Madrid wants to fight climate change and air pollution. The governors of Spanish Capital plan to surround the city with a green wall consisting of half a million trees, stretching for 75 km. "El Bosque Metropolitano" or the Metropolitan Forest, is to be the largest green infrastructure that will be built in Europe in the next decade. In addition to the huge amount of trees, the forest will also consist of new parks, recreational areas and green bridges over the city's main highways. According to reports, once the construction is completed, the investment will consume 175,000 tonnes of carbon dioxide per year. Madrid's authorities have high hopes for the project. The Metropolitan Forest is to influence the air quality in the city, clean it and help reduce CO2 emissions. Experts emphasize that the Metropolitan Forest project is also a response to desertification that is beginning to affect southern Europe. The construction of the EUR75 million green wall is scheduled to start in early September and will take 12 years to complete.