After the Kyoto Protocol: can soil scientists make a useful contribution?
1999
Smith, K.A.
Over 170 countries have ratified the UN Framework Convention on Climate Change (UNFCCC) which aims at 'the stabilisation of greenhouse gases in the atmosphere at a level that will prevent dangerous anthropogenic interference with the climate system'. The Kyoto Protocol, signed in 1997, commits the developed ('Annex 1') countries to a reduction in gaseous emissions. The global increase in atmospheric CO(2), the main greenhouse gas, comes mainly from fossil fuels (6.5 Gt Cyr(-1)), together with about 1.6 Gt Cyr(-1) from deforestation. The atmospheric increase is only 3.4 Gt Cyr(-1), however, due to a net sink in terrestrial ecosystems of about 2 Gt Cyr(-1), and another in the oceans. Increasing net carbon sequestration by afforestation of previously non-forested land is one way of reducing net national emissions of CO(2) that is permitted under the Kyoto Protocol. Future modifications may also allow the inclusion of carbon sequestration brought about by other forestry and agricultural land management practices. However, associated changes in net fluxes of two other greenhouse gases identified in the Protocol--nitrous oxide (N(2)O) and methane (CH(4))--will have to be taken into account. Growth of biomass crops can increase N(2)O emissions, and drainage of wetlands for forestry or agriculture also increases them, as well as emissions of CO(2), while decreasing those of CH(4). The problems of how to quantify these soil sources and sinks, to maximize soil C sequestration, and to minimize soil emissions of CH(4) and N(2)O, will present a major scientific challenge over the next few years-one in which the soil science community will have a significant part to play.
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