Anthropogenic Forcing Uncertainty and Arctic Temperature Change

Arctic surface temperatures have been increasing since about 1970, with both greenhouse gases and aerosol forcing playing a role (Fyfe et al 2013, Navarro et al 2016). The Arctic has a particularly strong response to absorbing black carbon (BC) aerosols (Sand et al. 2013), making it important to quantify the potential impacts of aerosols in general, and BC specifically, on past and future Arctic temperature trends.

Coupled climate model experiments are a central tool in understanding Arctic climate changes, but the large temperature variability seen in both models and observational data impede our understanding of the role of individual driving forces. We use a hybrid modeling framework in which we combine regional GCM responses with climate model emulation including uncertainty in aerosol (and other) responses. This approach allows the rapid exploration of a large parameter space in order to quantify the potential role of individual anthropogenic forcing agents. Uncertainty in the temperature response to BC (Stjern et al. 2017), cooling aerosols, and species-specific temporal response profiles (Sand et al. 2015) are incorporated into this method so we can determine if there are regions of parameter space where specific aerosol components, such as BC, might have a significant impact on past and future Arctic temperatures.

Fyfe, J.C. et al. (2013) One hundred years of Arctic surface temperature variation due to anthropogenic influence. Scientific reports, 3, p.2645.

Navarro, J.A. et al. (2016) Amplification of Arctic warming by past air pollution reductions in Europe. Nature Geoscience, 9(4), pp.277-281.

Sand, M. et al. (2013) The Arctic response to remote and local forcing of black carbon. Atmos. Chem. Phys. 13, 211-224

Sand, M. et al. A standardized global climate model study showing unique properties for the climate response to black carbon aerosols. J. Climate. 28, 2512-2526 (2015)

Stjern, C. W. et al. Rapid adjustments cause weak surface temperature response to increased black carbon concentrations (2017) J. Geophys. Res. Atmos. 122, 11,462-11,481.