Joyce Rosenthal

Projecting Heat-Related Mortality Impacts Under a Changing Climate in the New York City 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.

Impacts of Heat and Ozone on Mortality Risk in the New York City Metropolitan Region Under a Changing Climate

Climate change may lead to both increased heat and ozone (O3) levels in urban areas over the coming century. To assess potential human health impacts of these changes, models are needed for projecting regional-scale temperature and O3 changes under climate change, and for characterizing the independent and joint health effects of heat and O3. To meet these needs, mortality transfer functions for summer heat and O3 were developed and applied in a regional health risk assessment for the New York City metropolitan region. The objective was to analyze and project the relative impacts of climate-related changes in mean daily temperature and 1-hour maximum O3 concentrations on acute non-accidental mortality from all internal causes of death. Exposure-response relationships were developed using a 10-year record of daily summer observations for the region (1990–1999). This was done using a time series Poisson regression model that jointly estimated O3 and temperature effects on mortality, controlling for time trends and day of week effects. To project impacts into future decades, we developed a integrated modeling system that took global scale climate projections for the 2020s, 2050s, and 2080s, using the Intergovernmental Panel on Climate Change (IPCC) A2 and B2 emission scenario assumptions, and down-scaled these to a 36 km grid using regional models for climate and air quality. Regional downscaling was carried out using the GISS-MM5 linked global-regional model system for climate and the Community Multiscale Air Quality (CMAQ) model for air quality. Mortality risks were projected using the transfer functions estimated from the 1990s data. Results showed that both O3 and heat stress had measurable impacts on mortality risk, but that the relative impacts changed over time. This modeling strategy could be applied in other metropolitan areas and for other health outcomes to assess health impacts of heat and O3 under a changing climate.

Modeling the Impact of Global Climate and Regional Land use Change on Regional Climate and Air Quality Over the Northeastern United States

In recent years, the focus of global climate change research has shifted towards the assessment of regional scale consequences. This paper describes the design and initial results of a modeling study aimed at simulating the effects of global climate change and regional land use change on climate and air quality over the northeastern United States in order to project the associated public health impacts in the region. To this end, modeling tools on a variety of scales are being linked. Specifically, regional climate models are linked to both a global climate model and a regional land-use change model. Outputs from regional climate simulations are subsequently used both to assess changes in public health due to heat stress and to simulate regional and urban air quality. Finally, results from these air quality simulations are coupled to health impact models. This paper focuses on the air quality modeling aspect of the project. Global and regional climate change could conceivably alter regional and urban air quality in a variety of ways through both direct and indirect effects. Rising temperatures could have a direct effect on chemical reaction rates and mixed-layer heights, while changes in synoptic circulation patterns might influence the transport and mixing of pollutants as well as the occurrence of conditions conducive to high ozone concentrations. Additionally, anthropogenic emissions of the ozone precursors NOx and VOC are also expected to change in future decades, and it is necessary to understand whether future ozone air quality is more sensitive to changes in emissions or changes in climate. In this paper, we present initial results from regional-scale simulations for 3-months summer seasons under current and future climate conditions.

Air Quality in Future Decades – Determining the Relative Impacts of Changes in Climate, Emissions, Global Atmospheric Composition, and Regional Land Use

In recent years, there has been a growing realization that regional-scale ozone (O3) air quality is influenced by processes occurring on global scales, such as the intercontinental transport of pollutants (Jacob et al., 1999; Fiore et al., 2002, 2003; Yienger et al., 2000) and the projected growth in global emissions that alter the chemical composition of the global troposphere (Prather and Ehhalt, 2001; Prather et al., 2003). However, little work has been performed to date to study the potential impacts of regional-scale climate change on near-surface air pollution. Climate change can influence the concentration and distribution of air pollutants through a variety of direct and indirect processes, including the modification of biogenic emissions, the change of chemical reaction rates, changes in mixedlayer heights that affect vertical mixing of pollutants, and modifications of synoptic flow patterns that govern pollutant transport. Another parameter affecting local and regional meteorology and air pollution is land use, and significant land use changes associated with continued urbanization are expected to occur over the same time scales as changes in regional climate. The results presented in this paper build upon a recent study by Hogrefe et al. (2004a) who presented results of a modeling study aimed at simulating O3