Everything but the Oceans’ Sinks

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Cross-posted from The Environmentalist

Amidst alarms raised about the loss of ice in the polar regions, the extreme droughts across the US, the floods in the UK earlier this year, the increasingly unstable nature of the weather worldwide, a new concern has been raised about the Southern Oceans’ inability to absorb and store CO2:

The Southern Ocean around Antarctica is so loaded with carbon dioxide that it can barely absorb any more, so more of the gas will stay in the atmosphere to warm up the planet, scientists reported on Thursday.

Human activity is the main culprit, said researcher Corinne Le Quere, who called the finding very alarming. The phenomenon wasn’t expected to be apparent for decades, Le Quere said in a telephone interview from the University of East Anglia in Britain. “We thought we would be able to detect these only the second half of this century, say 2050 or so,” she said. But data from 1981 through 2004 show the sink is already full of carbon dioxide.

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This is very alarming. The southern ocean is the world’s strongest carbon sink, a “reservoir that absorbs and stores more carbon than they release, thereby offsetting greenhouse gas emissions.” If the sink has been filled, as seems to be the case, that carbon has no where to go but to the atmosphere, as our other sinks: the forests, the land, the rest of the oceans, are all stressed by loss of habitat, increased warming and their own carbon levels. Which means a speed-up of warming at a far faster rate than had been previously predicted.

This increase in the Southern Ocean has been attributed to a change in wind patterns caused by the following climate forcings:

1. Ozone depletion. The reduction of ozone has changed the temperature and increased wind patterns in the Southern Hemisphere. As these winds flow across the oceans they pull natural CO2 to the surface. This is a problem because natural CO2 does not bind easily with human caused carbon. The balance had been maintained through past wind patterns, which had helped to combin the two types of carbon. With the increased winds and level of stored carbon, that natural mixture has been disrupted.

2. Hemispheric Temperature Differential. The increasing differential in temperature between the Northern and Southern Hemisphere. The warming North pulls winds from the cooler South, thereby impacting CO2, as described in number 1 above.

“Since the beginning of the industrial revolution the world’s oceans have absorbed about a quarter of the 500 gigatons (500 billion tons) of carbon emitted into the atmosphere by humans,” Chris Rapley of the British Antarctic Survey said. “The possibility that in a warmer world the Southern Ocean — the strongest ocean sink — is weakening is a cause for concern.”

According to the measurements gathered by the University of East Anglia’s researchers, the concern is all too real.