Cities biggest polluters, says new UN report

Posted: 30 March 2011

 A new report by UN-HABITAT says that cities are the biggest cause of pollution of our planet, and that unprecedented disaster, wide-scale disruption and loss face many of the world’s cities because of climate change.

Cities report cover

According to UN-HABITAT's new Global Report on Human Settlements: Cities and Climate Change, rapid urbanisation means that more and more people are living in urban areas, and that they are therefore most vulnerable to the impacts of climate disruption.

The report says the real battle against climate change is taking place in our cities. Cities are responsible for the majority of our greenhouse gases. But they are also places where the greatest efficiencies can be made," Dr. Joan Clos, Executive Director of UN-HABITAT, told a news conference in London this week. Stressing the all important urban dimension of climate change, he said: "City authorities have an important level of influence over both greenhouse gas emissions and adaptation to climate change."

"This makes it imperative that we understand the form and content of our urbanisation so that we can reduce our footprint and plan more sustainable and more resilient cities in the future. If we ignore this now, hundreds of millions of people will be at risk from the effects of climate change in the future."

Almost 40% of carbon dioxide emissions<br>in California comes from passenger vehicles.<br>© US Environmental Protection Agency
Almost 40% of carbon dioxide emissions in California comes from passenger vehicles. © US Environmental Protection Agency

With a call for immediate action by cities of the world, the report states that, if concerted action is not taken to reduce greenhouse gases and promote more environmentally sustainable and fairer urban development, there will be a deadly collision between urbanization and climate change.

This collision has been, and continues to be, fuelled by two human-induced factors. The first is urbanization, and the second is the impact of greenhouse gases that this report describes as having been "unleashed by development and manipulation of the environment".

"Urban enterprises, individual use of vehicles and rising consumer populations are key sources of greenhouse gases. Not only are cities major contributors to climate change, but with ever-increasing densities, they will also be the hardest hit when nature strikes back," said Joan Clos.  "We have to have robust local level responses to climate change if we are to have any real impact."

 CO2 emissions, population growth and national income

According to this report, many cities exceed the recommended annual average figure of 2.2 tonnes of CO2 equivalent value per capita. "A dynamic, complex and strong link exists between economic development, urbanization and CO2," says the report.

Some of the possible effects on the world’s cities:

  • As many as 200 million people will be displaced by climate change by 2050.
  • It is predicted that sea level rise and its associated impacts will, by the 2080s, affect five times as many coastal residents as they did in 1990.
  • In coastal North African cities, a 1-2 degree increase in temperature could lead to sea level rise exposing 6-25 million residents to flooding.
  • By 2070, almost all cities in the top ten exposure to flooding risk category will be located in developing countries (particularly in China, India and Thailand).
  • Today around 40 million people live in a 100-year flood plain. By 2070 the population living at this risk level could rise to 150 million people. The estimated financial impact of a 100-year flood would also rise from US$3 trillion in 1999 to US$38 trillion in this time.
  • In Latin America, 12-81 million residents could experience increased water stress by the 2020s. By the 2050s this number could rise to 79-178 million.

But not all is bleak. According to the report, the time to address this is now. Well planned cities with efficient urban transport provision and solid adaptation and mitigation strategies can actually have less impact on climate change and provide clear economic and social opportunities for their inhabitants. 

The report is available for download here.