photo: Shayne Kaye via flickr.
The first year-by-year study of the amount of carbon dioxide absorbed by the world's oceans since the industrial revolution confirms a disturbing trend: Oceans are struggling to keep up with all the carbon humans are spewing into the atmosphere, with the proportion of emissions absorbed declining as much as 10% since 2000. The study, led by Samar Khatiwala from the Lamont-Doherty Earth Observatory of Columbia University, has been published in the latest edition of Nature, but this is the gist of it: The study examines the accumulation of industrial carbon in the oceans going back to 1765 and continuing up through 2008. Starting in 1950 there was a large increase in the amount of emissions being absorbed by the oceans, but it wasn't until 2000 that the the percentage of emissions started declining -- even though in absolute terms the tonnage absorbed continued to increase. Last year oceans set a new record for carbon absorption, taking up 2.3 billion tons of CO2.
chart: Samar Khatiwala/Lamont-Doherty Earth Observatory
In case this whole idea is new to you, Khatiwala describes what's happening,
The more carbon dioxide you put in, the more acidic the ocean becomes, reducing its ability to hold CO2. Because of this chemical effect, over time, the ocean is expected to become a less efficient sink of manmade carbon. The surprise is that we may already be seeing evidence for this, perhaps compounded by the ocean's slow circulation in the face of accelerating emissions.
Want something even more basic: More than one quarter of all the human sources of CO2 emissions are absorbed by the oceans.
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