Various campaigns to plant millions of trees have become a popular response by urbanites to a changing climate. Many, however, have not reached their loudly proclaimed targets.

With great fanfare, trumpets blowing and drums beating, it was announced in Copenhagen in 2015 that 100,000 trees would be planted by 2025. In the usual style, this message fitted precisely into a carbon dioxide emission reduction plan. Six years later, many of the planted saplings had already died. It was concluded that the growth of the trees had been hindered by residents driving cars and bicycles, as well as the salt used by municipal services. The city still tends to replace large, mature trees with small saplings, which, unfortunately, continue to face the aforementioned series of problems.