[Timwi]

I'm not surprised the Ruhr area (the cluster of cities in West Germany surrounding Essen) sweeps the “30% greenery” benchmarks.

This area was especially rich in coal deposits, leading to massive coal extraction during the industrial revolution. There was air pollution and industrial waste everywhere. The area quickly gained a reputation as the dirtiest, most polluted place on the planet. The colloquial term “Ruhrpott” (Ruhr cauldron) came out of this.

So in the 2000s, the city governments (Essen, Bochum, Duisburg, Dortmund, etc etc) decided on an ambitious project to counteract this perception. This paid off. Essen made the top three “Europe’s greenest city” three years in a row and won in the third (2015–2017).

Sometimes, a history of being known as the worst in something leads to greater enthusiasm to become the best.