A valuable new paper has been published which further documents the large role of land use/land cover on long term near-surface air temperature trends. The paper is
He, J. F., J. Y. Liu, D. F. Zhuang, W. Zhang, and M. L. Liu
2007: Assessing the effect of land use/land cover change on the change of urban heat island intensity Theor. Appl. Climatol. DOI 10.1007/s00704-006-0273-1
The abstract reads,
âDue to rapid economic development, China has experienced one of the greatest rates of change in land use=land cover during the last two decades. This change is mainly urban expansion and cultivated land reduction in urban growth regions, both of which play an important role in regional climate change. In this paper, the variation of the urban heat island (UHI) caused by urbanization has been evaluated with an analysis of land use change in China. First, meteorological observation stations were grouped by different land cover types (dry land, paddy field, forest, grassland, water field, urban, rural inhabitable area, industrial and mineral land, and waste land) throughout China. These stations were subdivided into urban and non-urban classes. Then, a new method was proposed to determine the UHI intensity from the difference between the observed and the interpolated temperature of urban type weather stations. The results indicate that the trends of UHI intensity in different land change regions are spatially correlated with regional land and its change pattern. During 1991â2000, the estimated UHI intensity has increased by 0.11 _C per decade in spring and has fluctuated in other seasons throughout China resulting from land use change.â?
There is an interesting definition of âglobal warmingâ? in the paper. It reads,
âGlobal warming can be partitioned into (1) the urban heat island effect, (2) the effect of deforestation, (3) the effect of secular micro-climate shift, (4) the influence of general global warming with particular reference to the tropics (Harger, 1995).â?
They also write
âWe found that the variability of UHI intensity has a strong spatial connection with the pattern of land use, i.e. the influence of the UHI effect on urban stations is not only related to land use change type, but also to land use change structures. In regions where land use change type represented the sharp expansion of an urban area and the reduction in water area, the urban stations were often easily affected by UHI. On the other hand, in regions where land use change type was the expansion of urban area accompanied by an increase in water area or vegetation area, the urban stations were seldom affected by UHI.â?
In the last sentence, it should be emphasized that while they did not find an âUHIâ? effect, there certainly must have still been a land use/land cover change effect on the temperatures. Urbanization is just one of a diverse spectrum of types of the human alterations of the Earthâs landscape.