Background
The authors report that "mineral aerosols have complex, highly varied optical properties that, for equal loadings, can cause differences in the surface IR flux between 7 and 25 Wm^-2 (Sokolik et al., 1998)," but that "only a few large-scale climate models currently consider aerosol IR effects (e.g., Tegen et al., 1996; Jacobson, 2001) despite their potentially large forcing."

What was done
In an attempt to persuade climate modelers to rectify this situation, Vogelmann et al. say they "use[d] high-resolution spectra to obtain the IR radiative forcing at the surface for aerosols encountered in the outflow from northeastern Asia," based on measurements made by the Marine-Atmospheric Emitted Radiance Interferometer from the NOAA Ship Ronald H. Brown during the Aerosol Characterization Experiment-Asia."

What was learned
The five scientists determined, in their words, that "daytime surface IR forcings are often a few Wm^-2 and can reach almost 10 Wm^-2 for large aerosol loadings."  These values, in their words, "are comparable to or larger than the 1 to 2 Wm^-2 change in the globally averaged surface IR forcing caused by greenhouse gas increases since pre-industrial times."

What it means
In a massive understatement of fact, Vogelmann et al. say their results "highlight the importance of aerosol IR forcing which should be included in climate model simulations."  And if a forcing this big (relative to the size of the forcing being studied) is routinely omitted in current state-of-the-art climate models, one wonders what other major factors the models continue to ignore.

References
Jacobson, M.Z.  2001.  Global direct radiative forcing due to multicomponent anthropogenic and natural aerosols.  Journal of Geophysical Research 106: 1551-1568.

Sokolik, I.N., Toon, O.B. and Bergstrom, R.W.  1998.  Modeling the radiative characteristics of airborne mineral aerosols at infrared wavelengths.  Journal of Geophysical Research 103: 8813-8826.

Tegen, I., Lacis, A.A. and Fung, I.  1996.  The influence on climate forcing of mineral aerosols from disturbed soils.  Nature 380: 419-422.