Oceans being turned to acid, say scientists

The world's seas are turning acid, with potentially dire effects for marine life, as a result of the carbon dioxide emissions from industry and transport that are causing global warming, a report from the Royal Society has warned.

By the end of the century there could be wide-reaching and harmful changes in the ocean food chain, directly affecting a range of vital organisms from plankton to coral, and having a knock-on effect on larger marine animals, says the report from a working group of senior British scientists.

It also warns that ocean acidification could itself be a possible cause of a speeding-up of climate change.

The findings are yet another reason for the G8 leaders meeting next week to take action to cut carbon dioxide emissions, the scientists say, calling for a substantial research effort into the problem to launched immediately.

Researchers have only very recently realised that the massive amounts of carbon dioxide released by burning fossil fuels in huge amounts have yet another dangerous effect on the planet besides raising temperatures. About half of the carbon dioxide produced remains in the atmosphere while the rest dissolves in the oceans - and when it does so, it reacts with sea water to produce carbonic acid.

"Basic chemistry leaves us in little doubt that our burning of fossil fuels is changing the acidity of our oceans," said Professor John Raven, chair of the working group.

"The rate of change we are seeing to the ocean's chemistry is a hundred times faster than has happened for millions of years. We just do not know whether marine life - which is already under threat from climate change - can adapt."

In their natural state the oceans are slightly alkaline, but the massive carbon dioxide volumes produced since the industrial revolution - about 450 billion tonnes - have already increased the sea's acidity by measurable extent, the report says.

Although this has not yet had a detectable damaging effect on marine life, the further acidification likely to take place by the end of the century almost certainly will.

In particular, it will damage the huge number of organisms which need to build their shells or their skeletons from calcium carbonate, such as tiny plankton, corals, shellfish, starfish and sea urchins. Some of these are vital components at the bottom end of the ocean food web on which other life depends.

"The combined effects of climate change and ocean acidification mean that corals could be rare on tropical and subtropical reefs, such as the Great Barrier Reef, by 2050," the report says.

"This will have major ramifications for hundreds of thousand of other species that dwell in the reefs as well as for as for the people that depend upon them, both for food and to help protect coastal areas from, for example, tsunamis."

The rising acidity levels could also further boost global warming.

- INDEPENDENT