July 16th, 2019
Over 100 of the world’s major cities will experience climate conditions that do not currently exist on the planet today by 2050, scientists have found.
The new study in PLoS ONE analysed 520 of the world’s major cities to see how their climates will look by mid-century under a business as usual climate model.
The study found that 77 per cent of future cities are “very likely” to experience a climate that more closely resembles that of another existing city with a different climate.
The study conservatively estimates that 22 per cent of cities examined will actually experience climate conditions that do not currently exist on the planet today, with many expecting to see much drier conditions.
Almost two-thirds of the cities that will experience novel climate conditions are in the tropics, including Manaus in Brazil and major Asian metropolises such as Kuala Lumpur, Jakarta, and Singapore.
Cities in the tropics will experience smaller changes in average temperature but will see a significant increase in extreme rainfall events and in the severity and intensity of droughts.
Cities from the Northern hemisphere will see the most dramatic shift to warmer conditions by mid-century, with Madrid, for example, expected to more closely resemble Marrakech by 2050.
Summers and winters will get warmer across Europe, the study finds, with increases of 3.5˚C and 4.7˚C respectively, equivalent to a city shifting around 1,000 km further south towards the subtropics.
This will lead London’s climate to more closely resemble that of Barcelona, the study finds, with Stockholm also likely to feel more like Budapest within a few decades.
Dublin’s climate may resemble that of current-day Paris by mid-century, the study found. During the recent June heatwave, the French capital activated its emergency heatwave plan as high humidity levels in the city made 40C feel closer to 47C.
By mapping such shifts, the researchers hope to help land managers and city planners visualize the future climate of their respective cities and make effective decisions to prepare for the change.
infographic by Statista
From London to Barcelona
Londoners can start to consider how Barcelona, their 2050 climate equivalent, has taken action to combat their own environmental challenges, the study said by way of example. In 2008, Barcelona experienced extreme drought conditions that lead to the importation of €22m of drinking water.
Professor of Climate System Science at the University of Edinburgh, Gabi Hegerl, said that the most striking finding of the study is that most of the cities that will move to unknown climatic conditions are in the tropics.
“Some of these are large and fast-growing cities, and the new conditions could be harmful or dangerous as they are presently inexperienced in coming with extreme events,” she said.
Professor Richard Betts, the Head of Climate Impacts Research at the Met Office Hadley Centre, said that the study helps to put climate change in the context of human experience and show that cities in the tropics such as Singapore are “entering unknown climate territory”.
“Without the benefit of knowing that the new climate conditions are already liveable somewhere in the world, it is harder to know whether people will be able to adapt and stay in these cities, or whether they will eventually look to move elsewhere,” he added.
While praising the paper’s powerful illustration of what climate change could mean in reality for our major cities, Dr Friederike Otto of the University of Oxford said that “it should be taken as an illustration only, not as a prediction”.
“[The authors] aggregate over many variables and do not address model uncertainty systematically,” he said.