Research Spotlight: New emissions scenarios say 2°C warming may be unavoidable

Abstract

When it comes to modeling climate change, researchers rely on the specification of plausible emissions scenarios to explore how climate will change over the coming century. Using a standardized set of carbon dioxide and other greenhouse gas scenarios, researchers from different modeling centers can compare results and more methodically assess uncertainty in the Intergovernmental Panel on Climate Change (IPCC) reports. The emissions scenarios used in the past two IPCC reports were published in 2001 and need to be updated to take into account more recent socioeconomic modeling results. In a new study, Arora et al. use a completely new set of scenarios, referred to as representative concentration pathways (RCPs). These will form the basis for new climate projections to be assessed in the IPCC's Fifth Assessment Report (due out in 2014). Using an upgraded Earth system model—which takes into account carbon dioxide and other greenhouse gases, aerosols, land use change, and the flow of carbon between the atmosphere and the underlying ocean and land surface—the researchers are able to calculate the carbon dioxide emissions compatible with each RCP and, in particular, the emissions reductions required to meet certain levels of global warming. (Geophysical Research Letters, doi:10.1029/2010GL046270, 2011)