However, this effect may decline because of efforts to reduce SO2 emissions. Recent models of the earth's climate system which take account of both GHG warming and aerosol cooling produce good agreement with historic temperature trends. The report concludes that 'the balance of evidence suggests a discernible human influence on global climate'. This is a greater rate of change than any experienced in the last 10,000 years and would place considerable stress on natural ecosystems. Under the same scenario, the predicted rise in sea level due to oceanic thermal expansion and ice melt is 50 cm by 2100.
Major uncertainties remain on the timing, magnitude and regional patterns of climate change.
The predictions are critically dependent on factors such as population, economic growth and energy policy. Key scientific uncertainties concern understanding of sources, sinks and concentrations of GHGs, and of the effects of clouds, oceans, polar ice, aerosols and vegetation. The ultimate aim of the Convention is 'stabilization of GHG concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system'. However, as a first pragmatic step towards its goal, the Convention aimed to restrain the increase in GHG emissions. All countries were required to prepare inventories of their emissions and sinks for all GHGs not covered by the Montreal Protocol, and developed countries undertook to draw up national programmes aimed at returning their GHG emissions to 1990 levels by 2000.