Earth Systems Science
Prof. Joseph Alcamo
Center for Environmental Systems Research
University of Kassel, Germany
Lecture I: Introduction -- Definitions and Driving Forces
Prof. Joseph Alcamo
Earth Systems Science
Earth Systems Science
Objectives:
Understanding the basic principles of earth systems science especially as it
concerns the global water system, global land resources, and atmospheric
change.
Prof. Joseph Alcamo
Earth Systems Science
Earth Systems Science
Lecture I: Definitions and Driving Forces
Prof. Joseph Alcamo
Earth Systems Science
The Concept of “Earth System”
Definition: earth system:
The various large-scale living and non-living components of the earth,
together with their interactions.
Definition: earth system science
Branch of knowledge dealing with Earth as a whole; study of the sum of
processes operating in the atmosphere, hydrosphere, biosphere,
cryosphere, and lithosphere, and their interactions
What is included: earth science (atmospheric sciences, geosciences) plus
”large scale“ biological/ecological sciences.
Prof. Joseph Alcamo
Earth Systems Science
The Concept of “System”
Definition of a system: A set of components that interact and
function together as a unit.
Characteristics:
• Complexity ≈ Number of components and connections.
• “Open” or “closed” system:
A closed system = no mass or energy exchange with its
environment (surroundings). With respect to mass, the earth
system is almost a closed system.
An open system = significant mass or energy exchange with its
environment. With respect to energy, the earth system is almost
an open system.
Prof. Joseph Alcamo
Earth Systems Science
Example of an Open System
Solar constant
1350 W/m2
Prof. Joseph Alcamo
Earth Systems Science
The “Spheres” of
the Earth System
Prof. Joseph Alcamo
Earth Systems Science
Spheres of the Earth System
• Atmosphere – Gas and aerosol component of the earth
system above the lithosphere.
• Lithosphere – Non-living part of the soil environment.
• Hydrosphere – Water-related component of the earth
system – groundwater, soil water, lakes, rivers, oceans.
• Biosphere – Total living component of the earth system.
Sometimes
• Cryosphere – Areas of permanent/predominantly ice and
snow.
• Ecosphere – Domain of living part of the environment.
• Technosphere – Domain of society
Prof. Joseph Alcamo

Earth Systems Science
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Prof. Joseph Alcamo
Earth Systems Science
Biogeochemical cycles
Definition: Cycles of elements through the atmosphere, hydrosphere, lithosphere, and
biosphere.
Especially important because they make available the critical elements to support life.
Prof. Joseph Alcamo
Earth Systems Science
Driving Forces of Global Environmental
Change
Definition of driving forces: With respect to the earth
system, the determinants of environmental changes.
Prof. Joseph Alcamo
Earth Systems Science
Prof. Joseph Alcamo
Earth Systems Science
Driving Forces of Global Environmental Change
Proximate
Drivers
Emissions to the
atmosphere
Emissions to the
hydrosphere
Land use changes
Soil degradation
Prof. Joseph Alcamo
Earth Systems Science
Secondary
driver
Prof. Joseph Alcamo
Earth Systems Science
Anthropogenic Driving Forces
Secondary
Drivers
Proximate
Drivers
Energy production
Agriculture
Industry
Fishery
Emissions to the
atmosphere
Emissions to the
hydrosphere
Tourism
Household
consumption
Secondary
driver
Prof. Joseph Alcamo
Land use changes
Soil degradation
Transport
Earth Systems Science
Population Growth Rate
Primary driver
Prof. Joseph Alcamo
Earth Systems Science
Anthropogenic Driving Forces
Primary
Drivers
Secondary
Drivers
Proximate
Drivers
Change in population
Energy production
Agriculture
Industry
Fishery
Emissions to the
atmosphere
Emissions to the
hydrosphere
(growth or shrinkage)
Change in economy
(growth or shrinkage)
Structural change in
the economy
Tourism
Technological change Household
Societal changes (e.g. consumption
Institutions, Law,
Transport
Land use changes
Soil degradation
Governance)
Prof. Joseph Alcamo
Earth Systems Science
Primary Driver: Population Change
Exponential Growth
World Population Growth, in Billions
Number of years to add each billion (year)
All of Human History
First Billion
Second
130 (1930)
30 (1960)
Third
Fourth
(1800)
15 (1975)
Fifth
12 (1987)
Sixth
12 (1999)
Seventh
14 (2013)
Eighth
14 (2027)
Ninth
21 (2048)
Sources: First and second billion: Population Reference Bureau. Third through ninth billion: United Nations, World
Population Prospects: The 2004 Revision (medium scenario), 2005. www.prb.org/presentations/gb-poptrends_all.ppt
© 2006 Population Reference Bureau
Basic demographic variables
Rate of natural increase
=
birth rate - death rate
Birth rate (natality)
=
births
.
(%)
1000 people – year
Death rate (mortality)
=
deaths
.
(%)
1000 people – year
General fertility rate
(per 1000 women
in reproductive years)
=
births
(%)
1000 women – year
Geographic Variability of Demographic Indicators
Birth rate (%/a)
Factors Affecting Birth Rate
•
•
Fertility Rate
Population Pyramid
Factors Affecting Birth Rate
Fertility Rate
• Educational level of
women
• Family planning
programs
Total Fertility Rate
• Changing role of
(births/woman-year)
children within
workforce (reduction
of child labor)
.
Net result: fertility rates higher in developing countries,
but decreasing
worldwide
Factors Affecting Birth Rate
Population Pyramid
•
Number of people of each gender in various age groups
World-wide summary
Reference:
US Census Bureau.
Global Population
Profile 2002
Factors Affecting Birth Rate
Population Pyramid
•
Number of people of each gender in various age groups
•
Despite decreasing fertility rates, many new parents in developing
countries.
Many women of
parenting age.
Source: John W. Kimball
Biology Textbook
Population: Industrialized and Developing
Population: Industrialized and Developing
World Population Growth 1950-2050 Population in billions
World: 7,225,984,325
14:50 GMT 12 April, 2014
Source: United Nations, World Population
Prospects as Assessed in 2012.
Demographic Transition
Source:
UNEP, GEO-5
Demographic Transition – Four Stages
Stage
Feature
Consequences
1
Pre-industrial, large families to support
agriculture. Poor nutrition, sanitation (e.g.17th
C Eur).
high birth rate,
high mortality
2
Early industrial phase. Improved nutrition,
sanitation
high birth rate,
lower mortality
3
Later industrial phase. Less agriculture, fewer
large families needed. Education/prosperity
reduces desire for large families (e.g. U.S.,
Can, Rus.)
lower birth rate,
lower mortality
4
Post-industrial. Higher level of prosperity,
education. (Dk, Swe)
low birth rate  mortality
Demographic Transition – Four Stages
Stage
Feature
Consequences
1
Pre-industrial, large families to support
agriculture. Poor nutrition, sanitation (e.g.17th
C Eur).
high birth rate,
high mortality
2
Early industrial phase. Improved nutrition,
sanitation
high birth rate,
lower mortality
3
Later industrial phase. Less agriculture, fewer
large families needed. Education/prosperity
reduces desire for large families (e.g. U.S.,
Can, Rus.)
lower birth rate,
lower mortality
4
Post-industrial. Higher level of prosperity,
education. (Dk, Swe)
low birth rate  mortality
Demographic Transition
t 2x = 0.69
r
= 0.69
0.015
= 57.5 yrs
Growth rate (%/yr)
DDT Campaign
Death rate drops
faster than birth rate
Source: John W. Kimball
Biology Textbook
Source: FAO
Population: Urbanization
1950 29%
2010 50%
2050* 66%
* UN, World Urbanization
Prospects (2104)
Scenarios of Global Population
(UN Revisions 2012)
High
Medium
Low fertility
Medium fertility: converge on 1.85
Low: - 0.5
High: +0.5
Prof. Joseph Alcamo
Introduction to Earth Systems Modeling
Summary about Global Population Trends
Industrialized countries
•
Birth rate  mortality
•
Population stabilizing
Developing countries
•
Fertility decline  birth rate decline  population
growth slows
•
But, large population reaching parenting age 
population increase first exponential, then linear, then
stabilizes or declines
•
World population
2014  7.2 B
2100 (UN, 2012)  7 to 17 B
Implication of Population Changes on Global
Change
Why Worry About Population Changes?
Population trends  affect the number of consumers of resources,
and the type and intensity of consumption (secondary drivers) 
changes in magnitude and type of greenhouse gas emissions,
wastewater discharges, land requirements (proximate drivers) ...
Anthropogenic Driving Forces
Primary
Drivers
Change in population
Secondary
Drivers
Proximate
Drivers
Energy production Emissions to the
(growth or shrinkage)
atmosphere
Agriculture
 Change in economy
Emissions to the
Industry
(growth or shrinkage)
hydrosphere
Structural change in Fishery
Land use changes
the economy
Tourism
Soil degradation
Technological change Household
Societal changes (e.g. consumption
Institutions, Law,
Transport
Governance)
Another prim driver -- econ