Background
The authors note that "modifications to the high-latitude environment, driven by rising surface air temperatures, include ... increasing ... precipitation," and since "river runoff is driven mainly by precipitation and surface air temperature," as they rightly state, one might therefore expect, especially in a world supposedly experiencing a warming that is claimed to be unprecedented over the past two millennia (Mann and Jones, 2003), there would be "an acceleration of the hydrological cycle in many northern regions, including increasing freshwater discharge," which climate alarmists have long contended could shut down the ocean's thermohaline circulation and raise all sorts of havoc with earth's climate.

What was done
In a study that investigated the validity of these claims for a big part of high-latitude North America, Dery et al. examined the characteristics and trends of river discharge into the Hudson, James and Ungava Bays (HJUBs) for the period 1964-2000.  This drainage system, comprised of 42 rivers, accounts for 18% of the planet's total freshwater discharge to the Arctic Ocean, which discharge volume, as they describe it, is more than that of "any other large river basin in Eurasia and North America."

What was learned
The researchers report that linear trend analyses revealed decreasing discharge over the 37-year period in 36 of the drainage system's 42 rivers, such that "total annual freshwater discharge into HJUBs diminished by 96 km³ (-13%) from its value in 1964."  In addition, they note that an observed "gradual salinization of the upper ocean during summer over the period 1966-94 on the inner Newfoundland Shelf is in accord with a decadal trend of a diminishing intensity in the continental meltwater pulses," much of which decreased intensity is the result of diminished river discharge to the HJUBs.

What it means
In a world of global warming hysteria, and in a part of that world (high-latitude North America) where claims of unprecedented regional warming are particularly rampant, there is evidence that just the opposite of what is typically claimed by climate alarmists has actually occurred over the past several decades: regional temperatures, especially those over the eastern half of the HJUBs' drainage basins cooled, precipitation over the region declined, and river discharge from the basins to the Arctic Ocean decreased, all of which phenomena tend to discredit claims of an impending CO2-induced-by-way-of-global-warming shutdown of the ocean's thermohaline circulation.

Reference
Mann, M.E. and Jones, P.D.  2003.  Global surface temperatures over the past two millennia.  Geophysical Research Letters 30: 10.1029/2003GL017814.