Lecture Outlines
Natural Disasters, 7th edition
Patrick L. Abbott
Natural Disasters
and the Human Population
Natural Disasters, 7th edition, Chapter 1
Natural Disasters in 2004 and 2005
• More than 280,000 people killed by natural
disasters in 2004, almost 100,000 in 2005
• 2005 Pakistan earthquake: 88,000 people killed
– 3.3 million left homeless
– 2nd wave of deaths from winter storm
• 2005 Hurricane Katrina
– 2004 Hurricane Ivan was dress rehearsal, close miss
– 2005 Hurricane Katrina was direct hit on Mississippi,
engulfed much of Gulf Coast
– Failure of Mississippi River and Lake Pontchartrain
levees flooded parts of New Orleans up to 20 feet
Evidence of a natural disaster? Ocotillo, Ca
2010
Bear Grylls??
Human Fatalities in Natural Disasters
• Sawtooth-shaped curve caused by largest natural disasters
• Biggest killers (in order): hurricanes, earthquakes, floods, severe
weather, landslides, volcanic eruptions, tornadoes and tsunami
• Most mega-killer disasters occur in densely populated belt through
Asia, along Indian Ocean – number of fatalities is proportional to
density of population
• Effects on survivors
– Increase in altruism
Figure 1.4
Economic Losses from Natural Disasters
• Destruction and damage to structures, loss of productivity
and wages
• Increase in economic losses over time is result of increase
in human population and urbanization
• Most expensive events caused by storms and occurred in
U.S., Europe and Japan
Natural Hazards
• Hazard exists even where disasters are infrequent
• Evaluate site risk
• Mitigation prior to event
– Engineering, physical, social and political
plans and actions to reduce death and
destruction from natural hazards
• Mitigation after event
– Rebuilding and re-inhabiting same site
– Case history: Popocatepetl Volcano, Mexico
• Eruptions in 822, 1519 and beginning
again in 1994
• Currently 100,000 people living at base
Figure 1.5
Magnitude, Frequency, and Return Period
• Inverse correlation between frequency (how often it occurs) and
magnitude (how big it is) of a process
– Frequent occurrences are low in
magnitude, rare occurrences are
high in magnitude
– Small-scale activity is common, big
events are rare
– Larger the event, longer the return
period (recurrence interval)
• Probability estimates of various size
(10-fatality, 1000-fatality, etc.)
occurrences can be considered
• Cost-benefit ratio can be considered in
conjunction with return-period of given
magnitude event
Overview of Human Population History
• Difficult to assess early human population growth
• Human species ‘began’ approximately 160,000 years ago,
with a few thousand people
• Human
population has
grown to over 6.7
billion people in
2008
• Growth rate is
exponential
Figure 1.7
Side Note: Interest Paid on Money:
An Example of Exponential Growth
Visualize exponential growth in terms of doubling time
• Number of years for population to
double in size, given annual percentage
growth rate
• Doubling time =
70
% growth rate/year
• Example of interest paid on money
– Linear growth: $1000 + $100 / year
– Exponential growth: $1000 + 7% / year
• Example of water lily plant in pond
– Doubles in size every day
– Covers half the pond the day before it
covers the whole pond
Figure 1.9
The Last 10,000 Years of Human History
• Flat population growth curve until 8,000 years ago
– Agriculture established
– Domestication of animals
– Growth rate increased to 0.036%/year
• By 2,000 years ago, population ~200 million people
– Better shelter, food, water supplies  faster population growth
– Growth rate of 0.056%/year
• By 1750, population
~800 million people
Figure 1.8
The Last 10,000 Years of Human History
• By 1750, population ~800 million people
– Public health principles, causes of disease recognized
– Birth rates soared, death rates dropped
•
•
•
•
•
•
1810: ~1 billion
1925: ~2 billion
1960: ~3 billion
1974: ~4 billion
1987: ~5 billion
1999: ~6 billion
Insert figure 1.10 here
• By 2013, projected population ~7 billion
Figure 1.10
The Human Population Today
• Present population: (insert number)
– Growth rate = 1.2%/year
– Doubling time = 58 years
• Growth rate =
fertility (birth) rate – mortality (death) rate
• Human population grows by about 80 million
people per year
Future World Population
• Demographic transition theory:
– Mortality and fertility rates decline from high to low levels
because of economic and social development
• Population Reference Bureau estimates world population
growth rates are dropping
– From 1.8% in 1990 to 1.2% in 2008
– Due to urbanization and increased opportunities for women
Future World Population
Figure 1.12
Future World Population
• BUT population explosion continues
– From 1950 to 2000 population grew from 2.5 billion to 6 billion
– Growth rate of 1.2%/year means population of 9 billion in 2050
• Consider no. of births / woman to predict 2150 population
– Average 1.6 children/woman: 3.6 billion
– Average 2 children/woman: 10.8 billion
– Average 2.6 children/woman (current average): 27 billion
Demographic Divide
• Wealthy countries: low birth rates, long life expectancies
• Poor countries: high birth rates, short life expectancies
• Examples of Japan’s shrinking population vs. Nigeria’s
expanding population
Insert table 1.10
Carrying Capacity
• How many people can Earth support?
– Calculations of carrying capacity vary considerably
– Increasing amounts of food can be produced
– People can migrate from areas of famine or poverty
to less crowded or wealthier areas
– BUT Earth’s
resources are
finite, so
solutions are
temporary
Figure 1.15
Carrying Capacity
• Example of Rapa Nui (Easter Island)
– Isolated Pacific island with poor soil and little water
– Settled by 25-50 Polynesians in 5th century
• Survived easily on chickens and
yams, plenty of free time
• Developed elaborate competition
between clans with moai (statues)
– Civilization peaked at 1550, with
population of ~7000
Figure 1.14
Carrying Capacity
• Example of Rapa Nui (Easter Island)
– Reached by a Dutch ship in 1722
• Found about 2,000 people living in caves
• Primitive society, constant warfare
– Rapa Nui’s carrying capacity had been drastically
lowered by society’s actions:
• Transportation of moai had required cutting down trees
• Erosion of soil made yams scarce
• Lack of canoes made fishing difficult and escape impossible
End of Chapter 1