Download Terrestrial Ecosystem Response to Climate

Terrestrial Ecosystem
Response to Climate
Change
Global Change and Effects on Terrestrial
Ecosystem
Introduction

Temperature, precipitation, latitude and altitude all
determine distribution of major terrestrial ecosystems
(biomes).

Plants found within the different biomes are influenced
by soil type, water shed conditions and amount of sun.

Specific combinations of temperatures and
precipitation ensure the survival and thriving of plants
within a given environment (known as Climate
space).
Terrestrial Ecosystems are an…
•
•
•
Integral part of global carbon system
Plants take in and store carbon dioxide from the atmosphere through photosynthesis
Below ground microbes decompose organic matter and release organic carbon back into the
atmosphere
www.bom.gov.au/.../ change/gallery/9.shtml
Cycle shows how nature’s sources of CO2 are self regulating – that which is released will
be used again – Anthropogenic carbon not part of natures cycle – is in excess
Major Biomes and Their Vegetation
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Tundra – no trees, lichens, grasses and shrubs
Taiga (or Boreal Forest) – coniferous evergreens
Temperate forests – include evergreens (spruce),
deciduous forests (oaks), mixed forests, and
temperate rain forests (sequoias)
Tropical rain forests – greatest amount of
diversity in vegetation (vines, orchids, palms)
Grasslands – grasses, prairie clover
Deserts – cacti, small bushes
Major Terrestrial Biomes
•
•
Geographic distribution of biomes are dependent on temperature,
precipitation, altitude and latitude
Weather patterns dictate the type of plants that will dominate an
ecosystem
faculty.southwest.tn.edu/. ../ES%20%20we16.jpg
Million years before present
570 505
438 408 360 286 245
208
144
66
2 10K
tundra
Global Distribution of Vegetation
18,000 years ago
desert
conifers
grassland
woodland
Prentice, C.I., Guiot, J., Huntley, B., Jolly D. and Cheddadi, R., 1996,
Reconstructing biomes from palaeoecological data:
a general method and its application to European pollen data at 0 and 6 ka.
Climate Dynamics 12:185-194.
taiga
Global Distribution of Vegetation 6,000 years ago
temperate deciduous
cold deciduous
taiga
tundra
conifers
grassland
desert
woods & scrub
Prentice, C.I., Guiot, J., Huntley, B., Jolly D. and Cheddadi, R., 1996,
Reconstructing biomes from palaeoecological data:
a general method and its application to European pollen data at 0 and 6 ka.
Climate Dynamics 12:185-194.
Global Distribution of Vegetation - Present
tundra
taiga
temperate deciduous
warm mix
grassland
tropical R.F.
Prentice, C.I., Guiot, J., Huntley, B., Jolly D. and Cheddadi, R., 1996,
Reconstructing biomes from palaeoecological data:
a general method and its application to European pollen data at 0 and 6 ka.
Climate Dynamics 12:185-194.
cold deciduous
Shifts in Terrestrial Habitat
• 18,000 years ago Spruce
trees and oak trees filled
small pockets of habitat –
as climates warmed
Spruce trees migrated
into the Northern
Hemispheres and the
Oak trees expanded in to
Southeastern U.S.,
Western Europe and
Southern Europe
18Kya
18 kya
ice
ice sheet
oak
spruce
spruce
9Kya
9 kya
ice
ice
spruce
oak
Present
Present
spruce
ice
• Shifts in vegetation occur
slowly tree species were
able to successfully
expand into favorable
regions
spruce
oak
oak
Distribution of spruce and oak forests in Northern Hemisphere since the
glacial period 18,000 kya
tundra
PRESENT
taiga
taiga
DAY
BIOMES
desert
temp.
decd.
forest
desert
grassland
trop.
rain
forest
scrub
forest
desert
temp
rain
forest
Tundra
Location:
Regions south of the ice caps of the Arctic
and extending across North America,
Europe and Siberia (high mountain tops)
Greenland
Alaska
N. Europe
Siberia
Yakutsk
Canada
Ice land
Average Temperature: -40°C to
18°C
Average Precipitation:
150 to 250 mm of rain per year
Type of vegetation:
Almost no trees due to short growing
season and permafrost; lichens, mosses,
grasses, and shrubs
Average annual temperature
and precipitation
Yakutsk, Russia
Location:
62.1 N; 129 W
earthobservatory.nasa.gov
Boreal Forest (Taiga)
Canada
S.W. U.S
Europe
Asia
Temperature:
-40°C to 20°C, average summer
temperature is 10°C
Precipitation:
300 to 900 millimeters of rain per year
Vegetation:
Coniferous-evergreen trees
Location:
Canada, Europe, Asia, and the United States
Other:
Coniferous forest regions have cold, long,
snowy winters, and warm, humid summers;
well-defined seasons, at least four to six frostfree months
Boreal Forest (Taiga)
Average annual temperature
and precipitation
Beaverlodge, Alberta, Canada
55oN; 119o W
earthobservatory.nasa.gov
Temperate Forests
Four types:
1. deciduous forests
2. evergreen forests
3. mixed deciduous and evergreen
4. temperate rain forests
Location:
Eastern United States, Canada,
Europe, China, and Japan
Average Yearly Temperature:
Between -30°C to 30°C; hot summers, cold
winters; sunlight varies between seasons
Average Yearly Precipitation:
750 to 1,500 mm of rain per year
Vegetation:
Deciduous - Broadleaf trees (oaks, maples,
beeches), shrubs, perennial herbs, and mosses.
Evergreen – (N. America) – Spruce, Hemlock,
Pine and Fir trees
Temperate Rainforests – (CA, OR, & WA) –
made up of Red wood and Sequoias
www.windows.ucar.edu/.../ earth/forest_eco.html
Average annual temperature and rainfall
Staunton, Virginia, United States
38oN; 79oW
earthobservatory.nasa.gov
Tropical Forests
General Characteristics:
Average Temperature: 20°C to 25°C, must remain
warm and frost-free
Average Precipitation: 2,000 to 10,000 millimeters of
rain per year
Average Humidity: Between 77 – 88%
Types of Vegetation: Large trees reaching up to 240
feet, have the most diverse trees than any other
biome: vines, orchids, ferns
Tropical rainforests:
• Cover less than 6% of Earth’s land surface
• Produce more than 40% of Earth’s oxygen
• Contain more than half of all the worlds
plants and animals
• ¼ of all medicines come from rainforest plants
• Scientists believe more than 1400 tropical plants
thought to be potential cures to cancer
Tropical Rainforest
Amazon river basin
Zaire
India S.E. Asia
New Guinea
Madagascar
Queensland
3 major geographical areas:
1. America: Amazon river basin
2. Africa:
Zaire basin, small area of W. Africa, Eastern portion of Madagascar
3. Asia:
West coast of India, Assam, S.E. Asia, New Guinea and Queensland,
Australia
"Rainforests", http://passporttoknowledge.com/rainforest/GEOsystem/Maps/se_asia.html, (3/18/02)
Tropical Forest
Campa Pita, Belize
15 N latitude
earthobservatory.nasa.gov
Average annual temperature and
precipitation
Southeast Asia Tropical Rainforest
Monsoons role
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SE Asia has a tropical wet climate which is influenced by ocean wind
systems originating in the Indian Ocean and China Sea
2 monsoon seasons:
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Northeast monsoons (Oct. – Feb) – bring heavy rains to Eastern side of
the islands
Southwest monsoons (April – Aug) – more powerful of the two seasons –
brings heavy rainfall to the western side of the islands – Eastern side of
islands dry – but windy (due to rain shadow)
Change in monsoon cycle bring heavy consequences
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Ex. 1992 – 1993 – logging degraded primary foresting making it vulnerable
to fires. A drought brought on by El Nino created devastating fires
destroying 27,000 km2 of acreage.
In 1998 the same type of thing happened again when El Nino created a
weak monsoon season – destroying many plant and animal species.
Grasslands
Location: The prairies of the Great
Plains of North America, the pampas of
South America, the veldt of South
Africa, the steppes of Central Eurasia,
and surrounding the deserts in
Australia
Temperature: Dependent on latitude,
yearly range can be between -20°C to
30°C
Precipitation: About 500 to 900 mm of
rain per year
Vegetation: Grasses (prairie clover,
salvia, oats, wheat, barley,
coneflowers)
Other: Found on every continent
except Antarctica
Average annual temperature and rainfall
Ingeniera White, Argentina
40oS; 6oW
earthobservatory.nasa.gov
Deserts
Location: Found north and south of the
Equator
Temperature: Average of 38°C (day),
average of -3.9°C (night)
Precipitation: About 250 mm of rain per yr
Vegetation: Cacti, small bushes, short
grasses
Other:
Perennials survive for several years by
becoming dormant and flourishing when
water is available. Annuals are referred to
as ephemerals because some can complete
an entire life cycle in weeks.
Average yearly temperature and rainfall
El-Oasr el-Akhdar, Egypt
26oS; 30oE
earthobservatory.nasa.gov
So … what are the predictions?????
woodland
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Arid deserts in Southwestern U.S.
will shrink as precipitation increases
Savanna/shrub/woodland systems
will replace grasslands in the Great
Plains
Eastern U.S. – forests will expand
northerly – weather conditions will
become more severe
Southeastern U.S. – increasing
droughts will bring more fires –
triggering a rapid change from
broadleaf forests to Savannas
Climate change p. 104
shrub land
grassland
forest
arid
Present day
grassland
forest
grassland
shrub land
grassland
woodland
Predicted Distribution
Predicted Change in Biomes
Loss of existing habitat that could occur under doubling of CO2
concentration. Shades of red indicate percentage of vegetation
models that predicted a change in biome type.
Predictions of Sugar Maple in Eastern North America
predicted new
growth
Distribution of Sugar
Maple in Eastern North
America will change due
to an increase in
temperature and a
decrease in moisture
shifting further north east.
predicted new
growth
overlap
overlap
present range
present range
Prediction based on
increased temperature
Prediction based on increased
temperature and decrease
precipitation
More Predictions
 Douglas Fir found in
wet coastal mountains of
CA and OR will shrink in
low lands and be
replaced by Western
pine species which are
more drought tolerant.
 Overall Western U.S.
climate is predicted to
shift to favor more
drought tolerant species
of pine
Western Hemlock
and Douglas fir
found on Western
slope
Wet western
slope will
shrink and be
replaced by
pine and oak
Eastern slope
will become
drier and shift
to Juniper and
Sagebrush
Frequency of forest fires will increase,
reducing total American boreal forest area.
Shifts in Terrestrial
Habitat
•
It is predicted that at the
end of this century there
will be large scale shifts in
the global distribution of
vegetation in response to
anthropogenic climate
change.
•
With man doubling the
amount of carbon dioxide
entering into the
atmosphere the climate is
changing more rapidly then
plant migration can keep
up.
www.usgcrp.gov/usgcrp/ seminars/960610SM.html
Potential distribution of the major world
biomes under current climate conditions
Projected distribution of the major world biomes by
simulating the effects of 2xCO2-equivalent concentrations
Boreal and Alpine
Vegetation
•
Research indicates the greatest
amount of change will occur at
the higher latitudes
•
Northern Canada and Alaska are
already experiencing rapid
warming and reduction of ice
cover
•
Vegetation existing in these areas
will be replaced with temperate
forest species
•
Tundra, Taiga and Temperate
forests will migrate pole ward
•
Some plants will face extinction
because habitat will become too
small (ex. Mountain tops of
European Alps)
Predicted changes in Siberian vegetation in
response to doubling of CO2
Climate change
Grasslands and Shrub Lands
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Grassland will change to deserts or shrub lands
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Exposing greater amounts of soil
Increasing soil temperature – poor nitrogen content – poor plant
growth
Barren soil exposed to winds and transported into atmosphere as
dust and trapping IR – leading to more warming
Models of:
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Climate change
Plant growth
Soil – water
Predict shifts in distribution of major North American prairie
grasses over a 40 year period
Impacts on Lebanon?
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recent studies found that the Arab region
experienced an uneven increase in
surface air temperature ranging from 0.2
to 2.0ºC that occurred from 1970 to 2004
Impact high…
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Semi-arid and arid regions are highly
vulnerable to climate change
If temperature gets higher
If precipitation gets lower
 pressure on natural and physical systems
would be intensified
climate change impact
35
The Arab region will…
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Face an increase of 2 to 5.5 C in surface
temperature by 2100
Face a decrease in precipitation from 0 to
20%
 shorter winters
 dryer and hotter summers
 higher rate of heat waves
 higher level of weather variability
 more frequent occurrence of extreme
weather events
climate change impact
36
Impact on freshwater sources
37
climate change impact
Status of freshwater here
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Reminder: most of the Arab countries are
located in arid and semi-arid regions; low
and limited water resources + high
evaporation
Total water resources = total renewable
ground water + internal surface water
resources + external surface water resources
climate change impact
38
First order impacts…
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Mediterranean hydrological systems
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Wetter winters
Dryer and hotter summers
Increase in evaporation from water bodies…
Increase Evapotranspiration from crops
Egypt
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Increase the potential irrigation demand by 6 to
16% by 2100
climate change impact
39
Drought
40
climate change impact
Drought frequency
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Increased during the last 20 to 40 years in
Morocco, Tunisia, Algeria and Syria
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Of the 22 drought years in the 20th century, 10
occurred in the last 20 years, and three were
successive (1999, 2000, 2001) in Morocco
Recent droughts in Jordan and Syria worst ever
recorded
Varying conditions of water shortage in
Lebanon in the last 10 years
climate change impact
41
BUT NOT JUST DROUGHTS
42
climate change impact
Yemen: recent floods (October 2008)
Dubbed the 'Manhatten of the desert', Shibam's 2,000-year-old
mud-brick buildings are in danger of collapsing after recent floods
43
climate change impact
Observed Changes in Physical and Ecological Systems
(from IPCC
2001)
5/7/2017
hydrology /
glaciers
sea ice
animals
plants
study covers
large area
study based on
remote sensing
44
Those at Risk
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Northern countries (Russia, Sweden, Finland) ½ of
existing terrestrial habitats at risk
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In Mexico, it’s predicted that 2.4% of species will lose
90% of their range and threatened with extinction by the
year 2055

Population at greatest risk are the rare and isolated
species with fragmented habitats or those surrounded by
water, agriculture or human development

Polar bears facing extinction by prolonged ice melts in
feeding areas along with decline in seal population
 35% of worlds existing terrestrial
habitat predicted to be altered
 Studies found that deforestation in
different areas of the globe affects
rainfall patterns over a considerable
region
 Deforestation in the Amazon
region of South America
(Amazonian) influences rainfall
from Mexico to Texas and in the
Gulf of Mexico
 Deforesting lands in Central
Africa affects precipitation in the
upper and lower U.S. Midwest
www.sciencedaily.com/.../ 09/050918132252.htm
Key Conclusions from IPCC
Recent Regional Climate Changes, particularly Temperature Increases, have
Already Affected Many Physical and Biological Systems
(high confidence, or >67% sure)
Biotic change: 44 regional studies, 400 plants and animals, 20 to 50 years
Physical change: 16 regional studies, 100 processes, 20-150 yrs
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5/7/2017
non-polar glacier retreat
reduction in Arctic sea ice extent and thickness in summer
earlier plant flowering and longer growing season in Europe
poleward and upward (elevation) migration of plants, insects and animals
earlier bird arrival and egg laying
increased incidence of coral bleaching
increased economic losses due to extreme weather events
47
Phenology
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Phenology: the study of a plant or animal’s
progression through its life cycle in relation to
the seasons
Another main indicator of climatic fingerprint

5/7/2017
In Britain, for example, flowering and leafing occur
6 to 8 days earlier for every degree C rise in
temperature
48
Phenological Changes
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Life-cycles of plants and animals have been
affected by global change
Temperatures affecting plants growing season,
flowering time and timing of pollination by insects
have all been altered
Studies already showing
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Mediterranean deciduous plants now leaf 16 days earlier
and fall 13 days later than 50 years ago
Plants in temperate zones flowering time occurring earlier
in the season
Growing season increased in Eurasia 18 days and 12 days
in N. America over past two decades
Phenological Changes
Penuelas J and Filella I 2001. Response to a warming world. Science 294: 793 – 795
Important to know the particular species’
requirements

Migratory black-tailed godwit
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Shore bird
Winters between Britain and Iberia
Breeding in summer in Iceland
Breeding pairs – high partner fidelity
Male and females winter in different locations – but arrive in
Iceland typically within 3 days of each other
?: how this degree of synchrony is maintained when the
environmental conditions at the different sexes’ wintering sites are
dissimilar?
Pied flycatcher
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Migration is timed to availability of food for its nestlings
However – in parts of the Netherlands the caterpillars is now at its
food peak early in the season. There – the flycatcher population is
in decline
Will it be able to adapt in time?
5/7/2017
51
Biological communities and species shift
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Some species do not migrate – but will shift their geographical position or
range in response to CC
Climate is but one factor of many that determine a species’ spatial
distribution – species rarely move uniformly with each other in response to
climate change
Plus
Different species migrate at different rates
Thus: takes time for ecological communities to stabilize after a period of CC
Species at the leading edge of shifts/migrations tend to migrate faster than
those already established
Changes are asymmetrical: species invading faster from lower elevations or
latitudes than resident species receding upslope or poleward
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Result: increase in species richness of communities at leading edge of migration
Transitory biodiversity
Plus: many of today’s systems are either managed or bound by land managed by
humans == effective barrier to species migration
Problem: old ecological communities disrupted + impeding species migration halted
5/7/2017
52
Arctic lakes
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1997 - 2004: decline of 1170 large lakes (> 40
ha); 11%
Total regional lake surface area decreased by
6% (93 000 ha); 125 lakes vanished;
Northerly lakes increasing in size – by 12% (13
3000 ha)
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5/7/2017
Increased precipitation in the north
Southerly declines in lake area have outpaced
northerly gains in lakes
The more southerly permafrost soils  no longer
permanently frozen  allow lakes to rain
53
Mountain snow and ice
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Note: mountain snowpacks affect quantity and timing of water in
streams supplying ecosystems in surrounding lowlands
Nearly all mountains of sufficient height on Earth have snow caps
Those will be reduced in volume – especially at lower latitudes
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Smaller mountain snow caps may be seasonally thicker due to extra
precipitation
Already happening – at lower and mid latitudes (China, N.A. and
Europe)
Plus: snow-cap melt run off will shift away from summer and fall
when biological (and human) demand for water is greatest
compared to winter and early spring
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Annual cycle of water supply for many terrestrial and human systems will
see reduced temporal buffering
1/6th of the human population relies on glaciers and seasonal snowpacks
for water supply
Over 50% of river flow dominated by snow melt in: all of Canada, NW
states of US, all of Scandinavia (exc Denmark) Balkan Europe, Russia,
NE China, much of Chile, SW Argentina and S of New Zealand
5/7/2017
54
Water and ice
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In terms of human # - most critical region:
China and parts of India
Supports 2 billion people
Largest volume of ice outside of polar and
peri-polar regions
Nearly 70% of the Ganges’ summer flow and
50-60% of other of the regions’ major rivers:
melt water
5/7/2017
55
Tops of
mountains…

Global warming thermally determined
zonation on mountains changes and
rises
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Cannot migrate above mountain summits
Alpine biome is 3% of the vegetated
terrestrial surface – and shrinking

Ural Mountains
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Mountain pygmy possum (S-E
Australia)
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5/7/2017
Temperatures risen by more than 4 C in 20th
century
Tree lines have risen between 20 and 80 m
upslope
Reducing regional alpine lines by 10 – 20%
Habitat favored by skiers
Under serious threat
56
Highland forests of
Monteverde, Costa
Rica
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20 species of 50 anurans (frogs
and toads) in a 30 km2 study area
went extinct –
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Changes behavior of animals

5/7/2017
including endemic golden toad (1987)
Population crashes all associated with
decline in dry-season mist frequency
– due raising of cloud-bank base
(presumed)
Harlequin frogs gathered near
waterfalls  increased change of
attack by parasitic flies  increased
mortality
57
‘A message from the frogs’ – Blaustein and Dobston (Nature 2006)
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The harlequin frogs of tropical
America are at the sharp end of
climate change. About two-thirds of
their species have died out, and
altered patterns of infection
because of changes in temperature
seem to be the cause.
Climate change has already
altered transmission of a pathogen
that affects amphibians – leading
to widespread populations and
extinctions
67 % of the 110 species of
harlequin frogs endemic to the
region have died in past 20 years
78-83% of extinctions occurred in
unusually warm years in the tropics
Shifting temperatures are the
ultimate trigger for the expansion of
a pathogenic fungus
5/7/2017
58
‘A message from the frogs’ – Blaustein and Dobston (Nature 2006)

“The powerful synergy
between pathogen
transmission and
climate change should
give us cause for
concern about human
health in a warmer
world.”
5/7/2017
59
Climate Change
and Human Health
Climate change should be billed as a 'health' not
'environmental' disaster
The researchers from George Mason University's
Center for Climate Change Communication (4C),
whose study was recently published in the BMC public
health journal, said the health impacts of climate
change had been 'dramatically under-represented' in
discussions by scientists, policy-makers and NGOs
who instead focused on 'geographically remote'
impacts like melting ice caps in the Arctic.
60
Epidemiological Framework
Social
Environment
Host
Agent
Ecosystems
Global
61
Climate change and health: pathway from driving forces,
through exposures to potential health impact.
Modulating
influences
Adaptive
capacity
 Regional
weather
changes
Population
dynamics
Unsustainable
economic
development
 Heatwaves
Mitigation
measures
 Extreme
Greenhouse
gases (GHG)
emissions
Temperature-related
illness and death
Extreme weatherrelated health effects
Mitigative
capacity
Driving
forces
Health effects
CLIMATE
CHANGE
weather
 Temperature
 Precipitation
Natural
causes
Microbial
contamination
pathways
Air pollution-related
health effects
Transmission
dynamics
Water and food-borne
diseases
Agroecosystems,
hydrology
Socioeconomics,
demographics
Vector-borne and
rodent-borne diseases
Effects of food and
water shortages
Mental, nutritional,
infectious and other
health effects
Health-specific
adaptation
measures
Research
needs
Evaluation of
adaptation
Source: Climate Change and Human Health – Risks and Reponses. Summary (WHO, 2003)
Climate Change and Human Health Pathways
POOR RAINS
Inadequate in volume and distribution
Poor grass
Poor Harvest
People Underfed
(Malnutrition)
Poverty
Animal death
Less meat, less milk
Overgrazing where grass
is good
Animals underfed
Over-grazing,
trees cut down
for fuel
Grass /vegetation cover
lost
LAND
DEGRADATION
64
Model projections
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Projected impacts of heat waves
Average summer mortality rates attributed to
hot weather episodes
Changes with doubling or tripling of carbon
dioxide
-> projections of mortality can double or triple
in next several decades
65
What have we seen?
Recent Heat Waves
Location
Year
Approx. No.
Deaths
Western Europe
2006
3,392*
Europe
2003
72,000#
India
1998
2,541^
USA
1995
670
USA
1993
200
USA
1966
500
Aust [Melbourne]
1959
145^
------------------------------------------------------------------------------------------------------------------------------------------------------------
* Netherlands 1,000; Belgium 940.
# Italy 20,089; France 19,490; Spain 15,090; Germany 9,355.
^ Estimation. Total probably higher.
India: June 2003
T: 122 degrees F >
1400 deaths
July Floods
Japanese B
encephalitis
Summer 2003 heat wave

France, Germany, Italy, Spain, & Portugal

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Up to 72,000 deaths
Temperature was 10 degrees C (18 degrees
F) above 30 year average
67
European Heatwave 2003
Hotter?
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Expect more extreme weather events But not all extreme
weather events are attributable to CC
Need to know: what is expected with natural variability
assuming no carbon dioxide forcing and with climate
forcing from additional anthropogenic greenhouse gases
UK HadCM3 model: an exceptionally warm summer up to
2020 will become a normal summer by the 2040s in
Europe … they projected an increase 100-fold over the
next four decades
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So…Effects of Climate Change

DIRECT: Thermal stresses: extremes


Respiratory consequences:


of hot or cold
changes in patterns of exposure to spores,
moulds, etc.
Direct effects:

loss of life or health due to: storms, floods,
drought
Air pollution and climate change
Pollen and
Groundlevel ozone
Heat
waves
Droughts
and fires
Socio/economic/
emotional factors
Floods and
fungi
Indoor
pollutants
Diesel
particles
mold
Asthma:
2-3 x
since
1984
Pollen and
carbon
dioxide
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Emerging infectious diseases

30 diseases new to medicine since 1976



New diseases…
Old diseases…
As climate changes


Change the range at which they occur
Extremes affect vector populations
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Infectious Diseases




Increased mean, minimum temps along with
wetter winters affects the range, proliferation and
behavior of vector organisms
Developed world populations generally have
more resources to face such problems
Malaria currently affects 350 million people
annually, 2 million deaths
Potential for transmission of malaria from 45% 60% of world’s population
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Biologic response to changes in climate



Global warming and wider fluctuation in weather help to
spread diseases
Temperatures – affect growth, development and survival
of microbes and the vectors
Weather affects the timing and intensity of disease
outbreaks (McMichael et al, 2003)
Biologic response to changes in climate:
Infectious diseases

Warmer environment and mosquitoes






Boost rate of reproduction
Increase the number of blood meal
Prolongs their breeding season
Shorten the maturation period of microbes they carry
Warmer winters – tick-borne lyme disease spreading northward
in Sweden, US and Canada (Epstein, 2005)
Heavy downpours




Drive rodents from burrows: risk of zoonotic diseases
Create mosquito breeding sites
Faster fungal growth in houses
Flush pathogens and chemicals into waterways


Milwaukee’s cryptosporidiosis outbreak in 1993
Katrina’s flood: water-borne pathogens and toxins spread.
Extreme weather events and disease
clusters

Extremes!



High correlation between droughts & floods and
rodent-borne and mosquito-borne diseases
Sequence of extremes
Example: Hurricane Mitch (Honduras)

6 feet of rain in 3 days
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Precipitation extremes




Past century average annual precipitation:
7%
Heavy rain events (> 2 inches/day): 14%
Very heavy rain events (> 4 inches/day): 20%
Western drought + Devastating rains
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Diseases Carried By Mosquitoes
West Nile
Malaria
Dengue Fever
Yellow Fever
West Nile (1937:
Uganda. Now:
Spreading across
Canada)
Wet spring. Dry, hot summer
Climate change will
influence spread of WNV
And occurrences of other
Vector diseases
Four main types of transmission cycle for infectious diseases
Anthroponoses
Direct transmission
Indirect transmission
HUMANS
HUMANS
VECTOR/VEHICLE
VECTOR/VEHICLE
HUMANS
HUMANS
ANIMALS
ANIMALS
Zoonoses
VECTOR/VEHICLE
VECTOR/VEHICLE
ANIMALS
HUMANS
Source: Climate Change and Human Health – Risks and Reponses. Summary (WHO, 2003)
ANIMALS
HUMANS
Does climate change have a measurable
impact on health?
Climate sensitivity:
 5% increase in diarrhoeal disease for each 1o C temperature increase
 (developing countries only)
Change in relative risk:
 Projected temperature changes relative to 1961-1990, overlaid on
population
 distribution map to give per capita increase in diarrhoea risk.
Disease burden attributable to climate change:
 Relative risk under each scenario/time point multiplied by WHO
estimates of
 current and future 'baseline' diarrhoea burden in each region.
 Estimated 2.4% of diarrhoea (47,000 deaths) attributable to CC in 2000,
and
 approximately 5% ( 60,000 deaths) in 2020. (World Health Report
2002)
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Primary
economic,
technological
social, cultural
drivers
Environmental
change
An EcoHealth View
Health impact
e.g., + UVrad
thermal stress
T, soils
Ecosystem
change
Climate change will
Impact on all these
Relationships!!
+mosquitoes
+/- food
Health impact
Livelihood
population
Social, political
Economic
relations
Jobs,poverty
consumption
Socio-economic
Level of risk
Health impact
INDIRECT: Effects of Climate Change
MANY UNCERTAINTIES
 Alterations in range and activity of vector-borne
pathogens e.g., malaria, West Nile virus, dengue
 Possibility of new infectious disease agents
 Changes in person-person infections including foodborne and water-borne
 Nutritional and health consequences of local and
regional changes in agricultural production
 Consequences of sea level rise

Loss of home, employment, population displacement
Human impacts of other forms of overload

Human environments and livelihoods deteriorate




Social destabilization and conflict will escalate
Some of the world’s poorest populations becoming
more “demographically entrapped” McMichael, 1997
limited data
Land exceeds carrying capacity starvation, disease,
fratricide
Rwanda prototype 1980s
Vector-borne diseases



Climate change, by altering local weather
patterns and by disturbing life-supporting
natural systems has significant implications
for human health
Models suggest that higher temperatures will
enhance the geographic range and
transmission rates of vector-borne diseases
Children will be disproportionately affected,
as they are more prone to infection and death
from parasites.
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Food security and malnutrition



Many of Africa’s poor are very highly dependent
on climate-related factors for their livelihoods.
Weather disruptions exacerbated by climate
change negatively impact Africa’s economic
growth and food security, and thus aggravate
malnutrition
Undernourishment is a well-studied cause of
stunted physical and intellectual development
and increased disease susceptibility in children.
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Food Production


In some countries affects nutritional status,
child growth, health
Depletion of ocean resources unless offset by
advances in aquaculture jeopardize health in
developing/poor countries
Sea-level rise





Displacement of coastal population
Predicted rise of 0.5 m would immediately
inundate 10% of land in Bangladesh
Alters sewage and waste disposal
Viability of coral reefs and wetlands
Again affects range of disease vectors
Land degradation



Absolute numbers of malnourished persons
increasing
Many world’s fisheries overexploited
World loss of biodiversity


We have occupied, damaged or eliminated natural
habitats of many species
Fastest loss of species ever; we may cause 1/3 of all
species alive in last century to be gone before end of
this century
Land degradation


Agricultural productivity: to maintain food
production have to resort to maintaining vigor
and resilience by diversity of species to be
source of genetic additives
A high number of medicinal drugs come from
naturals; can’t be replicated in labs

Science continues to test many new drugs from nature
each year
Climate Change and Environmental
Justice

Oil-related health consequences






Vulnerabilities – coping, adaptation



Extraction: Nigeria, Ecuador, Mexico
Refining and Benzene
Utility plants and mercury
Air pollution and inner city truck routes
Economic inequities
Restoration, prevention
Public health infrastructure
Still: No nation is immune
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And the future?


Further change is anticipated with further
warming
IPCC scientific consensus




Warming will continue through the rest of the this
century and beyond
Questions: how much warming and at what rate
Depends on future emissions of GHG
So what can be done?
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