A fifth of the world’s major cities will face “unknown” climate conditions by 2050, researchers warned on Wednesday, as rising temperatures heighten the risks of drought and flooding.
Climate scientists at the Crowther Lab, a research group based at ETH Zurich, a science and technology university, analysed 520 cities across the world, including all capitals and most urban centres with a population of more than 1 million.
The study showed that 22% of the cities will experience unprecedented climate conditions by 2050, such as more intense dry and monsoon seasons, said Jean Francis-Bastin, the lead author of the report.
Almost 70% of the world’s population is expected to be living in urban areas by 2050, according to the United Nations.
In Europe, cities will warm by an average of about 2.5 degrees Celsius across the year, but summers and winters could be 3.5C and 4.7C warmer, respectively, Francis-Bastin said. Globally, temperatures are likely to be 2.4C warmer on average - enough to kill nearly every coral reef and soar past targets set out in the Paris Agreement.
Cities in tropical regions will see more severe flooding and droughts, researchers said.
The study may help cities modify their planning to combat specific climate risks, Francis-Bastin said.
Meanwhile, more than 7,000 colleges, universities, technical schools and community colleges from around the world declared a climate emergency in a joint letter which was set to be delivered to the United Nations on Wednesday.
Networks of schools pledged to increase sustainability curriculum and campus outreach, boost climate change research and skill-building opportunities for students and reach carbon neutrality by 2050, some as soon as 2030.