: Every few decades, the average temperature of surface water there changes dramatically.

Scientists want to know why that is, especially because these temperature shifts affect the weather. New research suggests that human activity is part of the cause.

Scientists originally thought that maybe some mysterious pattern in deep-ocean currents, such as an invisible hand stirring a giant bathtub, created this temperature see-saw.

And that may be part of it. But there’s a new idea: The cause isn’t in the water; it’s above it — a kind of air pollution called aerosols.

NASA Earth ObservationsThis NASA map shows the size of aerosol particles in the atmosphere. Green areas indicate larger, more naturally occurring particles like dust. Red areas indicate smaller aerosol particles, which can come from fossil fuels and fires. Yellow areas indicate a mix of large and small particles.Click to see a high-resolution version of this image

Ben Booth, a climate scientist at Britain’s Met Office Hadley Center, says that aerosols create clouds.

“The more aerosols you have, the more places there are for water vapor to condense,” he says. “And so what aerosols do is they cool.”

They cool the ocean because clouds reflect sunlight back into space before it can hit the ocean.

Aerosols are fine particles like soot or sulfur compounds, mostly from burning fuel. They seed a kind of cloud that’s especially good at reflecting solar radiation back into space. Even on their own, without clouds, these aerosols act like sunblock.