Tony McMichael, AOEmeritus Professor (Population Health)

National Centre for Epidemiology and Population Health The Australian National University

tony.mcmichael@anu.edu.au

Climate Change and Human Population Health: Past, Present, Future

Department of Defence, June 2013

Deaths Attributable to Climate Change: Year 2000

14 WHO statistical regions scaled by estimated annual mortality (selected causes, in 2000) due to change in climate during 1970-2000.

(Patz et al, 2007: based on McMichael, et al, 2004)

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

Physical systems(river flow, vegetation, soils, ocean temp, etc.)

Biological &ecological processes

Economic/social impacts: infrastructure, economic productivity, jobs, coastal displacement, resource-related conflict/warfare

Human Health• Injuries/deaths; mental stress• Thermal stress impacts

Indirect (‘secondary’) impacts, ecologically-mediated: changes in food, water, mosquitoes

Indirect (‘tertiary’) health impacts – socially & politically mediated

Direct (‘primary’) impacts (extreme weather, heatwaves, air pollution)

• Infectious diseases• Under-nutrition• Mental stresses• Trauma/deaths

Climate Change:

Impacts

Climate Change: Health Impact Pathways

Relationship between Rainfall Index (combines rainfall and temperature) in Spring (April-June) and Barley Yields in Czech Republic since 1940s.

Dry WetNormal Range

Spring Barley Yield (deviation, %)

Rainfall Index, April-June

Brazdil et al, 2008

5-year running mean yield deviation

64

36

20

80

Percentage change in yields to 2050

-50 -20 0 +20 +50 +100

UN Devt Prog, 2009

Not including climate-related:

•Flood/storm/fire damage•Droughts – range,

severity•Pests (climate-sensitive)•Infectious diseases

(ditto)

CLIMATE CHANGE to 2050: MODELLED CHANGES IN CEREAL GRAIN YIELDS (due to temperature and soil moisture)

Poor Countries are Projected to Fare Worst

eg. dengue, malaria;Ross River virus, Lyme disease

eg. nutrition-related immune function

Climate Change: Diverse Influence Paths on Infectious Diseases

Social-demographic influences

NCEPH/CSIRO/BoM/UnivOtago, 2003

Dengue Fever: Estimated ‘receptive’ region for Ae. aegypti

mosquito vector, under alternative climate-change

scenarios for 2050

Risk region for mediumemissions scenario, 2050

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome..

....

..Carnarvon.

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. Risk region for high

emissions scenario, 2050

Climate Change Influences on Health in Australia

Already apparent: baseline risks amplified by underlying climate change Uptrend in av annual no. of heat-days deaths, hospitalisations

Increases in no./severity bushfires injury/death, resp. hazard, mental health

Severe flooding (due to increased sea-surface temp, increased rainfall?)

Probable current health impacts: but not yet clearly identified Rising rates of some food-borne enteritis (diarrhoeal) diseases Altered (urban) air quality: ozone formation, aeroallergens Mental health impacts, esp. in some (drying) rural regions: e.g. MD Basin

Predicted future health impacts More extreme weather events trauma/deaths, infectious disease, depression Water shortages, affecting food yields, domestic hygiene Mosquito-borne infections – shifts in range and seasonality:

Dengue, Ross River virus, Barmah Forest virus, Japanese encephalitis, etc. Increased thermal stress at work, esp. in outdoor workers and under-ventilated

factories: accidents/injuries, organ damage; reduced work capacity

Sahara dries

Acute cooling: 536 CE ‘Event’

Mediaeval Warm Period,

Europe

Roman Warm Period

Holocene Climatic

Optimum I, II

Drought & cooling in East Mediterranean

region

11 10 9 8 7 6 5 4 3 2 1 0 2 4 6 8 10 12 14 16 18 20 22Millennia BCE (1000s of yrs) Centuries CE (100s of yrs)

Variations in NH Temp, oC (rel. to Holocene average)

+4

+3

+2

+1

0

-1

-2

-3

BCE/CE

Post-glacial warming following Younger Dryas cooling, 12.8-11.6K BP

Modelled range of projected global

temperature rise to 2100 (vs.1990) = + 2-5oC

Little Ice Age: Europe, China

Holocene

Changes in Average Northern Hemisphere Temperature over the Past 11,000 Years

Early agrarian societies begin to

form: Egypt, Sumer, southern China

Faster warming

since 1975

Acute cooling: Tambora

eruption 1815

AJ McMichael, 2012)

1500 1550 1600 1650 1700 1750 1800

War Fatality Index, Europe

Nth Hemi-sphere

Temperature Variation

oC

Rate of Migrations,

Europe

European Temperature

Variationstandardised units

Cold Period1570-1660

Zhang et al., PNAS, 2011

Europe’s coldest period, 1570-1660, during Little Ice Age Food yields down, grain prices tripled … conflict , war, displacement

Famine-years/decade x 2Epidemic rate x 3Adult height ↓1.5cm

Northern (> 20oN) Hemisphere temperature

variations, o( cf 1961- 90 av.)

No. of internal wars (per decade)

Populationsize(millions)

1000 1200 1400 1600 1800 2000

WarsRebellions

1000 1200 1400 1600 1800 2000

C

N. Song S. Song Yuan Ming Qing

Five (grey) periods of cold in China

Temperature, Conflict, Warfare within China, 1000-1940: Relationship to Fall of Dynasties

Adapted from Zhang et al, 2009

The ‘Little Ice Age’

Hsiang et al., Nature 2011

Affected (n= 93 countries)

(n= 82 countries)

Probability of new civil conflicts breaking out in El Niño years is double that seen in cooler La Niña years

Annual Civil

Conflict Rate

(% of countries

embroiled)

El Niño Index (NINO3: May-Dec average Sea-Surface Temperature)

Civil Conflicts, 1950-2004, in Countries Affected or Not/Little Affected by ENSO

StrongerWeaker

Now, over to Colin Butler ………