Climate change is magnifying threats such as flooding, wildfires, tropical storms and drought. In 2020 the U.S. experienced a record-breaking 22 weather and climate disasters that each caused at least $1 billion in damage. So far in 2021, the count stands at 18.

I study urban issues and have analyzed cities’ relationship with nature for many years. As I see it, cities are quickly becoming more vulnerable to extreme weather events and permanent shifts in their climate zones.

I am concerned that the pace of climate change is accelerating much more rapidly than urban areas are taking steps to adapt to it. In 1950, only 30 percent of the world’s population lived in urban areas; today that figure is 56 percent, and it is projected to rise to 68 percent by 2050. Failure to adapt urban areas to climate change will put millions of people at risk.

As the Intergovernmental Panel on Climate Change shows in its latest report, released in August, global climate change is widespread, rapid and accelerating. For cities in temperate latitudes, this means more heat waves and shorter cold seasons. In subtropical and tropical latitudes, it means wetter rainy seasons and hotter dry seasons. Most coastal cities will be threatened by sea-level rise.

Around the globe, cities will face a much higher probability of extreme weather events. Depending on their locations, these will include heavier snowfalls, more severe drought, water shortages, punishing heat waves, greater flooding, more wildfires, bigger storms and longer storm seasons. The heaviest costs will be borne by their most vulnerable residents: the old, the poor and others who lack wealth and political connections to protect themselves.

Extreme weather isn’t the only concern. A 2019 study of 520 cities around the world projected that even if nations limit warming to 2 degrees Celsius above preindustrial conditions, climate zones will shift hundreds of miles northward by 2050 worldwide. This would cause 77 percent of the cities in the study to experience a major change in their year-round climate regimes.

For example, the study authors predicted that by midcentury, London’s climate will resemble that of modern-day Barcelona, and Seattle’s will be like current conditions in San Francisco. In short, in less than 30 years, three out of every four major cities in the world will have a completely different climate from the one for which its urban form and infrastructure were designed.

A similar study of climate change impacts on more than 570 European cities predicted that they will face an entirely new climate regime within 30 years — one characterized by more heat waves and droughts, and increased risk of flooding.

Read the full article about climate change and cities by John Rennie Short at GreenBiz.