What was done
Working with "previously unexplored observational temperature data for the period 1802-62 from Overtornea and Kalix in the Tornedalen area in subarctic Sweden (~66°N)," together with similar data from the nearby Haparanda weather station, the authors developed "a continuous Tornedalen temperature series" that stretches from 1802 to 2002.

What was learned
Over the two-century period of record, mean annual air temperature rose by 1.97°C, with the greatest increase occurring in winter (2.83°C) and the smallest increase in summer (0.88°C).  This warming, in the words of the authors, "culminated in the 1930s," so that "the warmest decade was the 1930s."

What it means
Throughout the period of the most significant greenhouse gas buildup during the course of the industrialization of the world, i.e., 1930 and onward, the Tornedalen temperature series indicates there has been no net warming in that area of Northern Sweden, just as there has been no net warming in most of the United States over this period (see U.S. Climate Data on our sidebar).  Hence, these particular data provide no evidence for any CO2-induced greenhouse warming, and they demonstrate there is nothing unusual about the warming of the past quarter-century that climate alarmists typically describe as being unprecedented over the last two millennia.

Pretty much the same story is told by comparative data the authors present for Vardo, Oulu, St Petersburg, Uppsala and Helsinki: if the temperature trends of these five sites were averaged together, they too would show little to no net warming since the 1930s.  Also, the Uppsala temperature series, which is the longest of the lot, indicates it was equally as warm as it has been recently back in the 1730s and 40s.