Although regional climate change is attributable to many effects, the relevance of those effects is vague because the response to regional forcings is not adequately understood for the last century. Shindell and Faluvegi (2009) thus examined the susceptibility of various regions to changes in forcing. By determining the relationship between forcing and location reaction, and integrating observations of climate change from the twentieth century, Shindell and Faluvegi derived the importance of aerosols and resulting radiative forcing throughout time and location. This information explained that radiative forcing location influences climate response. Aerosols were proven to have great importance for both global and regional climate change. Further, the results demonstrate that, over the past three decades, the Arctic warming trend is influenced by the black carbon and aerosol emissions of the Northern Hemisphere.— Aly Stark
Shindell, D. and Faluvegi, G., 2009. Climate response to regional radiative forcing during the twentieth century. Nature Geoscience, 2, 294–300.
Shindell and Faluvegi began by creating latitude bands and finding the response of the surface temperature to various levels of well-mixed greenhouse gases (WMGHG), ozone, and aerosols. Through this modeling, they found that when the forcing occurs within a specific latitude band, the mean temperatures follow the forcing per local unit area. Therefore, when the global mean radiative forcing is considered, the mid-latitude forcing and polar forcing must be greater than the tropical forcing (~ 2.4 and ~7 times, respectively). Higher latitude forcings are thus more sensitive to global forcing when compared to other regions.
Shindell and Faluvegi then compared the results from the modeling to the past patterns of surface temperature over various regions and time periods. These comparisons examined global and gradient responses and found significant implications for Arctic trends. The surface temperatures of the Arctic are warm until 1930, cooler from 1930–1975, and rapidly warmer onwards. Although there were differences between the observed and the recreated global and gradient responses, Shindell and Faluvegi accredit the discrepancies to internal variability and aerosol forcing. The models demonstrate a necessity for aerosol provided cooling.
From modeling and comparisons, the results illustrate the prevalence of aerosol presence in both global and regional climate response. Further, forcing in the northern hemisphere has a particularly strong effect on the Arctic climate. As the forcing at the mid-latitude northern hemisphere oscillates between positive and negative, the temperatures of the Arctic transition from warmer to cooler. It is estimated that aerosols are one of the main contributors to the increased Arctic surface temperature; responsible for 1.09 ± 0.81° C of the 1.48 ± 0.28°C increased warming. As increased aerosol forcing continues, coupled black carbon and tropospheric ozone contributions, Arctic warming will also increase