Stronger trade winds explain warming

Climate skeptics' favourite topic of conversation - a supposed 'hiatus' in surface temperature warming.
Over the last 13 years, surface temperatures have risen more slowly than projected, leading to accusations that climate change is a grand conspiracy perpetrated by the world's scientific establishment.


Like all conspiracy theories, it's nonsense. Surface temperature is only one of the factors expected to change due to mankind's greenhouse gas emissions, others include rainfall and an increase in the number of extreme weather events. The Met Office has already linked the latter to the fact that half of England is currently under water.

Matt England at the University of New South Wales set out to explain the lower-than-expected surface temperature rise by comparing climatic trends over the last 20 years. They looking around the globe, and found the answer in the trade winds of the Pacific Ocean, publishing their results in Nature Climate Change.

They spotted that the wind acceleration over the Pacific has been twice as high in the past two decades as in those previous. That pushes a lot of warm water in two directions - to the west of the ocean and down into its interior.

"When you do that you do get a lot of heat taken up by the ocean and you also get a much cooler east Pacific and that also drives further cooling in other regions," England says.

Adding further weight to this explanation, they found a similar acceleration in trade winds in the Pacific during the 30 years after World War II, which coincided with a similar period of plateauing temperatures.

The really concerning part is what happens when those trade winds drop to more normal levels. "The heat that is there can find its way [again] to the surface of the ocean, it's not like we are getting a correction for global warming," explained England. "So global temperatures look set to rise rapidly out of the 'hiatus', returning to the levels projected within as little as a decade."

Meanwhile, if we continue 'business as usual' without reducing emissions, we may eventually overwhelm the ability of the oceans to take up the excess heat.


"We show by 2030 these hiatus will be a thing of the past if we keep increasing greenhouse gases and in the future any hiatus will be shorter lived and much less effective at halting global warming," says England.