Deep emission cuts essential to stop acid oceans

Posted: 17 December 2009

Deep and immediate cuts in CO₂ emissions are needed to stall ocean acidification and prevent mass extinction of marine species, food insecurity and serious damage to the world economy, according to a report released at the Copenhagen Climate Summit.

The IUCN report takes stock of the latest science on oceans acidification and spells out the steps that are urgently needed to stop its acceleration.

Cold-water coral reefs are home to a wide variety of other species. Selligrunnen reef, Trondheimsfjorden, Norway.© WWF/Erling Svensen
Cold-water coral reefs are home to a wide variety of other species. Selligrunnen reef, Trondheimsfjorden, Norway.© WWF/Erling Svensen
Cold-water coral reefs are home to a wide variety of other species. Selligrunnen reef, Trondheimsfjorden, Norway.© WWF/Erling Svensen
Increased release of CO₂ in the atmosphere is making seawater more acidic and is threatening ecosystems and species precious for our food and economy. It is also reducing the ocean's ability to absorb CO₂ and regulate climate. Previous episodes of ocean acidification were linked to mass extinctions of some species, and it is reasonable to assume that this episode could have the same consequences. There can be little doubt that the ocean is undergoing dramatic changes that will impact many human lives now and in coming generations, unless we act quickly and decisively. "Ocean acidification can be best described as the evil twin of climate change," says Dan Laffoley, lead editor of the guide, Marine Vice Chair of IUCN's World Commission on Protected Areas and member of Natural England's Chief Scientist's team.

Corrosive water

The ocean provides about half of the Earth's natural resources and humankind takes direct advantage of this through our fisheries and shellfisheries. The ocean also absorbs 25 per cent of all the carbon dioxide we emit each year, and produces half the oxygen we breathe.

Aragonite saturation
Aragonite saturation
This map shows the percentage decrease in aragonite saturation from 1865 to 2095 in a business-as-usual CO2 emission scenario. The largest relative changes are in the high northern and southern latitudes where the waters are coldest and absorb more CO2 from the atmosphere.
Ocean acidity has increased by 30 per cent since industrialization began 250 years ago. If CO₂ levels in the atmosphere continue to rise, sea water acidity could increase by 120 percent by 2060 - greater than anything experienced in the past 21 million years. By 2100, 70 per cent of cold water corals may be exposed to corrosive water. Given the lag between CO₂ emissions and a stabilization of acidification, it could take tens of thousands of years before the ocean's properties are restored and even longer for full biological recovery. This demands immediate and substantial emissions cuts and technology that actively removes CO₂.

Ocean Acidification: The Facts, a special introductory guide for policy advisers and decision makers can be downloaded here