Past and Future Climate Forcing

Climate change is again in the news. First the failure of the COP61 meeting to agree on terms for the Kyoto Protocol and now the apparent rejection of the protocol by President Bush leaves the future of climate policy uncertain. To move forward it is important understand the drivers of climate change in order to inform discussions of where mitigation efforts need to be focused. This paper will present a quantitative overview of the physical drivers of past and future climate changes. The paper will first address attribution of past climate changes, then the radiatively important substances that will drive future climate change, and, finally, the mitigation of climate change in the context of the recent Hansen et al. “alternative scenario”.2