Background
With respect to the Arctic, the authors state that "warming is predicted to enhance atmospheric moisture storage resulting in increased net precipitation," citing as the basis for this statement the Arctic Climate Impact Assessment (2005). Likewise, Peterson et al. (2002) have written that "both theoretical arguments and models suggest that net high-latitude precipitation increases in proportion to increases in mean hemispheric temperature," citing the works of Manaabe and Stouffer (1994) and Rahmstorf and Ganopolski (1999). Do real-world data bear them out?

What was done
Using three different data sets, Rawlins et al. calculated trends in the spatially-averaged water equivalent of annual rainfall and snowfall across the six largest Eurasian drainage basins that feed major rivers that deliver water to the Arctic Ocean for the period 1936-1999, over which time interval climate alarmists claim the globe's mean temperature rose to a level -- and at a rate -- that was unprecedented over the past two millennia.

What was learned
All three data sets indicated that annual rainfall across the total area of the six basins decreased consistently and significantly over the 64-year period. Annual snowfall, on the other hand, exhibited "a strongly significant increase," but only "until the late 1950s." Thereafter, it exhibited "a moderately significant decrease," so that "no significant change [was] determined in Eurasian-basin snowfall over the entire 64 year period." The researchers' bottom-line finding, therefore, was that annual total precipitation (including both rainfall and snowfall) decreased over the period of their study; and they note that this finding is "consistent with the reported (Berezovskaya et al., 2004) decline in total precipitation."

What it means
Either (1) the theoretical arguments and model predictions that suggest "net high-latitude precipitation increases in proportion to increases in mean hemispheric temperature" are wrong, or (2) late 20th-century temperatures may not have been much warmer than those of the mid-1930s, or (3) both of the preceding options may apply.

References
Arctic Climate Impact Assessment. 2005. Arctic Climate Impact Assessment - Special Report. Cambridge University Press, New York, New York, USA.

Berezovskaya, S., Yang, D. and Kane, D.L. 2004. Compatibility analysis of precipitation and runoff trends over the large Siberian watersheds. Geophysical Research Letters 31: 10.1029/20004GL021277.

Manabe, S. and Stouffer, R.J. 1994. Multiple-century response of a coupled ocean-atmosphere model to an increase of atmospheric carbon dioxide. Journal of Climate 7: 5-23.

Peterson, B.J., Holmes, R.M., McClelland, J.W., Vorosmarty, C.J., Lammers, R.B., Shiklomanov, A.I., Shiklomanov, I.A. and Rahmstorf, S. 2002. Increasing river discharge to the Arctic Ocean. Science 298: 2171-2173.

Rahmstorf, S. and Ganopolski, A. 1999. Long-term global warming scenarios computed with an efficient coupled climate model. Climatic Change 43: 353-367.