It is cities, not nations, that will play a bigger role in preventing the world’s temperatures from rising more than two degrees following landmark climate talks in Paris, according to an official from a global network on climate change. Government leaders and representatives from around the world will meet in the French capital at the end of this month and into December with hopes of producing a legally binding agreement to cap global warming. “The mayors of the world are those in the best position to take the actions needed, and they [already] are,” said Zachary Tofias, head of sustainable communities at the C40 Cities Climate Leadership Group, which involves more than 80 cities worldwide. He was speaking on the sidelines of the World Green Building Council Congress in Hong Kong last week, which focused on sustainable city development. Research by the leadership group – which started with 40 cities a decade ago but has since grown to a network of 80 including Hong Kong – shows that cities have increased the rate at which they are tackling climate change by a scale of “260 per cent since 2011”. Those actions will be delivered over the next five years. “This is critical as actions made from the treaty made at COP21 in Paris won’t kick in till 2020,” he added. The organisation advises and provides technical support to cities on how to achieve their sustainable goals and replicate successes of other cities. READ MORE: Environmental authorities to unveil status report on Hong Kong government's actions to tackle climate change “Cities are very much action-oriented. Mayors get elected and re-elected on whether garbage is picked up in their cities. National governments are not, for the most part.” Tofias pointed to the “carbon locked-in effect”, which refers to investments or policy decisions being made to date that “locked-in emissions” which had consequences for the future. Scientists have found that to keep global warming within two degrees – the pre-industrial average that experts claim is necessary to stave off the most serious effects of warming – total global carbon emissions cannot exceed 1,000 gigatonnes. As of 2012, about 80 per cent of this budget has already been committed by policy decision in infrastructure globally, Tofias said. About a third of the remaining 20 per cent will be locked in by infrastructure decisions made in urban areas in the net five years, largely in the “global south”, or developing cities of the world. READ MORE: Low-carbon investments: Hong Kong businesses can capitalise on Paris climate talks, experts say “Based on the business as usual trajectory, the remaining 20 per cent of the carbon budget will be locked-in based from decisions that will be made in the next five years,” he said. “The carbon locked-in effect means that mayors are in a position today to impact what is going to happen tomorrow. The decisions made today re going to be much cheaper than in the future.” “By choosing low-carbon objectives, power, buildings, industry and transportation sectors over less efficient technologies in the near term, the investment cost needed would four times less over the long-term.” And the built environment will naturally be the area where local governments could focus their efforts on – particularly in existing private buildings – given that the entire sector is responsible for around 30 per cent of global greenhouse gas emissions, said Bruce Kerswill, chairman of the World Green Building Council. “With the right government incentives,” said Kerswill. “It’s been recognised that the biggest impact can be made with the lowest cost in the least amount of time”. The council has set a target for all newly constructed buildings to be “net zero” in emissions by 2050.