Lecture OutlinesNatural 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, Ca2010

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

Figure 1.5

• 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

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

Figure 1.7

• Human population has grown to over 6.7 billion people in 2008

• Growth rate is exponential

Side Note: Interest Paid on Money: An Example of Exponential Growth

Visualize exponential growth in terms of doubling time

Figure 1.9

• 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

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

• 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 Insert figure 1.10 here• 1974: ~4 billion• 1987: ~5 billion• 1999: ~6 billion

• By 2013, projected population ~7 billion Figure 1.10

The Last 10,000 Years of Human History

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

• 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

Figure 1.15

Carrying Capacity

– BUT Earth’s resources are finite, so solutions are temporary

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

Figure 1.14

• 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

• 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

Carrying Capacity

End of Chapter 1