“History has repeatedly shown that data and facts alone do not inspire humans to change their beliefs or act,” said Jean-François Bastin, the lead author of the paper. “The intangible nature of reporting on climate change fails to adequately convey the urgency. It is hard to envisage how 2C of warming, or changes in average temperature by 2100, might impact on daily life.”
Water shortages will affect scores of cities now in temperate climates as a result of the global heating, which is forecast to rise by as much as 3.5C in European cities in summer and 4.7C in winter. Barcelona was affected by extreme drought just over 10 years ago, endangering many inhabitants and resulting in tens of millions of euros being spent on importing drinking water. It is becoming more likely that London and cities in similar latitudes will experience the same problems in the future, say the researchers.
The residents of about a fifth of cities globally – including Jakarta, Singapore, Yangon and Kuala Lumpur – will experience conditions currently not seen in any major cities in the world.
“These are environmental conditions that are not experienced anywhere on the planet at the moment,” Tom Crowther, founder of the Crowther Lab in Switzerland, which carried out the research, told the Guardian. “That means there will be new political challenges, new infrastructure challenges, that we have not faced before.” He said, this unprecedented level of change “blew my mind”.
Rainfall will be a particular problem for such cities, with extreme flooding becoming more common alongside more frequent and severe droughts.
Crowther said: “We are absolutely not prepared for this. Planning for climate change needs to start yesterday. The sooner it starts, the less the impact will be.”
London homeowners relishing the prospect of a Catalan climate might need to think again. Mike Lockwood, a professor of space environment physics at Reading University, who was not part of the research team, said: “Bringing Barcelona’s climate to London sounds like it could be a good thing, if you don’t suffer from asthma or have a heart condition – except London clay shrinks and is brittle if it gets too dry, then swells and expands when very wet. The greater swings in ground moisture expected in a warmer world would cause massive subsidence problems.”