Cities and their residents are the main drivers of global warming, yet also offer the best means for slowing the rate and impact of climate change, according to the 2009 annual edition of The Little Green Data Book.  The annual compilation of statistics on environment-related issues was released today by the World Bank on the occasion of the 17^th Session of the United Nations Commission on Sustainable Development.  

The Little Green Data Book 2009 points to the world’s cities as key determinants of climate change, because most economic activity takes place in urban areas. This makes cities hubs of relative affluence, which in turn raises their levels of greenhouse gas emission - one of the reasons why, historically, developed countries have produced more greenhouse gases than developing countries. But such economic activity is spreading as urbanization continues throughout the world: by 2050, an estimated 70% of earth’s population will live in cities. 

If energy-use patterns remain unchanged, greenhouse gas emissions will rise significantly - since cities on average derive about 72% of their energy from coal, oil, and natural gas. (Cities are also the main users of renewable energy, but these sources still make up just a small share of total energy consumed.). An important distinction, nevertheless, needs to be made: that people who live in more dense city-centers, on average, often produce 30% to 50% less GHG emissions than their suburban neighbours.  

Commenting on the Little Green Data Book 2009, Katherine Sierra, Vice President for Sustainable Development at the World Bank, said, “National and city governments around the world face major challenges - and opportunities - as they weigh the choices for their future energy mix. There is no doubt that public policies can improve energy efficiency and reduce carbon dioxide emissions. And these decisions will be vitally important, not only to the cities and countries concerned, but to the future wellbeing of our world at large.”

Key messages from the 2009 Little Green Data Book   

Many cities are vulnerable to sea level rise from global warming - Energy policies by nations - and by extension, cities - will have a direct bearing on the well-being of many of the world’s great coastal cities. Some 360 million urban residents live in low-elevation coastal zones, leaving them exposed to sea level rise and storm surges that will result from the melting of polar ice shelves.

Scientists estimate that sea levels rose 0.17 meters in the 20^th century and predict a further 1 meter rise over the next 100 years (which could be adjusted upward if a catastrophic event - such as the melting of the west Antarctic ice sheet - was to occur). Developing countries will be less able than developed countries to adapt to the challenges of such climatic shifts.

Policy decisions can make a significant difference - As fast-developing, large-population countries such as China and India urbanize and absorb a greater share of global manufacturing, their carbon dioxide emissions are expected to increase - even though per-capita emission levels in the next decades will continue to be lower than those of developed countries. Nevertheless, these countries should be able to benefit from the experience of countries such as Germany and Sweden that have dramatically reduced per-capita carbon dioxide emissions over the last 40 years.

The relationship between urban planning and infrastructure investment is key - Being more densely-settled, urban areas offer options that are more cost-effective than those of rural areas for providing access to water, sanitation, and solid waste management services. For instance, regions such as Latin America and the Caribbean, and Eastern and Central Asia, which have some of the highest urbanization rates, also have greater access to sanitation services than regions with the lowest urbanization rates, such as Sub-Saharan Africa and South Asia.

Compact cities tend to be more sustainable than sprawling cities. Denser cities use less energy for transportation, with lower transport-related gas emissions, and are able to provide services at lower cost and can implement more energy-efficiency measures.

Similarly, countries favouring private transport use more energy per passenger kilometer than countries with high levels of public and non-motorized modes. As density increases, people tend to use more public transportation, lowering transport-related energy use per capita. High energy use per capita in the United States and Western Europe can be ascribed to high incomes; in the Middle East, to fuel subsidies.

About the report

In its tenths annual edition, The Little Green Data Book 2009 is a pocket-sized quick reference on key environmental and development data for over 200 countries.  For more information, please visit the World Bank website.

Source: World Bank