Climate change bringing longer heatwaves, infectious diseases

Major cities worldwide could face severe crises if global warming continues unabated, reaching 3°C above pre-industrial levels, a new report warns.

The study, published by the American institute WRI, examines climate risks for nearly 1,000 major cities housing 2.1 billion people – 26% of the global population and over 50% of urban dwellers.

“The difference between 1.5°C and 3°C is a matter of life and death for billions,” said Roger van den Berg of WRI.

The report highlights stark contrasts between 1.5°C and 3°C warming scenarios:

• Heatwave duration in major cities could increase from 16.3 days to 24.5 days
• Annual heatwave frequency could rise from 4.9 to 6.4
• Demand for air conditioning and energy would surge
• Mosquito-borne diseases like dengue, Zika, and chikungunya could spread more widely

Low-income cities are expected to bear the brunt of these impacts. Sub-Saharan Africa faces heightened risks of frequent heatwaves and disease spread.

Cities like Freetown in Sierra Leone and Dhaka could experience month-long heatwaves, averaging seven episodes annually in a 3°C warmer world.

Current global commitments put the planet on track for a 2.9°C temperature rise, according to recent UN data.

“The time has come to prepare cities for a much hotter world, doing everything we can to drastically reduce greenhouse gas emissions,” van den Berg concluded.