Health Impacts of Climate Change and Health

Conference: Public health benefits of strategies to reduce greenhouse gas emissions

London School of Hygiene and Tropical Medicine 25 Nov 2009

A.J. McMichael

National Centre for Epidemiology and Population Health The Australian National University

Canberra, Australia

Outline

1. Political context

2. Climate change: summary of recent science

3. Health Risks and Impacts1. Research tasks; impact pathways

2. Examples: infectious disease, food yields/under-nutrition

4. Adaptation, Mitigation – and ‘Co-Benefits’

5. Conclusion

Climate and Health Council

Letter to Yvo de Boer, Exec Sec, UN Framework Convention on Climate Change, Nov 10, 2009

“Whilst human-induced climate change looms as the greatest threat to public health this century, the hopeful health message is:

“What is good for the climate is good for health.

“There is ample evidence to support this.”

The Cassandra EffectOne who foresees, on available evidence, a likely disaster; yet judges that this can’t be prevented – and, that anyway, others won’t believe the forecast.

• CC is counter-intuitive: How could humans do that?

• ‘Climate’ vs. ‘weather’ confusion

• Cover-up of ignorance

• Influence of hired pens/lobbyists

• Resistance (esp. from ideological Right) to calls for collective action and government intervention. Spectre of “world government”.

LSHTM as ‘epicentre’: Potted History

1993-95: Health chapter, IPCC Second Assessment Report (1996)*: McMichael (co-chair), Haines, Kovats, et al

1996: WHO/UNEP book Climate Change and Human Health (eds: McMichael, Haines, Slooff, Kovats)

1999: McMichael AJ, Haines A (eds) Climate Change and Impacts on Human Health. London: Royal Society

1995-2000: LSHTM as international leader in CC/Hlth research; MRC (first) Program Grant awarded, 2000 (LSHTM, Univ East Anglia)

1998-2000: Health chapter, IPCC Third Assessment Report (2001)

• 2003-06: Health chapter, IPCC Fourth Assessment Report (2007)

2001-2004: WHO contract: estimation of burden of disease attributable to CC

2000s: Special reports with/for WHO – Vulnerability, Adaptation, etc.

2008: UK Dept Health: Health Effects of Climate Change in UK: ed. Kovats

* no health chapter in IPCC First Assessment Report

CO2 ppm

Temp oC

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

390

370

350

330

310

290

270

250

14.5

14.3

14.1

13.9

13.7

13.5

Correlation between atmospheric carbon dioxide concentration and Earth’s average surface temperature

Year

CO2

concentration

Earth’s Temperature (background wobble due

to natural influences)

Graph from: Hanno, 2009

Greenhouse Gas Concentrations and Temperature Rise: Recent Science

• Global av temperature: clearcut (albeit naturally wobbly) uptrend

• Geophysical ‘fingerprints’ implicate increased GHG concentration as main cause of 0.7oC rise since 1950

• Global climate models, now highly-coupled, perform well on record of past ‘forcings’/temperature relationship – globally and regionally

• Six internationally-agreed plausible ‘human futures’ scenarios (i.e. story-lines yielding GHG emissions at high, medium, low levels)

• Repeated runs with many models yield a range of best central estimates for the 6 scenarios of 1.8-4.0oC, by 2100 [IPCC 2007]

• Range in projected temperature rise to 2030-40 mostly due to residual uncertainties about climate system response to existing or imminent atmospheric GHGs

• Uncertainties re warming in later decades mostly reflect unknowable ‘human futures’

West Antarctic ice sheet

Arctic ice sheets

East Antarctic ice sheet

60myr 50myr 40myr 30myr 20myr 10myr Now

Millions of Years Before Present

12

8

4

0Temp oC * (vs 1961-90 av temp)

+3oC+5oC

Earth’s Temperature Chart, since Dinosaur Extinction 65m yrs ago

?

Sea level 25-40 metres higher

than todayTripati et al Science

2009

Paleocene

* Temp measured at deep ocean

+1.5oC

last 2m yr = ice-

age

Climate Change occurring faster than expected

IPCC’s Fourth Assessment Report (2007) now looks conservative [in addition to cautious review process]

Subsequent research shows increasing rates of:

Global Greenhouse Gas emissions Ice melting (Arctic sea ice, Greenland/Antarctic ice-sheets, alpine glaciers)

Sea level rise

Also: Increasing saturation of carbon ‘sinks’ (land and oceans)

Estimated amount of carbon stored in permafrost = twice the atmospheric carbon

1m: half of Bangladesh rice fields2m: most of Mekong Delta

Cyclone Ketsana, Sept 2009 Approaching Vietnam

Rainfall estimates, NOAA(USA), Sept 29

Northern Cambodia

Hoi An, Central Vietnam

Climate Change and Health Research Tasks and Policy Foci

Human society: • Population size• Economic activity• Culture, governance

Human pressure on environment

Based on: McMichael et al., Brit med J, 2008

Adaptation: Reduce health impacts/risks

Human impacts: • Livelihoods• Social stability• Health

Health Co-benefits?

Unintended health effects

Mitigation of Climate Change: Reduce GHG

emissions

Climate - environmental changes, affecting:• Meteorological conditions• Water flows• Food yields• Physical (protective) buffers• Microbial activity• Extreme weather events

4

Risks to humans better

understood2

3Natural environmental

processes

1a-c

Need for local prevention

Climate Change: Health Impact Pathways

Physical systems(river flows, soil moisture, ocean temp)

Biologicalcycles, in nature … &

Ecological links/function

Economic/social impacts: infrastructure, farm/factory production, GDP growth, jobs, displacement

Human Health:• Injuries/deaths• Thermal stress

Indirect health impacts –ecologically mediated

Indirect health impacts – socially mediated

Direct impacts (extreme weather events, heatwaves, air pollutants, etc.)

• Infectious diseases• Under-nutrition• Mental stresses• Other disorders

Climate ChangeImpacts

Regions afflicted by problems due to environmental stresses: • population pressure • water shortage• climate change affecting crops • sea level rise • pre-existing hunger• armed conflict, current/recent From UK Ministry of Defence

[May RM, 2007 Lowy Institute Lecture. Sydney]

Climate Change: Multiplier of Conflicts and Regional Tensions

Flo o d s

M a lar ia

D ia rr h oea

M a ln u tri tio n

02 04 06 08010 01 2 0 0 2 4 6 8 1 0

Deaths (thousands) DALYs (millions)

2000 2030

Deaths and DALYs attributable to Climate Change, 2000 & 2030Selected conditions in developing countries

WHO/McMichael,Campbell-Lendrum, Kovats et al, 2004

Now (2000)

Future (2030)

Deaths Total Burden

Climate and Infectious Disease

• Climatic conditions set geographic and seasonal limits of potential transmission.

• Other environmental, social and behavioural factors – and public health strategies – determine where/when actual transmission occurs.

Model-fitted relationship of monthly Salmonellosis case counts in relation to monthly av. temperature in

five Australian cities, 1991-2001

0

10

20

30

40

50

60

70

80

90

100

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Average MonthlyTemperature oC

Sal

mo

nel

la c

ou

nt

Perth

Brisbane

Adelaide

Melbourne

Sydney

D’Souza et al., 2003

Daily temperature

19971993

Overall estimate from regression analysis:

7% increase in daily cases per 1o C rise

Daily hospitalizations for diarrhoea, by daily temperature: Lima, Peru.

(Shaded region is 1997-98 El Niño event)

Checkley et al, Lancet 2000

Daily Hospitalisations

Estimated Mortality Impacts of Climate Change: Year 2000

14 WHO regions scaled according to estimated annual death rates due to the change in climate since c.1970.

(Patz, Gibbs et al, 2007: based on McMichael, Campbell-Lendrum, Kovats, et al, 2004)

Estimated annual deaths due to climate change: malnutrition (~80K), diarrhoea (~50K), malaria (~20K), flooding (~3K)

Bluetongue virus: Has climate change caused a northwards extension, in Europe, of Culicoides midge vectors?

1998: Northern limit C. imicola midge

2004: Northern limit C. imicola midge

1998: Northern range of virus (in sheep)

2004: Northern range* of virus (in sheep)

Source: Purse et al, 2005 Nature Reviews Microbiology

C. pulcaris C. obselitus C. imicola

Current northern limit

Northern limit < 1998

Northern limit

Southern limit

* Suggests additional midge species are also now contributing

Midge species: potential vectors of BT Virus

[“European” Midge species]

Schistosomiasis: Modelled Future Impact of Climate Change on Schistosoma japonicum Transmission in China

Source: Zhou et al., Potential Impact of Climate Change on Schistosomiasis Transmission in China Am J Trop Med Hyg 2008;78:188–194.

2030: + 0.9oCNow

2050: + 1.6oC

“Recent data suggest that schistosomiasis is re-emerging in some settings [with previous successful disease control]. ….

“Along with other reasons, climate change and ecologic transformations have been suggested as the underlying causes.”

Northwards drift, over past 4 decades, of the winter ‘freezing zone’ that limits water-snail survival – associated with 1-1.5oC temperature rise in SE China

NCEPH/CSIRO/BoM/UnivOtago, 2003

DENGUE FEVER: Estimated geographic region suitable for A. aegypti vector, and hence transmission: Climate conditions now and in alternative scenarios for 2050

2050 risk region: Medium GHG emissions scenario

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome..

....

..Carnarvon.

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome

..

Brisbane

..

..

...

Current risk region, for dengue transmission Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome..

..

..

..

Carnarvon. 2050 risk region: High GHGemissions scenario

Brisbane

Brisbane

Global statistical model (Hales), applied to Australia: mosquito survival in relation to water vapour pressure (rainfall, humidity).

TRANSMISSION POTENTIAL

0

0.2

0.4

0.6

0.8

1

14 17 20 23 26 29 32 35 38 41

Temperature (°C)

Plasmodium Incubation time

0

10

20

30

40

50

15 20 25 30 35 40

(day

s)

Biting frequency

0

0.1

0.2

0.3

10 15 20 25 30 35 40

Temp (°C)(p

er d

ay)

Survival probability

0

0.2

0.4

0.6

0.8

1

10 15 20 25 30 35 40

(per

day

)

Temp (°C) Temp (°C)

Malaria Transmissibility: Temperature and Biology

P.vivaxP.falciparum

Based on Martens WJM, 1998

---------------- Mosquito ------------------

Baseline 2000 2025 2050

Ebi et al., 2005

Climate Change and Malaria Potential transmission in Zimbabwe

Bulawayo

Climate suitability: red = high; blue/green = low

High probability

Medium probability

Low probability

Harare

Highlands

Ebi et al., 2005

Bulawayo

Harare

Baseline 2000 2025 2050

Climate Change and Malaria Potential transmission in Zimbabwe

Climate suitability: red = high; blue/green = low

Ebi et al., 2005

Bulawayo

Harare

Baseline 2000 2025 2050

Climate Change and Malaria Potential transmission in Zimbabwe

Climate suitability: red = high; blue/green = low

Photo-synthetic

activity

20o C 30o C 40o C

Food Yields: General Relationship of Temperature and Photosynthesis

0%

100%

Example: Field & Lobell. Environmental Research Letters, 2007:

Globally averaged: +0.5oC reduces crop yields by 3-5%. So: +2oC would mean 12-20% fall in global grain production.

+2oC

+2oCPlus:•Floods, storms, fires•Droughts – range, severity•Pests•Diseases

World -0.6 to-0.9

Developed countries +2.7 to +9.0

Developing countries -3.3 to -7.2

Southeast Asia -2.5 to -7.8 South Asia -18.2 to -22.1 Sub-Saharan Africa -3.9 to -7.5 Latin America +5.2 to +12.5

From: Tubiello & Fischer, 2007

% Change (range)

Modelled impact of climate change on global cereal grain production:

Percent change, 1990-to-2080

Are the zones being pushed

south, by warming?

… and here?Health

Consequences?

Marked wet summer and dry winter

Wet summer and low winter rainfall

Uniform rainfall

Marked wet winter and dry summer

Low rainfallWet winter and low summer rainfall

AridWinter dominant Winter

Summer dominant Summer Uniform

Crucial for wheat-belt

Australia: Climate change, seasonal rainfall zones, farm yields, health impacts

Mitigation and Adaptation

Avoiding the Unmanageable

Managing the Unavoidable

‘Vulnerability’ and ‘Adaptation’

D Schroter et al, 2004

External exposure: climatic and

environmental conditions

Sensitivity of exposed population: immune status, nutritional status,

housing conditions, etc.

Adaptive Capacity:Local governance

Community cohesionFunds available

Public health capacity

Potential health impact - risk of occurrence

of malaria

Actual adaptive actions e.g. Regional government Meteorological forecasts

Community Surface-water control Mosquito spraying Rapid case treatment Household/personal House repairs Bed-nets

Net Vulnerability to risk of malaria

Population Health Impact: actual outcome

Vulnerability, Adaptation and Malaria Risk

Reducing Health Impacts of Climate Change … Health Co-Benefits as ‘bonus’

Disease burden

Mitigation beginsemissions reduction (etc.)

Potential health

impact of climate

change

now 2050 2100

Health Co-Benefits (local/regional)Baseline burden

Health impact averted by mitigation

Impact avoidance via

adaptation

Urgent Policy Tasks – to reduce:

• Atmospheric GHG concentrations

• Vulnerability of populations

• Pre-existing (amplifiable) disease rates

Watch out on Starboard !!

WAIT: We are in the middle of a conference on iceberg avoidance

TITANIC