The Kyoto Protocol is an international environmental agreement intended to stabilise and then reduce greenhouse gas concentrations in the atmosphere in order to limit the effects of climate change.
The Protocol was adopted on 11 December 1997 in Kyoto, Japan, although it was not enforced until 16 February 2005.
It established a legally-binding commitment for industrialised nations to reduce their collective greenhouse gas emissions by 5.2 per cent from 1990 levels.
Four greenhouse gases – carbon dioxide, methane, nitrous oxide and sulphur hexaflouride – and two other groups of gases – hydrofuorocarbons and perfluorocarbons – are covered by the Protocol.
Kyoto also defined the UN's official carbon offset mechanisms: the Clean Development Mechanism and Joint Implementation scheme. These mechanisms help industrialised countries to meet their commitments by enabling them to purchase carbon credits under emission trading schemes. Credits can also be awarded for funding sustainable environmental projects and are used to offset signatories' actual greenhouse gas emission levels.
Kyoto has been a source of long-standing controversy ever since the US refused to ratify the treaty in protest at the fact large emerging economies such as China and India faced no binding constraints on their greenhouse gas emissions.
The Protocol is due to expire in 2012 and a successor to the agreement designed to include the US and impose some form of emission targets on all nations was meant to be agreed at the Copenhagen Summit in December 2009.
However, the Copenhagen Summit ended without a binding deal and negotiators are now hoping to reach an agreement at the Mexico Summit in December 2010.
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