Interaction of warming climate with a growing, shifting population could subject more people to sweltering conditions
U.S. residents' exposure to extreme heat could increase four- to six-fold by mid-century, due to both a warming climate and a population that's growing especially fast in the hottest regions of the country, according to new research.
This graphic illustrates the expected increase in average annual person-days of exposure to extreme heat for each US Census Division when comparing the period 1971-2000 to the period 2041-2070. Person-days are calculated by multiplying the number of days when the temperature is expected to hit at least 95 degrees by the number of people who are projected to live in the areas where extreme heat is occurring. The scale is in billions.
The study, by researchers at the National Center for Atmospheric Research (NCAR) and the City University of New York (CUNY), highlights the importance of considering societal changes when trying to determine future climate impacts.
"Both population change and climate change matter," said NCAR scientist Brian O'Neill, one of the study's co-authors. "If you want to know how heat waves will affect health in the future, you have to consider both."
Extreme heat kills more people in the United States than any other weather-related event, and scientists generally expect the number of deadly heat waves to increase as the climate warms. The new study, published May 18 in the journal Nature Climate Change, finds that the overall exposure of Americans to these future heat waves would be vastly underestimated if the role of population changes were ignored.
The total number of people exposed to extreme heat is expected to increase the most in cities across the country's southern reaches, including Atlanta, Charlotte, Dallas, Houston, Oklahoma City, Phoenix, Tampa, and San Antonio.
The research was funded by the National Science Foundation, which is NCAR's sponsor, and the U.S. Department of Energy.
Climate, population, and how they interact
For the study, the research team used 11 different high-resolution simulations of future temperatures across the United States between 2041 and 2070, assuming no major reductions in greenhouse gas emissions. The simulations were produced with a suite of global and regional climate models as part of the North American Regional Climate Change Assessment Program.
Using a newly developed demographic model, the scientists also studied how the U.S. population is expected to grow and shift regionally during the same time period, assuming current migration trends within the country continue.
Total exposure to extreme heat was calculated in "person-days" by multiplying the number of days when the temperature is expected to hit at least 95 degrees by the number of people who are projected to live in the areas where extreme heat is occurring.
The results are that the average annual exposure to extreme heat in the United States during the study period is expected to be between 10 and 14 billion person-days, compared to an annual average of 2.3 billion person-days between 1971 and 2000.
Of that increase, roughly a third is due solely to the warming climate (the increase in exposure to extreme heat that would be expected even if the population remained unchanged). Another third is due solely to population change (the increase in exposure that would be expected if climate remained unchanged but the population continued to grow and people continued to moved to warmer places). The final third is due to the interaction between the two (the increase in exposure expected because the population is growing fastest in places that are also getting hotter).
"We asked, 'Where are the people moving? Where are the climate hot spots? How do those two things interact?'" said NCAR scientist Linda Mearns, also a study co-author. "When we looked at the country as a whole, we found that each factor had relatively equal effect."
At a regional scale, the picture is different. In some areas of the country, climate change packs a bigger punch than population growth and vice versa.
For example, in the U.S. Mountain region--defined by the Census Bureau as the area stretching from Montana and Idaho south to Arizona and New Mexico--the impact of a growing population significantly outstrips the impact of a warming climate. But the opposite is true in the South Atlantic region, which encompasses the area from West Virginia and Maryland south through Florida.
Exposure vs. vulnerability
Regardless of the relative role that population or climate plays, some increase in total exposure to extreme heat is expected in every region of the continental United States. Even so, the study authors caution that exposure is not necessarily the same thing as vulnerability.
"Our study does not say how vulnerable or not people might be in the future," O'Neill said. "We show that heat exposure will go up, but we don't know how many of the people exposed will or won't have air conditioners or easy access to public health centers, for example."
The authors also hope the study will inspire other researchers to more frequently incorporate social factors, such as population change, into studies of climate change impacts.
"There has been so much written regarding the potential impacts of climate change, particularly as they relate to physical climate extremes," said Bryan Jones, a postdoctoral researcher at the CUNY Institute for Demographic Research and lead author of the study. "However, it is how people experience these extremes that will ultimately shape the broader public perception of climate change."
About the article
Title: Future population exposure to U.S. heat extremes
Authors: Bryan Jones, Brian C. O'Neill, Larry McDaniel, Seth McGinnis, Linda O. Mearns, and Claudia Tebaldi
Publication: Nature Climate Change
On the Web
For news releases, images and more: http://www.
The University Corporation for Atmospheric Research (UCAR) manages NCAR under sponsorship by the National Science Foundation. Any opinions, findings, conclusions, or recommendations expressed in this release do not necessarily reflect the views of the National Science Foundation.
Laura Snider | EurekAlert!
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy