Climate Change, Extreme Heat,
and Public Health
Jeremy Hess, MD, MPH, FACEP
Assistant Professor, Emergency Medicine, Environmental Health
Emory University Schools of Medicine and Public Health
Consultant, Climate Change Program, CDC
Yale School of Public Health Alumni Day
Overview
• My opinions alone, and no
conflicting interests to report
• Today is not a good day to die
(of heat stroke)
• Sinks, bathtubs, and
thermodynamics
• If not now, then when?
• So what do we do?
Sunny, clear, high 74°F, low 54°F
NO HEAT DEATHS TODAY
Heat Mortality, US
Thermal Homeostasis
• Population is aggregate of
individuals
• Individual heat budgets
• Narrow physiological
temperature range
– Behavioral maintenance
– Physiological maintenance
• Heat exhaustion
• Heat stroke
• Humidity matters (AT, THI)
Handling Heat Illness
Susceptibility Factors
Protective
Harmful
• Intact thermoregulatory
mechanisms
• Impaired thermoregulation
–
–
–
–
Sweating
Thirst
Renal function
Cardiovascular function
• Intact recognition of adverse
exposure
• Intact behavioral response
• Resources
• Agency
• Social capital
– Impaired sweating
(anticholinergics)
– Impaired thirst impulse
– Kidney and CV disease
– Obesity
• Impaired cognition
• Impaired behavioral response
• Inadequate access to preventive
resources
• Social isolation
• Lack of agency
Human Heat Exposure
Global Climate
Hazard
Climate Variability
Mesoscale Climate
Exposure
Neighborhood
Microclimate
Immediate
Environment
Susceptibility
Physiologic
Susceptibility
Hotlanta
Hotlanta (at Night)
Abundant Examples
Chicago, 1995
California, 2006
Climate Variability and Long Term Change
SINKS, BATHTUBS, AND THE LAWS
OF THERMODYNAMICS
GHG Concentrations Last 10K Yrs
CO2
CH4
NOx
CO2 and Temperature
2010 Tied for Warmest Year
Sunny, hazy, high 92°F, low 70°F
ALUMNI DAY, 2091
Heat Mortality, US
Evolving
Estimates
• 0.6°C temperature rise to date
• Projections suggest 10x that by 2100
• Increasing heat wave:
• Frequency
• Severity
• Threats to long-term habitability of
large portions of the planet
Projected Change, 2040-2060
Projected Change, 2060-2080
Number of Days over 100F
Shifting Temperature Distributions
Heat Waves
• A period of abnormally and
uncomfortably hot and usually
humid weather
• Combination of high temps and
stagnant air masses
•Persistent – days to weeks
European Heat Wave 2003
UK
2,091
Italy
3,134
France
14,802
Portugal
1,854
Spain
4,151
Switzerland
975
Netherlands
1,400-2,200
Germany
TOTAL
1,410
29,817-30,617
Did CC Make It More Likely?
75% of Add’l Risk Anthropogenic
What the Future Holds
Stott PA, Stone DA, Allen MR. Human contribution to the European heat wave of
2003. Nature 2004, doi:10.1038/nature03089.
Mitigation and Adaptation
SO WHAT DO WE DO?
Mitigation Health Benefits
Moving Our Coping Range
Public Health Adaptation
1896
1900
1904
1908
1912
1916
1920
1924
1928
1932
1936
1940
1944
1948
1952
1956
1960
1964
1968
1972
1976
1980
1984
1988
1992
1996
2000
2004
2008
2006
2010
2014
2018
2022
2026
2030
2034
2038
2042
2046
2050
2054
2058
Scenario Based Planning
Historical Trends
Linear Projections
110
105
100
95
90
Tmax
85
Tmean
Tmin
80
Tmax
75
Tmean
Tmin
70
65
60
Projected Extremes 100 US Cities
Projected extreme value
distributions
Projected average (2035)
In Conclusion
• Heat is already the country’s leading weather-related cause
of death
• Heat is also associated with a significant burden of
morbidity
• Our GHG emissions are adding to the atmospheric sink
faster than it is depleted
• The result is a steady, delayed, significant warming
• Temperatures will increase, but the greatest concern is in
the extremes
• Mitigation is fundamentally important – remember the
delay!
• Adaptation is necessary now and will need to be
increasingly aggressive in the future
Thank you!