Buying time - reducing diesel black carbon offers an immediate opportunity for climate and public health benefits
As delegates from countries around the world congregated in Copenhagen this past December to consider global action to combat climate change, they confronted a political, scientific, technical, and economic issue of unprecedented complexity and scope. To avoid the worst impacts of global warming, many scientists say we must guard against two related but different risks: (1) the cumulative warming due to increasing concentrations of greenhouse gases in the atmosphere and (2) the threat of near-term climate impacts that could plunge us into a cycle of rising seas and an abrupt shift to a much warmer climate regime.
While the focus of mitigation to date has been on limiting greenhouse gas concentrations in the atmosphere, some scientists argue that even if we are able to put the planet on a pathway to return global carbon dioxide (CO2) levels to 350 parts per million (ppm) before the end of the century, we may still have already set off irreversible changes such as the melting of Arctic summer ice and loss of ice sheets.1 An ice-free, and therefore darker, Arctic Ocean will absorb and trap more heat, which could ultimately contribute to the disintegration of the Greenland ice sheet and sea level rise.2
Not only must we take action to reduce global greenhouse gas emissions significantly by midcentury, we must quickly reduce several short-lived pollutants that can have an immediate impact by slowing the rate of warming.