climate change and health

1. Climate Change and Human Health:
an overview
Sari Kovats
Centre on Global Change and Health,
Department of Public Health and Policy,
London School of Hygiene and Tropical
Medicine.
17 October 2005
RSS Meeting

2. International environment
agenda
 1972 Club of Rome Limits to Growth .
 1972 UN World Conference on the Human Environment.
 1987. World Commission on Environment and Development “Our
Common Future”
 WSSD. [World Summit on Sustainable Development] Rio 1992
– Framework Conventions on Climate Change, Biodiversity and others.
– Agenda 21
 1997 Kyoto Protocol
 WSSD - Johannesburg 2002 [Rio+10]
– UN Kofi Annan proposed five key areas for particular focus: WEHAB
[Water, Energy, Health, Agriculture, Biodiversity]
 2005 Kyoto Protocol comes into force. US opts out.
 Millennium Development Goals

3. Shifting environmental burdens
Local
Immediate Delayed
Risks to
human health
Risks to life
support systems
Global
Smith et al. 1999

4. Source: WHO, 2003: Climate change and human health: risks and responses.

6. Past changes in global mean temperature

7. -1.00
0.00
1.00
2.00
3.00
4.00
5.00
6.00
1961 1971 1981 1991 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091
Year
Change
in
Global
Temperatures
wrt
1961-90
(°C)
IS92A
A1FI
A2a
A2b
A2c
A2(Mean)
B1a
B2a
B2b
B2(mean)
Source: IPCC, 2001
Global mean temperature..
future projections

8. Several models -
All SRES Envelope
1990
1900 2000 2100
I Risks to Unique and Threatened Systems
II Risks from Extreme Climate Events
III Distribution of Impacts
IV Aggregate Impacts
V Risks from Future Large-Scale Discontinuities
Reasons for concern
Temperature
change
(
o
C)
I II III IV V
6
5
4
3
2
1
0
-1
A1F1
A1B
A1T
A2
B1
B2
IS92A
Observed

9. Changes in phenomenon Confidence in
observed
changes
(latter half of
1900s)
Confidence in
projected
changes to
2100
Higher maximum temperatures
- more hot days
Likely Very likely
Higher minimum temperatures,
- fewer cold days and frost days
Very likely Very likely
Increase of heat index over land areas Likely Very likely
More intense precipitation events Likely,
(N mid to high
latitudes)
Very likely
Increased summer continental drying and
associated risk of drought
Likely, in a few areas Likely, over most mid-
latitude
continental
interiors.
Increase in tropical cyclone peak wind
intensities
Not observed in the
few analysis
available
Likely, over some
areas
Increase in tropical cyclone mean and
peak precipitation intensities
Insufficient data Likely, over some
areas
IPCC WORKING GROUP I Third Assessment Report 2001

10. Climate change
may entail
change in
variance, as well
as a change in
mean

11. :
1999-2002 versus 2003
Mortality in Paris during 2003 heat wave

12. approx 27,720 deaths
2003 – Italy, 1/6 to 15/8 3134 (15%) in all
Italian capitals.
Deaths in same period in 2002 (Conti et al., 2005)
2003 – France
1/8 to 20/8
14802 (60%) Average of deaths for same period in
years 2000 to 2002
(Insitut de Veille
Sanitaire, 2003)
2003 – Portugal
1/8 to 31/8
1854 (40 %) Deaths in same period in 1997-2001 (Botelho et al., 2005)
2003 – Spain
1/8 to 31/8
3166 (8%) Deaths in same period 1990-2002 (Navarro et al., 2004)
2003- Switzerland,
1/6 to 31/8 [3 months]
975 deaths
(6.9%)
Predicted values from Poisson
regression model.
(Grize et al., 2005)
2003 – Netherlands
01/06 – 23/08
1400 deaths Number of degrees above 22,3 °C
multiplicated with the estimated
number of excess deaths per degree
(25-35 excess deaths
(Centraal Bureau voor de
Statistiek (CBS), 2003)
2003 - Baden-
Wuertermburg, Germany
01/08 – 24/08
1410 deaths Calculations based on mortality of past
five years
(Sozialministerium
Baden-Wuerttemberg,
2004)
2003 – Belgium 1297 deaths for
age group over
65
Average of deaths for same period in
years 1985 to 2002
(Sartor, 2004)
2003 – England and Wales
04/08-13/08
2091 (17%). Average of deaths for same period in
years 1998 to 2002
(Johnson et al., 2005)

13. Impacts of climate change
 Agriculture and food security
 Sea level rise, coastal flooding and coastal
areas.
 Biodiversity and ecosystems
 Water resources
 Human health
 Infrastructure, industry and human
settlements
 Weather disasters (floods, storms).

14. REGIONAL
WEATHER
CHANGES:
- extreme
weather
- temperature
- precipitation
Air pollution
levels
Contamination
pathways
Transmission
dynamics
HEALTH EFFECTS
Heat-related
illness, death
Flood, storm-
related health
effects
Air pollution effects
Water- and food
borne diseases
Vector-borne and
rodent-borne
disease
Adaptation
measures
Moderating
influences
CLIMATE
CHANGE
How climate change affects health

15. past Future
2020s, 2050+
present
learn
?analogues
mechanisms
responses
detection
attribution
predictive
modelling
three research tasks
Empirical studies
[epidemiology]

16. Complexity: different types of
evidence for health effects
 Health impacts of individual extreme events
(heat waves, floods, storms, droughts);
 Spatial studies, where climate is an
explanatory variable in the distribution of the
disease or the disease vector
 Temporal studies,
– inter-annual climate variability,
– short term (daily, weekly) changes (weather)
– longer term (decadal) changes in the context of
detecting early effects of climate change.
 Experimental laboratory and field studies of
vector, pathogen, or plant (allergenic) biology.

17. Assessment of causality…
 measure and control confounders;
 describe the geographical area from which the health
data are derived;
 use appropriate observed meteorological data for
population of interest (the use of reanalysis data may
give spurious results for studies of local effects);
 have plausible biological explanation for association
between weather parameters and disease outcome;
 remove any trend and seasonal patterns when using
time-series data prior to assessing relationships;
 report associations both with and without adjustments
for spatial or temporal autocorrelation.

18. Detection and attribution
 What is the scientific evidence that global
climate change is affecting human health?
 Where and how should we be looking for
evidence?
 Considering the paucity of data, what do
we accept as evidence within this context?

19. Tick-borne Encephalitis, Sweden: 1990s vs 1980s:
winter warming trend
Early
1980s
Mid-
1990s
White dots indicate locations where ticks were reported. Black line indicates study region.
(Lindgren et al., 2000)

20. Evidence on biological effects of
observed climate change
 effects on physiology: metabolic or
development rates of animals, and plant
processes;
 effects on distributions: response to shifts in
mean temperature and precipitation conditions
 Effect on phenology: timing of life-cycle
events, e.g. budding of flowers or egg laying;
 Adaptation: species with short generation
times and rapid population growth rates may
undergo some micro-evolution.
Hughes 2000

21. Evidence of northward shifts:
Europe
 Bluetongue virus- disease and vector in Europe
– (Mellor and Hamblin, 2004; Purse et al., 2005)
 Leishmaniasis (which also affects humans) in
dog reservoir
– ? role of previous underreporting (Lindgren and Naucke,
2005)
 Tick vectors-
– Sweden (Lindgren and Talleklint, 2000; Lindgren and
Gustafson, 2001)
– Denmark (Skarphedinsson et al., 2005)
– Canada (Barker and Lindsay, 2000)

22. How CC differs from other environmental
health risk assessments
 Scenario based.
– Population not individual exposure
assessment
 Future worlds:
– Population growth
– Development pathway
 disease baseline
 relationship between climate and impacts
(adaptive capacity)

23. Global Burden of Disease
 Standard method developed by WHO.
 Based on best-available quantitative evidence
 Estimates by region, age, sex
 Combined metric – DALY
– Disability adjusted life year
 Identifies global and regional health priorities…

24. Impact models
Estimates of populations at risk
• hunger
• water stress
• coastal flooding
• malaria
• dengue
Greenhouse gas
emissions
scenarios
Defined by IPCC
Global climate
scenarios:
Generates series of maps of
predicted future distribution of
climate variables
30 year averages
2020s
2050s
2080s
Time
2050 2100
2020s 2050s 2080s
Modelling impacts of climate change

25. Assumptions:
e.g. heat-related mortality
 Adaptive capacity
– Climate change concept, reflects ability of a
population to cope with impacts of climate change
 Acclimatization
– Threshold of mortality response moves
 Changes in exposure response relationship
– E.g. due to changes in air conditioning access, etc.
– Evident for both heat and cold effects
– ?independent of aging population
 Evidence base
– Published studies that show observed changes since
1900….Heat (Davies, Keatinge) and cold (Kunst, Keatinge,
Carson)
.8
.9
1
1.1
1.2
1.3
Relative
risk
0 10 20 30 40
Maximum temperature (lag 0)
All-cause mortality

26. Urban area Health
outcome
measure
Model Climate
scenario
Non-climate
assumptions
Results ref
UK Heat- and
cold-related
mortality
and hospital
admissions.
Empirical-
statistical
model,
derived
from
observed
mortality.
UKCIP
scenarios
2020s,
2050s,
2080s
No population
growth. No
acclimatization
assumed.
Medium-high climate
change scenario would
result in an estimated
2800 heat deaths per
year in the UK in the
2050s (250%
increase). Greater
reductions in cold-
related mortality.
Keatinge et al.
(Department
of Health,
2002)
Lisbon,
Portugal
Heat-related
death
Empirical-
statistical
model,
derived
from
observed
summer
mortality.
2xCO2
emissions
RCMs:
PROMES
and
HadRM2
SRES population
scenarios.
Assumes some
acclimatization.
Increases in heat
related mortality, by
2020s, to range 5.8-
15.1 deaths per
100,000, from baseline
5.4-6 deaths per
100,000
(Dessai, 2003)
Six cities in
Australia
[Adelaide,
Brisbane,
Hobart,
Melbourne,
Perth,
Sydney]
Two cities in
New Zealand
[Auckland,
Christchurch]
Heat- and
cold-related
mortality in
over 65s
Empirical-
statistical
model,
derived
from
observed
monthly
mortality.
High,
medium
and low
emissions.
CSIROMk2,
ECHAM4
Population
growth, and
population
ageing.
No
acclimatization.
Increases in heat-
related mortality in
over 65s, increases
large in temperature
cities. Less reductions
in cold related
mortality.
(McMichael et
al., 2003)

27. High child,
high
adult
High child,
very
high
adult
M F Both M F M F
(000) (000) (000) (000) (000) (000) (000)
Addictive substances
Tobacco 3 893 1 014 4 907 43 7 84 26
Alcohol 1 638 166 1 804 53 15 125 30
Illicit drugs 163 41 204 5 1 1 0
Environmental risks
Unsafe water, sanitation hygiene 895 835 1 730 129 103 207 169
Urban air pollution 411 388 799 11 11 5 5
Indoor smoke from solid fuels 658 961 1 619 93 80 118 101
Lead exposure 155 79 234 5 4 4 3
Climate change 76 78 154 9 9 18 18
Occupational risks
Risk factors for injury 291 19 310 14 1 18 1
Carcinogens 118 28 146 1 0 1 1
Airborne particulates 217 26 243 3 0 3 0
Ergonomic stressors 0 0 0 0 0 0 0
Noise 0 0 0 0 0 0 0
World Africa
World Health Report 2002
Global Burden of Disease
World Health Organization

28. Diarrhoea incidence in AfrD
0.8
0.9
1
1.1
1.2
1.3
1.4
1990 2000 2010 2020 2030 2040
Year
Ann.
Incidence/1000
No cc
UE (low)
UE (mid)
UE (high)
Applying the relative risk to baseline
incidence

29. Three eras of public health practice
Era Risk Source Public health
response
Industrial revolution
1870-1930
Infectious disease
Cholera, diphtheria,
TB
Water, air,
crowding
Technical
solutions
Sewerage, domestic
hygiene, urban
design
Economic
development
1930-1970
Ways of living.
Acute toxicity, lung
cancer, chemicals
Lead, asbestos,
waste
Lifestyle change
Petrol standards,
monitoring and
reporting,
Sustainable
Development
1970-
Global stress
Melanoma, disease
spread, allergies,
toxicity
UV radiation,
climate
change,
environmental
degradation
Governance
solutions
CFC controls, limit
energy use,
environmental
management.
Source: Brown et al. 2005, p 5.

30. Conclusions
 Estimates of near term impacts for health policy
decision makers
 Need scenarios of extremes
 Downscaling
– Interactions between cc and UHI [urban heat island]
 Importance of population projections
 Competing trends
 Importance of metrics
– Deaths, YLL, dollars.
 Modifiers and adaptive capacity
– Must be evidence based, but up to a point….