https://phys.org/news/2018-07-cities-proxies-climate.html

Experiments in cities also have advantages over experiments performed in labs or in specially designed "growth chambers" that attempt to mimic higher temperature or drier soil conditions. Cities are larger than experimental chambers and organisms like trees have lived at higher temperatures their entire lives in cities, whereas other experimental methods can only increase temperature for short periods. Thus, urban areas can show how plants and animals respond to changes in climate over long stretches of time, which lab and growth chamber studies can't quite match.

"Our review synthesized existing studies that used cities as proxies for climate change, particularly higher temperatures," said Steve Frank, a professor in the Department of Entomology and Plant Pathology at NC State and a co-author of a paper describing the research.