Climate Feedback

Cities: key players in the climate change arena

Posted by Olive Heffernan on behalf of Paty Romero-Lankao

Cities play key and diverse roles in the climate change arena. Regarding mitigation, a high proportion of energy, industrial and transportation emissions is generated by urban areas. Although most of the electricity and fuels are produced outside cities, they are aimed at satisfying cities’ “thirst” of energy. Therefore, urban areas place a huge burden not only on the absorptive capacity of the local environment; they also influence wide patterns of energy and land use in the surrounding and more distant areas, in the livelihoods and quality of life of people living outside cities’ boundaries.

As of vulnerability and adaptation, urban centers concentrate a large proportion of coastal and other populations most at risk from the effects of climate change (IPCC Summary for Policy Makers). The need for urban and local authorities and civil groups to develop actions to reduce greenhouse gases is part of the agenda of several cities in United States, Europe, Asia and Latin America ( Yet, the need to act to increase cities’ capacity to adapt to climate change and to understand the mechanisms to increase their resilience is not so well established, especially in developing countries. The irony here is that many of the urban areas more vulnerable to the negative impacts of climate change are those with almost negligible contributions to the greenhouse gases in the atmosphere. For instance, each citizen of Los Angeles emits an average of 15.6 tons CO2 e. These amounts are huge when compared to amounts in Mexico City, where each inhabitant releases four times less than in Los Angeles (3.6 tons CO2 e). If we multiply the per capita numbers by the total population, then Los Angeles and Mexico City emit 234 and 64.8 million Tons per year respectively (See footnote 1).

At the same time, cities are centers of diverse kinds of innovations (including technological innovation) that may contribute to de-carbonizing our societies and making them more sustainable and resilient. Only through the transformation of the infrastructure, especially transport, and the use of power in cities’ buildings, in the behavior, and in the production and consumption patterns of their residents, will it be possible to reduce greenhouse gases. Furthermore, urban centers might cope with the impacts of climate related events by introducing changes in the availability of water and other natural resources, in environmental conditions, and in buildings characteristics. There are examples of well governed cities, which have introduced actions to ensure the provision of infrastructure and services, and urban planning and management that reduces the vulnerability of people, industries and infrastructures. Yet, those cases are exceptional, and adaptation practices which increase cities’ resilience are taking place on a very limited basis (IPCC Summary for Policy Makers).

Further reading:

Romero Lankao, P. 2007: “Are we missing the point? Particularities of urbanization, sustainability and carbon emissions in Latin American cities”, Environment and Urbanization Volume 19, No. 1, pp.159-175

Hunt, J. (2004), “How can cities mitigate and adapt to climate change?, Building, research and information 32(1), p.55


  1. Report this comment

    Eli Rabett said:

    It seems to me that zoning and construction codes could contribute a huge amount to decarbonization of urban zones at relatively low costs (e.g. all roofing has to have a high reflectance, etc.) A discussion of specifics would be of great value.

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    JSleeper said:

    It doesn’t make sense to me to compare the per capita CO2 emissions of Mexico City to that of Los Angeles without considering factors such as income and relative wealth, geography, population density, and CO2 per capita of GDP produced.

    Perhaps comparing LA to European cities like London, Paris, Berlin, and the like would be more illustrative. Europeans have more comparative levels of wealth and income, yet produce much less CO2.

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    Bill Hewitt said:

    Cities are, without doubt, hugely important to solving the climate crisis. I noted recently that “The OECD reports that ‘60-80% of worldwide energy consumption occurs in urban areas.’”

    There are many solid and far-reaching initiatives being pursued by cities and coalitions of cities. ICLEI’s “Cities for Climate Change” is one, as noted above, and it’s being very effective. Another is C40 ( and they’re having a very big summit in NYC next week about which you’ll be seeing a lot of news. There’s much more going on.

    In the end, it must be said that cities themselves, when planned well, are the antidote to sprawl. NYC’s new PlaNYC estimates that 15.6 million metric tons of GHG will be avoided annually by attracting 900,000 new residents to the city.

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    Steven Craig / High Efficiency Fitness Company said:

    Hi nature. I am a scientist and fitness equipment inventor in Columbus Ohio (Google MSN Yahoo AOL etc. ‘Body Oars’ if you want to see some of my inventions)

    I majored in Horticulture and I noticed something, extremely obvious about Global Warming, science has simply overlooked.

    The following is from an Article I posted at

    Please reprint this, you don’t have to mention us. We are not trying to get any personal Pub.

    Ten ways to chill Global Warming, without parking a single Hummer

    Columbus 5.14.07. NASA web sites explain how the Ozone layer blocks well over 90% of the sun’s heat energy from reaching the surface of earth. It is a clear thick insulation that allows our planet to live as a giant terrarium. However the energy that reaches the surface does one of three things; it is reflected, absorbed or consumed.

    Just as that Ozone Layer blocks almost all of the sun’s heat energy from coming in, it also keeps it from going away. This is the same natural effect that heats greenhouses, so even though your white concrete stays cool in the hot sun, almost all of the heat that it reflects still ends up warming our atmosphere.

    Then dark things soak up the sun’s heat, but if they do not use it, it just radiates back up into the atmosphere. So both absorbed and reflected solar energy ends up heating the planet, because they are not heat consumers.

    Nature operates only one major solar heat eating process on earth; “photosynthesis”, and it is very cool.

    Thick damp land vegetation gobbles up the sun’s heat energy and then replaces it with a very cool bonus, extremely cold oxygen gas. A child’s hands can prove that healthy well watered tree leaves will stay very cool in the hot sun, all day long. Plants under the seas also consume some heat but oceans radiate and reflect so much they cause most weather, and in the water the coolness they create first sinks as warmer waters rise.

    Green plants make their own carbohydrates (food). They get the carbon (carbo) from the crap we animals exhale, fires and rotting plants, but they need far more hydrogen (the hydrate part) then the air can provide. So they use photosynthesis to separate it from water, which is why healthy plants grow ravenously in damp soil.

    However water is made of two elements, the other, oxygen, we animals need to live but plants have little use for it. Just as they absorb the carbon dioxide that animals exhale nature’s amazing balance uses the leaves to reimburse its animals, with pure clean oxygen gas. Now for the super cold part:

    The trees don’t make the oxygen gas, it expands from liquid water. However in that instant it grows 500-1000 times in size.

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    Steven Craig said:

    I have noticed something freezing cold that science has totally missed about forests and global Warming.

    Anyways the sun provides earth with far more heat energy in just one day, then all man made heat sources likely have produced since the beginning of time, combined.

    This means that the balance between the 3 solar energy surface interactions (reflected, absorbed and consumed) have maybe a billion times more influence on earth’s average surface temperatures then the burning of fossil fuels could possibility have.

    Even if all of our new heat sources combined were actually tipping the balance enough to cause this global warming, a small increase in earth’s solar energy consumption could easily compensate for it.

    Modern science has not only missed the fact that forests eat solar heat for dinner, but that photosynthesis is a constant expander. Certainly you know that expansion is nature’s most powerful cooling process, followed by time.

    Plants use photosynthesis to separate hydrogen from water to make plant food, but they just release the oxygen. But it expands from liquid to gas, between 500-800 times.

    The canned air (gas) that we clean electronics with expands 150-200 times which is more then enough to frost bite.

    Because forests discharge bone chilling cold oxygen high enough in the atmosphere that it must mix into the air, forests act just like earth’s natural coils on air conditioners, as earth’s rotation powers the fan.

    Humanity could easily reverse global warming by simply replanting enough forests.

    We waste enough fresh water (flowing from rivers into seas, to irrigate most of earth’s deserts. The hottest just happen to be under sea level.

    All we need to do is irrigate them with this wasted fresh water source and then we can turn them into natural atmospheric air coolers.

    Modern science is trying to design a big umbrella to float between the sun and earth. They went from asking "What is heating up the earth? to Science fiction, instead of just asking the second question, What has stopped cooling the planet?

    You know we just stupidly chopped down around 80% of earth’s forests. No other heat source (short of a meteor strike) could even be close.

    I am opening a blog called

    On it I list many more ways to grow forests on wastelands, as well as other related reports. I know I don’t have fancy stats, but I at least try to use common sense.

    Scientists won’t even talk to me because they are trained to argue over who makes up the best sounding stories(theories)instead.

    Yet any third grade science class can prove what I just told you by taking temperatures of tree leaves.

    You likely already realize they get quite cool during high levels of growing even in on very hot days in direct sunlight.

    Have have never felt a hot well watered healthy growing tree leaf, be they don’t exist.

    So instead of trying to tell scientists I have decided to tell business people who can make a fortune on selling trees and buying up deserts, and others that hopefully care.

    Please help me start an organization dedicated to regrowing forests on all wastelands. Let some 3td graders verify this and please report it.

    You realize that the American Medical Society ignored the proof that infections are caused by contamination. So for 50 years they would not recommending that surgeons should wash their hands before operating.

    We don’t have 50 years to screw around with that standard stupidity of Theory Science, which has not changed.

    Steven Craig

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