Por debajo de la necesidad urgente de urbanización sostenible y de alta calidad en China (un enfoque nuevo que se asienta luego de décadas de crecimiento sin control) está el asunto del dinero. Los fondos públicos solo pueden cubrir una pequeña cantidad de la inversión total necesaria para construir infraestructura baja en carbono en las ciudades de todo el país. En las zonas específicas de conservación energética y protección ambiental, algunos estiman que los fondos públicos estatales cubrirán menos del 25 por ciento de los costos (Bond Magazine 2018). En las ciudades de China, esto significa que es imperativo movilizar capital privado. Un mayor interés en los bonos verdes (cuya intención específica es financiar proyectos relacionados con la sostenibilidad) sugiere que esta herramienta de financiamiento podría ser una opción viable.

El Banco Mundial emitió los primeros bonos verdes oficiales en 2009. En los 10 años que siguieron, la emisión global acumulada en bonos verdes superó los US$ 521.000 millones. Hacia 2018, los bonos verdes representaban alrededor del uno por ciento del mercado global (Tay 2019). Después de emitir las pautas nacionales de financiamiento ecológico, en 2016, China se convirtió rápidamente en el segundo mercado más grande del mundo en bonos verdes; en 2018, la cantidad total de dinero recaudado mediante bonos verdes emitidos por el país (de los cuales no todos coinciden con las definiciones y estándares internacionales) fue de unos US$ 31.000 millones (Meng et al. 2018), y llegaron a casi US$ 22.000 millones en la primera mitad de 2019 (Meng, Shangguan y Shang 2019).

En general, los proyectos que más se benefician de los ingresos por bonos verdes son grandes, tienen amplios horizontes de inversión y dependen de tecnología comprobada; las líneas de metro y otros transportes no contaminantes son buenos ejemplos. Los ingresos por bonos verdes se pueden asignar a activos existentes, como una planta de energía solar en una ciudad, o a inversión capital futura.

En junio de 2019, la Nueva Zona Ganjiang de la provincia de Jiangxi emitió el primer bono municipal de China con una etiqueta “verde” (Red de Seguridad de China 2019). El bono seguía las reglamentaciones del Banco Popular de China, el banco central del país, y se emitió para financiar tuberías inteligentes de servicios públicos. La emisión se suscribió en exceso (12 veces), lo cual indica que los inversionistas de china están dispuestos a financiar proyectos ligados a infraestructura e industria sostenibles (ibídem).

Más al sur, en Shenzhen, dos bonos verdes sin etiquetar ayudaron a financiar un proyecto de Ciudad Internacional Baja en Carbono (CIBC) lanzado en 2012. CIBC es un proyecto de demostración insignia de la Sociedad China y Europea de Urbanización Sostenible. Cuando se complete, cubrirá más de 53 kilómetros cuadrados y exhibirá una serie de edificios ecológicos y tecnologías bajas en carbono (Zhan, de Jong y de Brujin 2018).

Las ciudades como Shenzhen, que ya tienen un PIB y un presupuesto municipal relativamente altos, pueden permitirse experimentar con métodos innovadores de financiamiento para sortear barreras y restricciones financieras. Muchas ciudades aún dependen de la venta del suelo como principal recurso municipal de financiamiento para inversiones capitales. Este es un problema grave, en particular para las ciudades más pequeñas, porque el valor y la cantidad del suelo, así como el nivel de interés del sector privado en el suelo, son inferiores que en ciudades más grandes. A menudo, los gobiernos locales más pequeños se deben conformar con vender suelo a una industria contaminante o no ideal, como una empresa siderúrgica. Las ciudades chinas que desean reducir la huella de carbono podrían observar ciertos aspectos de las labores de financiamiento de Shenzhen para diversificar el financiamiento y no recurrir a la venta del suelo.

Esta alternativa se validó más en noviembre de 2018, cuando un medio de financiamiento local de Wuhan emitió bonos verdes con ventajas fiscales y recaudó US$ 400 millones (Davis 2018). Los ingresos por bonos se asignarán para expandir el transporte público sostenible (Moody’s Investors Service 2018).

Los funcionarios municipales pueden aumentar la eficacia y la viabilidad de los bonos verdes si ofrecen incentivos como subsidiar las tasas de interés; reunir distintos activos ambientales (como inversiones en energía solar, agua y limpieza de contaminación) y formar bonos más grandes para atraer a grandes inversionistas; y adjuntar indicadores mensurables para crear responsabilidad y transparencia (IISD 2018). El monitoreo, los informes y la verificación también son parte esencial de los bonos verdes.

Los bonos verdes son un instrumento de deuda que puede aprovechar capital privado para proyectos orientados a prevención contra eventos climáticos; como tales, resultan naturalmente adecuados para las necesidades de las ciudades chinas cortas de efectivo que intentan lograr la transición a ser bajas en carbono. En adelante, es casi seguro que los bonos verdes tendrán una función más importante en el sector financiero de China y el mundo.

Extraído y adaptado de “Green Bond Financing and China’s Low-Carbon City Development” (“Financiamiento por bonos verdes y el desarrollo de ciudades bajas en carbono en China”), por Carl Hooks. Tesis de maestría, Universidad de Pekín, 2019.

Fotografía: Los bonos verdes ayuradon a financiar la construcción del sitio de demostración de la Ciudad Internacional Baja en Carbono (CIBC) en Shenzhen. Crédito: Instituto Paulson.

Referencias

Bond Magazine. 2018. “王琰: 关于我国发展绿色市政债券的探讨” [Exploración del desarrollo de bonos verdes municipales en China]. 中央财经大学绿色金融国际研究院 [Instituto Internacional de Financiamiento Verde de la Universidad Central de Finanzas y Economía] (blog). 24 de octubre. https://mp.weixin.qq.com/s/z9-3ndosGAIwxSmNNYFDOQ.

Red de Seguridad de China. 2019. “江西赣江新区发行全国首单绿色市政专项债” [La nueva área Ganjiang en Jiangxi emite el primer bono verde municipal del país]. 新浪财经 [Sina Finance], 21 de junio. http://finance.sina.com.cn/stock/relnews/hk/2019-06-21/doc-ihytcerk8306348.shtml.

Davis, Morgan. 2018. “Wuhan Metro Seals Landmark Green Deal for LGFVs.” Global Capital Asia, 29 de noviembre. https://www.globalcapital.com/article/b1c12qj1rmd7p2/wuhan-metro-seals-landmark-green-deal-for-lgfvs.

IISD (Instituto Internacional de Desarrollo Sustentable). 2018. “How to Issue a Green Bond in China: A Step-by-Step Guide.” Londres: Iniciativa de Bonos Climáticos. https://www.climatebonds.net/files/files/How-to%20GreenBonds%20China.pdf.

Meng, Alan Xiangrui, Monica Filkova, Ivy Lau, Sherry Shangguan, Jin Shang y Xiaopeng Chen. 2019. “China Green Bond Market 2018.” Londres: Iniciativa de Bonos Climáticos, Pekín: China Central Depository & Clearing Company (febrero). https://www.climatebonds.net/resources/reports/china-green-bond-market-2018.

Meng, Alan Xiangrui, Sherry Shangguan y Jin Shang. 2019. “China Green Bond Market Newsletter H1 2019 / 中国绿色债券市场季报 2019 上半年度.” [En inglés y en chino.] Londres: Iniciativa de Bonos Climáticos, Pekín: China Central Depository & Clearing Company (31 de julio). https://www.climatebonds.net/resources/reports/china-green-bond-market-newsletter-h1-2019.

Moody’s Investors Service. 2018. “Moody’s Assigns Green Bond Assessment (GBA) of GB1 to Wuhan Metro’s Proposed Green Senior Perpetual Securities.” 20 de noviembre. https://www.moodys.com/research/Moodys-assigns-Green-Bond-Assessment-GBA-of-GB1-to-Wuhan–PR_391149.

Tay, Shirley. 2019. “Investors Are Pouring into Green Bonds. That May Not Be for the Best.” CNBC, 29 de enero. https://www.cnbc.com/2019/01/30/investors-are-pouring-into-green-bonds-that-may-not-be-for-the-best.html.

Zhan Changjie, Martin de Jong y Hans de Brujin. 2018. “Funding Sustainable Cities: A Comparative Study of Sino-Singapore Tianjin Eco-City and Shenzhen International Low-Carbon City.” Sustainability 10, n.º 4256 (17 de noviembre de 2018): 1–15.

En el corazón de Shenzhen, China, se eleva entre una abrumadora panoplia de rascacielos futuristas el enorme centro cívico de la ciudad, que tiene forma de ola. Hace cuarenta años, esta zona albergaba apenas unas pocas aldeas pesqueras en el delta del río de las Perlas. Hoy, unos 24 millones de personas viven en la zona urbana periférica de Shenzhen. En China, Shenzhen terminó por representar algo mucho más grande que sí misma.

En el centro de una colina, una estatua que representa al venerado exlíder chino Deng Xiaoping dando zancadas deliberadas hacia el centro cívico ayuda a explicar los motivos. Deng tomó control de China en 1978, tras la muerte de Mao Zedong. La transición marcó un final a décadas de aislamiento del mundo exterior, dominadas por una planificación autoritaria. Deng viró al país en una dirección radicalmente nueva: lanzó el programa Reforma y Apertura para suavizar las restricciones que habían regido en el país durante tanto tiempo. Y Shenzhen abrió el camino hacia el futuro.

Deng otorgó a la ciudad recién creada una licencia para operar como un superlaboratorio económico, un lugar donde explorar la promesa de la economía de libre mercado. Fue una propuesta a todo o nada, y desde entonces Shenzhen triunfó ampliamente.

Sin embargo, su crecimiento espectacular tuvo un costo. A medida que la zona sobrepasaba el entorno, pantanoso por naturaleza, y pasaba de ser un páramo literal a un centro económico neurálgico, gran parte del terreno cubierto sucumbió al asfalto y el concreto. Durante las tormentas, la abundancia de terreno pavimentado provocó inundaciones generalizadas, así como emisión de contaminación urbana a gran escala sobre la bahía de Shenzhen y el delta del río de las Perlas, que están cerca.

Shenzhen no es la única que enfrenta estos problemas. Pero, embarcada en su función de foco nacional de innovación, se convirtió en un laboratorio único donde se piensa cómo construir ciudades habitables en toda China y más allá.

Diez kilómetros al noreste de la estatua de Deng, el profesor Huapeng Qin está parado en un techo, rodeado de sensores que miden la velocidad del viento, la temperatura y la evaporación. Busca soluciones. Qin trabaja en el campus satelital local de la Universidad de Pekín, y está al frente de una labor para convertir a Shenzhen en una “ciudad esponja”. Mediante el uso de técnicas que imitan la naturaleza, estas ciudades pueden captar, limpiar y almacenar lluvia, lo cual reduce el riesgo de inundaciones y evita que los sistemas locales de drenaje y tratamiento de aguas se saturen.

Si bien parte de ideas seculares, el concepto moderno de ciudad esponja comenzó a formarse en Europa, Australia y Estados Unidos a principios y mediados de la década de 1990. El movimiento fue una reacción a dos fenómenos comunes en el desarrollo urbano. Primero, tal como ocurrió en Shenzhen, las ciudades con desarrollo más acelerado cubren de pavimento grandes extensiones de suelo, y así eliminan una cantidad importante de manto boscoso natural, rellenan lagos y humedales, y alteran gravemente el ciclo hidrológico natural. Segundo, el enfoque tradicional para gestionar el agua pluvial en ciudades se centró en alejar del suelo la mayor cantidad posible de lluvia, tan rápido como sea posible, no en capturarla para reutilizarla.

La idea de ciudad esponja marca un cambio significativo, que se aleja de la “infraestructura gris” tradicional (como tuberías y represas de concreto) y va hacia la infraestructura “verde” o natural, como jardines pluviales y bosques. El enfoque de ciudad esponja pretende restaurar algunas de esas funciones naturales porque permite que las zonas urbanas transformen la amenaza del agua pluvial en un beneficio: agua adicional para momentos de sequía. Por lo tanto, las técnicas de ciudad esponja tienen múltiples beneficios. Pueden ayudar a disminuir el impacto de las inundaciones, mejorar la calidad y el suministro del agua, y solucionar problemas medioambientales.

El concepto de ciudad esponja llegó hace relativamente poco a China, pero ganó ímpetu enseguida. Esto se debe, en parte, al tremendo crecimiento del país en las últimas décadas, lo que cambió el entorno de forma drástica.

También, se debe a una nueva mentalidad sobre los riesgos de buscar la prosperidad a toda costa. En julio de 2012, en Pekín, una tormenta inmensa provocó una inundación que causó 79 muertes y un gasto de alrededor de US$ 1.700 millones en daños. El incidente motivó a los líderes nacionales.

A fines de 2013, el presidente Xi Jinping promocionó oficialmente el concepto de ciudad esponja, y al año siguiente el Ministerio de Vivienda y Desarrollo Urbano y Rural emitió un conjunto de pautas técnicas orientadas a asegurar que el 70 por ciento de la escorrentía de la superficie se capte en el lugar. Además, el gobierno central lanzó lo que terminaría por ser un programa piloto de 30 ciudades para probar el concepto.

Shenzhen es solo una de las ciudades piloto, y no es una coincidencia que el concepto de ciudad esponja haya avanzado más allí que en cualquier otra parte de China. Desde políticas financieras hasta el sector tecnológico, “Shenzhen siempre estuvo muy dispuesta a tomar ideas prestadas de fuera de China, y probarlas”, dice Qin. La idea de ciudad esponja es coherente con esto. “Primero, fueron apenas proyectos piloto desperdigados, pero ahora el concepto se está incorporando al plan de reordenamiento territorial de Shenzhen”.

En este caso, Qin y sus estudiantes intentan aprender más sobre técnicas para crear techos verdes, con el uso de plantas sembradas en suelo diseñado con poco peso para absorber la lluvia donde cae y luego distribuirla de a poco. Dichas técnicas son “muy similares a los sistemas naturales”, dice Qin. “Los sistemas naturales parecen muy sencillos, pero los procesos son muy complejos. Entonces, intentamos comprender esos procesos”.

Una ciudad esponja tiene varios bloques de edificios intercambiables. A gran escala, al proteger o restaurar bosques y suelo con cobertura natural, el agua tiene más oportunidad de decantar. En escalas menores, hay varias opciones. Se puede usar pavimento permeable en calzadas, veredas y senderos para permitir que el agua se filtre hacia el suelo, en vez de escurrirse al sistema local de agua pluvial. Los estanques de captura y los humedales construidos ayudan a captar y filtrar el agua, y permiten que esta se propague de a poco hacia el nivel freático local. Los llamados jardines pluviales cumplen una función similar a escala más pequeña, y se pueden incorporar con facilidad a los espacios verdes de los vecindarios o incluso a los hogares. Los techos verdes capturan y filtran la lluvia, y además riegan las plantas que, según dice Qin, reducen la temperatura de la superficie hasta en nueve grados Celsius.

La aceptación en Shenzhen del concepto de ciudad esponja fue impulsada por el espíritu de innovación, pero también por el hecho de que allí los efectos de un ciclo hidrológico desequilibrado no suelen pasar desapercibidos. Las lluvias fuertes pueden saturar las plantas locales de depuración, lo cual envía aguas residuales cargadas de nutrientes directo a la bahía de Shenzhen y el delta del río de las Perlas, y esto a su vez produce gran cantidad de algas.

Además, la gente está preocupada por el impacto del cambio climático. En 2018, en lo que podría ser un anticipo de lo que vendrá, el supertifón Mangkhut azotó la ciudad y derribó la mitad de los árboles. Según Qin, los modelos informáticos predicen que, con el cambio climático, la precipitación anual total será comparable a los niveles actuales, pero mucho más “súbita”: serán mucho más frecuentes los eventos extremos como tormentas breves de alta intensidad.

En las últimas décadas, esta zona absorbió una afluencia de millones de personas, y en gran parte le dio la espalda al agua, que antes era una de sus características determinantes. Hoy, Qin y otras personas de toda la ciudad se dedican a hallar nuevas formas de avanzar. Las lecciones que aprenden y aplican allí son los primeros pasos de lo que pronto podría ser una transformación generalizada, no solo en la ciudad que los rodea, sino en toda China.

“Las ciudades esponja son apenas un ejemplo de cómo China aborda la agenda de la sustentabilidad”, dice Zhi Liu, director del Centro de Desarrollo Urbano y Políticas de Suelo de la Universidad de Pekín y el Instituto Lincoln. Al reconocer la urgencia de construir para la resiliencia ante eventos climáticos extremos y otros problemas, dice: “Esto no es algo que China quiere hacer para quedar bien. Surge de una necesidad”.

Hasta hace dos años, el lote de 42,5 hectáreas de espacio verde que hoy se conoce como parque del Lago de Miel era una estación abandonada de experimentos agrícolas. Los atractivos dominantes del parque, no muy lejano del centro de Shenzhen, eran una descuidada arboleda de lichis y dos estanques con peces. Hoy, cuando se accede al parque a pie, uno siente que está caminando por un renderizado arquitectónico. Pero si nos acompaña un experto, enseguida resulta evidente que el parque no solo es agradable por su estética, sino que también es decididamente funcional.

Yaqi Shi, directora técnica de la empresa Techand Ecology & Environment, con base en Shenzhen, ayudó a diseñar el parque. Los senderos por los que caminamos, me explica, se construyeron con pavimento permeable, y los contornos ondulantes del parque están acogidos por paulares que ayudan a detener y captar escorrentía. Techand cultivó en su propio vivero juncáceas nativas que tejen una serie de estanques en medio del parque. En todo el parque hay carteles que indican varios elementos de una ciudad esponja y explican cómo funcionan.

Shi, cuyo enfoque profesional es la restauración ecológica, se expresa con la economía abrupta de una ingeniera. Pero el placer se evidencia en su voz cuando habla de la evolución de este proyecto. “El parque resultó tener un concepto que apela mucho al usuario”, dice.

Mientras caminamos, Shi señala una biblioteca, un centro de juegos para niños y el registro civil local, todo dentro de los límites del parque. Al borde de un estanque, hay un pabellón que ofrece un fondo ideal donde los flamantes recién casados pueden posar para un retrato.

Al caminar con Shi también se hace evidente que gran parte de la tecnología detrás de las ciudades esponja, en realidad, no es muy tecnológica, lo cual sorprende. El verdadero arte del enfoque no se basa tanto en tener ingenio técnico, sino simplemente en aplicar la reflexión. Ella explica, por ejemplo, que bajo gran parte de Shenzhen subyace una capa de arcilla que impide que el agua penetre muy profundo en el suelo. Para que los pavimentos permeables funcionen, hay que contratar constructores que excaven la arcilla, a veces hasta casi dos metros, y la reemplacen con gravilla y suelo más permeable.

Sin embargo, cuando se tiene una idea de dónde mirar, Shenzhen empieza a parecer una ciudad totalmente distinta. En el extremo noroeste, un suburbio relativamente nuevo llamado Guangming adaptó el concepto de ciudad esponja en su totalidad. El parque Nueva Ciudad, construido hace poco en el suburbio, es un modelo de retención de agua pluvial en el lugar, que incluye desde celosías que absorben agua en el estacionamiento hasta pavimento permeable en los senderos, paulares y minihumedales artificiales diseñados para detener y absorber agua. El enorme centro deportivo público adyacente tiene un techo verde y una gran extensión de ladrillos y pavimento permeables. Los tanques de digestión de la planta Guangming de tratamiento de aguas están cubiertos con un techo verde muy grande, y lo mismo ocurre en la escuela de idiomas extranjeros. Las calles frente a la estación del tren de alta velocidad, a donde llegan los trenes bala desde Hong Kong, están hechas de pavimento permeable.

Después de un rato en este lugar, es difícil resistir la tentación de vaciar la botella de agua poco a poco en las veredas y las calles de Shenzhen, solo para experimentar la novedosa sensación de ver el agua desaparecer en lo que uno creería que es asfalto o concreto normal.

De regreso en el centro, Xin Yu, de Nature Conservancy, me muestra otra faceta de la revolución de la ciudad esponja. Nos encontramos en el lobby del hotel Hilton, a poco menos de dos kilómetros del centro cívico y la estatua de Deng Xiaoping sobre la colina, que está cerca. Luego de unas rápidas cortesías, Yu me lleva por una puerta trasera de servicio. En comparación con la elegancia espaciosa del lobby, parece que pasamos por un portal a otra dimensión.

Nos hallamos en los estrechos callejones de una zona conocida como Gangxia, una antigua aldea agrícola que Shenzhen se tragó de a poco, y que luego metamorfoseó en un laberinto atestado de edificios de departamentos de cinco y seis pisos. Gangxia y las llamadas aldeas urbanas son un fenómeno que se encuentra en casi todas las ciudades de China, y atestiguan el ritmo frenético con que el país se urbanizó en los últimos 40 años. Suelen ser desagradables, pero son un refugio importante para migrantes de bajos ingresos que, de otro modo, no podrían costear los alquileres altos de casi todas las zonas urbanas. En general, llegan para formar comunidades más bien autónomas con pequeños negocios que atienden todas las necesidades de los residentes, desde vendedores de verduras hasta salas modestas de karaoke.

Yu me lleva ágilmente entre los callejones estrechos, y pronto se evidencia que la palabra “aldea” no le queda bien a esta región. A los edificios, atestados y de alta densidad, se los llama “departamentos con apretón de manos”: se construyeron tan cerca unos de otros que los residentes vecinos pueden asomarse por la ventana y darse la mano. Los restaurantes se preparan para la avalancha del almuerzo, y los cuchillos que pican verduras marcan el ritmo staccato del ambiente. Yu cuenta que allí los negocios son animados y competitivos en extremo: “Estos callejones están vivos de verdad”.

Los residentes originales de Gangxia técnicamente no poseían el suelo sobre el cual se construyeron sus casas, pero sí tenían derecho a usarlo. Cuando Shenzhen creció, en los 80 y los 90, reemplazaron sus propias casas por edificios de departamentos; en general, se quedaban con un piso y alquilaban los demás, para aprovechar el aumento de los alquileres.

The Nature Conservancy (TNC) tuvo un papel importante en demostrar que se puede incorporar un pensamiento esponja incluso en el corazón de la selva urbana. “Hay muchas ideas, pero el gobierno o las empresas no necesariamente pueden probar cosas”, dice Yu. “Las ONG sí. Podemos descifrar qué ideas funcionan y llevarlas al gobierno para promoverlas de forma más amplia“ (debido al clima político de China, los funcionarios de Shenzhen no estaban disponibles para reunirse para esta historia).

Yu abre la puerta de un edificio de departamentos que parece insulso, sube varios tramos de escaleras hasta el techo y llega a un rincón inverosímil de verde frondoso. Un marco entramado con múltiples niveles cruje con toda variedad de plantas. Este techo verde, cuenta Yu, absorbe más del 65 por ciento de la lluvia que lo toca.

No siempre fue fácil mostrar qué es posible. Cuando TNC comenzó con este proyecto de techo verde, Yu y sus colegas tuvieron que enfrentarse a vecinos furiosos que creían que iban a agregar un piso al edificio de forma ilegal.

“La gente llamaba a distintos departamentos gubernamentales: la policía, el buró de construcción o la administración de la ciudad”, dice Yu. Eso llevó a que vinieran varios equipos de control del código local, quienes usaron escaleras para acceder al edificio y un soplete cortador para intentar desmantelar el marco que sostiene el jardín. “Nos pedían siempre los documentos de aprobación”, dice Yu, y se ríe. “Pero en realidad no existen. No podíamos obtenerlos en ningún lugar”.

Sin embargo, con el tiempo, las labores como esta generaron más conciencia sobre el concepto de ciudad esponja. “La consulta pública, el modo que tenemos de que el público entienda de qué se trata, son muy importantes”, dice Liu, del Instituto Lincoln. “Creo que las ONG pueden tener un gran papel en esta área, y TNC es una ONG internacional de confianza en China”.

El trabajo de TNC también se ganó el apoyo de funcionarios y líderes comerciales. Yu recibió una invitación para ser miembro del comité técnico en el programa municipal de ciudad esponja en Shenzhen. Cuando el gigante corporativo tecnológico Tencent decidió incorporar técnicas de ciudad esponja a su nueva y emblemática sede central en Shenzhen, acudió a TNC para pedir ideas. Y Pony Ma, fundador, presidente y director ejecutivo de Tencent, no solo es miembro de la junta de directores de TNC en China, sino también delegado de la poderosa Asamblea Popular Nacional. Allí, logró que las ciudades esponja sean parte de una plataforma personal más amplia que defiende las soluciones basadas en la naturaleza. Ma también inspiró a otros líderes comerciales a involucrarse (e invertir) en garantizar que sus empresas cumplan los estándares de ciudad esponja de Shenzhen.

Unos 2.000 kilómetros al norte de Shenzhen, en Pekín, en la oficina de Kongjian Yu parece brotar una planta en cada rincón donde no logró encajar un libro. Esa sensación parecida al libro Donde viven los monstruos tiene total coherencia con la personalidad de Yu, impulsada por una especie de energía inquieta. Es difícil imaginar que se quede sentado en un lugar por más de cinco minutos.

Yu nació en una pequeña aldea agrícola en la provincia costera de Zhejiang, emigró y obtuvo un doctorado en Diseño en Harvard en 1995. Al regresar a China, se sintió profundamente descorazonado por el camino que había seguido el desarrollo. “Cuando volví, me impactó la escala de la urbanización”, dice. “No podía creer cómo el proceso ignoró todo nuestro patrimonio natural y cultural, rellenó humedales, destruyó ríos, taló árboles y liquidó tantos edificios antiguos”.

La Universidad de Pekín contrató a Yu como profesor de planeamiento urbano y arquitectura paisajística. En el mundo serio de la teoría china del desarrollo, se hizo fama de una especie de hippie, y de tábano molesto. Se convirtió en escritor prodigioso y orador incansable, y presentó una serie de cartas abiertas a los principales líderes de China. Apeló a que el país abandonara la manía de construir plazas públicas monumentales; abogó por un resurgimiento de los enfoques tradicionales chinos de agricultura, gestión hidrológica y asentamientos; y sugirió que sería mejor gastar el dinero asignado a los desfiles anuales del Día Nacional para construir parques buenos.

Por sobre todas las cosas, reprochaba la obsesión del país con el concreto, un repudio a décadas de mentalidad. “En la era de Mao, la filosofía china era que los humanos pueden vencer a la naturaleza”, dice Yu. “Y eso provocó muchos desastres”.

Esa actitud no hizo más que acelerarse en los años posteriores a la muerte de Mao, y hacia principios del s. XXI, China rompía récords de cantidad de concreto volcado al año. Vaclav Smil, gurú de desmitificación de los sistemas globales, estimó que China usó más cemento en apenas tres años, de 2011 a 2013, del que Estados Unidos usó en todo el s. XX.

Si bien Yu halló oposición a su franqueza, también accedió a una demanda cada vez mayor de esta nueva forma de pensar en los sistemas. Hoy, además de ser decano de la Escuela de Arquitectura y Paisajismo de la Universidad de Pekín, lidera una oficina de consultoría de arquitectura y urbanismo paisajista de 600 personas llamada Turenscape. Los gobiernos municipales de todo el país acuden a la ayuda de la empresa de forma habitual. Yu también escribió la guía definitiva para profesionales sobre ciudades esponja en China, que consta de dos volúmenes, y contribuyó en el libro Nature and Cities (Naturaleza y ciudades) del Instituto Lincoln de Políticas de Suelo. Su trabajo también aparece en Design with Nature Now (Proyectar con la naturaleza hoy).

Un principio fundamental de su enfoque general es un concepto que llama fan guihua. Este suele traducirse como “planificación negativa”, pero sería más preciso denominarlo “planificación inversa”. En esencia, es una réplica al tipo de desarrollo que dio forma al crecimiento de China durante tanto tiempo.

“Se planifica lo que no está construido”, explica Yu. “Se planifica lo que debería protegerse”. Por supuesto, esta es una idea bastante radical en la China contemporánea. Aun así, durante su trabajo, Yu se dio cuenta de algo sorprendente: la idea de vivir con el agua, en vez de luchar contra ella, era un concepto muy conocido históricamente.

En el centro y sur de la costa de China, que incluye la zona donde hoy está Shenzhen, con los siglos había evolucionado un método característico para captar agua de lluvia y gestionarla con cuidado en acequias de barro para cultivar moras, gusanos de seda y peces, una especie de sistema de acuaponía a escala del entorno. Y cuando Yu y sus alumnos investigaron con mayor profundidad, descubrieron que ciertos conceptos parecidos a los de la ciudad esponja habían sido principio fundamental de la planificación de ciudades en China durante siglos. Dice que, tradicionalmente, muchas ciudades tenían la capacidad de absorber dos tercios de las precipitaciones en su territorio.

Con este hallazgo, la idea de gestionar el agua de otra forma (y los peligros de las alteraciones drásticas en el ciclo hidrológico) se convirtieron en un tema principal del trabajo de Yu.

Por su parte, la naturaleza empezó a enfatizar cada vez más el problema.

En la inundación de 2012 de Pekín “murieron 79 personas. Ahogadas. En la calle”, dice Yu. “En la capital, ahogamos a 79 personas. ¿Cómo puede ser? Vergonzoso. Eso se convirtió en un asunto político de inmediato”.

Yu escribió otra carta a los altos líderes; en ella dijo que, si se adoptaba el enfoque de ciudad esponja y se creaba un entorno resiliente, podría haber esperanza. Da la casualidad que Xi Jinping había asumido hacía poco como secretario general del Partido Comunista y presidente de China.

Luego de décadas en que el país luchó contra la notable contaminación y otros problemas ambientales, Xi se jugó la reputación al crear una “civilización ecológica” en China. A veces resulta difícil discernir los contornos exactos de dicho concepto, pero, a grandes rasgos, se trata de un empuje nacional hacia la sostenibilidad ecológica y la creación de un modelo ecológico alternativo de desarrollo exclusivamente chino para el resto del mundo. Tanto la idea de ciudad esponja como una aceptación más amplia del desarrollo de bajo impacto encajan a la perfección con las aspiraciones más amplias de Xi.

“China está atravesando una crisis ambiental. Tenemos que hacerlo”, dice Yu. “Cuando la gente no puede respirar, cuando el agua está contaminada, creo que él es muy susceptible a estos temas. Creo que de verdad quiere construir su legado al hacer esto”.

El mayor desafío de lograr que las ciudades esponja funcionen a gran escala no tiene nada que ver con construir jardines pluviales, instalar pavimento permeable ni apaciguar a los vecinos. “El mayor problema son las finanzas”, dice Liu.

Liu llegó al Instituto Lincoln luego de 18 años en el Banco Mundial, y se centra más que nada en la gobernación y los problemas financieros asociados con el uso del suelo en China. No será fácil escalar el concepto de ciudad esponja, y él cita los desafíos de Shenzhen como ejemplo. Las mejoras de ciudad esponja en Shenzhen, que comenzaron oficialmente en 2017, hoy cubren el 24 por ciento de la superficie total de la ciudad. El gobierno tiene el objetivo de aumentarlo al 80 por ciento hacia 2030. Pero alcanzar ese objetivo será un reto importante.

El gobierno central garantizó un total de US$ 5.800 millones (40.000 millones de yuanes chinos) para incentivar a Shenzhen y las otras 29 ciudades piloto a invertir y ejecutar labores de ciudad esponja. Pero quiere que en cada uno de esos lugares al menos un 20 por ciento del área desarrollada alcance el estándar de ciudad esponja hacia fines de este año.

Liu dice que alcanzar ese estándar en un kilómetro cuadrado de suelo urbano desarrollado suele costar entre US$ 22 millones y US$ 29 millones (entre CNY 150 y CNY 200 millones). Las 30 ciudades piloto pueden recibir del gobierno entre 400 y 600 millones de yuanes chinos al año durante tres años. Eso alcanza para actualizar hasta cuatro kilómetros cuadrados al año.

Para alcanzar (e incluso superar) el objetivo del gobierno central del 20 por ciento para 2020, Shenzhen llevó unos 235 kilómetros cuadrados al estándar, con un costo que podría estimarse entre US$ 5.000 millones y US$ 7.000 millones.

“No es fácil pedir al gobierno municipal que consiga esa cantidad de dinero”, dice Liu. Shenzhen lo logró debido a su poderoso presupuesto municipal y a las inversiones privadas de los gigantes tecnológicos e industriales de la ciudad. Pero Liu agrega: “si vas a las ciudades del interior, donde el financiamiento municipal es débil, esto es muy difícil” (en la página siguiente se explora el papel potencial de los bonos verdes en la mezcla de financiamiento de ciudades esponja).

Liu destaca que, en el caso de los desarrollos nuevos, las ciudades pueden implementar estándares que exigirán a los desarrolladores pagar las mejoras, un costo que en general recae sobre los residentes y los estudios. “Si se observan los costos para desarrollo por adelantado, no es muy costoso hacer ciudades esponja”, dice Liu. Sin embargo, modernizar desarrollos existentes es un desafío mucho más grande.

“El problema más difícil es que el financiamiento público se usa para el bien público, con muy poca posibilidad de que se recupere el costo”, continúa. “Esa es la peor parte de la historia en China. Es un tema de prioridades. Las ciudades tienen demasiado entre manos. Así, a fin de cuentas, son muy pocas las que pueden conseguir el dinero suficiente”.

La infraestructura para ciudades esponja es “igual que el alumbrado”, dice Liu. “Es un bien público compartido, pero nadie quiere pagarlo”.

En verdad, el mayor desafío de llevar la ciudad esponja a la realidad puede ser desenmarañar la mecánica de financiamiento. Aun así, el costo de no enfrentar el desafío podría ser mayor de lo que todos consideran.

“En realidad, es como pensar en adquirir un seguro”, dice Liu. “Todos nos enfrentamos a incertidumbres, pero la tendencia de tormentas más intensas es bien evidente . . . El costo de no actuar podría no parecer tan alto hoy, pero cuando nos enfrentemos a un resultado catastrófico en 10 o 20 años, nos arrepentiremos de no haber gastado el dinero antes”.

Incluso con tanto en juego, la idea de las ciudades esponja podría implicar mucho más que eso. De vuelta en Shenzhen, parado sobre el techo del edificio de departamentos de Gangxia, Yu, de TNC, dice que las ciudades esponja hacen mucho más que domar las inundaciones y guardar agua para las épocas de sequía. “Si solo se habla de gestión de agua pluvial o de controlar la escorrentía, la persona promedio no necesariamente lo va a aceptar, porque no se sentirá conectada con eso”, dice. “Pero las características como los techos verdes son otra cosa. Pueden tener un efecto sinérgico. Ayudan a absorber la lluvia, pero también mejoran la vista del vecindario, contribuyen a la biodiversidad urbana y crean un espacio verde que pueden usar todos”.

Matt Jenkins, que se desempeñó como editor de la revista Nature Conservancy, es un escritor autónomo que trabajó para The New York Times, Smithsonian, Men’s Journal y muchas otras publicaciones.

Fotografía: Shenzhen, China, es una de las 30 “ciudades esponja” piloto que está invirtiendo en soluciones de gestión de agua pluvial basadas en la naturaleza. Crédito: Wang Jian Xiong a través de Flickr CC BY 2.0.  

As Greece emerges from a decade-long financial crisis, the city of Athens is grappling with major challenges: E.U.-imposed austerity measures, a real estate collapse, ongoing security and migration issues, climate change, and now COVID-19. Kostas Bakoyannis, 41, was elected mayor in 2019, promising stability and reinvention. The son of two prominent Greek politicians, Bakoyannis is the city’s youngest elected chief executive but has had considerable experience. Holding undergraduate and graduate degrees from Brown University, Harvard University, and the University of Oxford, he was governor of Central Greece, mayor of Karpenissi, and served at the Greek Ministry of Foreign Affairs, the European Parliament, and the World Bank. He also holds positions with the Hellenic Agency for Local Development and Local Government, European Council on Foreign Relations, and United Nations Sustainable Development Solutions Network. On a recent visit to Cambridge, he spent time with Lincoln Institute Senior Fellow Anthony Flint.

Anthony Flint: You have said that you are focused not on grand projects, but on day-to-day quality of life in a city trying to make a comeback in a more incremental fashion. What are your reflections on your successful campaign and the experience thus far of being at the helm of local government?

Kostas Bakoyannis: I think in any campaign, it’s always about the message and not the messenger. Elections in the past in Greece have been about candidates higher up, talking down to the people. I took a different approach and started walking out in the neighborhoods. I listened with care and found that the people want a city to build its self-confidence and be optimistic again. Now we are reinventing city services and reinventing the city. Athens has three records: the least urban green per capita in Europe, the most asphalt, and our houses have the most square meters. We want to reclaim public space and especially reclaim space from the automobile. We have been studying traffic circulation, and are planning to close parts of the city center to cars. We will also create an archeological walkway around the city.

All in all, I’m living my dream. I’m giving it my all. I’ve been in local government for 10 years; higher office doesn’t compare. One day, when I first began my journey in local government, I was depressed and thinking we are a failure, and then I walked out and saw a playground we had just opened. It’s not about resolving the conflict between North and South Korea. It’s real, tangible, incremental change, improving the quality of life.

AF: Athens has been vexed over the years by the problem of vacant buildings and storefronts, graffiti, homelessness, and a general image of being dark and dirty. Can you tell us about your plans to clean things up?

KB: There was a very good article in an international magazine about the Greek economy, but at the top there was a photo of Athens, with two homeless people sleeping in front of closed stores that were full of graffiti. This is our challenge. Don’t forget that we are in a global race to attract talent, technology, and investment. And Athens is changing day by day. To mention a few examples: We have adopted the “broken windows” theory of social behavior [which suggests that visible signs of crime and decay invite more of the same] and are coordinating with the police. We have special equipment and run campaigns to clean up graffiti. We have a program called Adopt Your City, and public-private partnerships that are already bearing fruit. We are asking people who care and love the city to come help us. Regarding drugs, reforms have been made. The parliament recently passed a measure on supervised spaces for drug use—we haven’t operated one yet, but we are preparing to make it mobile, so it doesn’t stay too long in any one neighborhood. Local government will be able to operate such spaces. We are reclaiming public space, like Omonia Square, a city landmark—I think that’s going to be a symbol. There are elevated expectations about public space . . . it’s not just public works. We are producing more of a product, an experience.

AF: As part of that effort, you attracted controversy for clearing out squatters in the neighborhood of Exarchia, an effort that included dawn raids and relocating refugees and undocumented immigrants. How do you fulfill your campaign promise to restore law and order and curtail illegal immigration, while still being sensitive to the human lives at stake?

KB: Here is an example: An individual calling himself Fidel was running a hostel in a school, occupying it, and charging money. We securely moved the children to take advantage of social service provisions. Greek media have a thing about Exarchia. It becomes a political weapon for one side or the other. I don’t look at it that way. We have 129 neighborhoods, and Exarchia is a neighborhood with its own issues. Much of what we do has to do with persisting and insisting—it’s a question of who will get tired first. We will not get tired first.

On the subject of pluralism, we’re the canary in the coal mine. We survived the economic crisis, and we’re stronger today than in the past 10 years. We have more depth to our democracy, stronger institutions. We isolated extremists. We confronted the Fascist Nazi party Golden Dawn—we went to neighborhoods where they were doing well. We didn’t wag our fingers and tell people they were bad for voting for Golden Dawn. We said: we can provide better solutions to the problems you face.

Athens is a Greek city, a capital city, and a center for Greeks around the world. Having said that, Athens is changing and evolving. I remember seeing a young woman who was black in a parade, and she was proudly holding the flag—I think what she was saying was, ‘I’m as Greek as you are.’ We want to make sure everyone living in the city has the same rights and obligations.

AF: What are the most important elements of your plans to help Athens combat climate change—and prepare for its inevitable impacts in the years ahead?

KB: Think different! It is all about working bottom up. What’s happening that is most interesting in terms of public policy is in the cities, which are true laboratories of innovation. Nation-states are failing—there’s so much partisanship, and a toxic environment, and bureaucracies that cannot handle real problems; cities are closer to the citizen. We are proud to be a part of C40. Athens has developed a policy for sustainability and resilience. Among other things, we are working on ambitious but realistic interventions to liberate public space, multiplying green space, and creating car-free zones. For us, climate change is not a theory or an abstraction. It is a real and present danger that we can’t just sweep under the rug. It demands concrete responses.

AF: You recently had the opportunity to return to Cambridge and Harvard. What level of interest did you find in the future of Athens? Are there things you have learned from American cities, and what can the United States learn from you?

KB: I was enthused and heartened by the level of interest and am thankful for the engagement. I must admit that I was very proud to represent a city with a long and glorious past and a promising, bright future. We may live on different sides of the Atlantic, and in very different cities, but it is interesting that we face similar challenges as urban centers evolve and are transformed. And it is always great to share experiences and learning moments. Policies to further resilience are the most obvious example. And of course, battling social inequalities is at the top of all of our agendas. I am glad to have begun promising and fruitful conversations which will continue in the months and years to come.

Photograph: Athens Mayor Kostas Bakoyannis. Credit: City of Athens.

Underlying the urgent need for sustainable, high-quality urbanization in China—a new approach taking hold after decades of unchecked growth—is the question of money. Public funds can supply only a small amount of the total investment needed to build low-carbon infrastructure in cities across the country. In the specific areas of energy conservation and environmental protection, some estimates state public funds will cover less than 25 percent of costs (Bond Magazine 2018). For Chinese cities, this means mobilizing private capital is imperative. A growing interest in green bonds—bonds specifically intended to fund projects related to sustainability—suggests this financing tool could be a viable option.

The World Bank issued the first official green bonds in 2009. In the 10 years following, cumulative global green bond issuance exceeded $521 billion. As of 2018, green bonds account for about one percent of the global market (Tay 2019). China has rapidly become the world’s second largest green bond market since releasing national green finance guidelines in 2016; the total amount of money raised through state-issued Chinese green bonds—not all of which align with international definitions and standards—was about $31 billion in 2018 (Meng et al. 2018) and hit almost $22 billion in the first half of 2019 (Meng, Shangguan, and Shang 2019). 

Generally speaking, the projects that benefit most from green bond proceeds are large, have long investment horizons, and rely on proven technology—metro lines and other clean transportation are good examples. Green bond proceeds can be allocated to existing assets, such as a solar energy plant operating in a city, or to upcoming capital investment.

In June 2019, the Ganjiang New Area in Jiangxi Province issued the first municipal bond in China bearing a “green” label (China Securities Network 2019). The bond followed the regulations of the People’s Bank of China, the country’s central bank, and was issued to finance smart utility pipelines. The issuance was 12 times oversubscribed, indicating that investors in China are willing to finance projects tied to sustainable infrastructure and industry (Ibid). 

Farther south, in Shenzhen, two unlabeled green bonds helped finance an International Low Carbon City (ILCC) project launched in 2012. The ILCC is a flagship demonstration project of the China-E.U. Partnership on Sustainable Urbanization. When completed, it will cover more than 53 km2 and display an array of green buildings and low-carbon technologies (Zhan, de Jong, and de Brujin 2018).

Cities like Shenzhen, which have a relatively large GDP and municipal budget, can afford to experiment with innovative financing methods in order to circumvent financial barriers and constraints. Many cities still rely on sales of land as the main municipal finance resource for capital investment. This is a serious problem for smaller cities in particular, because the value and amount of their land and level of private sector interest in the land are all lower than in larger cities. Oftentimes, smaller local governments will have to settle for selling land to a nonideal or polluting industry, such as a steel company. Chinese cities hoping to reduce carbon footprints could look to aspects of Shenzhen’s financing efforts to diversify funding away from land sales. 

This alternative was further validated in November 2018 when a local finance vehicle in Wuhan issued offshore green bonds and raised $400 million (Davis 2018). The bond proceeds will go toward expanding sustainable public transportation (Moody’s Investors Service 2018).

Municipal officials can increase the efficacy and feasibility of green bonds by providing incentives such as interest rate subsidies, bundling different environmental assets (such as solar, water, and pollution cleanup investments) into larger bonds to attract big investors, and attaching measurable indicators to create accountability and transparency (IISD 2018). Monitoring, reporting, and verification is also a key part of green bonds.

As a debt instrument that can harness private capital for climate-oriented projects, green bonds appear naturally suited to the needs of cash-strapped cities in China that are trying to achieve low-carbon transition. Green bonds will almost certainly play a larger role in the Chinese and global financial sector going forward.

Excerpted and adapted from “Green Bond Financing and China’s Low-Carbon City Development” by Carl Hooks. Master’s thesis, Peking University, 2019.

Photograph: Green bonds helped finance construction of the International Low-Carbon City demonstration site in Shenzhen. Credit: Paulson Institute.

References

Bond Magazine. 2018. “王琰: 关于我国发展绿色市政债券的探讨” [Exploring the development of green municipal bonds in China]. 中央财经大学绿色金融国际研究院 [International Institute of Green Finance of the Central University of Finance and Economics] (blog). October 24. https://mp.weixin.qq.com/s/z9-3ndosGAIwxSmNNYFDOQ.

China Securities Network. 2019. “江西赣江新区发行全国首单绿色市政专项债” [Jiangxi Ganjiang New Area issues country’s first municipal green bond]. 新浪财经 [Sina Finance], June 21. http://finance.sina.com.cn/stock/relnews/hk/2019-06-21/doc-ihytcerk8306348.shtml.

Davis, Morgan. 2018. “Wuhan Metro Seals Landmark Green Deal for LGFVs.” Global Capital Asia, November 29. https://www.globalcapital.com/article/b1c12qj1rmd7p2/wuhan-metro-seals-landmark-green-deal-for-lgfvs.

IISD (International Institute for Sustainable Development). 2018. “How to Issue a Green Bond in China: A Step-by-Step Guide.” London: Climate Bonds Initiative. https://www.climatebonds.net/files/files/How-to%20GreenBonds%20China.pdf.

Meng, Alan Xiangrui, Monica Filkova, Ivy Lau, Sherry Shangguan, Jin Shang, and Xiaopeng Chen. 2019. “China Green Bond Market 2018.” London: Climate Bonds Initiative; Beijing: China Central Depository & Clearing Company (February). https://www.climatebonds.net/resources/reports/china-green-bond-market-2018.

Meng, Alan Xiangrui, Sherry Shangguan, and Jin Shang. 2019. “China Green Bond Market Newsletter H1 2019 / 中国绿色债券市场季报 2019 上半年度.” [In English and Chinese.] London: Climate Bonds Initiative; Beijing: China Central Depository & Clearing Company (July 31). https://www.climatebonds.net/resources/reports/china-green-bond-market-newsletter-h1-2019.

Moody’s Investors Service. 2018. “Moody’s Assigns Green Bond Assessment (GBA) of GB1 to Wuhan Metro’s Proposed Green Senior Perpetual Securities.” November 20. https://www.moodys.com/research/Moodys-assigns-Green-Bond-Assessment-GBA-of-GB1-to-Wuhan–PR_391149.

Tay, Shirley. 2019. “Investors Are Pouring into Green Bonds. That May Not Be for the Best.” CNBC, January 29. https://www.cnbc.com/2019/01/30/investors-are-pouring-into-green-bonds-that-may-not-be-for-the-best.html.

Zhan Changjie, Martin de Jong, and Hans de Brujin. 2018. “Funding Sustainable Cities: A Comparative Study of Sino-Singapore Tianjin Eco-City and Shenzhen International Low-Carbon City.” Sustainability 10, no. 4256 (November 17, 2018): 1–15.

At the heart of Shenzhen, China, the city’s massive, wavelike Civic Center stands surrounded by a mind-boggling panoply of futuristic skyscrapers. Forty years ago, this area was home to just a few scattered fishing villages on the Pearl River Delta. Today, approximately 24 million people live within Shenzhen’s greater urban area.

In China, Shenzhen has come to stand for something much bigger than itself. On a hill downtown, a statue of revered former Chinese leader Deng Xiaoping striding purposefully toward the Civic Center helps explain why. Deng took control of China in 1978, after the death of Mao Zedong. The transition marked an end to decades of isolation from the outside world that had been dominated by command-and-control planning. Deng turned the country in a radically new direction, launching the Reform and Opening program to loosen the strictures that had bound the country for so long. And Shenzhen led the way into the future.

Deng granted the newly created city a license to operate as an economic superlaboratory, a place to explore the promise of the free-market economy. It was a sink-or-swim proposition, and in the years since, Shenzhen has succeeded wildly. Yet Shenzhen’s spectacular growth has come at a cost. As the area transcended its naturally marshy environment and turned from literal backwater into economic powerhouse, much of its land cover succumbed to blacktop and concrete. During storms, the abundance of paved-over land caused widespread flooding, as well as large-scale releases of urban pollution into nearby Shenzhen Bay and the Pearl River Delta.

Shenzhen is hardly alone in facing these problems. But continuing in its role as a national hotspot of innovation, it has become a unique laboratory for thinking about how to build livable cities throughout China and beyond.

Six miles northeast of Deng’s statue, Professor Huapeng Qin stands on a rooftop, surrounded by sensors measuring wind speed, temperature, and evaporation. He is looking for solutions.

Based at the local satellite campus of Peking University, Qin is at the forefront of an effort to turn Shenzhen into a “sponge city.” Using techniques that mimic nature, sponge cities can catch, clean, and store rain, which reduces the risk of flooding and keeps local drainage and water treatment systems from being overwhelmed.

Although it takes its cue from centuries-old thinking, the modern concept of the sponge city began forming in Europe, Australia, and the United States in the early to mid-1990s. The movement was a reaction to two common phenomena in urban development. First, just as happened in Shenzhen, most rapidly developing cities pave over huge amounts of land, eliminating a significant amount of natural forest cover, filling in lakes and wetlands, and severely disrupting the natural water cycle. Second, the traditional approach to urban stormwater management has focused on moving as much rain as possible off the land as quickly as possible, not capturing it for reuse.

Sponge city thinking marks a significant shift away from traditional “gray infrastructure”—think concrete pipes and dams—to “green,” or natural, infrastructure such as rain gardens and forests. The sponge city approach aims to restore some of those natural functions by allowing urban areas to transform the menace of stormwater into a boon: extra water for dry times.

Sponge city techniques therefore have multiple benefits. They can help soften the impact of flooding, improve both water quality and water supply, and help fix environmental problems. The sponge city concept is a relatively new arrival in China, but it has gained traction here fast. That’s partly due to the country’s tremendous growth over the past several decades, which has drastically altered the landscape. It’s also due to a new mindset about the risks of pursuing prosperity at all costs. In July 2012, a huge rainstorm in Beijing led to flooding that caused 79 deaths and an estimated $1.7 billion in damage. The incident galvanized national leaders.

In late 2013, President Xi Jinping officially endorsed the sponge city concept, and the following year the Ministry of Housing and Urban-Rural Development issued a set of technical guidelines aimed at ensuring that 70 percent of surface runoff be captured in place. The central government also launched what would ultimately become a 30-city pilot program to prove out the concept. Shenzhen is one of the pilot cities, and it’s no coincidence that the sponge city concept has gotten more traction here than anywhere else in China. From financial policy to the tech sector, “Shenzhen has always been very willing to borrow ideas from outside China and try them out,” says Qin. The sponge city idea is no different. “First it was just scattered pilot projects, but now the concept is being incorporated into Shenzhen’s master plan.”

In this case, Qin and his students are trying to learn more about techniques for creating green roofs, using plants grown in a medium of lightweight engineered soil to catch rain where it falls, slowly meting it out afterward. Such techniques are “very similar to natural systems,” Qin says. “Natural systems look very simple, but the processes are very complex. So we’re trying to understand those processes.”

A sponge city has several interchangeable building blocks. At a large scale, protecting or restoring forests and natural ground cover helps give water a chance to sink in. At smaller scales, there are several options. Permeable pavement can be used on roadways, sidewalks, and pathways to allow water to infiltrate the ground, rather than wash off into the local stormwater system. Retention ponds and constructed wetlands help catch and filter water, allowing it to slowly percolate into the local water table. So-called rain gardens perform a similar function at a smaller scale, and can easily be incorporated into neighborhood green space or even homes. Green roofs catch and filter rain, along the way watering plants that, Qin says, can help reduce surface temperature by up to nine degrees Celsius.

Shenzhen’s embrace of the sponge city concept has been driven by its spirit of innovation, but also by the fact that the effects of an unbalanced water cycle are often plain to see here. Heavy rains can overwhelm local water treatment plants, sending nutrient-laden wastewater directly into Shenzhen Bay and the Pearl River Delta, causing large algae blooms. People are also worried about the impacts of climate change. In what may have been a taste of what’s to come, Super Typhoon Mangkhut, which hit in 2018, blew down half the trees in the city.

Qin says computer models predict that with climate change, total annual rainfall will be comparable with current levels, but that precipitation will be much “flashier”: extreme events like short-duration, high-intensity rainstorms will become more common. This area has absorbed an influx of millions of people over the past few decades, largely by turning its back on the water that was once its defining characteristic. Now, Qin and others across the city are committed to finding new ways forward. The lessons they are learning and applying here are the first steps in what may soon be a sweeping transformation—not only in the city around them, but also throughout China.

“Sponge cities are just one example of how China is taking up the sustainability agenda,” says Zhi Liu, director of the Peking University-Lincoln Institute Center for Urban Development and Land Policy. Acknowledging the urgency of building climate resilience in the face of extreme weather and other challenges, he says, “This is not something China wants to do in order to look good. It comes out of necessity.”

Until two years ago, the 105-acre patch of green space now known as Honey Lake Park was an abandoned agricultural experiment station. The dominant features of the park, which sits not far from downtown Shenzhen, were a neglected grove of lychee trees and two fish ponds. Today, walking into the park feels like walking into an architectural rendering. Yet in the company of an expert, it quickly becomes clear that the park is not only aesthetically pleasing but also eminently functional.

Yaqi Shi, a technical director with the Shenzhen-based Techand Ecology & Environment company, helped design the park. The paths that we are walking on, she explains, are constructed of permeable pavement, and the park’s rolling contours are hugged by small swales that help slow and catch runoff. A series of ponds in the middle of the park is sown with native rushes that Techand raised in its own nursery. Signs throughout the park point out the various sponge city elements and explain how they work.

Shi, whose professional focus is ecological restoration, speaks with the brisk economy of an engineer. But the delight in her voice is evident when she speaks of the evolution of this project. “The park turned out to have a really user-friendly feeling,” she says. As we walk, Shi points out a library, a children’s play center, and the local wedding registration office, all within the boundaries of the park. A pavilion at the edge of a pond provides an ideal backdrop for cooing newlyweds to pose for portraits.

A walk with Shi also makes it clear that much of the technology underlying sponge cities is, in fact, surprisingly low-tech. The real art of the approach lies not so much in being technically clever, but simply in being thoughtful. Shi explains, for example, that much of Shenzhen is underlain by a layer of clay, which prevents water from infiltrating very far into the ground. To make permeable pavements work means hiring contractors to dig out the clay, sometimes to a depth of six feet, and replace it with gravel and more permeable soil.

Nonetheless, once you get a sense of what to look for, Shenzhen suddenly starts to seem like an entirely different city. On the northwest side, a relatively new suburb called Guangming has wholeheartedly embraced the sponge city concept. The suburb’s recently built New City Park is a model of retaining stormwater in place, from a water-absorbing latticework in the parking lot to permeable pavement on the paths, to swales and miniature, artificial wetlands designed to slow and soak up water. The massive adjacent public sports center has a green roof and a vast expanse of permeable bricks and pavement. The anaerobic digesters at the Guangming water treatment plant are covered by an enormous green roof; there’s another at the foreign languages school. Over at the high-speed rail station, where bullet trains thunder in from Hong Kong, the streets out front are made of permeable pavement.

After a while here, it’s hard to resist the temptation to, little by little, empty your water bottle onto Shenzhen’s sidewalks and streets, simply for the novel sensation of watching the water disappear into what otherwise appears to be regular blacktop and concrete.

Back downtown, the Nature Conservancy’s Xin Yu shows me another side of the sponge city revolution. We meet in the lobby of a Hilton hotel just a mile from the Civic Center and the nearby hilltop statue of Deng Xiaoping. After quick pleasantries, Yu takes me out a back service door. Compared to the airy elegance of the hotel lobby, it feels as if we’ve passed through a portal into another dimension.

We find ourselves in the narrow alleyways of an area known as Gangxia, a former farming village that Shenzhen gradually engulfed, and that subsequently metamorphosed into a crowded warren of five- and six-story apartment buildings. Gangxia and other so-called urban villages are a phenomenon found in practically every Chinese city, and are testament to the frenetic pace at which the country has urbanized over the past 40 years. They are often gritty, but they’re an important haven for low-income migrants who otherwise wouldn’t be able to afford the high rents of most urban areas. They typically come to form largely self-contained communities with small businesses that cater to all the needs of their residents, from vegetable sellers to modest karaoke parlors.

Yu nimbly leads me through the narrow back alleys, and it quickly becomes clear that “village” is a misnomer. The densely packed buildings here are known as “handshake apartments,” built so close together that residents of neighboring buildings can reach through their windows to shake each other’s hands. Restaurants are preparing for the lunchtime rush, and the air is filled with the staccato rhythm of vegetables being chopped. Business here, Yu says, is vibrant and extremely competitive: “These alleyways really are alive.”

Gangxia’s original residents didn’t technically own the land upon which their houses were built, but they did have rights to use that land. As Shenzhen grew during the 1980s and 1990s, they replaced their own houses with apartment buildings, often keeping one floor for themselves and renting out the rest, to take advantage of rising rents.

The Nature Conservancy (TNC) has played an important role in showing that it’s possible to incorporate sponge thinking even in the heart of the urban jungle. “There are a lot of ideas, but the government or companies can’t necessarily try things out,” Yu says. “NGOs can. We can figure out what ideas work and take them back to the government to promote more broadly.” (Due to the current political climate in China, Shenzhen municipal officials were not in a position to meet for this story.)

Yu opens a gate to an otherwise nondescript apartment building and climbs several flights of stairs to the roof—and an improbable flourish of lush greenery. A multilevel lattice framework groans with plants of every description. This green roof, Yu says, catches over 65 percent of the rain that lands on it.

Showing what’s possible hasn’t always been easy. When TNC first started this green roof project, Yu and his colleagues had to contend with angry neighbors who thought they were illegally adding another story to the building. “People kept calling different government departments: the police, or the construction bureau, or the city administration bureau,” Yu says. That led to several visits from local code enforcement teams, who used ladders to gain access to the building and a cutting torch to try to dismantle the garden’s supporting framework. “They kept asking for approval documents,” Yu says, and laughs. “But those don’t really exist. We had nowhere to go to get them.”

With time, however, efforts like this have spread broader awareness of the sponge city concept. “Public consultation—how you get the public to understand what this is about—is very important,” says Liu of the Lincoln Institute. “I think NGOs can play a big role in this area, and TNC is a trusted international NGO in China.”

TNC’s work has also gained the backing of officials and business leaders. Yu was invited to be a member of the technical committee for Shenzhen’s municipal sponge city program. When corporate tech giant Tencent decided to incorporate sponge city techniques in its iconic new headquarters in Shenzhen, the company turned to TNC for ideas. And Tencent’s founder, chairman, and CEO, Pony Ma, is not only a member of TNC’s board of directors for China, but also a delegate to the powerful National People’s Congress. There, he has made sponge cities part of a broader personal platform of advocating for nature-based solutions. Ma has also inspired fellow business leaders to commit to—and invest in—ensuring that their businesses meet sponge city standards in Shenzhen.

Some 1,200 miles north of Shenzhen, in Beijing, Kongjian Yu’s office seems to sprout a plant from every spot where he hasn’t managed to stuff a book. The Where the Wild Things Are feel is entirely consistent with Yu’s personality, which is driven by a kind of restless energy. It’s hard to imagine him sitting in one spot for five minutes.

Yu, who was born in a small farming village in coastal Zhejiang Province, went abroad and earned a Doctor of Design degree at Harvard, in 1995. Upon returning to China, he was deeply disheartened by the direction that development had taken. “When I came back, I was shocked by the scale of urbanization,” he says. “I was amazed by how this process ignored all our natural and cultural heritage, filling in wetlands, destroying the rivers, cutting down the trees, and wiping out all these old buildings.”

Yu was hired as an urban planning and landscape architecture professor at Peking University. In the staid world of Chinese development theory, he has made his name as something of a flower child—and a gadfly. Yu became a prodigious author and tireless lecturer, and turned out a series of open letters to China’s top leaders. He called for China to abandon its mania for building monumental public squares; advocated for a revival of the traditional Chinese approaches to farming, water management, and settlement; and suggested that the money allocated for annual National Day parades be better spent building good parks.

Above all else, Yu railed against China’s obsession with concrete, a repudiation of decades of thinking here. “The philosophy in China, in Mao’s era, was that humans can beat nature,” Yu says. “And that caused a lot of disasters for us.”

That attitude only accelerated in the years after Mao’s death, and by the early 21st century, China was setting records for the amount of concrete it was pouring each year. Global systems demystification guru Vaclav Smil has estimated that China used more cement in just three years, 2011 to 2013, than the United States did in the entire 20th century.

While Yu has encountered opposition to his outspokenness, he has also tapped into a growing demand for this new kind of systems thinking. Today, in addition to serving as dean of Peking University’s College of Architecture and Landscape, he heads a 600-person landscape architecture and urbanism consultancy called Turenscape. Municipal governments across China routinely seek the company out for help. He wrote the definitive two-volume practitioners’ guidebook on sponge cities in China, and contributed to the Lincoln Institute of Land Policy book Nature and Cities. His work is also featured in Design with Nature Now.

A core tenet of Yu’s overall approach is a concept he calls fan guihua. The concept is frequently translated as “negative planning,” but might be more accurately rendered as “inverse planning.” It’s essentially a counter to the type of development that has shaped China’s growth for so long. “You plan what’s not built,” Yu explains. “You plan what should be protected.”

This, obviously, is a fairly radical idea in contemporary China. Yet in the course of his work, Yu came to a surprising realization: the idea of living with water, rather than battling it, was a concept that had historically been very familiar. In central and southern coastal China, including the area where Shenzhen now stands, a distinctive method had evolved over centuries to catch rainfall and carefully manage it with earthen dikes to raise mulberries, silkworms, and fish, a sort of landscape-scale aquaponics system. And when Yu and his students looked deeper, they realized that sponge city-like concepts had been a fundamental principle of Chinese city planning for centuries. Traditionally, he says, many Chinese cities had the capacity to absorb two-thirds of local rainfall within their boundaries.

With this discovery, the idea of a different way of managing water—and the perils of a drastically altered hydrologic cycle—became a major theme of Yu’s work. Nature, for its part, began putting an increasingly fine point on the issue. During the 2012 flood in Beijing, “seventy-nine people were killed. Drowned. On the street,” Yu says. “In the capital, we drowned 79 people. How is that possible? We lost face. That immediately became a political issue.”

Yu wrote another letter to high-level leaders saying that adopting the sponge city approach and creating a resilient landscape might offer hope. As it happens, Xi Jinping had recently become the secretary general of the Communist Party and president of China. After decades of the country struggling with notorious pollution and other environmental problems, Xi has staked his reputation on creating an “ecological civilization” in China.

The exact contours of that concept are sometimes difficult to discern, but in broad outline it encompasses both a nationwide push for ecological sustainability and the creation of a green, uniquely Chinese alternative development model for the rest of the world. Both sponge city thinking and a more expansive embrace of low-impact development fall squarely within Xi’s larger aspirations.

“China’s in an environmental crisis. We have to do this,” Yu says. “When people can’t breathe, when the water is polluted—I think he’s very sensitive to those issues. I think he really wants to build his legacy on doing this.”

The biggest challenge to making sponge cities work on a broad scale has nothing to do with building rain gardens, installing permeable pavement, or placating neighbors. “Finance is a major issue,” says Liu.

Liu, who came to the Lincoln Institute after 18 years with the World Bank, is largely focused on governance and financing issues associated with land use in China. Taking the sponge city concept to scale won’t be easy, and he cites the challenges in Shenzhen as an example. Sponge city improvements in Shenzhen, which officially began in 2017, now cover 24 percent of the city’s total surface area. The government has a goal of increasing that to 80 percent by 2030. But hitting that target will be a significant challenge.

The central government has pledged a total of $5.8 billion (40 billion Chinese yuan) to incentivize Shenzhen and the 29 other pilot cities to invest in and carry out sponge city work. But it wants each of those places to bring at least 20 percent of its developed area up to the sponge city standard by the end of this year.

Liu says that bringing a square kilometer of already developed urban land up to the standard typically costs $22 million to $29 million (150 to 200 million CNY). The 30 pilot cities are each eligible for 400 to 600 million Chinese yuan per year from the central government for three years. That’s enough to upgrade, at most, four square kilometers per year. To meet—and actually exceed—the central government’s 20 percent by 2020 target, Shenzhen brought about 235 square kilometers up to standard, at a cost that likely ran anywhere from $5 billion to $7 billion.

“Asking the municipal government to come up with that kind of money is not easy,” Liu says. Shenzhen was able to pull it off because of its strong municipal budget and private commitments from the city’s tech and manufacturing giants. But, he adds, “if you go to the interior cities where the municipal finance is very weak, it’s very difficult.”

Liu points out that in the case of new development, cities can implement standards that will require developers to pay for improvements, a cost typically passed on to residents and firms. “If you look at the upfront costs for development, sponge cities are not a very expensive thing to do,” Liu says. Retrofitting existing development, however, is a much bigger challenge.

“The toughest issue is that public finance is used to finance the public good, with very little opportunity for cost recovery,” he continues. “That’s really the toughest story about China. It’s a matter of priority. The cities just have too much on their plate. So by the end of the day, very few cities can find enough money.”

Sponge city infrastructure is “just like a streetlight,” Liu says. “It’s a shared public good, but nobody wants to pay for it.”

In truth, the biggest challenge of turning the sponge city into reality may well be unraveling the financing mechanics. Yet the cost of not rising to the challenge may be higher than anyone fully appreciates.

“It’s really like thinking about buying insurance,” Liu says. “We are all facing uncertainties, but the trend of more intense storms is quite clear . . . The cost of inaction might not look that high today, but when we’re faced with a catastrophic outcome in 10 or 20 years, we’ll regret that we didn’t spend the money earlier.”

Even given those high stakes, the sponge city idea could ultimately be about even more. Back in Shenzhen, standing on the roof of the apartment building in Gangxia, TNC’s Yu says sponge cities do a lot more than tame floods and save water for dry seasons. 

“If you only talk about stormwater management or runoff control, the average person won’t necessarily buy in, because they’ll feel like it doesn’t have any connection to them,” he says. “But features like green rooftops are different. They can have a synergistic effect. They help absorb rainfall, but they also improve the neighborhood view, contribute to urban biodiversity, and create a green space that everybody can use.”

Matt Jenkins, who has previously worked as an editor for Nature Conservancy magazine, is a freelance writer who has contributed to The New York Times, Smithsonian, Men’s Journal, and numerous other publications.

Photographs (in order of appearance):

Shenzhen, China, is one of 30 pilot “sponge cities” in China that are investing in nature-based stormwater management solutions. Credit: Wang Jian Xiong via Flickr CC BY 2.0.

Xiangmi Park, also known as Honey Lake Park, is a former agricultural research area in Shenzhen that was redesigned for community use. Bioswales, permeable pavement, and other elements allow it to double as a stormwater management tool. Credit: Vlad Feoktistov.

Rooftop garden on the Tencent Binhai towers in Shenzhen. Tencent founder and CEO Pony Ma is an advocate of sponge cities who has inspired fellow business leaders to invest in nature-based solutions in Shenzhen. Credit: The Nature Conservancy/Theodore Kaye.

A couple of years ago, landscape architect Pamela Conrad got curious about the climate impact of her work. How much carbon dioxide did her chosen materials release into the atmosphere? How much carbon was sequestered, or captured, by any given project’s mix of trees, shrubs, grasses, and other plants? What factors could she adjust to improve the net outcome? Conrad, a principal at the San Francisco firm CMG Landscape Architecture, decided to investigate.

“I went online and I just assumed there was going to be some magical tool that I could download, and it would just tell me,” she says. “I kind of expected to find it that afternoon.” That didn’t happen. She did find helpful tools and data intended to help gauge and improve the emissions impact of the built environment, but what she was looking for didn’t seem to exist: a tool to help landscape architects understand, in a holistic way, the climate impacts of their work.

Beyond her personal curiosity, this struck Conrad as a surprising absence. “We haven’t been measuring anything outside the building,” she says. That meant crucial conversations with policy makers and clients weren’t happening, because “we haven’t had the data.” Because landscape architecture can not only reduce emissions but also make tangible contributions to carbon sequestration, this field is perfectly positioned to offer “climate positive design,” as Conrad calls it: design that sequesters more carbon dioxide than it emits.

Conrad set out to make the tool she couldn’t find, with the support of a research grant from the Landscape Architecture Foundation. She worked with environmental consultants and tech developers to create a beta version of the free, web-based app now known as Pathfinder. The app, which formally launched in September 2019, has been used by 300 firms and counting. It is intentionally simple and accessible. Users enter various details of a project, large or small, from a backyard garden to a city plaza. The interface asks for information about materials (e.g., sand, crushed stone), plant types (e.g., trees, lawn), and other details.

On the back end, the app draws on data from sources including the U.S. Forest Service and the Athena Impact Estimator software created by the Athena Sustainable Materials Institute (ASMI) for building materials. It provides a kind of carbon profile for each project and offers suggestions to improve it, such as substituting a no-mow meadow for a lawn, or a wood deck for paving. The suggestions are intended to reduce the time it will take for each project to become carbon neutral, and then carbon positive. In the course of designing Pathfinder, Conrad tapped into a vein of similar efforts in other corners of the architecture and construction sectors that are contributing fresh insight to broader discussions of policy, planning, and land use. ASMI, a nonprofit collaborative, has been a pioneer on this front: since 2002 it has provided a variety of software tools that help designers measure the building, construction, and material impacts of their projects and materials.

Interest in this sort of resource is surging. Stephanie Carlisle, a principal at Philadelphia architecture firm KieranTimberlake, caused a stir earlier this year with a lengthy call-to-arms essay on the contribution of architects to climate change in Fast Company. New construction contributes massively to carbon emissions, she wrote: “Although it’s become mainstream to discuss energy efficiency and advocate for minimizing those impacts, architects, engineers, and planners have yet to truly reckon with the magnitude and consequences of everyday design decisions.”

Carlisle says she has been heartened by the enthusiastic response to the essay. As it happens, KieranTimberlake introduced its own carbon measurement tool, Tally, a few years ago. Tally was designed to be folded into workflow processes, as a plug-in to a 3D modeling software commonly used in the industry called Revit. This means, Carlisle explains, that a designer can substitute and change material and other options Tally allows architects to compare the climate impacts of various materials on a work in progress, then run a report on its potential carbon impact. “It tells designers where to spend their energy,” she says. Some 200 firms now use Tally, and its sales rose about 150 percent last year.

Tally, Pathfinder, and other similar tools fit into a broader trend of architects and landscape architects responding to climate change. “These [projects] are great pieces of the puzzle,” says Billy Fleming, Wilks Family Director for the Ian L. McHarg Center at the University of Pennsylvania and a coeditor of the recently published Design with Nature Now, a collaboration between the university and the Lincoln Institute of Land Policy. “The core of [the challenge] is absolutely about social, technical, and political systems that have to be reorganized around an international mobilization and response to climate change. So these efforts should be treated as the beginning of a conversation—not the end of it.”

Indeed, both Carlisle and Conrad emphasize that these tools are just a means to an end. Such tools are “directly empowering architects and engineers,” Carlisle says, but they can also help establish common benchmarks that make it easier for communication around carbon standards to “make its way into policy and code.” That’s starting to happen—Carlisle cites Marin County’s recent introduction of carbon standards for construction materials, and Conrad notes that San Francisco is embarking on a sustainable neighborhoods framework that factors in carbon sequestration standards—but they say there’s still not enough awareness of the possible positive impacts of design outside the design professions, or perhaps even within them. “We need way more investment in R&D, and in tools,” Carlisle says.

Conrad extends the point: as much as she intends Pathfinder to offer “really quick, accessible answers” with practical impacts on real projects, she also wants it to serve as an educational experience that builds awareness. “Landscape architects are the primary target,” she says. “But I see [potential use for] a lot of other players in the space, like policy makers using it to set standards.” While it’s easy for an individual to use Pathfinder to plan a backyard renovation, large-scale landowners can use it to gauge the impact of setting aside portions of development for trees and other elements that build climate resilience. A simple slider interface shows the user that, for example, a combination of 400 large trees and 1,100 medium-sized ones can sequester 2.3 million kilograms of carbon. “Once we’re able to measure what we’re doing and collect that data and get that feedback,” Conrad continues, “then we can start understanding what we’re doing and evolve our practices.”

Conrad has been spreading the word about Pathfinder through conferences and webinars, and has been taking suggestions that will guide updates in 2020. Late last year, she helped organize the Climate Positive Design Challenge, aimed at landscape architects, which established specific targets for projects large and small to achieve carbon-positive status: five years for parks, for instance, or 20 years for streetscapes or plazas. Pathfinder is meant to play a central role in helping designers meet that challenge. 

“We could potentially take a gigaton of carbon dioxide out of the atmosphere over the next 30 years,” Conrad says. “We think you can cut emissions [on a given project] in half, and increase sequestration by two or three times, just by having the right information in front of you.”

Rob Walker is a journalist covering design, technology, and other subjects. His book The Art of Noticing was published in May 2019. 

Photograph: The web-based app Pathfinder was the brainchild of landscape architect Pamela Conrad, who created the tool to measure the climate impacts of her work after discovering that no such tool existed. Credit: Courtesy of CMG Landscape Architecture.