China’s Belt & Road Initiative must bring cost-effective new low-carbon methods to developing countries and avoid outdated polluting technologies in order to ensure global climate goals are met, a new study said.

The 126 countries in the Belt & Road region now account for 28% of global emissions, but on their current trajectory, that could rise to 66% by 2050, researchers, led by Ma Jun, a Special Advisor to China’s Central Bank, said.

That could mean global carbon levels would rise to nearly double the level needed to keep temperature increases to below 2 degrees Celsius, a major goal of the Paris agreement.

“If B&RCs (Belt & Road countries) follow historical carbon-intense growth patterns… it may be enough to result in a 2.7-degree path, even if the rest of the world adheres to 2-degree levels of emissions,” the report said.

The research was published jointly by China’s influential Tsinghua Center for Finance and Development, which provides recommendations to policymakers, along with London-based Vivid Economics and U.S.-based Climate Works.

The study estimated that more than $12 trillion in infrastructure investment would need to be “decarbonised”, and called for safeguards to ensure existing low-carbon technologies and practices were implemented, although even that might not be enough to meet 2050 goals.

The Belt & Road Initiative is a Beijing-led program aimed at boosting economic integration through infrastructure and energy investments in Asia and beyond. Signatory countries account for about a quarter of the global economy.

Although China has promised to decarbonise its energy system, it has continued to approve and finance coal projects, using $1 billion in “green finance” to fund coal-fired power projects in the first half of 2019.

According to a study by environmental group Greenpeace, China has also invested in 67.9 gigawatts of coal-fired power in Belt & Road countries since 2014, compared to 12.6 GW of wind and solar.

China has also been criticized for investing in overseas coal-fired power projects using polluting technology no longer permitted at home

Li Gao, a senior Chinese climate official, told reporters on the sidelines of a briefing on Friday that as a matter of principle, China would not use outdated technology in overseas projects, but in practice, this would depend on circumstances and the actual standards of the hosting country.