INTRODUCTION: PURPOSE AND OBJECTIVES OF THE IPCC

In the near future significant changes in the global climate can be expected, with an increase in mean air temperature of 3–4°C. For the northern temperate regions and high latitudes in particular, these changes are likely to affect a wide variety of physiographic features over vast regions, human living conditions, socio-economic structures and development, and natural ecosystems. The effects of a rise in global air temperature could be devastating: extensive melting of the polar icecaps and the resultant rise in sea level would impact coastal areas, and changes in atmospheric circulation would affect agricultural productivity and food supplies, as well as water resources in many countries.

In the early 1970s some scientists first warned of the possible impacts of human activities on the global climate (Budyko, 1972) and predicted a warming of 1.5–2°C in the coming decades. At that time, however, few climatologists supported the view that significant climate warming would result from increased concentrations of CO2 in the atmosphere. On the contrary, it was widely believed that climate cooling would occur, and such a cooling trend was observed during the 1970s, according to data from the world meteorological network. Nevertheless, the first World Climate Conference (WMO, 1979) concluded that the human impacts on climate were serious, and that the problem required further study, but noted that science could not give a definite answer to the question of whether climate warming or cooling would occur.

The situation changed rapidly in the 1980s, when observation data showed a sudden rise in global air temperature.