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Urban Warming in Jakarta, Indonesia
Reference
Tokairin, T., Sofyan, A. and Kitada, T. 2010. Effect of land use changes on local meteorological conditions in Jakarta, Indonesia: toward the evaluation of the thermal environment of megacities in Asia. International Journal of Climatology 30: 1931-1941.

Background
The authors note that the population of Jakarta, the capital of Indonesia, was approximately 12 million strong in 2000, while it was a much smaller 5 million in the 1970s; and they indicate that with the rapid population increase of the past few decades, the city's urban area also expanded rapidly, adding to the strength of the urban heat island of the original "old city" as it existed back in the 1970s.

What was done
To evaluate the warming power of the newer infrastructure that was created around the central old city, Tokairin et al. analyzed the air temperature increase in the initially-urbanized area of Jakarta over the 30-year period between the 1970s and the 2000s, using air temperature data provided by the country's National Climatic Data Center, after which they made a rough estimate of the sensible heat in the old city during the 2000s that originated in, and was transported from, the newly developed urban area.

What was learned
The three researchers report that (1) "the sea breeze developed at an earlier time of day in the present day than in the 1970s," (2) "in the present-day case, a converging flow developed over the old city in association with the low pressure which formed over the same location," (3) "the daytime average and maximum air temperature in the old city were higher in the present day than in the 1970s by 0.6 and 0.9°C , respectively, due to the advection of heat from the new area," and (4) "the amount of heat advected into the old city was estimated to be -0.7 Wm-2 in the 1970s and 77 Wm-2 in the 2000s."

What it means
Tokairin et al. report that there were only three megacities in Asia with a population greater than 10 million people in 1985, but that the United Nations (2005) has estimated there will be 13 such cities by 2015. For these megacities and their growing populations, expanding and intensifying urban heat islands will likely prove to be of more immediate significance than will any additional global warming that may develop concurrently.

Reference
United Nations. 2005. World Urbanization Prospects: The 2005 Revision Population Database. Population Division, Department of Economic and Social Affairs, United Nations.

Reviewed 16 March 2011