Whilst setting a financial value on all such effects is difficult to do precisely, figures have been produced for the most significant. In 2000 the government valued the annual cost of climate change induced by greenhouse gas emissions from UK air transport at £1.4 billion, rising to £4.8 billion per annum by 2030. The effect of noise was costed at around £25 million per annum in 2000, and for the same year the effect on air quality was costed at between £119 million and £236 million per annum. Based on figures produced by the European Environment Agency the AEF has calculated a much higher total external cost for 2000 of around £6 billion. Global environmental effects Whilst carbon emissions from all UK activities other than aviation had declined by 9 per cent in the 10 years between 1990 and 2000, carbon emissions from aviation activities doubled in the same period. Air transport in the UK accounted for 6.3 per cent of all UK carbon emissions in 2006. When the radiative forcing effect of other emissions are taken into account the total effect of emissions attributable to aviation is estimated to be twice that of its carbon emissions alone. Although the government has committed to reducing total UK carbon emissions by 60 per cent from existing levels by 2050, its policy is based on the use of "… economic instruments to ensure that growing industries are catered for within a reducing total." Even if this reduction in total carbon emissions is achieved, research published in February 2006 concluded that aviation could account for between 24 per cent and 50 per cent of the UK's carbon budget by 2050. The government recognises that there are no viable alternative aviation fuels, and whilst it accepts that the exemption of aviation fuel from fuel tax is anomalous, it sees no scope for a unilateral approach in addressing this. The strategy adopted in the White Paper seeks to mitigate the global effects of air transport primarily through emissions trading schemes. Although the Kyoto Protocol implemented emissions trading as a means to reduce emissions at national levels, the global nature of air transport means that all air travel is excluded from this mechanism. The government is seeking to redress this through the International Civil Aviation Organization (ICAO), which has been working on the environmental issue since 1998, but progress is slow. In the meantime efforts are