25 ‘megacities’ produce 52% of the world’s urban greenhouse gas emissions

The megacity of Shanghai, China is one of the worst emitters of greenhouse gases on the planet (Shutterstock)
The megacity of Shanghai, China is one of the worst emitters of greenhouse gases on the planet (Shutterstock)

Over half of all the urban greenhouse gas emissions on the planet come from just 25 cities, new research has shown.

These ‘megacities’ are vast metropolises spewing millions of tonnes of CO2 and other harmful gases into the atmosphere.

The three biggest polluters on the list are all Chinese cities with Handan taking the top spot.

Amazingly, all the cities in the world cover just 2% of its surface. But with over half of the global population living in a city, they are serious contributors to climate change.

This latest study, published in the journal Frontiers in Sustainable Cities, is the first global balance sheet of greenhouse gasses (GHGs) emitted by major cities around the world.

The aim was to examine how much of an effect the policies introduced after the 2015 Paris Agreement are having.

‘Nowadays, more than 50% of the global population resides in cities. Cities are reported to be responsible for more than 70% of GHG emissions, and they share a big responsibility for the decarbonization of the global economy,’ wrote study co-author Dr Shaoqing Chen, of Sun Yat-sen University, China.

‘Current inventory methods used by cities vary globally, making it hard to assess and compare the progress of emission mitigation over time and space.’

The findings of the study showed both developed and developing countries have cities with high total GHG emissions, but the megacities in Asia (such as Shanghai in China and Tokyo in Japan) were especially important emitters.

The inventory of per capita emissions showed that cities in Europe, the US, and Australia had significantly higher emissions than most cities in developing countries.

China, which was classified as a developing country, also had several cities where per capita emissions matched those of entire developed countries.

However, the researchers point out that many developed countries outsource high carbon production chains to China, which increases export-related emissions for the latter.

Megacities: the worst offenders

Most expensive cities in the world to live in have been revealed - and London only just makes it onto the list Aerial view of Tokyo cityscape with Fuji mountain in Japan.
Tokyo also makes the list (Getty Images/iStockphoto)

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

The worst 75 cities for total emissions were as follows (with figures in megatonnes of CO₂ equivalent):

  1. Handan, China (199.71)
  2. Shanghai, China (187.93)
  3. Suzhou, China (151.79)
  4. Dalian, China (142.51)
  5. Beijing, China (132.58)
  6. Tianjin, China (125.89)
  7. Moscow, Russia (112.53)
  8. Wuhan, China (110.86) 
  9. Qingdao, China (93.56)
  10. Chongqing, China (80.58)
  11. Wuxi, China (76.88)
  12. Urumqi, China (75.32) 
  13. Guangzhou, China (71.03)
  14. Huizhou, China (68.74)
  15. Shijiazhuang, China (67.80)
  16. Zhengzhou, China (66.16)
  17. Tokyo, Japan (66.08) 
  18. Shengyang, China (64.10)
  19. Kaohsiung, China (63.64)
  20. Kunming, China (62.96)
  21. Shenzhen, China (62.91)
  22. Hangzhou, China (61.41)
  23. Hong Kong, China (55.90)
  24. Yinchuan, China (55.49)
  25. Chengdu , China (54.49)
  26. New York City, US (51.31)
  27. Manilla, Philippines (49.47)
  28. Bangkok, Thailand (49.22)
  29. Dubai, UAE (48.26)
  30. Seoul, Korea (48.06)
  31. Nanjing, China (47.94)
  32. Istanbul, Turkey (47.53)
  33. Frankfurt, Germany (45.73)
  34. Jakarta, Indonesia (43.86)
  35. Changchun, China (42.62) 
  36. Guiyang, China (42.09) 
  37. Saint Petersburg, Russia (42.07)
  38. Singapore, Singapore (40.38) 
  39. Jinan, China (38.49)
  40. Perth, Australia (36.33)
  41. San Diego, USA (35.02)
  42. Jiaxing, China (33.94)
  43. London, United Kingdom (33.58)
  44. Houston, USA (33.41)
  45. Stuttgart, Germany (32.82)
  46. Caracas, Venezuela (31.77) 
  47. Chicago, USA (31.48)
  48. Harbin, China (30.81)
  49. Mexico City, Mexico (30.69)
  50. Lanzhou, China (29.87)
  51. Lagos, Nigeria (29.33)
  52. Xi’an, China (28.15)
  53. Berlin, Germany (27.48)
  54. Taiyuan, China (26.73)
  55. Los Angeles, USA (26.55) 
  56. Tshwane, South Africa (26.14) 
  57. Nanchang, China (25.17) 
  58. Sao Paulo, Brazil (24.95) 
  59. Johannesburg, South Africa (24.72) 
  60. Changsha, China (24.64) 
  61. Hohhot, China (23.47) 
  62. Durban, South Africa (22.68) 
  63. Mumbai, India (22.57) 
  64. Hanoi, Vietnam (22.42)
  65. Torino, Italy (21.86)
  66. Cape Town, South Africa (21.53) 
  67. Yokohama, Japan (20.96)
  68. Nanning, China (20.90) 
  69. Santiago, Chile (20.03) 
  70. Osaka, Japan (19.76)
  71. Hamburg, Germany (19.45)
  72. Chennai, India (19.32) 
  73. Hefei, China (18.81) 
  74. Toronto, Canada (18.08) 
  75. Rotterdam, Netherlands (17.54)

Chen and his colleagues make three key policy recommendations in the study.

Firstly: ‘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.”

Second, development of methodologically consistent global GHG emission inventories is also needed, to track the effectiveness of urban GHG reductions policies.

Lastly: ‘Cities should set more ambitious and easily-traceable mitigation goals. At a certain stage, carbon intensity is a useful indicator showing the decarbonization of the economy and provides better flexibility for cities of fast economic growth and increase in emission.

‘But in the long run, switching from intensity mitigation targets to absolute mitigation targets is essential to achieve global carbon neutrality by 2050.’

Moscow city skyscraper and skyline architecture, Moscow international business financial office with Moscow river, Aerial view skyscraper of Moscow City business center in autumn season, Russia.; Shutterstock ID 1687499335; purchase_order: -; job: -; client: -; other: -
Moscow is in the top ten megacities for emitting greenhouse gases (Shutterstock)

In 2015, 170 countries worldwide adopted the Paris Agreement, with the goal limiting the average global temperature increase to 1.5°C.

Following the agreement, many countries and cities proposed targets for greenhouse gas mitigation.

Sadly, the UNEP Emissions Gap Report 2020 shows that, without drastic and strict actions to mitigate the climate crisis, we are still heading for a temperature increase of more than 3°C by the end of the 21st century.

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