Third runway's sky-high emissions

Having a third airport runway will increase carbon emissions by up to 269 million tonnes in 50 years and this will come at a cost of about HK$50 billion, a study has found.

The emissions estimate from the study, commissioned by the Airport Authority, is higher than Friends of the Earth's estimate in November that the runway would cause up to 216 million tonnes of extra emissions in 50 years. But the estimated cost is far below Friends of the Earth's figure of between HK$200 billion and HK$630 billion.

Activists have accused the authority of turning a blind eye to the snowballing level of carbon emissions and asked if the social and environmental costs were worth paying.

The authority commissioned environmental consultancy ERM to conduct the carbon-cost study for the third runway last year.

According to the results released yesterday, the airport's carbon emissions will peak at 27 million tonnes by 2031 - 62 per cent higher than its 2011 level.

The extra carbon that the third runway will generate ranges from 36 million to 269 million tonnes for the 50 years until 2061, depending on the method of calculation used.

One method - which gives a lower estimate - is to count emissions from planes taking off, landing and cruising within the city's boundaries. Another, which gives a higher figure, takes into account all the carbon emitted during the entirety of a flight that takes off or lands in the city.