Over half of the world’s urban greenhouse gas emissions take place from just 25 mega cities, 23 of which are located in China, a study has found.
The cities that emit the most greenhouse gases include Handan, Suzhou, Dalian, Beijing and Tianjin in China, but also Tokyo, Japan, and Moscow, Russia.
China’s President Xi Jinping has pledged to cap carbon emissions by 2030 and achieve carbon neutrality by 2060, part of its commitment to the Paris Agreement.
The international accord signed by 194 states and the European Union sets forth the goal to limit average global temperature increases to within 1.5°C.
However, research by the United Nations has found that unless we take more drastic action, we are on track for a more than 3°C increase by 2100.
And, based on the findings of the new study, China in particular will need to step up its switch from coal to renewables if it is to meet President Xi’s goals in this area.
At present, China is running a whopping 1,058 coal-fired power plants, that’s more than half of the world’s capacity.
Even though cities only cover some two per cent of the Earth’s total surface area, they are major contributors to the climate crisis, the team explained.
‘Nowadays, more than 50 percent of the global population resides in cities,’ said paper author and urban environmental management researcher Shaoqing Chen of the Sun Yat-sen University in Guangzhou.
‘Cities are reported to be responsible for more than 70 percent of GHG emissions, and they share a big responsibility for the decarbonization of the global economy.
‘Current inventory methods used by cities vary globally, making it hard to assess and compare the progress of emission mitigation over time and space.’
According to the team, 113 of the 167 cities studied set targets for reducing their levels of greenhouse emissions, with 40 having carbon neutrality goals, but the findings show that we are a long way off meeting Paris Agreement targets.
‘Breaking down the emissions by sector can inform us what actions should be prioritized to reduce emissions from buildings, transportation, industrial processes and other sources,’ said Dr Chen.
The two main sources of greenhouse gas emissions, the team found, came from so-called stationary energy in the transportation sector.
Stationary energy emissions, including those from electricity and fuel consumption by residential, commercial, industrial and institutional buildings contributed 60–80 percent of emissions in European and North American cities.
Road-based transportation accounted for more than 30 percent of greenhouse gas emissions in one third of the cities, while less than 15 percent of total emissions were traced back to railways, waterways and aviation.
Based on their data, the team has proposed three policy recommendations.
First, Dr Chen said, ‘Key emitting sectors should be identified and targeted for more effective mitigation strategies.
‘For example, the differences in the roles that stationary energy use, transportation, household energy use, and waste treatments play for cities should be assessed.’
Next, he added, urban greenhouse gas reductions policies need to be monitored with methodologically consistent emissions inventories.