One approach which has spread since the mid 1990s, by which time it had been
reasonably established in the USA, is tradable pollution quotas – marketable
permits or tradable credits. These work by setting a level or standard and allocating a
quota to the potential polluter, fishing fleet, etc. Any emissions or catch above that
standard are penalised, but if the country or business does not use its whole quota it
is free to sell its surplus, perhaps by auction, or possibly save it for a later date. An
authority may need to regulate how tradable quotas are sold to prevent speculation
and hoarding. The approach is useful for transboundary issues, and negotiations to
control global carbon emissions and regulate ocean fisheries exploitation have
explored tradable emissions quotas.