Projecting Heat-Related Mortality Impacts Under a Changing Climate in NYC
Projecting Heat-Related Mortality Impacts Under a Changing Climate in NYC
Objectives: We sought to project future impacts of climate change on summer heat-related premature deaths in the New York City metropolitan region.
Methods: Current and future climates were simulated over the northeastern United States with a global-to-regional climate modeling system. Summer heat-related premature deaths in the 1990s and 2050s were estimated by using a range of scenarios and approaches to modeling acclimatization (e.g., increased use of air conditioning, gradual physiological adaptation).
Results: Projected regional increases in heat-related premature mortality by the 2050s ranged from 47% to 95%, with a mean 70% increase compared with the 1990s. Acclimatization effects reduced regional increases in summer heat-related premature mortality by about 25%. Local impacts varied considerably across the region, with urban counties showing greater numbers of deaths and smaller percentage increases than less-urbanized counties.
Conclusions: Although considerable uncertainty exists in climate forecasts and future health vulnerability, the range of projections we developed suggests that by midcentury, acclimatization may not completely mitigate the effects of climate change in the New York City metropolitan region, which would result in an overall net increase in heat-related premature mortality.
Although a large body of retrospective studies provides evidence of acute associations between daily temperatures and premature deaths from many causes, additional tools are needed to anticipate the future effects of climate change on ambient temperatures and associated mortality. Over the 20th century, the average annual temperature in the United States increased by 1°F. Temperatures in the 31-county metropolitan region centered around New York City have exceeded those national trends, with a 2°F warming trend between 1900 and 1997. Recent trends in anthropogenic emissions and their modeled impacts on global climate strongly suggest that both emissions and warming trends will continue to affect atmospheric processes into the 21st century. Annual average temperatures for the region in the 2050s have been projected to rise by 2.5°F to 6.5°F, with summer temperature increases of 2.7°F to 7.6°F.
Cities such as New York may be at particular risk from climate change because the urban heat island further augments regional temperature increases. Urban heat islands are created when human-made surfaces in cities made of concrete, asphalt, metal, and stone absorb incident sunlight during the day, which is re-radiated as heat, especially at night. This, along with few trees and vegetation to provide cooling, produces an overall effect of urban areas tending to have higher surface and near-surface air temperatures than surrounding suburban and rural areas. Some communities in densely populated urban centers are among those most vulnerable to heat. The diverse urban population of New York includes millions of residents 65 years and older or residents with cardiovascular or respiratory illness, risk factors that increase vulnerability to summer heat stress.
Several recent studies have used climate models to project future heat-related mortality impacts of global warming, usually at relatively coarse spatial scales. A global climate model applied in the United Kingdom projected a 250% increase in annual heat-related deaths by the 2050s across 4 greenhouse gas scenarios. With a high-emission-change scenario in 6 temperate Australian cities, a 75% increase in annual heat-related mortality among people 65 years and older by 2050 was projected. A study in Portugal projected that summer heat-related deaths in Lisbon may increase by up to 6 times by the 2050s. A regional impacts study of California concluded that by the latter decades of the 21st century, summer heat-related mortality could be 2 to 7 times greater than it is now, even after taking possible heat acclimatization (e.g., increased use of air conditioning, gradual physiological adaptation) into account.
General circulation models are global scale models that take into account the dynamics of physical processes in the atmosphere and oceans but at relatively coarse resolution. Hence, one cannot realistically use these models to address the need for locally relevant projections of the potential effects of global warming on public health. One approach to address this limitation is dynamical downscaling, in which the general circulation model outputs are used as initial and boundary conditions for finer-scale simulations by regional climate models. We used such a system, developed by the New York Climate and Health Project, to project daily mean temperatures at local scales for the 2050s and to evaluate potential impacts of climate change on summer heat-related mortality in the New York City metropolitan region.
Objectives: We sought to project future impacts of climate change on summer heat-related premature deaths in the New York City metropolitan region.
Methods: Current and future climates were simulated over the northeastern United States with a global-to-regional climate modeling system. Summer heat-related premature deaths in the 1990s and 2050s were estimated by using a range of scenarios and approaches to modeling acclimatization (e.g., increased use of air conditioning, gradual physiological adaptation).
Results: Projected regional increases in heat-related premature mortality by the 2050s ranged from 47% to 95%, with a mean 70% increase compared with the 1990s. Acclimatization effects reduced regional increases in summer heat-related premature mortality by about 25%. Local impacts varied considerably across the region, with urban counties showing greater numbers of deaths and smaller percentage increases than less-urbanized counties.
Conclusions: Although considerable uncertainty exists in climate forecasts and future health vulnerability, the range of projections we developed suggests that by midcentury, acclimatization may not completely mitigate the effects of climate change in the New York City metropolitan region, which would result in an overall net increase in heat-related premature mortality.
Although a large body of retrospective studies provides evidence of acute associations between daily temperatures and premature deaths from many causes, additional tools are needed to anticipate the future effects of climate change on ambient temperatures and associated mortality. Over the 20th century, the average annual temperature in the United States increased by 1°F. Temperatures in the 31-county metropolitan region centered around New York City have exceeded those national trends, with a 2°F warming trend between 1900 and 1997. Recent trends in anthropogenic emissions and their modeled impacts on global climate strongly suggest that both emissions and warming trends will continue to affect atmospheric processes into the 21st century. Annual average temperatures for the region in the 2050s have been projected to rise by 2.5°F to 6.5°F, with summer temperature increases of 2.7°F to 7.6°F.
Cities such as New York may be at particular risk from climate change because the urban heat island further augments regional temperature increases. Urban heat islands are created when human-made surfaces in cities made of concrete, asphalt, metal, and stone absorb incident sunlight during the day, which is re-radiated as heat, especially at night. This, along with few trees and vegetation to provide cooling, produces an overall effect of urban areas tending to have higher surface and near-surface air temperatures than surrounding suburban and rural areas. Some communities in densely populated urban centers are among those most vulnerable to heat. The diverse urban population of New York includes millions of residents 65 years and older or residents with cardiovascular or respiratory illness, risk factors that increase vulnerability to summer heat stress.
Several recent studies have used climate models to project future heat-related mortality impacts of global warming, usually at relatively coarse spatial scales. A global climate model applied in the United Kingdom projected a 250% increase in annual heat-related deaths by the 2050s across 4 greenhouse gas scenarios. With a high-emission-change scenario in 6 temperate Australian cities, a 75% increase in annual heat-related mortality among people 65 years and older by 2050 was projected. A study in Portugal projected that summer heat-related deaths in Lisbon may increase by up to 6 times by the 2050s. A regional impacts study of California concluded that by the latter decades of the 21st century, summer heat-related mortality could be 2 to 7 times greater than it is now, even after taking possible heat acclimatization (e.g., increased use of air conditioning, gradual physiological adaptation) into account.
General circulation models are global scale models that take into account the dynamics of physical processes in the atmosphere and oceans but at relatively coarse resolution. Hence, one cannot realistically use these models to address the need for locally relevant projections of the potential effects of global warming on public health. One approach to address this limitation is dynamical downscaling, in which the general circulation model outputs are used as initial and boundary conditions for finer-scale simulations by regional climate models. We used such a system, developed by the New York Climate and Health Project, to project daily mean temperatures at local scales for the 2050s and to evaluate potential impacts of climate change on summer heat-related mortality in the New York City metropolitan region.
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