Friday, 30 December 2011

Korea - temperature

A discussion at Watts up with That (WWUT)
... reports on a paper which shows the due to its high energy use the effect of the Urban Heat Island in South Korea accounts for much of its apparent rise in temperatures. (Quantitative estimates of warming by urbanization in South Korea over the past 55 years (1954―2008) KIM Maeng-Ki   and KIM Seonae )

This posting examines that claim.

The two Koreas have similar land areas, 100,000 km2 for the South and 120,000 km2 for the North. The population of the South, 49 million, is twice the of the North, 24 million. Where they differ most markedly is in their CO2 emissions. From 1990 to 2008 (the last year with data available) South Korea's CO2 emission have increased from 260 million metric tons to 509 million while those of North Korea have fallen from 240 million to 8 million. At WWUT someone has commented it would be nice to compare North and South Korea - and this is what I am about to do.

In the current NCDC average temperature data set there are data for 28 stations in North Korea and 60 in South Korea. From these I extracted 9 stations with long-term data from the North and 11 from the South. Two of the stations in the North went back to 1906 and four stations in the South went back to that year or earlier. In the North the remaining stations were mainly for the period 1961 to present, the critical period for temperature change. Periods of missing data were infilled using data from other stations. In the case of North Korea many stations had gaps for the period 1944 to 1960 (the Korean War) and some years were infilled by reference to stations from South Korea.

The first analysis I carried out was to do a double-mass plot  of average cumulative monthly temperature from South Korea against similar values for North Korea.

The plot is an almost perfect straight line. Had temperature for South Korea risen more rapidly than that of the North, due to the urban heat island effect, then the line would have curved upwards from the point when the effect cut in.

I also looked at the tempeature anomaly, with respect to 1906 to 1950, for the two countries.

This shows that temperature in both countries rose at a similar rate. If one assumes that in North Korea, with its minimal energy use (its per capita CO2 emissions at 3.3 t/p/a are 1/3 those of the South at 10.6 t/p/a) there is no heat island effect then it is questionable whther the effect can be as large as the authors of the paper mentioned have concluded.

As a caveat I should mention that my sole criteria for choosing stations was length of record and I only used data from the NCDC data base. It may be that the authors had access to larger data base of South Korean data.

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