The world's oceans are getting warmer, stormier and more acidic. They are becoming less productive as the ecosystems within them collapse. Melting glaciers and ice sheets is causing sea levels to rise, increasing the risk of flooding and devastation for hundreds of millions of people living in coastal areas.
The latest Intergovernmental Panel on Climate Change (IPCC) special report on how the oceans and icy regions of the planet are changing in response to rising levels of carbon dioxide in the atmosphere is a predictably gloomy reading. The final text, addressed and discussed by dozens of scientists and policymakers from 36 countries during last week's marathon meetings in Monaco, refers to almost 7,000 relevant scientific studies.
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For decades, the oceans have provided a buffer against the full impact of a warming planet. Since 1970, the report says, they have absorbed more than 90 percent of the excess heat associated with greenhouse gases and absorbed about a quarter of the carbon dioxide emitted by cars, power plants and factories. As the oceans warm up, the layers of water within them blend less and the oxygen and nutrient supply decreases. The upper layers of the world's seas have lost 1-3 percent of their oxygen in recent years, and increased CO2 absorption has made the water more acidic, complicating the lives of coral-like creatures that need to build carbonate shells. In the meantime, the report predicts that about 15% of the animals are likely to disappear by the end of the century, and that fish catches could fall by as much as a quarter from average levels between 1986 and 2005.
More to the poles, permafrost – permanently frozen soil – is at risk. Even if the average global temperature increase is limited to 2 ° C above pre-industrial levels – it is already an ambitious goal – a quarter will melt. If greenhouse gas emissions and temperatures rise further, nearly 70% of this near-surface permafrost could melt. Frozen on this earth is 1,460-1,600 gigatonnes of carbon, the report says, nearly double the amount already in the atmosphere, much of which could be released if the soil thaws.
The IPCC process is rooted in science, but reaching any consensus is complicated. Politics requires some sacrifices. Major fossil fuel producers, such as Saudi Arabia, for example, often question the strong conclusions of such reports. For the sake of unanimity, part of the language has been weakened. Even so, this latest report provides a new unified picture of Earth's oceans and ice kingdoms, which should better inform policy makers. And better informed can mean better protection.