Urbanised territories as a specific component of the Global Carbon Cycle

The biosphere role of urbanised territories in the Global Carbon Cycle (GCC) is considered. Indeed, despite the relatively small area of land taken up by urbanised territories (similar to2% of total land area), these territories are responsible for ca. 97% of anthropogenic CO2 emissions. The major sources of these emissions are transport, industries and the conversion of natural to urban land, as well as cement production for the building sector. Urbanisation changes the characteristics of the vegetation and soils on the territories of the cities, which in turn leads to the change of parameters of the carbon cycle. Therefore, in our work we will consider only the change in carbon flows associated with the land conversion caused by urbanisation. Although at the present time, the influence of these processes on the GCC is not significant, With the current high rate of urbanisation, the situation may rapidly change in the near future. The first step of the investigation is to assemble a global database on cities, specifically on urban population and the areas. The data for 1001 cities and the UN prognosis of urban population growth is used in order to predict the dynamics of urban territories growth until the year of 2020, when a peak in urbanisation is projected. This is done over a regional scale, namely for the eight world regions. The next step is to calculate the dynamics of regional CO2 emissions resulting from conversion of natural ecosystem into urban land during the process of urban growth. As a result, we find that urbanised territories of the economies in transition, and all highly industrialised regions, play the role of carbon sink, while the other regions act as sources. (C) 2003 Elsevier B.V. All rights reserved.