What was done
In a paper published in the same issue of Climatic Change as this one, Chung et al. (2004a) evaluated temperature changes experienced at 14 urban and rural sites in Korea between the past normal period of 1951-1980 and the current normal period of 1971-2000.  In this study, Chung et al. (2004b) evaluate temperature changes at 10 urban and rural Korean stations over the past 29 years (1974-2002).

What was learned
The authors report that "the annual temperature increase in large urban areas was higher than that observed at rural and marine stations."  Specifically, they note that "during the last 29 years, the increase in annual mean temperature was 1.5°C for Seoul and 0.6°C for the rural and seashore stations," while increases in mean January temperatures ranged from 0.8 to 2.4°C for the ten stations.  In addition, they state that "rapid industrialization of the Korean Peninsula occurred during the late 1970s and late 1980s," and that when plotted on a map, "the remarkable industrialization and expansion ? correlate with the distribution of increases in temperature."

What it means
As in the study of Chung et al. (2004a), Chung et al. (2004b) found that over the past several decades, much (and in many cases most) of the warming experienced in the urban areas of Korea was the result of local urban influences and is not indicative of regional background warming.  To properly evaluate the latter phenomenon, which may or may not be influenced by anthropogenic CO2 emissions, these large urban-induced increases in temperature must be evaluated and subtracted from the temperature increases derived from the raw temperature data recorded at all non-rural sites.

Reference
Chung, U., Choi, J. and Yun, J.I.  2004a.  Urbanization effect on the observed change in mean monthly temperatures between 1951-1980 and 1971-2000.  Climatic Change 66: 127-136.