Because the carbon dioxide (CO2) emitted by fossil fuel use is the largest source of anthropogenic GHG emissions, the climate challenge is often characterized as the need to "decarbonize" the economy by eliminating fossil fuels. However, carbon is literally the fuel of life; the natural carbon cycle annually circulates twenty times as much carbon as released from fossil fuels and the majority is biogenic carbon fixed through photosynthesis. Although rapid release of fossil carbon is the primary cause of rising atmospheric CO2 concentrations, the real problem is an imbalance in the carbon cycle rather than fossil fuel use per se. Thus, the real need is to bring the carbon cycle into balance and eventually restore a global net carbon sink.
|Global Carbon Stocks and Flows|
What distinguishes CDR from other climate protection strategies is that it is not about reducing emissions, i.e., decreasing the rate at which an activity emits CO2 down to progressively lower levels and eventually to zero (a "carbon neutral" state). Rather, it is about increasing the rate of negative emissions, i.e., going "beyond carbon neutral" to speed up the net downward flow of CO2 from the atmosphere into various forms of fixed carbon. As such, it is a crucial complement to all of the essential efforts to reduce the upward flow of CO2 and other GHG emissions.
A well-known example of CDR is reforestation, which by itself can increase the negative emissions rate for some decades but not necessarily permanently. Although not usually seen in this light, bioenergy is helpful only if it involves CDR. For example, biofuel use does not reduce CO2 emissions in the transportation sector and so any benefit depends on whether producing a biofuel's feedstock increases the rate at which CO2 is removed from the atmosphere in other sectors.
At present, CDR is under-researched, under-developed and under-appreciated by policymakers and the public. No coherent science, technology and policy strategy exists to systematically pursue CDR on a par with the efforts underway to reduce emissions. The Center for Carbon Removal spun off from U-C Berkeley is educating policymakers and others about the opportunities for CDR. The most important and tangible opportunities for moving beyond carbon neutral entail protecting and restoring carbon-rich ecosystems. Known as "Natural Climate Solutions," these approaches are summarized in a scientific article and featured on a Nature Conservancy website that explains such options and their many benefits.