Carbon

This chapter elucidates the importance of carbon to the Earth system and outlines the global debate on its use and impact. The element manifests itself through a number of reservoirs: the crust and mantle (the overwhelming majority), dissolved forms of inorganic carbon, living organic material and atmospheric trace gases (including the infamous 'greenhouse' variety), representing just 0.00064%, but responsible for the absorption of out-going infra-red radiation from Earth's surface. The chapter then outlines how variations in Earth’s atmospheric levels of CO2 and methane are related to the exchange of carbon between these reservoirs, which combine to act as a global thermostat over geological timescales. These processes have not always been human-induced: the Earth’s history is peppered with periods of volcanic activity, resulting in wild extremes in global temperature. However, the crucial difference in such phenomena and human-induced carbon is the abrupt ‘gorging’ and ‘dumping’ we are engaged in over a relatively minute timeframe, hindering ocean acidity levels in seas from rebalancing. As the first agent sentient of the effect it is having on the Earth’s metabolism, humanity must make unprecedented changes in its relationship to carbon. As the chapter points out, dramatic changes have been enacted before, when urbanized communities have been faced with the consequences of poor sanitation and pollution. However, decisions dictated by market economics or arbitrary, politically-derived thresholds risk making the rate of change simply too slow. The fundamental realization is that our relationship to energy, and where this energy is sourced, must change, fast.