Atmospheric carbon dioxide concentrations have increased more or less steadily over the past 20 years, continuing a trend more than a century old that is attributed largely to rising consumption of fossil fuels and large-scale destruction of forests by slash-and-burn agriculture and logging. One study estimates that to stabilize global CO2 at twice that of today (1994), current emissions would need to be cut immediately by a factor of 25. By 1997, the UN Intergovernmental Panel on Climate Change concluded that to stabilize the world climate fossil fuel use needed to be cut by 60%.
In 1997 it was reported that international negotiators had all but given up on preventing a doubling of the atmospheric concentration of CO2. The momentum of growth was so great that making the changes required to slow global warming significantly was likened to "trying to turn a supertanker in a sea of syrup."
There are four basic requirements to combating climate change: (1) A global reduction in greenhouse gas emissions, possibly coupled with increases in the size of greenhouse gas sinks; (2) A means of achieving this as cheaply as possible in order that they human population does not suffer a sharp drop in its standard of living; (3) The transfer of technical and financial resources to developing countries to enable them to participate effectively in implementing the UN Framework Convention on Climate Change, which was signed by 154 governments in Brazil during the UN Conference on Environment and Development in June 1992; and (4) Procedures that allow the developing countries to complete their industrialization. Ratifying countries are committed to prepare and report on national strategies to limit emissions of greenhouse gases. Through the Global Environmental Facility, countries have contributed substantial resources to curb conditions that cause global warming.
By warming global climate, an El NiÃ±o or any other warm period may help temporarily brake the ongoing rise in atmospheric carbon dioxide due to human activity. The rate of increase of atmospheric carbon dioxide levels slowed significantly about 2 years after each of four warm spells that occurred between 1980 and 1991, including the major El NiÃ±o of 1982-83. Global vegetation growth – as measured by light reflected from photosynthetically active leaves – also sped up after a comparable time lag, suggesting that the plants were sopping up the excess carbon dioxide. The findings implicate ecosystem processes – perhaps interactions between soil microbes and plants – as a middleman between warming and plant growth. Experts say it is unclear, however, whether such plant growth might restrain carbon dioxide buildup over the long haul.