Balancing the Global Carbon Budget

The global carbon budget is, of course, balanced. The conservation of carbon and the first law of thermodynamics are intact. “Balancing the carbon budget” refers to the state of the science in evaluating the terms of the global carbon equation. The annual increases in the amount of carbon in the atmosphere, oceans, and land should balance the emissions of carbon from fossil fuels and deforestation. Balancing the carbon budget is not the real issue, however. The real issue is understanding the processes responsible for net sources and sinks of carbon. Such understanding should lead to more accurate predictions of future concentrations of CO 2 and more accurate predictions of the rate and extent of climatic change. The recent past may be insufficient for prediction, however. Oceanic and terrestrial sinks that have lessened the rate of growth in atmospheric CO 2 until now may diminish as feedbacks between the carbon cycle and climate become more prominent.