用自然武器對抗氣候變化

China’s response to the encroachment of its northern deserts on cities such as Beijing is a tree-planting exercise, the Three-North Shelterbelt. But while the so-called Green Great Wall is one of the world’s most ambitious environmental projects, it is just one of many attempts to protect cities against pollution, storms and temperature rises by tapping into a valuable resource: nature.

面對中國北方沙漠對北京等城市的侵蝕，中國政府的對策是植樹造林：建造“三北防護林”。不過，雖說這個所謂的“綠色長城”是世界上最雄心勃勃的環(huán)境工程之一，但它只是人類利用一項寶貴的資源——大自然——保護城市免受污染、風暴和氣溫升高侵擾的諸多嘗試中的一個。

It has long been known greenery improves air quality, which is why large urban parks, such as the Maidan in Kolkata, India, or New York’s Central Park, are often referred to as the “lungs of the city”. But as pollution and increasingly intense storms threaten urban areas, planners are starting to recognise that nature has more than one purpose.

人類很早就知道綠色植物可以改善空氣質量，這就是為什么大型城市公園——如印度加爾各答馬坦公園(Maidan)或紐約中央公園(Central Park)——常被稱為“城市之肺”。但隨著污染和日益強烈的風暴危及城市地區(qū)，規(guī)劃者們開始認識到，大自然還另有用途。

So-called “green infrastructure” can be used to soak up water that can otherwise inundate municipal areas. When superstorm Sandy hit New York and New Jersey late in 2012, for example, storm water flowed through subway tunnels and shut down ground-level power and communications networks.

所謂的“綠色基礎設施”可用來吸收能夠淹沒城市地區(qū)的洪水。例如，2012年晚些時候超級颶風桑迪(Sandy)襲擊紐約州和新澤西州時，暴雨帶來的降水灌進了地鐵隧道，并導致地面電力和通訊網絡中斷。

“The frequency, unpredictability and intensity of storms is overwhelming a lot of conventional systems,” says Jason Scott, co-managing partner at Encourage Capital, an asset management firm specialising in investments that can help to resolve social and environmental problems.

Encourage Capital聯席管理合伙人杰森•斯科特(Jason Scott)表示：“風暴的次數之多、預測之難和強度之大，令很多傳統(tǒng)的系統(tǒng)難以應付。”Encourage Capital是一家資產管理公司，聚焦于能幫助解決社會和環(huán)境問題的投資。

Severe rainstorms are responsible for sending large amounts of untreated water — containing everything from motor oil and lawn fertiliser to raw sewage — into drinking water systems and open waterways.

大暴雨會使大量未經處理的水——含有從機油、草坪肥料到污水等各種污染物——涌入飲用水系統(tǒng)和開放水道。

“In places like Milwaukee and Chicago, storm water is combining with sewer overflow and going in people’s homes, so it’s not a theoretical problem — it’s very real,” says Mr Scott.

“在密爾沃基、芝加哥等地，暴雨降水與下水道溢出的污水一道涌入民宅，所以這不是一個理論問題，而是一個非常實際的問題，”斯科特說。

Green infrastructure — such as grass roofs, planters and permeable pavements that allow water to filter the soil below them and soak up storm water — can help prevent this. “The idea behind the green infrastructure approach is to mimic the way nature handles water,” says Larry Levine, senior attorney in the water programme at the Natural Resources Defence Council, a US environmental group.

綠色基礎設施——例如草坪屋頂、綠植以及可讓雨水滲入下面土壤并吸收暴雨降水的透水路面——可以幫助防止這種情況發(fā)生。“綠色基礎設施模式背后的理念是要模擬大自然處理水的方式，”美國環(huán)保組織“自然資源保護委員會”(Natural Resources Defence Council)水資源項目資深律師拉里•萊文(Larry Levine)說。

Nature can improve cities’ air quality. In Ahmedabad, the Indian state of Gujarat’s largest city, where summer temperatures can be above 40C, a development plan includes linking the city’s Sabarmati River with lakes, building a series of parks and planting trees.

自然可以改善城市空氣質量。在夏季氣溫可超過40攝氏度的印度古吉拉特邦最大城市艾哈邁達巴德(Ahmedabad)，一項開發(fā)計劃就包括將流經該市的薩巴爾馬蒂河(Sabarmati River)與湖泊相連接，建造一系列公園，種植樹木。

Such schemes can help to control summer temperatures, says Ian Mell, lecturer in planning and civic design at Liverpool university. “They’re using trees and better management of the lakes and river to moderate the extremities of the climate,” he says.

利物浦大學(Liverpool University)規(guī)劃與城市設計專業(yè)講師伊恩•梅爾(Ian Mell)表示，此類項目能夠幫助控制夏季的氣溫。他說：“他們正在利用森林以及對湖泊、河流更好的管理來緩和極端氣候。”

Other natural assets can be tapped, too. “In some parts of the world, mangroves are tremendous at flood protection and preventing soil erosion,” says Mr Levine. “Green infrastructure of that sort is very much part of the toolkit for climate change adaptation.”

其他自然資源也可以被利用。“在世界的一些地方，紅樹林在防洪和防止水土流失方面作用巨大，”萊文說，“此類綠色基礎設施恰恰是那種適應氣候變化的手段。”

But while green infrastructure does much to tackle flooding, air pollution and inhospitable city temperatures, it can be hard to persuade developers and investors it is worth the extra money.

雖然綠色基礎設施在很大程度上可以應對洪水、空氣污染以及極端的城市氣溫，但很難說服開發(fā)商和投資者相信值得為此投入更多資金。

“It’s about learning how to understand the upfront costs and how they translate to benefits over time,” says Eric Mackres, building efficiency manager at the World Resources Institute’s Ross Center for Sustainable Cities.

世界資源研究所(World Resources Institute)羅斯可持續(xù)城市中心(Ross Center for Sustainable Cities)的建筑節(jié)能管理人埃里克•麥克雷斯(Eric Mackres)說：“這事關學會如何理解前期成本以及它們日后如何轉化為收益。”

This is a particular difficulty in growing economies, where the race to develop means that urban centres are being built at terrific speed, often without sufficient planning. “The scale of development means climate change gets addressed later,” says Mr Mell.

在成長型經濟體推廣尤為困難，因為這些經濟體的發(fā)展競賽意味著，城市中心正以驚人的速度建設，但通常沒有進行充分規(guī)劃。“發(fā)展的規(guī)模意味著，氣候變化問題被放到后面解決，”梅爾說。

Some older cities are creating financial incentives for developers to go green. In Washington DC, for example, regulations have been introduced that make it mandatory for buildings in certain areas to include green infrastructure. The city has introduced a stormwater retention credits trading scheme for developments where this is not technically feasible.

一些歷史悠久的城市正在提供經濟方面的獎勵，激勵開發(fā)商開發(fā)更多綠色基礎設施。例如，華盛頓(Washington DC)已出臺相關法規(guī)，強制要求某些區(qū)域的建筑必須包括綠色基礎設施。華盛頓還出臺了一個雨水儲存積分交易機制，面向那些不具備建設綠色基礎設施技術條件的開發(fā)項目。

Credits, which are traded in an open market, can be bought from developers operating in parts of the city not covered by the regulations but who have nonetheless invested in sustainable projects.

可在公開市場交易的積分，可以從在不受該規(guī)定管轄的城市區(qū)域運營、但還是投資了可持續(xù)發(fā)展項目的開發(fā)商那里購買。

Mr Scott believes that more of these kinds of innovative financial arrangements will be needed to increase the adoption of urban green infrastructure. “A lot of the solutions are financing solutions because the capital markets don’t know how to value these projects,” he says.

斯科特認為，未來需要更多此類創(chuàng)新金融安排，以增加城市綠色基礎設施的應用。他說：“很多解決方案都是融資方案，因為資本市場不知道如何估值這些項目。”