Climate change: Just 25 mega-cities emit 52 per cent of the world's urban ...

Climate change: Just 25 mega-cities emit 52 per cent of the world's urban ...
Climate change: Just 25 mega-cities emit 52 per cent of the world's urban ...

Just over half of the world's urban greenhouse gas emissions come from just 25 mega-cities, with Shanghai, Tokyo and Moscow topping the list, a study has found. 

Researchers from the Sun Yat-sen University in China recorded, for the first time, the greenhouse emission levels of 167 cities located across the globe.

Twenty-three Chinese cities — including Beijing and Handan — were also found to be among the most intensive urban greenhouse gas emitters.

Even though cities only cover some 2 per cent of the Earth's total surface area, they are major contributors to the climate crisis, the team explained.

Moreover, they said, current urban greenhouse gas mitigation efforts are not enough to meet global targets to limit the extent of climate change by the century's end. 

In 2015, 170 countries committed to the Paris Agreement — which set forth the goal to limit average global temperature increases to within 2.7°F (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 5.4°F (3°C) increase by 2100.

Just over half of the world's urban greenhouse gas emissions come from just 25 mega-cities, with Shanghai (pictured, Tokyo and Moscow topping the list, a study has found

Just over half of the world's urban greenhouse gas emissions come from just 25 mega-cities, with Shanghai (pictured, Tokyo and Moscow topping the list, a study has found

THE WORST EMITTERS

In their study, Dr Chen and colleagues looked at greenhouse gas emissions from 167 cities across 53 countries.

The worst 25 cities for total emissions were as follows (with figures in megatonnes of CO₂ equivalent):

Handan, China (199.71) Shanghai, China (187.93) Suzhou, China (151.79) Dalian, China (142.51) Beijing, China (132.58) Tianjin, China (125.89) Moscow, Russia (112.53) Wuhan, China (110.86)  Qingdao, China (93.56) Chongqing, China (80.58) Wuxi, China (76.88) Urumqi, China (75.32)  Guangzhou, China (71.03) Huizhou, China (68.74) Shijiazhuang, China (67.80) Zhengzhou, China (66.16) Tokyo, Japan (66.08)  Shengyang, China (64.10) Kaohsiung, China (63.64) Kunming, China (62.96) Shenzhen, China (62.91) Hangzhou, China (61.41) Hong Kong, China (55.90) Yinchuan, China (55.49) Chengdu , China (54.49)

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'Nowadays, more than 50 per cent 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 per cent 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.' 

In their study, Dr Chen and colleagues first conducted sector-level greenhouse gas emissions inventories of 167 cities — from Durban, South Africa to Milan, Italy — from within 53 different countries across the globe.

Each city was chosen for its representativeness in terms of urban size and regional distribution, the team explained.

Next, they assessed how each city's efforts to reduce their carbon footprint had been performing by comparing changes in emission levels from 2012–2016 with their stated short-, mid- and long-term carbon mitigation goals.

The team found that cities with high greenhouse gas emission levels could be found in both developed and developing countries — but noted that megacities like Shanghai and Tokyo) were particularly significant emitters. 

In addition, cities in Europe, the US and Australia tended to put out more emissions than the majority of urban centres in developing countries.

China — classified by the UN as a developing country — had several cities that matched the per capita emissions levels of developing countries, largely thanks to how the latter often outsource high-carbon production chains to China.

Of the 42 cities with available longitudinal data, the team

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