If you want to do something good for the environment, you should avoid some areas.

With heat waves of up to 38 degrees and periods of drought in summer, followed by cyclones and floods in autumn, Houston is one of the most endangered storm zones in America.

Nevertheless, the city has risen to become the fourth largest metropolitan area.

The American urban economist Edward Glaeser has repeatedly attacked this as ecologically unacceptable: "If America is to become greener, then we have to build more in Boston or San Francisco and less in Houston or Oklahoma."

Especially after the recent American tornado disasters, it is astonishing that Houston appears in the collection of examples "The resilient city".

In it, the Brandenburg landscape architect and university professor Elke Mertens reports on the creation of a “green-blue infrastructure”, which she observed on research trips through eleven large cities in North, Central and South America.

By this she means the conversion of urban problem areas into compensation zones for cooling, ventilation, evaporation and storage for water, air and soil.

Joseph Beuys' former documenta art campaign of "urban forestation" almost seems to be becoming an everyday planning practice.

Manageable municipal pilot projects

In Houston, a concrete river called Buffalo Bayou previously ran from the city to the suburbs. In 2015 the city administration renatured the river valley as a wetland, flood zone and recreational area. The buildings and park furniture were anchored so deep in the ground that they would not swim away with the next high tide. The city also used citizens' initiatives to regenerate neglected parks, and created cisterns as retention basins and vegetation zones for new habitats.

The author has not collected any spectacular large-scale projects for the irrigation of deserts or land reclamation in coastal regions, but rather focuses on manageable municipal pilot projects that are not always original, but consistently practicable.

Toronto takes care of the creation of multifunctional "green" streets, planting resilient city trees, reforestation of quarries and promotes "urban farming" in former industrial buildings.

Since 2017, a Google subsidiary called “Sidewalk Labs” has been planning to reurbanize the shores of Lake Ontario with a “Smart City”;

but the announcement that the road surfaces for self-driving cars should be heated in winter does not bode well.

The example of Bogotá

Vancouver, on the other hand, the city of birth of Greenpeace, has been working since 2009 to become the “greenest city in the world”. Almost one hundred percent of the electricity comes from renewable sources, fresh water consumption through rainwater storage tanks has halved, and the planting of roof gardens and facades is in full swing. But how the city on the Pacific coast protects itself from rising sea levels remains unclear.

New York has known what climate change means since the monster Hurricane Sandy in 2012. If the water level continues to rise, a quarter of the city will be flooded by 2080. The described expansion of the once inaccessible Governors Island in the Bay of Manhattan into an elevated city park can do little to change that, despite all the landscaping finesse. New water fronts and embankments on the East River in Queens seem more useful. They do not protect against the floods with sheet pile walls, but rather create controlled flood zones that hold back the water and slowly drain it back into the river. Instead of the pedestrian-friendly redevelopment of Times Square, the author would have better examined how New York, under Mayor Bloomberg, has been transforming its waterfront around Manhattan into a lively green boulevard since 2002,which also absorbs floods.

Surprisingly, Bogotá and Medellín in Colombia turn out to be high-tech cities with exemplary transport systems consisting of trams, elevated and cable cars as well as green plans with parks and vegetation corridors that can make many Europeans jealous. In the Brazilian Manaus in the Amazon basin, the climatic effects of the deforestation are most clearly noticeable, which is why most of the ecological research stations work here. If the proportion of the rainforest that has been destroyed increases from twenty to twenty-five percent today, the author quotes current research, then the world's air conditioning is broken. While Rio de Janeiro is increasingly environmentally conscious, the drawing board city of Brasília, founded in 1960, cannot be revitalized in terms of landscape planning either.

The author dedicates a historical-geographical representation with current ecological-political perspectives to each city. Research into environmental data and climate impacts is always worthwhile, but its predictable degenerative tendency is tiring. Instead of the illustration with many postcard motifs, site plans, terrain sections and construction drawings would be more helpful. Rather unintentionally, the book makes it clear that sectorally optimized green planning does not go far enough in urban ecology. But gradually, landscape and urban planners also seem to see the future of resilient cities no longer in their dissolution, but in their spatial concentration and technical modernization, as wise urban economists have long recognized.

Elke Mertens: "The resilient city".

Landscape architecture for climate change.

Birkhäuser Verlag, Basel 2021. 256 pp., Ill., Hardcover, € 42.95.