Uptake of Carbon Dioxide in Oceans Widely Underestimated: Study

The previous estimates of the movement of carbon between the atmosphere and oceans have not accounted for the temperature differences at the water's surface and a few meters below

A new study published in the journal Nature Communications, the world's oceans absorb more carbon dioxide than what has been suggested by most scientific models. According to the study led by researchers from the University of Exeter, there is a considerably higher net flux of carbon into oceans.

Prof. Andrew Watson, the co-author of the study, explained in a statement that, "Half of the carbon dioxide we emit doesn't stay in the atmosphere but is taken up by the oceans and land vegetation 'sinks'."

Crucial Ignored Temperature Differences

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Representational Picture

Previous estimates of the movement of carbon (known as "flux") between the atmosphere and oceans have not accounted for temperature differences at the water's surface and a few meters below.

It calculates CO2 fluxes from 1992 to 2018, finding up to twice as much net flux in certain times and locations, compared to uncorrected models. Researchers have assembled a large database of near-surface carbon dioxide measurements - the "Surface Ocean Carbon Atlas" - that can be used to calculate the flux of CO2 from the atmosphere into the ocean."

Watson added, "Previous studies that have done this have, however, ignored small temperature differences between the surface of the ocean and the depth of a few meters where the measurements are made. Those differences are important because carbon dioxide solubility depends very strongly on temperature."

Independent Method of Calculation

Watson said further, "We used satellite data to correct for these temperature differences, and when we do that it makes a big difference - we get a substantially larger flux going into the ocean. The difference in ocean uptake we calculate amounts to about 10 percent of global fossil fuel emissions."

Dr. Jamie Shutler, of the Centre for Geography and Environmental Science on Exeter's Penryn Campus in Cornwall, added: "Our revised estimate agrees much better than previously with an independent method of calculating how much carbon dioxide is being taken up by the ocean.

Shutler added, "That method makes use of a global ocean survey by research ships over decades, to calculate how the inventory of carbon in the ocean has increased. These two 'big data' estimates of the ocean sink for CO2 now agree pretty well, which gives us added confidence in them."

(With inputs from agencies)