Some challenges of urban sustainability are air and water quality and ecological footprint of cities. In Spain, the drinking water is scarce and the beaches are receding. More than half of Spain is covered in excessive amounts of particulate matter, Nitrogen Dioxide, and ozone. These pollution things are happening form road traffic, which is more then 50% responsible for the Nitrogen Dioxide emissions. These are mostly from diesel vehicles. The global carbon emissions are twice the size higher then they should have been to avert prevent the effects that were mentioned in 2015. Spain is getting warmer and drier from climate change. The Mediterranean area of Spain was already got warmer by 1.5 degrees Celsius, the global average is 1.1 degrees Celsius. With the urgent climate change happening, Spain is more likely to to see a big change in temperatures in the next couple decades to come. To help with the traffic pollution, Madrid has invested heavily into renewable energy and ICT grids.
Madrid is Spain's largest built up urban area. Most of Madrid'd growth over the last few decades has taken place outside it's historic urban cores. In Madrid there is not only a high density residential population not only in the suburbs but also in the city. Since Spain has become a democracy and part of the European Union, Spain has improved a lot. Since 1980, Spain's gross domestic product per capitals increased 5%. Madrid has 40 surrounding towns that create the Madrid metropolitan area. This makes Madrid 2,060.23 square miles in diameter.