Chap.27 Global Climate Change
Chap.28 Population Growth, Resource Use, and
Sustainability
Chap.29 Habitat Loss, Biodiversity, and
Conservation
th
Smith & Smith (2015) Elements of ecology. 9 . Ed. Pearson.
Part Eight Human Ecology
人類生態學
鄭先祐 (Ayo) 教授
生態科學與技術學系
國立臺南大學 環境與生態學院
Chap.27
全球氣候變遷
Global Climate Change
Smith & Smith (2015) Elements of ecology. 9th. Ed. Pearson.
鄭先祐 (Ayo) 教授
生態科學與技術學系
國立臺南大學 環境與生態學院
Satellite image of Hurricane Katrina in the Gulf of Mexico
(August 2005)
3
Chapter 27 Global Climate Change
 Change is inherent in Earth's climate system so the
term global climate change is redundant.
 The amount of tilt in Earth's rotation affects the
amount of sunlight striking the different parts of
the globe.
 Tilt of Earth's axis varies from 22.5° to 24° over a
cycle of 41,000 years.
 Variations in Earth's climate have been affecting
life and its evolution for millions of years
 The human species has the ability to alter
Earth's climate.
4
27.1 Greenhouse Gases Influence Earth's
Energy Balance and Climate
Greenhouse gases (water vapor, carbon dioxide, and
ozone) absorb thermal radiation emitted by the Earth's
surface and atmosphere.

This energy acts to warm the surface and the lower
atmosphere.
Greenhouse effect.

The average surface air temperature of the earth is 30°C higher
than it would be without the absorption and reradiation of
thermal energy.
Since the industrial period began, the concentrations of
greenhouse gases in Earth's atmosphere have increased
dramatically.
5
27.2 Atmospheric Concentration of Carbon
Dioxide Is Rising
 The atmospheric concentration of CO2 has
increased by more than 25 percent over the past
100 years
 Continuous observations of atmospheric CO2
started in 1958
 Earlier evidence from air bubbles trapped in
the glaciers of Greenland and Antarctica
 CO2 concentrations have risen exponentially since
the mid-19th century, after the onset of the
Industrial Revolution (combustion of fossil fuels)
6
Fig. 27.1 Concentration of
atmospheric CO2 as
measured at Mauna Loa
Observatory, Hawaii.
7
Fig. 27.2 Historical record of atmospheric CO2 over the past
300 years. Data collected prior to direct observation (1958 to
present) are estimated from various techniques including
analysis of air trapped in Antarctic ice sheets.
8
Fig. 27.3 (a) Historical record of annual input of
CO2 to the atmosphere from the burning of fossil
fuels since 1750.
9
Fig. 27.3 (b) Carbon emissions form the
burning of fossil fuels by the top 10 countries
in 2008.
 Currently, 70
percent of the
total CO2
emissions from
the burning of
fossil fuels
come from the
developed
countries
 Of this, the
United States
accounts for
more than
22 percent!
10
27.2 Atmospheric Concentration of Carbon
Dioxide Is Rising
 Deforestation is also a major cause of increased
atmospheric levels of CO2 because of loss of
vegetation (less plants to use CO2 in
photosynthesis) and increased decomposition and
burning of "leftover" biomass.
11
Fig. 27.4 Historical record of annual input of CO2 to the
atmosphere from the clearing and burning of forest (a) globally.
12
Fig. 27.4 Historical record of annual input of CO2 to the
atmosphere from the clearing and burning of forest (b) in selected
geographic regions.
13
27.3 Tracking the Fate of CO2 Emissions
 Average annual amount of carbon released to the
atmosphere during the 1990s was 8.5 gigatons
(Gt).
 6.3 Gt from fossil fuel combustion
 2.2 Gt from forest clearing
 Annual accumulation of carbon in the atmosphere
only 3.2 Gt.
 5.3 Gt must have flowed from the atmosphere
into other main pools of the global carbon cycle
(oceans, terrestrial environments).
14
27.3 Tracking the Fate of CO2 Emissions
Determining the fate of CO2 requires input from a
variety of scientific disciplines
Diffusion controls uptake of CO2 from the atmosphere
into the oceans

Estimated to be 2.4 Gt annually (in the 1990s)
The exchange of carbon between terrestrial systems
and the atmosphere is difficult to quantify.


Estimated by process of elimination
Net uptake by terrestrial ecosystems (0.7 Gt) = Emissions
from fossil fuels (6.3 Gt) – Atmospheric increase (3.2 Gt) –
Ocean uptake (2.4 Gt)…… 3.2 +2.4 = 5.6 6.3 – 5.6 = 0.7
15
27.3 Tracking the Fate of CO2 Emissions
 "Missing carbon" is the 2.9 Gt per year (0.7
uptake by terrestrial system and 2.2 Gt from
deforestation)
 Any possible net uptake of carbon by terrestrial
ecosystems may result from reforestation in
temperate Northern Hemisphere regions.
 Tropical forests may represent a much larger
sink of carbon than previously believed.
16
Fig. 27.5 The various releases and accumulation of carbon
associated with the global carbon cycle, shown graphically
over the period 1850-2000.
17
27.4 Atmospheric CO2 Concentrations
Affect CO2 Uptake by Oceans
 The rate of diffusion of CO2 is a function of the
diffusion gradient.
 Although the oceans have the potential to absorb
most atmospheric carbon derived from fossil
fuel combustion and deforestation, this does
not happen.
 Thin layer of warm water floating on a much
deeper layer of cold water.
 Mixing of CO2 does not extend into the deep
waters because of the thermocline.
18
Fig. 27.6 The major pattern of circulation in the Atlantic Ocean,
Atlantic surface waters, flowing northward from the tropics, col
and sink when they reach subarctic latitudes. After sinking , these
waters become part of the huge, deep, southward countercurrent
reaching all the way to the Antarctic.
19
Field Studies Erika Zavaleta
 E. Zavaleta
(University of
California, Santa Cruz)
has studied the
response of
California's
grassland
ecosystems to
changes in climate,
atmospheric CO2, and
N-deposition
 San Francisco Bay
Area
20
Field Studies Erika Zavaleta
 E. Zavaleta examined a grassland community
composed of annual grasses (dominant), annual
and biennial forbs, and occasional perennials.
 Annual forbs germinate with the onset of the
fall–winter rains and plants set seed and senesce
with the cessation of rain.
21
Field Studies Erika Zavaleta
 Experimental design
 32 plots surrounded by a solid belowground
partition.
 Each plot divided into four quadrants.
 Treatments
 Elevated CO2
 Warming
 Elevated precipitation
 N-deposition
 A census was conducted in May of each year to
determine species diversity.
22
Fig. 1 An experimental study plot at the Jasper Ridge
Biological Reserve.
23
Field Studies Erika Zavaleta
 After three years, several treatments had altered
total plant diversity (primarily by gains and losses
of forb species)
 N-deposition reduced diversity by 5 percent
 Elevated CO2 reduced diversity by 8 percent
 Elevated precipitation increased diversity by 5
percent
 Elevated temperature had no significant
effect
 All treatment combinations produced mean
declines in forb(非草屬的草本植物) diversity.
24
Fig. 2 Changes in the total, forb, and annual grass diversity under single and
combined global change treatments. Values are percent difference between
controls and elevated levels for each treatment, based on values of mean species
richness for each treatment.
Treatments: C, CO2; T, warming; P, precipitation; TC, warming and CO2; TCP,
warming, CO2, and precipitation; TCN, warming, CO2, and nitrogen; TCPN,
warming, CO2, precipitation, and nitrogen.
25
Field Studies Erika Zavaleta
 Zavaleta's experiments produced results that were
opposite of that expected
 Stimulated warming increased spring soil
moisture!
 This was a result of earlier plant senescence in
the elevated temperature treatments
 Lower transpirational water losses resulting
from earlier senescence.
26
Fig. 3 Warming and elevated CO2 effects on spring soil
moisture for 1999-2000. Values are mean soil moisture
from January to July for each year.
27
27.5 Plants Respond to Increased
Atmospheric CO2
 Elevated atmospheric CO2 affects plants.
 Direct, short-term effects
 CO2 fertilization effect is the increase in the rate
of photosynthesis because of higher rates of
diffusion of CO2 from the atmosphere into the
leaf
 Reduction in water loss because plants increase
their water-use efficiency.
 Long-term effects
 Plant growth and development
 The long-term effects of elevated CO2 can be
complicated.
28
27.5 Plants Respond to Increased
Atmospheric CO2
H. Poorter and M. Perez-Sob (Utrecht
University, The Netherlands) reviewed
results from 600 experimental plant studies



C3 species respond most strongly to elevated
CO2  average increase in biomass of 47
percent
CAM plants  21 percent
C4 plants  11 percent
Within C3 species, crop species show the
highest biomass enhancement (59 percent)
and herbaceous plants the lowest (41
percent)
29
Fig. 27.7 Distribution of biomass enhancement ratio (BER) for
several functional types of species. BER is the ratio of biomass
growth at elevated and ambient levels of CO2. Distributions are
based on 280 C3, 30 C4, and 6 CAM species. C3 species were
separated into three groups; crop, wild herbaceous, and woody
species.
30
27.5 Plants Respond to Increased
Atmospheric CO2
 The enhanced effects of elevated CO2 levels on
plant growth may be short-lived.
 More carbon is allocated to roots.
 Fewer stomata are produced.
31
Fig. 27.8 Time course of biomass enhancement ratio (BER) due
to elevated CO2. GER is the ratio of biomass growth at elevated
and ambient levels of CO2. Each line represents the results of
an experiment with a different tree species.
32
27.5 Plants Respond to Increased
Atmospheric CO2
 How do the results observed for leaves or single
plants translate into changes in the net primary
productivity (NPP) of terrestrial systems?
 Limited water or nutrient availability may limit
potential increases in productivity at elevated CO2
 An ongoing experiment (since 1996) at the Duke
Experimental Forest (North Carolina) has examined
the effect of elevated CO2
33
Fig. 27.9 The Free Air CO2 Experiment (FACE) at Duke Forest in North
Carolina. The circle of towers releases carbon dioxide into the
surrounding air, allowing scientists to examine the response of the forest
ecosystem to elevated concentrations of atmospheric carbon dioxide.
34
Fig. 27.10 (a) Net primary productivity (NPP) under ambient and
CO2 enrichment in the Duke Forest FACE experiment since it began
in 1996. Solid symbols represent elevated CO2 conditions; open
35
symbols denote ambient CO2 conditions.
Fig. 27.10 (b) Difference between NPP under elevated and
ambient CO2 conditions, with percentage stimulation of NPP
under elevated CO2 indicated above each data point.
36
27.5 Plants Respond to Increased
Atmospheric CO2
 Interactions occur between elevated CO2 and
other environmental factors, temperature,
moisture, and nutrient availability
 In some cases, productivity (measured as
biomass) increases with elevated CO2 and
decreases in others
37
27.5 Plants Respond to Increased
Atmospheric CO2
 Ecosystems of low-temperature environments tend
to show an initial enhancement of productivity
followed by downregulation
 W. Oechel examined arctic tundra and found an
initial productivity increase to a doubling of CO2
 Primary productivity returned to original levels
after three years of continuous exposure.
38
27.6 Greenhouse Gases Are Changing the
Global Climate
Earth's average temperature has increased by 0.74°C
over the past 100 years

1995–2006 rank among the warmest years since 1850
According to the Intergovernmental Panel of Climate
Change (IPCC), the increase in global average
temperature is "very likely" due to observed changes
in greenhouse gas (especially CO2) concentrations

Concentrations of CH4, CFCs, HCFCs, N2O, O3, and SO2 are
also increasing.
39
Fig. 27.11 Historic trends in greenhouse gas emissions as
illustrated by changes in the atmospheric concentrations of
methane and nitrous oxide.
40
27.6 Greenhouse Gases Are Changing the
Global Climate
 General circulation models (GCMs) have been
developed to help scientists determine how
increasing concentrations of greenhouse gases
may influence large-scale patterns of global climate.
 Although GCMs from different research institutions
differ in their predictions, certain patterns
consistently emerge
 Predict an increase in the average global
temperature and precipitation
 Expect warming to be greatest during the
winter months in the northern latitudes
 Predict increased variability of climate (e.g.,
more storms and hurricanes)
41
Fig. 27.12 Time series of globally averaged (a) surface air
temperature change, and (b) precipitation change from various
global circulation models under a scenario of rising atmospheric
contractions of greenhouse gases developed by the IPCC.
42
Fig. 27.13 Mean changes in (a) surface air temperature (oC)
for Northern hemisphere winter (DJF– December, January,
and February).
43
Fig. 27.13 Mean changes in (a) surface air temperature (oC)
for Northern hemisphere summer (JJA– June, July, and
August).
44
Fig. 27.13 Mean changes in (b) precipitation (mm/day) for
Northern hemisphere winter (DJF– December, January, and
February).
45
Fig. 27.13 Mean changes in (a) precipitation (mm/day) for
Northern hemisphere summer (JJA– June, July, and August).
46
27.6 Greenhouse Gases Are Changing the
Global Climate
Aerosols(氣物質), small particles suspended in the
atmosphere, absorb solar radiation and scatter it back to
space  reduction in the amount of radiation reaching
Earth's surface
Natural sources of aerosols




Winds blowing dust particles
Sea spray
Biomass burning
Volcanoes
Human sources of aerosols

Burning of fossil fuels  sulfate particles
47
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 Climate influences
 Physiological and behavioral response of
organisms
 Birth, death, growth rates of populations
 Relative competitive abilities of species
 Community structure
 Productivity
 Cycling of nutrients
48
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 Current research focuses on the response of
individuals, populations, communities, and
ecosystems to greenhouse warming.
 Relationship of European tree species and mean
annual temperature and rainfall.(Fig. 27.14)
 A. Prasad and L. Iverson (Northeast Research
Station, U.S. Forest Service) developed
statistical models to predict tree species
distribution based on shifts in temperature and
precipitation at doubled levels of CO2
49
Fig.27.14 Abundance (biomass t/ha) of three common
European tree species as it relates to mean annual
temperature (T) and precipitation (P).
50
Fig. 27.15 Distribution of (a) red maple, (b) Virginia pine, and (c)
white oak under both current climate and doubled CO2 climate as
predicated by the GFDL general circulation model.
51
Fig. 27.15 Distribution of (a) red maple, (b) Virginia pine, and
(c) white oak under both current climate and doubled CO2
climate as predicated by the GFDL general circulation model.
52
Fig. 27.15 Distribution of (a) red maple, (b) Virginia pine, and (c)
white oak under both current climate and doubled CO2 climate as
predicated by the GFDL general circulation model.
53
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 The distribution and abundance of animals are
directly related to features of the climate
 Northern limit of the winter range of the Eastern
phoebe (燕雀類的小鳥).(Fig. 27.16)
54
Fig. 27.16 Map showing the existing distribution of the Eastern phoebe
along the current average minimum January temperature isotherm, as well
as the predicted isotherm under a changed climate. The predicted isotherm
is based on temperature change due to a doubling of atmospheric CO2
concentration as predicted by the GFDL general circulation model.
55
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 The collective shifts in individual species'
distributions will change regional patterns of
species diversity.
 Prasad and Iverson examined the resulting
changes in local and regional patterns of tree
species richness.
 A marked decline in tree species richness in
the southeastern United States is predicted by
their models. (Fig. 27.17)
56
Fig. 27.17 (a) Current tree species richness as determined from
forest inventory data, and (b) potential future richness under the
climate patterns predicted by he GFDL climate model under
conditions of doubled atmospheric concentration of CO2.
57
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 For other taxonomic groups of organisms, we must
depend on more general relationships between
environmental features and patterns of diversity.
 D. Currie (University of Ottawa) found that the
richness of most terrestrial animal groups
covaries with features of the physical environment
related to energy and water balance of
organisms.
 More recently, Currie used the relationship between
climate and species richness to predict changes
under conditions of a climate change.
58
Fig. 27.18 Changes in (a) bird, and (b) mammal species
richness, relative to current species richness resulting from the
climatic changes associated with doubling of atmospheric CO2.
59
Fig. 27.18 Changes in (a) bird, and (b) mammal species
richness, relative to current species richness resulting from the
climatic changes associated with doubling of atmospheric CO2.
60
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 Changes in the growth and reproductive rates
of species in response to climate change may
influence the nature of species interactions
 This could alter patterns of zonation and
succession.
 The International Tundra Experiment (ITEX)
aims to understand the potential impact of
warming at high latitudes on tundra ecosystems
 Passive warming of tundra vegetation (Fig.
27.19)
 Manipulating snow depth
61
Fig. 27.19 The International Tundra Experiment (ITEX) uses
small, passive clear plastic, open-top chambers to warm the
tundra and extend the growing season. The chambers raise the
daily temperature of the tundra plant canopy by 1.5 oC to 1.7 oC,
which is in the range predicted by global climate simulations.
62
27.7 Changes in Climate Will Affect
Ecosystems at Many Levels
 Vegetation is indirectly affected by climate change,
and these indirect effects could cause a significant
rise in CO2 emissions from soils.
 Decomposition proceeds faster under warmer,
wetter conditions.
 Increased microbial respiration
63
Ecological Issues: Who Turned Up the Heat?
 Is the Earth's climate changing? YES!
 How do we know?
 Direct measures from instruments (instrumental
record) and observations of other surface
"weather variables"
 Land surface
 Sea surface
 Upper atmosphere
64
Fig. 1 (a) Combined annual land-surface air and sea-surface
temperature anomalies (溫度異常) (oC) from 1880 to 2010.
65
(b) Global pattern of surface temperature anomalies, as
defined in (a)
66
Ecological Issues: Who Turned Up the Heat?
 The global average surface temperature has
increased by 0.74°C since the early 20th century
 Minimum temperatures (0.2°C/decade) are
increasing about twice the rate of maximum
temperatures (0.1°C/decade)
 Global ocean heat content has increased
significantly since the late 1950s (0.4°C/decade)
 Most has occurred in the upper 300 m of the
ocean.
67
Ecological Issues: Who Turned Up the
Heat?
 Why is the climate changing?
 May be because instrumentation is located in urban areas that
are typically warmer than surrounding rural areas.
 IPCC has established that the warming trend is
independent of urbanization.
 It may be that there is not enough long-term data to fully
assess.
 Maybe the current warming is still in recovery following the
last glacial maximum (18,000 to 20,000 years ago).
 IPCC has stated that increase in global average temperature is
"very likely" due to observed changes in greenhouse gas
concentrations.
68
27.8 Changing Climate Will Shift the Global
Distribution of Ecosystems
 As Earth's climate has changed in the past, the distribution
and abundance of organisms (and their communities and
ecosystems) have changed.
 It is virtually impossible to develop experiments to study the
long-term response of communities to future climate change.
 Biogeographical models that relate the distribution of
ecosystems to climate may be the most informative.
 Tropical rain forest distribution would be reduced by 25
percent under conditions of doubled CO2
 This would devastate tropical rain forest ecosystems and
the diversity of life they support.
69
Fig. 27.20 Maps of the areas in the
tropical zone that could possibly
support rain forest ecosystems as
predicted by the Holdridge
biogeographical model of ecosystem
distribution. Map (a) is the area of
tropical rain forest under current
climate conditions, and (b) is the
predicted area under changed climate
conditions predicted by the United
Kingdom Meteorological Office general
circulation model for a doubled
atmospheric CO2 concentration.
70
Fig. 27.20 Maps of the areas in the
tropical zone that could possibly
support rain forest ecosystems as
predicted by the Holdridge
biogeographical model of ecosystem
distribution. Map (a) is the area of
tropical rain forest under current
climate conditions, and (b) is the
predicted area under changed climate
conditions predicted by the United
Kingdom Meteorological Office general
circulation model for a doubled
atmospheric CO2 concentration.
71
Fig. 27.20 Maps of the areas in the
tropical zone that could possibly
support rain forest ecosystems as
predicted by the Holdridge
biogeographical model of ecosystem
distribution. Map (a) is the area of
tropical rain forest under current
climate conditions, and (b) is the
predicted area under changed climate
conditions predicted by the United
Kingdom Meteorological Office general
circulation model for a doubled
atmospheric CO2 concentration.
72
27.9 Global Warming Would Raise Sea
Level and Affect Coastal Environments
 During the last glacial maximum (18,000 years
ago), sea level was 100 m lower than today.
 Over the past 100 years, sea level has risen 1.8
mm/year due to thermal expansion of ocean
waters and melting of glaciers.
73
Fig. 27.21 Time series of global mean sea level (deviation from
the 1980-1990 mean) in the past and as projected for the future.
For the period before 1870, global measurements of sea level are
not available.
74
27.9 Global Warming Would Raise Sea
Level and Affect Coastal Environments
 IPCC estimates that global mean sea level will rise
by 0.18 to 0.59 m from 1990 to 2100.
 A rise of this magnitude will have serious effects on
coastal environments (natural and human
populations).
 Thirteen of the world's largest cities are
located on coasts.
75
27.9 Global Warming Would Raise Sea
Level and Affect Coastal Environments
A sea-level rise will have major effects on coastal
ecosystems





Direct inundation (淹沒) of low-lying wetlands and dryland
areas
Erosion of shorelines
Increased salinity of estuaries and groundwater
Rising coastal water tables
Increased flooding and storm surges
Estuarine and mangrove ecosystems would no longer
be able support the coastal fisheries
76
27.10 Climate Change Will Affect
Agricultural Production
Domesticated plant species (wheat, maize, corn)
exhibit environmental tolerances to temperature and
moisture that control survival, growth, and
reproduction

The regions suitable for growing these crops will change
Increasing concentrations of CO2 may benefit these
crop plants

Cotton yield increased by 60 percent and wheat by more than
10 percent under elevated CO2 and irrigation.
77
Fig. 27.23 Regional shifts in areas suitable for crop
production under a changed climate as predicted by the
Goddard Institute for Space Studies GCM: (a) Shift in the
region suitable for corn production in the United States.
78
Fig. 27.23 Regional shifts in areas suitable for crop
production under a changed climate as predicted by the
Goddard Institute for Space Studies GCM: (b) Shift in the
region suitable for corn production in the northern Japan.
79
27.10 Climate Change Will Affect
Agricultural Production
 The negative effects of climate change are to
some extent compensated for by increased
productivity resulting from elevated CO2
 According to a collaborative study carried out
by the Environmental Change Unit (Oxford
University)
 An increase in productivity would be most
prevalent in developed countries.
 In developing nations, productivity would
decline by as much as 10 percent.
80
Fig. 27.24 Changes in cereal (wheat, corn, and rice) production in response to climate
change predictions from three different general circulation models. Changes are relative
to base line estimates of production for the year 2060. Four different scenarios are
evaluated. (1) Changes in grain production in response to changes in climate only, (2)
changes in climate together with expected increases in productivity due to elevated CO2,
(3) changes in production under scenario 2 plus the incorporation of level adaptations,
and (4) changes in production under scenario 2 with level 2 adaptations.
81
Fig. 27.24 Changes in cereal (wheat, corn, and rice) production in response to climate
change predictions from three different general circulation models. Changes are relative
to base line estimates of production for the year 2060. Four different scenarios are
evaluated. (1) Changes in grain production in response to changes in climate only, (2)
changes in climate together with expected increases in productivity due to elevated CO2,
(3) changes in production under scenario 2 plus the incorporation of level adaptations,
and (4) changes in production under scenario 2 with level 2 adaptations.
82
Fig. 27.24 Changes in cereal (wheat, corn, and rice) production in response to climate
change predictions from three different general circulation models. Changes are relative
to base line estimates of production for the year 2060. Four different scenarios are
evaluated. (1) Changes in grain production in response to changes in climate only, (2)
changes in climate together with expected increases in productivity due to elevated CO2,
(3) changes in production under scenario 2 plus the incorporation of level adaptations,
and (4) changes in production under scenario 2 with level 2 adaptations.
83
27.11 Climate Change Will Directly Affect
Human Health
 Effects of climate change on human health
 Direct
 Increased heat stress, asthma (氣喘),
cardiovascular and respiratory ailments
 Indirect
 Increased incidence of communicable
diseases, increased mortality/injury due to
increased natural disasters, changes in
diet/nutrition
84
27.11 Climate Change Will Directly Affect
Human Health
 Direct relationship between maximum summer
temperatures and human mortality rates
 1936: 4700 deaths due to heat-related causes
 1980: 1200 deaths (Dallas)
 1995: 566 deaths (Chicago)
 Climate change scenarios predict a significant rise
in heat-related mortality over the next several
decades
85
Fig. 27.25 This graph tracks maximum temperature (Tmax) , heat
index (HI), and heat-related deaths in Chicago each day from
July 11 to 23, 195. The maroon line shows maximum daily
temperature, the red line shows the heat index, and the bars
indicate number of deaths for the day.
86
Fig. 27.26 Average annual excess weather-related mortality for the years 1993,
2020, and 2050 in various cities of the United States. Future projections of
weather-related mortality has based on changes in climate predicted by the
Geophysical Fluid Dynamics Laboratory GCM.
87
27.11 Climate Change Will Directly Affect
Human Health
 The distribution and rates of transmission for
various infectious diseases will be influenced by
climate patterns.
 Insects are a primary vector of human disease
 Insect-borne viruses (arbovirus) —
mosquitoes, ticks, blood flukes
 Changes in climate will affect the distribution of
these insects.
88
27.11 Climate Change Will Directly Affect
Human Health
 Malaria is an insect-borne disease (female
Anopheles mosquito transmits protozoan parasite)
 Optimal insect breeding temperature = 20 –
30°C
 Dengue and yellow fever are insect-borne
diseases (Aedes mosquito transmits virus)
 Colonization by this mosquito is limited to
areas with an average daily temperature of 10°C
or higher
89
27.12 Understanding Global Change Requires the
Study of Ecology at a Global Scale
 Global carbon cycle
 Ecosystems influence atmospheric CO2 and
regional climate patterns
 Increase or decrease in productivity with
elevated CO2?
90
27.12 Understanding Global Change Requires the
Study of Ecology at a Global Scale
Loss of productivity with elevated CO2 (negative
feedback)
If the global distribution of tropical rain forests
declines dramatically 



Reduction in global primary productivity
Decrease in the uptake of CO2 from the atmosphere
Loss of CO2 storage as organic carbon in biomass
As CO2 levels further increase, the drying of these
former areas will kill plants, increase fires, and
transfer carbon to the atmosphere
91
27.12 Understanding Global Change Requires the
Study of Ecology at a Global Scale
 Increase in productivity with elevated CO2
(positive feedback)
 If world's ecosystems become more productive,
they will take up more CO2 from the
atmosphere.
92
27.12 Understanding Global Change Requires the
Study of Ecology at a Global Scale
 Changes in the distribution of rain forests can
directly affect climate by altering regional
precipitation patterns
 Removing the forest reduces transpiration and
increases runoff to rivers.
 Large-scale deforestation in the Amazon
Basin would result in a significant reduction in
annual precipitation  change the region's
climate
93
27.12 Understanding Global Change Requires the
Study of Ecology at a Global Scale
G. Bonan (NCAR) has studied the effect of warming
under elevated CO2 in northern latitudes.
Warming would significantly reduce snow cover and
shift the boreal forest to the north
Reduced snow cover and northern movement of the
boreal forest would reduce the regional albedo 
positive feedback loop

Snow has a high ability to reflect solar radiation back to
space (albedo)
94
Chapter 27 Global Climate Change
Ayo NUTN website:
http://myweb.nutn.edu.tw/~hycheng/