Climate change may make cities 8 degrees Celsius hotter by year 2100, say researchers!

New Delhi: The discourse on climate change and global warming is far from over. It has taken over a larger domain in the last few years and its rapidly growing effects have raised questions on Earth's habitability in the future.

Environmentalists' and scientists' concern over climate change and its effects are on another level altogether and with good reason.

Climate change is far from giving up and is causing some form of damage every other day, which scientists fear is bringing us closer to doomsday.

Now, in another concerning revelation, researchers have warned that under a dual onslaught of global warming and localised, urban heating, some of the world's cities may be as much as eight degrees Celsius (14.4 degrees Fahrenheit) warmer by 2100.

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.

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.

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.

Cities cover only about one percent of earth's surface but produce about 80 percent of gross world product and account for around 78 percent of energy consumed worldwide, said the researchers.

They produce more than 60 percent of global carbon dioxide emissions from burning coal, oil and gas for fuel.

The world's nations agreed in Paris in 2015 to the goal of limiting average global warming to two degrees Celsius over pre-Industrial revolution levels by curbing greenhouse gas levels in Earth's atmosphere.

For the latest study, researchers used data from the world's 1,692 largest cities for the period 1950 to 2015.

(With PTI inputs)