A new study of more than 13.000 cities around the globe has found that the number of days on which people are subjected to extreme heat and humidity has tripled since the 1980s.

The increase affects almost a quarter of the world’s population, according to its report published in Proceedings of the National Academy of Sciences.

Over the last couple of decades, over 100 million people have moved from the countryside to the cities where more than half of the world’s population now lives.

Scientists investigated maximum daily heat and humidity on more than 13.000 cities between 1983 and 2016.

A reading of 30 is the coarse equivalent of 106 degrees Fahrenheit on the so-called “real” heat index-the point at which even most healthy people have trouble working outdoors for long periods of time and those who are unhealthy may get extremely sick or even die.

The researchers then compared meteorological data to statistics about the population of each city during the same 33-year period.

The worst-hit town was Dhaka, the fast-growing capital of Bangladesh, where the peak heat level rose by 575 million days in the period studied.

In the United States, contamination in about 40 large cities has “rapidly,” risen, most notably in the Gulf Coast states of Texas, Louisiana, Mississippi, Alabama, and Florida.

Urban heat island

An urban heat island is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. (wikipedia)

National Academy of Sciences

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The National Academy of Sciences is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, (wikipedia)

Area code 651

Area code 651 is the telephone numbering plan code for Saint Paul, Minnesota, and the eastern suburbs of the Twin Cities. (wikipedia)

University of Minnesota

The University of Minnesota, Twin Cities is a public land-grant research university in the Twin Cities of Minneapolis and Saint Paul, Minnesota. (wikipedia)


Arizona AIR-iz-OH-nə; Navajo: Hoozdo Hahoodzo Navajo pronunciation: ; O’odham: Alĭ ṣonak) is a state in the Western United States, grouped in the Southwestern and occasionally Mountain subregions. (wikipedia)

Tucson, Arizona

Tucson is a city in and the county seat of Pima County, Arizona, United States, and is home to the University of Arizona. It is the second largest city in Arizona, with a population of 542, (wikipedia)

Proceedings of the National Academy of Sciences of the United States of America

Proceedings of the National Academy of Sciences of the United States of America is a peer-reviewed multidisciplinary scientific journal. (wikipedia)

Academy of sciences

An academy of sciences is a type of learned society or academy dedicated to sciences that may or may not be state funded. (wikipedia)