So-called carbon capture and storage (CCS) is often labelled expensive and unproven, though most of the problems are with the capture part of the process. When it comes to storing the billions of tonnes of carbon dioxide that would be captured, the answer for Britain seems obvious – they can put it under the North Sea, in the emptying natural gas fields. But where do nations without access to such convenient geology turn? One option is to pipe waste gas directly into the sea. In very deep water, scientists think carbon dioxide would form a dense slush that would stay on the seabed for hundreds of years. Wally Broecker, a climate expert at the Lamont-Doherty Earth Observatory at New York’s Columbia University, says 480bn tonnes of carbon dioxide could be safely dumped in the deep Pacific in this way: the amount created by about 16 years of the world’s current fossil fuel use.

Scientists in the US have tested this concept, and the impact it could have on deep-sea life. Experts at the Woods Hole Oceanographic Institution and the Monterey Bay Aquarium Research Institute released small amounts of liquid carbon dioxide into a series of plastic cylinders on the seabed, some 3,000m down in waters off California. A few weeks later, samples of marine life were taken from inside the experiments, the surrounding sea bed and from some 100m away. The scientists were interested in the reaction of three types of tiny sea creatures called foraminifera – single-celled organisms that make up a large part of life at the bottom of the deepest oceans and are a critical link in marine food webs. The study found the survival of the tiny creatures depended on whether they formed shells, called tests. Those that did not make shells, or used particles they scavenged from the surrounding seabed, were not affected.
The Guardian

Together in it
Bleaching and diseases are partners in coral crimes. An abnormal increase in temperatures around Florida Keys during the summer of 2005 led to Katrina—one of the worst hurricanes in US history. Humans left the coast for shelter further inland. The algae coexisting comfortably with the coral reefs fled the unusually warm waters, too, and 90 per cent of the reefs lost their colour. The algae were their source of food, oxygen and colour.

With time the temperatures decreased, the algae went back home and most of the reefs revived. Yet there were sections that remained bleached. These areas were afflicted by diseases. Marilyn Brandt and John McManus of National Center for Coral Reef Research at the University of Miami in USA, surveyed colonies in the Florida Keys before, during and after the bleaching of 2005 to establish a link between that and diseases. When a reef loses colour, it stops growing but the tissues remain intact.
So if the algae were to return, the reef would recover. If afflicted by diseases, chances of recovery are lost. When pathogens were around, the two worked hand in glove: bleaching made corals vulnerable to diseases and diseases exacerbated the bleaching.
Down To Earth Feature Service

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