Natural Carbon Sequestration in the Sea

A report recently published in the Financial Times told of the unregulated nature of deep sea fishing. The American Association for the Advancement of Science annual meeting in San Francisco was told that government fuel subsidies enable "fishing fleets to operate like roving bandits, using state-of-the-art technologies to plunder the depths" the paper's report said.

The conference also heard that fishing was virtually unregulated in international waters beyond countries' exclusive economic zones, with no agencies to monitor and control catches. Deep-water trawlers drag 15-tonne nets along the seabed, typically 500m-1km below the surface targetting fish such as the orange roughy and grenadiers that grow extremely slowly in the cold ocean depths.

Unlike my colleague Richard Laming who wrote about the topic in his Federal Union blog http://www.federalunion.org.uk/blog/ I personally am more interested in the reported side effects of this fishing than the fishing itself. Again, the Financial Times reports that the Conference was told that a side effect of bottom trawling is the destruction of deep-sea corals and sponge beds that have taken centuries or millennia to grow.

This is most significant and could have a major influence on climate change and the sequestering of carbon. One has only to look at the limestone crags on which this country is built to realise that over the ages a phenomenal amount of atmospheric carbon has been absorbed into the bodies and shells of sea creatures which when compressed have become limestone, chalk, calcite and the rest. Heat a piece of limestone and you drive off this carbon dioxide.

This process of sequestering carbon is on-going. Atmospheric carbon dissolves into the sea and creatures there use it to build their shells and skeletons. The flow of carbon from the atmosphere into the surface of the oceans is about five times that which flows into the atmosphere as a result of man's activities. A similar amount diffuses out of the sea.

It follows that any interference with this great sea engine of absorbtion is likely to result in an increase in atmospheric carbon, regardless of whether or not we burn fossil fuels.

The tragedy is that by not heeding our destruction of the sea's biodiversity we threaten to render all our emission cutting efforts quite useless.

Posted by Peter Sain ley Berry