What was done
Snow cover data for the entire territory of Poland were collected from 66 weather stations for periods ranging from 50 to 108 winter seasons, where a day with snow cover was defined as a day with at least one centimeter of snow covering at least 50% of the ground.

What was learned
The author reports that "during 1948-49 to 1997-98, both the duration and depth of snow cover display a slight decreasing trend," but that over longer periods of up to 108 winter seasons, "both the duration and depth of snow cover display neutral or near-neutral trends."

What it means
Falarz remarks that "the results point to only minor changes or even no change of snow cover during the 20th century in Poland," which is rather remarkable, since winter-season air temperature in Poland has been reported to be displaying, according to Falarz, "an increasing trend for both the minimum and maximum average by 0.5-0.8°C per 10 years [that's 5-8°C per century!!!], confirmed by statistical significance tests (Wibig and Glowicki, 2002)."  These observations make us wonder if the temperature increases might not be more indicative of urban heat island intensification than of real-world warming, which in turn makes us wonder to what degree this problem might be infecting temperature data from other countries.