是元凶还是受害者？如果政策制定者应对不当，答案可能两者皆是。

Cities in the 21st century are the engines of economic growth and provide employment and homes to the growing global middle classes.

21世纪的城市是经济增长的引擎，并为全球日益壮大的中产阶级提供了就业机会和住房。

As the world gets hotter, however, urban areas will need to put themselves at the heart of the international effort to mitigate the effects of climate change.

但随着全球气候变暖，城市地区必须把自己放在减轻气候变化影响的全球性努力的中心位置。

Along with the prosperity and innovation, global cities are the principal source of the carbon dioxide emissions warming the earth’s atmosphere.

伴随着城市的繁荣与创新，国际化大都市成为了二氧化碳排放的主要来源，正是这种气体导致了地球大气层变暖。

If the process is not halted, these great conurbations will be the worst affected by rising temperatures.

如果这个过程得不到遏制，这些中心城市将成为受气温上升影响最严重的地区。

A few figures tell the story.

举出一些数据即可说明问题。

The London School of Economics Cities programme projects that by 2050 cities will have swelled by another 2.5bn people, taking the overall total to about two-thirds of the global population.

伦敦政治经济学院(London School of Economics)的城市研究项目预计，到2050年，在城市居住的人口将再增加25亿，这将使城市总人口占全球人口的比重达到约三分之二。

On present trends these cities would be producing about four-fifths or more of the greenhouse gas being pumped into the atmosphere.

若目前的趋势延续下去，排入大气层的温室气体将有五分之四甚至更多是由城市制造的。

As the planet heats up, cities will fare the worst.

随着地球日益变暖，城市地区的状况将变得最为糟糕。

The Paris-based Organisation for Economic Cooperation and Development estimates that temperatures in urban areas already tend to be 3.5-4.5C higher than in the countryside.

据总部位于巴黎的经济合作与发展组织(OECD)估测，目前城市地区的气温通常已较乡村地区高出3.5至4.5摄氏度。

This difference could well increase by another 1C per decade.

未来这一温差很可能每十年扩大1摄氏度。

This would mean that, by the second half of the present century, some big cities could be as much as 10C hotter than their surrounding hinterlands.

这将意味着到21世纪下半叶，某些大城市的气温可能比周围内陆地区高出10摄氏度。

That begins to sound like unliveable.

大城市将因此逐渐变得不适宜居住。

Many large cities are situated in low-lying coastal areas, leaving them badly exposed to the dangers of flooding that come with rising sea levels and storm surges.

很多大城市位于地势偏低的沿海地区，存在因海平面上升和风暴潮而引发洪灾的隐患。

The sea does not differentiate between the rich and the poor.

大海对贫富一视同仁。

Among the cities judged most at risk by the OECD are Kolkata, Shanghai, Guangzhou, Miami, New York and Osaka.

被OECD评判为风险最大的城市包括加尔各答、上海、广州、迈阿密、纽约以及大阪。

Many of the same cities are vulnerable to the urban heat island effects that maximise ambient temperatures.

这些城市当中还有很多存在城市热岛效应，该效应能使城市环境下的温度显著上升。

The most affected by these trends are the urban poor — slum dwellers in emerging cities and those lacking cool shelter or air conditioning in long-established conurbations.

城市贫民将成为受这些趋势影响最大的群体——例如新兴城市中的贫民窟居民以及那些历史悠久的大城市中缺少凉爽栖身之所或者空调设施的人。

The story, however, is not one of unremitting gloom.

但前景并非一片黯淡。

As the OECD puts it: It is not cities per se that contribute to greenhouse gas emissions, but rather the way people move around the city, sprawling urban development, the amount of energy people use at home and to heat buildings.

正如OECD所言：城市本身并不是导致温室气体排放的来源，罪魁祸首在于人们在城市里的交通方式，城市的无序扩张，以及人们在家中使用的和用于楼内取暖的能源。

In each of those areas there is scope for the innovation and design that would greatly reduce both energy consumption and carbon production.

在上述这些方面，创新和设计都能显著降低能源消耗和碳排放。

Planning is crucial.

规划是重中之重。

Halting urban and suburban sprawl should be at the heart of mitigation strategies.

控制城区和郊区的不断扩张应成为减弱气候变化影响战略的核心。

The gulf between the emissions generated by different cities is, in significant part, a reflection of differing levels of urban density.

不同城市碳排放量的巨大鸿沟在很大程度上反映了城市密度的差异。

The city of Los Angeles generates a lot more CO2 than New York City, even though the latter has a much bigger population.

洛杉矶市产生的二氧化碳比纽约市要多得多，尽管纽约市拥有更加庞大的人口规模。

The need is to make new developments more compact and to concentrate building on brownfield sites in inner cities.

因此有必要使新的开发项目集约化，并集中建设内城的棕色地带（brownfield site，受到污染，被废弃或闲置的前工业和商业用地）。

For good reasons of public health, the internal combustion engine has a limited future in the world’s biggest cities.

出于公众健康原因，内燃机引擎在全球主要大城市应用前景有限。

Ask politicians in Beijing where they see the most acute sources of popular discontent and they are most likely to point to the smog-filled skies.

如果你询问北京的政府官员，在他们看来导致公众不满的最紧要因素是什么，他们很有可能会指向雾霾密布的天空。

Talk to the global plutocrats who have made their home in London and fast-deteriorating air quality is one of their biggest gripes.

和那些已经在伦敦安家的全球富豪们谈谈，你会发现迅速恶化的空气质量是他们最为不满的问题之一。

The future of urban transport lies in rapid transit systems and electric cars: battery technology, and thus journey range, is advancing by the year.

城市交通的未来在于快速运输系统以及电动汽车：电池技术以及相应的可行驶里程正在逐年提升。

Above all, what is required is co-ordination: between urban planners, developers, energy and transport specialists and the business community.

最重要的是，必须建立协调机制，让城市规划者、开发商、能源和交通运输专家以及商界展开协作。

The goal? To minimise demand for carbon-intensive energy and maximise the supply possibilities for renewables.

这一机制旨在尽可能降低对碳密集型能源的需求，同时尽可能地提高可再生能源的供给能力。

A report from the think-tank the Chicago Council On Global Affairs points to a strategy developed by the European Innovation Partnership on Smart Cities and Communities as a possible model.

芝加哥全球事务委员会(Chicago Council on Global Affairs)在其发表的一份报告中，将智能城市和社区欧洲创新伙伴行动(Smart Cities and Communities European Innovation Partnership)提出的一项方案列为了一种可能模式。

This focuses on speeding up the transformation of European cities into smart cities, with an emphasis on:

其中的重点是加速欧洲城市向智慧城市的转型，并且尤为强调以下方面：

? Sustainable urban mobility: alternative energies, public transport, efficient logistics and planning.

? 可持续的城市机动性：新型能源，公共交通，高效物流和城市规划。

? Sustainable districts and built environment: improving the energy efficiency of buildings and districts, increasing the share of renewable energy sources used and improving the living conditions of communities.

? 可持续发展的街区及人造环境：提高建筑物和街区的能源利用效率，增加可再生能源的使用占比，改善社区的居住条件。

? Integrated infrastructures and processes across energy, information and communication technologies, and transport: connecting infrastructure assets to improve the efficiency and sustainability of cities.

? 交叉整合能源、信息与通信技术、交通等领域的基础设施和流程：将基础设施资产联网，以提升城市的资源利用效率和可持续发展能力。

If all this sounds expensive, the costs of doing nothing are likely to be higher.

以上这些听起来或许耗费不菲，但什么都不做的成本很可能比这更高。

They will include bills for flood and storm defences, the disruption of complex urban economies threatened by extreme weather, the loss of high-value industries to less-polluted locations and increased personal and public health costs.

这些成本将包括防洪以及防风暴的费用，极端天气给复杂的城市经济体带来的干扰，高价值产业搬迁至污染较少地区所带来的损失，以及个人与公共健康费用的增长。

On the other side of the balance sheet are the opportunities: rapid urbanisation creates a chance to develop cities that are at once more dynamic and sustainable; innovation promises to be a source of economic growth; and better urban environments will promote human welfare.

我们应看到资产负债表另一边所体现的机遇：快速城市化进程创造了一个机会，以打造更有活力、可持续发展能力更强的城市；创新有望成为经济增长的一大来源；更好的城市环境则将有助于提升民众福祉。

The task cannot be left to cities alone.

这些任务不能仅靠城市自己完成。

Though mayors and city halls can learn from each other, it will fall to national governments to provide the regulatory regimes and fiscal incentives to accelerate development of climate mitigation and resilience.

虽然各个城市的市长和市政府能够互相学习，也还是要靠中央政府来提供监管机制以及财政刺激，以加快研究减轻气候变化影响及适应气候变化的方法。

The ideal answer would be a globally agreed carbon tax, but in the absence of such an agreement, national authorities must set the frameworks.

最理想的解决办法是在全球范围内就征收某种碳排放税达成协议，但在缺乏此类协议的情况下，各国政府必须制定相应政策框架。

National treasuries should also encourage the expansion of private financing through green bonds and other innovative instruments.

各国的财政部门同样应当通过运用绿色债券以及其他创新工具，鼓励私人部门融资。

There is an additional role for international financial institutions.

国际金融组织还应承担起额外的职责。

In the wake of last year’s COP21 agreement in Paris, mayors of leading cities have also called for the UN Intergovernmental Panel on Climate Change to produce a special report focusing on the impact of, and response to, global warming in cities.

在《联合国气候变化框架公约》第21次缔约方会议(COP21)于去年在巴黎举行之后，世界主要大都市的市长也向联合国政府间气候变化专门委员会(Intergovernmental Panel on Climate Change，IPCC)发出了呼吁，希望该机构撰写一份特别报告，重点讨论全球城市变暖造成的影响以及对此的应对办法。

This should provide a platform for multilateral organisations to play their part in promoting sustainable urban development, in providing finance and in spreading best practice and technological innovation.

这将为多边国际组织提供一个平台，以履行他们在促进城市可持续发展、提供资金支持以及推广最佳实践和技术创新方面的使命。

The future belongs to cities.

未来属于城市。

What sort of future will depend on how successful those cities are in nurturing more sustainable environments for citizens and workers.

我们会有什么样的未来，取决于城市在为公民和劳动者营造更可持续的环境方面做得有多成功。

Mitigating and adapting to climate change comes at the top of the list.

减弱以及适应气候变化的影响将成为城市的首要任务。

The good news is the more effective they are in meeting the challenge, the more prosperous and hospitable they will be.

好消息是，能够更加有效地应对挑战的城市，将变得更加繁荣、更加宜居。