A new schoolwork of more than 13,000 cities around the world
found that the number of days per person that residents are exposed to an
extreme combination of heat and humidity has tripled since the 1980s. The
authors say the trend, which Now it affects almost a quarter of the world's
population, it is the cumulative result of rising temperatures and skyrocketing
urban populations. The research is published in the journal PNAS . fashionglee
Why is it hotter in cities?
The lack of vegetation and the concentration of asphalt and
other impenetrable surfaces that tend to trap and concentrate heat create the
so-called heat island effect in cities, where temperatures are often slightly
higher than in the surrounding rural areas. "And that has its
consequences," says Cascade Tucholske, a fellow at Columbia University's
Earth Institute and lead author of the study. “This increases morbidity and
mortality. This affects people's working capacity and leads to a decrease in
production volumes. It aggravates pre-existing health conditions . "
In fresh decades, hundreds of millions of people take moved
from rural areas to cities, where more than half of the world's people nowadays
live, and therefore more and more people are exposed to these consequences .
The researchers combined infrared satellite imagery and
readings from thousands of ground-based instruments to determine maximum daily
temperature and humidity readings in 13,115 cities from 1983 to 2016. They
defined extreme heat as 30 degrees Celsius on the so-called "globe
temperature scale." The "wet onion" is an indicator that takes
into account the multiplier effect of high humidity on human physiology. This
is the time when even most healthy people have a hard time working outdoors for
long periods of time, and sick people can get worse or worse. To die . tophealthfitnesstips
To determine the number of person-days spent in such
conditions, the researchers compared the meteorological data with the city's
population statistics for the same time period. The analysis found that the
number of person-days to which citizens were exposed had tripled, from 40
billion per time in 1983 to 119 billion in 2016. By 2016, 1.7 billion people
were exposed to such conditions in question. of days.
Cities most affected
The worst hit city in terms of man-days was Dhaka, the
capital of Bangladesh, largely due to its rapid growth, with extreme heat waves
increasing by 575 million people per day during the study period. Its growing
population alone, from 4 million in 1983 to 22 million today, was responsible
for an 80% increase in exposure. This does not mean that there has not been
significant warming in Dhaka, but rather that population growth has been even
faster. Other major cities showing similar demographic trends include Shanghai
and Guangzhou, China; Yangon, Myanmar; Bangkok; Dubai; Hanoi; Khartoum; and
several cities in Pakistan, India, and the Arabian Peninsula. superhealthiness
On the other hand, in some cities, it was observed that
about half or more of its impact was caused only by climate warming compared to
population growth. These include Baghdad, Cairo, Kuwait, Lagos, Kolkata,
Mumbai, and other major cities in India and Bangladesh. Populations in European
cities were relatively unchanged, so the increased exposure was almost
exclusively due to increased heat. The researchers found that 17% of the cities
surveyed added a full month of extremely hot days during the 34-year study
period.
Christina Dhal, a temperature researcher at the Union of
Concerned Scientists, explains that the study "can serve as a starting
point to identify ways to address local heat problems," such as planting
trees and changing roofs with lighter colors or greenery so that they don't
trap as much heat ... "This study shows that significant and careful
investment will be required to keep cities livable in an increasingly warmer
climate." redditbooks
