World Top Cities May Be 8 Degrees Celsius Hotter By 2100 – Study

By Victor Ernest with AFP report

Due to global warming and urban heating, some of the world’s cities may be as much as eight degrees Celsius (14.4 degrees Fahrenheit) warmer by 2100, researchers warned on Monday.

Such a temperature spike can have dire consequences for the health of city-dwellers, robbing companies and industries of able workers, and put pressure on already strained natural resources such as water.

Worst-case-scenario

The projection is based on the worst-case-scenario assumption that emissions of planet-warming greenhouse gases continue to rise throughout the 21st century.

The top quarter of most populated cities, in this scenario, could see the mercury rise 7 C or more by century’s end, said a study in the journal Nature Climate Change.

For some, nearly 5 C of the total would be attributed to average global warming.

The rest would be due to the so-called Urban Heat Island (UHI) effect, which occurs when cooling parks, dams and lakes are replaced by heat-conducting concrete and asphalt — making cities warmer than their surrounds, the researcher said.

“The top five percent (of cities per population) could see increases in temperatures of about 8 C and larger,” study co-author Francisco Estrada of the Institute for Environmental Studies in the Netherlands told AFP.

Different projections

Estrada and a team used different projections of average planetary warming, combined with the UHI effect and potential harms, to estimate the future costs of warming on cities.

The median city, right in the middle of the range, stands to lose between 1.4 and 1.7 percent of GDP per year by 2050 and between 2.3 and 5.6 percent by 2100, they concluded.

“For the worst-off city, losses could reach up to 10.9 percent of GDP by 2100,” wrote the team.

UHI “significantly” increases city temperatures and economic losses from global warming, they added.

This meant that local actions to reduce UHI — such as planting more trees or cooling roofs and pavements, can make a big difference in limiting warming and minimising costs.