Tracking the variable North Atlantic sink
for atmospheric CO₂
The oceans are a major sink for atmospheric carbon dioxide (CO₂). Historically, observations have been too sparse to allow accurate tracking of changes in rates of CO₂ uptake over ocean basins, so little is known about how these vary. Here, we show observations indicating substantial variability in the CO₂ uptake by the North Atlantic on time scales of a few years. Further, we use measurements from a coordinated network of instrumented commercial ships to define the annual flux into the North Atlantic, for the year 2005, to a precision of about 10 %. This approach offers the prospect of accurately monitoring the changing ocean CO₂ sink for those ocean basins that are well covered by shipping routes.