Climate change: challenges and opportunities for global health

Abstract

Importance: Health is inextricably linked to climate change. It is important for clinicians to understand this relationship in order to discuss associated health risks with their patients and to inform public policy.

Objectives: To provide new US-based temperature projections from downscaled climate modeling and to review recent studies on health risks related to climate change and the cobenefits of efforts to mitigate greenhouse gas emissions.

Data sources, study selection, and data synthesis: We searched PubMed and Google Scholar from 2009 to 2014 for articles related to climate change and health, focused on governmental reports, predictive models, and empirical epidemiological studies. Of the more than 250 abstracts reviewed, 56 articles were selected. In addition, we analyzed climate data averaged over 13 climate models and based future projections on downscaled probability distributions of the daily maximum temperature for 2046-2065. We also compared maximum daily 8-hour average ozone with air temperature data taken from the National Oceanic and Atmospheric Administration, National Climate Data Center.

Results: By 2050, many US cities may experience more frequent extreme heat days. For example, New York and Milwaukee may have 3 times their current average number of days hotter than 32°C (90°F). High temperatures are also strongly associated with ozone exceedance days, for example, in Chicago, Illinois. The adverse health aspects related to climate change may include heat-related disorders, such as heat stress and economic consequences of reduced work capacity; respiratory disorders, including those exacerbated by air pollution and aeroallergens, such as asthma; infectious diseases, including vectorborne diseases and waterborne diseases, such as childhood gastrointestinal diseases; food insecurity, including reduced crop yields and an increase in plant diseases; and mental health disorders, such as posttraumatic stress disorder and depression, that are associated with natural disasters. Substantial health and economic cobenefits could be associated with reductions in fossil fuel combustion. For example, greenhouse gas emission policies may yield net economic benefit, with health benefits from air quality improvements potentially offsetting the cost of US and international carbon policies.

Conclusions and relevance: Evidence over the past 20 years indicates that climate change can be associated with adverse health outcomes. Health care professionals have an important role in understanding and communicating the related potential health concerns and the cobenefits from policies to reduce greenhouse gas emissions.

Figure 1.. Cumulative Distribution of Days in June Through August per Year of Daytime Maximum Temperatures Exceeding a Given Threshold, 1960–1999 and 2046–2065

The dotted line indicates the temperature thresholds for each city: 90°F (32°C) in Milwaukee, Atlanta, and New York and 100° (38°C) in Dallas. The estimates predict temperatures based on “business as usual” emissions scenario. The curves represent the average of an analysis conducted by the University of Wisconsin, Center for Climatic Research of more than 13 models.

Figure 2.. Relationship Between Days of High Temperatures and Ozone Levels

Number of days in Chicago, Madison, and Milwaukee for each year (1980–2012) in which temperature exceeded 32°C (90° F) and ozone exceeded 75 ppbv (parts per billion by volume). The y-axis scale shown in blue indicates range of 0 through 45 days.

Figure 3.. Relationship Between Active Commuting Transportation and Obesity, Diabetes, and Physical Activity

Data are for all 50 US states and 47 of the largest US cities in 2007. Data are derived from Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance System and the US Census. Data for these graphs were provided by Pucher et al 2010.

Figure 4.. Estimated Greenhouse Gas Emissions From Diet Types

Mean greenhouse gas emissions (in kilograms of carbon dioxide equivalents per day) comparing diet types from 55 504 individuals in the EPIC-Oxford cohort study. Data are for a 2000 kcal diet adjusted for sex and age. Data from Scarborough et al.