The emissions from burning fossil fuels is estimated at 6.5 gt per year, and the carbon released via land use change is 2.2 gt. suppose the uptake of carbon into the atmosphere has been recorded at 3.4 gt per year. if oceans are taking up 2.4 gt c per year, what is the estimated "missing sink" of carbon?

Combining the emissions released by fossil fuel burning and the carbon released via land use change, we get a total of 8.7 GT. Since the problem states that the oceans "take up" or sequester 2.4 gt carbon per year, we subtract that value from 8.7 GT, leaving us with 6.3 gt of carbon. Since the problem states that 3.4 gt carbon dioxide emissions end up in the atmosphere, the "missing sink" of carbon takes up 2.9 gt, a value we got by subtracting the 3.4 gt amount recorded from the 6.3 gt carbon left available after the oceans sequester the carbon dioxide.