25 cities emit over 50% of greenhouse gases: Study

AVERAGE GLOBAL TEMPERATURES HAVE ALREADY RISEN BY OVER 1°C COMPARED TO THE PRE-INDUSTRIAL BASELINE

LONDON/MADRID: Just 25 big cities - almost all of them in China - accounted for more than half of the climate-warming gases pumped out by a sample of 167 urban hubs around the world, an analysis of emission trends showed on Monday.

In per capita terms, however, emissions from cities in the richest parts of the world are still higher than those from urban centres in developing countries, researchers found in the study published in the Frontiers journal.

The study compared greenhouse gas emissions reported by 167 cities in 53 countries, and found that 23 Chinese cities among them Shanghai, Beijing and Handan - along with Moscow and Tokyo accounted for 52% of the total.

It included more cities from China, India, the US and the European Union because of their larger contribution to global emissions.

It highlighted the significant role cities play in reducing emissions, said study co-author Shaoqing Chen, an environmental scientist at Sun Yat-sen University in the southern Chinese city of Guangzhou.

“It is simple, logical,” he said. “If you don’t act, eventually you will suffer from (climate change),” he said.

Global temperatures have gone up on average by more than 1°C compared to the preindustrial baseline level and are still on track to exceed the 1.5-2°C limit set by the Paris Agreement.

Chen and other scientists cautioned, however, that some of the data available for use in their study was patchy, with some cities reporting numbers from as far back as 2005.

Research published in 2018 in the Environmental Research Letters journal analysed a much larger sample of 13,000 cities, big and small, finding 100 cities containing 11% of the world’s population drove 18% of its carbon footprint.

Still, the new analysis “contributes to the growing literature and our understanding of urban emissions”, said Yale University Geography and Urban Science professor Karen Seto, who co-authored the 2018 paper.

“It’s really difficult to compare apples to apples on city greenhouse gas emissions but you have to try, and the paper makes a pretty good effort,” added Dan Hoornweg, a professor at Ontario Tech University and former adviser to the World Bank on sustainable cities and the climate crisis.