Read the full story from the University of Wisconsin-Madison.
How deep is the ocean’s capacity to buffer against climate change?
As one of the planet’s largest single carbon absorbers, the ocean takes up roughly one-third of all human carbon emissions, reducing atmospheric carbon dioxide and its associated global changes.
But whether the ocean can continue mopping up human-produced carbon at the same rate is still up in the air. Previous studies on the topic have yielded conflicting results, says University of Wisconsin-Madison assistant professor Galen McKinley.
In a new analysis published online July 10 in Nature Geoscience, McKinley and her colleagues identify a likely source of many of those inconsistencies and provide some of the first observational evidence that climate change is negatively impacting the ocean carbon sink.
Full citation for the article:
Galen A. McKinley,Amanda R. Fay,Taro Takahashi & Nicolas Metzl (2011) “Convergence of atmospheric and North Atlantic carbon dioxide trends on multidecadal timescales,” Nature Geoscience, Published online 10 July 2011. doi: 10.1038/ngeo1193
Abstract: Oceanic uptake of carbon dioxide substantially reduces the rate at which anthropogenic carbon accumulates in the atmosphere1, slowing global climate change. Some studies suggest that the rate at which the oceans take up carbon has significantly decreased in recent years. Others suggest that decadal variability confounds the detection of long-term trends. Here, we examine trends in the partial pressure of carbon dioxide in the surface waters of three large biogeographic regions in the North Atlantic, using observational data collected between 1981 and 2009. We compare these oceanic observations with trends in atmospheric carbon dioxide levels, taken from a global observational network. We show that trends in oceanic carbon dioxide concentrations are variable on a decadal timescale, often diverging from trends in atmospheric carbon dioxide. However, when the entire 29-year period is considered, oceanic trends converge with atmospheric trends in all three regions; it takes 25 years for this long-term trend to emerge and overcome the influence of decadal-scale variability. Furthermore, in the southernmost biome, the data suggest that warming — driven by a multidecadal climate oscillation and anthropogenic forcing — has started to reduce oceanic uptake of carbon in recent years.