Thirty years till the big heat kicks in. If you live in Texas or Florida, rising temperatures will combine with population growth to create a sixfold rise in numbers of people exposed to extreme and potentially fatal heat events from 2041 onwards.
鈥淭he convergence of population and climate hotspots leads to an increase in exposure larger than that produced by either alone,鈥� says of the City University of New York.
The exposure to extreme heat is expected to rise over this century and into the next century. But although both climate and population change drive this, the population component has so far been overlooked, says Jones.
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So Jones and his colleagues combined data from 11 standard climate change models with their own models on projected population patterns. They defined any day with a maximum temperature at or above 35 藲C as an 鈥渆xtreme heat event鈥� and made projections of the likely number of people exposed to extreme heat between 2041 and 2070. They compared the outcome with known data for between 1971 and 2000.
Their results predict a four to six-fold increase in exposure to extreme heat by 2070.
The hotspots are mainly in the south and east, with some of the most affected including Houston, Dallas, San Antonio, Tampa, Orlando, Atlanta, Charlotte and Washington DC.
鈥淥ur results indicate that areas of eastern Texas, Florida, the south-east and mid-Atlantic are areas where rapid population growth, acting in concert with a warming climate, will lead to a significant increase in exposure to heat extremes,鈥� says Jones.
Only a few places could see reduced risks of exposure, as people move into cooler but still warming areas. 鈥淥nly in a few areas of the Rocky Mountains and Western Great Plains do we project a decrease,鈥� says Jones.
Dangerous like a tornado
Jones says that according to the US Centers for Disease Control and Prevention, around 650 to 700 Americans die each year from extreme heat. Yet predicting deaths in future scenarios is tricky because the extent to which populations will adapt to rising temperatures is not known.
鈥淥ur findings indicate that even a best-case scenario will lead to an increase in extreme heat exposure in the future, so from a planning perspective, identifying potential hotspots will help target public health efforts,鈥� says Jones. 鈥淏ecause heat doesn鈥檛 often kill in 鈥榙ramatic fashion鈥� like a tornado or hurricane, its deadliness is often understated.鈥�
Scott Greene of the University of Oklahoma in Norman says that projected impacts of heat events are likely to be more complicated, as people respond to different meteorological variables, not just heat.
鈥淗eat-related deaths have been decreasing over time in part due to the development of warning systems that have increased awareness of what to do and saved lives,鈥� he says.
Journal reference: Nature Climate Change, DOI: 10.1038/NCLIMATE2631
