Sian Berry, the Green Party candidate in the upcoming London mayoral election has suggested a personal carbon quota scheme as a strategy for individuals to reduce their individual carbon emissions.Speaking to Newsnight on BBC2, Ms Berry claimed the system could provide a financial benefit for individuals with the smallest carbon footprints."In general, poorer people do have lower carbon footprints, so if you set a quota that people can go above or they can trade below, those people will actually gain money from that system," she stated.Ms Berry explained that under such a system, individuals with a smaller carbon footprint would be able to sell their carbon "surplus" to an individual who has exceeded their allocated amount of carbon dioxide emissions.She added that any carbon emissions reduction system will need to encourage people to change their behaviour over the long-term in order to be effective.Last month, the Guardian reported that Ireland is currently exploring the feasibility of introducing a personal carbon trading scheme.