Feb 6, 2012

Earth’s oceans more acid in last 200 years than in earlier 21,000 years

New research conducted by specialists from the University of Hawaii came to a shocking conclusion: carbon emissions of anthropogenic origin have caused ocean acidification at a rate greater than natural.

This will lead to the extinction of many organisms that live in Earth’s waters, the most affected being mollusks and corals.

In certain regions of the planet, the acidity increased more in the last two centuries earlier than 21,000 years, the study said.

Increased acidity of oceans makes it difficult to build protective layers they need to survive among mollusks and corals.

Measurement of changes in ocean acidity level is a difficult operation, because it varies depending on the season, year and regions. To do this, scientists measured the saturation of aragonite, a form of calcium carbonate. As ocean acidity increases, the aragonite saturation decreases.

Direct observations of ocean acidification goes back only 30 years, but thanks to this new technique, scientists could simulate the conditions of the oceans 21,000 years ago until today.

In certain key areas where coral reefs are the aragonite saturation is 5 times lower than the lowest level ever recorded before the industrial age. Scientists say that this leads to a 15% decrease in the level of calcification of corals and other ocean organisms.

Scientists warn that the next 90 years, calcification rate recorded among marine organisms will fall by over 40%.

“Any significant drop below the minimum that bodies have become accustomed over thousands of years will be considerable stress for them and the ecosystems in which they live,” said Dr. Tobias Friedrich of the University of Hawaii.

“In certain regions of the planet, the rate of change in ocean acidity from human activity is 100 times that found in the previous 21,000 years,” said Friedrich.

Co-author, Professor Axel Timmermann, added: “Our research results indicate that we will witness a considerable reduction of the diversity, complexity and resilience of coral by the middle of this century”.

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