DM

2. Hazard trends - Cumulative
Hazard trends, 1900–2005

3. Interpretations
• Part of this rise is likely to be due to more accurate
recording and better communications with isolated
regions.
• Note the rapid rise since around 1960, when
satellite remote sensing and global
communications began.
• Population growth has led to more people living in
potentially hazardous locations. This means there
are greater numbers at risk.
• Many of these people at risk live in the developing
world, and are vulnerable due to their low coping
capacity.

4. Hazard trends
Number of natural disasters by type, 1970–2005

5. Interpretations
• Some types of disaster show clearer trends than others.
• The graph on the last slide compares trends in three disaster
types.
• The trend for earthquakes is fairly stable. There is no
evidence that the number of earthquake events is increasing.
There are likely to have been more people in earthquake-
prone areas in 2000 than in 1980, and this would explain the
slight rise in disasters.
• There is a clearer upward trend for floods and wind storms.
This may indicate an increase in the vulnerable population and
a rise in the number of hazardous events.
• It could be the result of global climate change and/or other
environmental changes.

6. Volcano Trends
• Around 50–70 volcanoes
erupt every year.
• There is no trend, upward or
downward, in eruption
frequency.
• Very large magnitude
eruptions (e.g. Mt Pinatubo in
1991) are rare.
• Notice that 8 of the top 10
eruptions have occurred since
1990.
Country Year
Number of
people
affected
Philippines
(Mt Pinatubo) 1991 1,036,065
Nicaragua 1992 300,075
Ecuador 2006 300,013
Indonesia 1982 300,000
Indonesia 1969 250,000
Comoros 2005 245,000
Philippines 1993 165,009
Papua New Guinea 1994 152,002
Ecuador 2002 128,150
Dem. Rep. Congo 2002 110,400
Top ten volcanic eruptions since
1900 by number of people affected

7. Edexcel AS Geography Unit 1
World at risk: Global hazard trends

8. Hurricane Trends
• Trends in hurricanes, especially in the Atlantic, are
a controversial matter.
• Some researchers have linked increased hurricane
activity to global warming.
• Others argue that there is a natural cycle in the
Atlantic called the Atlantic Multidecadal Oscillation
(AMO) which explains the high number of major
hurricanes in the 1940s and 1950s, and more
recently.
• Despite variations in major hurricane frequency,
there is a long-term trend in the USA of falling
hurricane-related deaths but rising economic costs.

9. Hurricane trends
• One certain trend is the rise in the number of people living on
the US coast.
• In Florida and the Gulf Coast, some coastal areas have seen
populations rise by 400% since 1980.
• This means increasing numbers of people are at risk from
hurricanes.
• Although awareness of hurricanes, education, warning and
evacuation systems have all improved in the USA, the
potential for economic loss continues to grow as coastal
populations rise.
• The full impact of rising populations was felt in 2005, when
the Florida and Gulf Coasts were struck by five major
hurricanes (Dennis, Emily, Wilma, Rita, Katrina), causing an
estimated US$120 billion in damage and the loss of 2,200
lives.

10. Global Warming
Global temperatures, 1850–2008
(IPCC – Intergovernmental Panel on Climate Change)

11. Global Warming
• Many scientists believe that increased global warming will
lead to more unpredictable weather and a rise in extreme
weather events.
• Global temperatures have risen since 1910, and at a
consistently rapid rate since the late 1970s.
• The fact that there are only few years of reliable data about
global temperatures makes the scientists’ task of accurately
predicting future changes more difficult.
• Some data, such as the 20 cm rise in global sea level since
1900 and the decline in Arctic sea ice since the 1970s, are
more reliable.
• There is growing suspicion that rising trends in drought and
flood events may herald the effects of global warming to
come.

12. Flood Disaster Trends
Reported global flood disasters and death tolls, 1977–2007

13. Flood Disaster Trends
• Trends in global flood disasters show significant rises since the
early 1990s.
• This could be an early signal of climate change.
• It may also be related to rising populations, rapid
urbanisation, deforestation and other land-use changes.

14. El Niño/La Niña
• As well as global warming, the El-Niño/La-Niña cycle is known
to have climatic consequences on a global scale.
• Changes in Pacific Ocean circulation have knock-on weather
effects in other parts of the world.
• Hazards associated with El-Niño are well known, such as
drought in Indonesia and flooding in Peru.
• El-Niño/La-Niña cycles, which are unpredictable, add yet
another layer of complexity to the calculation of hazard risk.

15. Human Trends
• Some trends among the human population add to increasing
risk.
• One of these is urbanisation. Over 50% of the world’s
population now lives in urban areas, compared to 29% in
1950.
• These crowded spaces are especially vulnerable to major
earthquakes, floods and hurricanes.
• World poverty continues to be a major issue, reducing the
capacity to cope with, and increasing the vulnerability to
hazards.
• Although the global proportion of people living on less than $1
per day is falling, total numbers rose from 36 million to 50
million in Latin America, and 164 to 314 million in Africa
between 1981 and 2001.

16. Human trends
• Pressure on land from growing populations leads to
deforestation and conversion to farmland.
• Deforestation can significantly increase hazard risk.
• The risk of landslide is greater on slopes when trees
are removed.
• With no vegetation to intercept rain, flash-flood risk
rises.
• Urban Disasters are in increasing trend as urban
population is increasing

17. Global Trends
Disasters related to human development levels
Overall, global trends show that the numbers of reported disasters and
people affected are rising, but the number of people killed by disasters is
falling.

18. Disaster Management
• Death tolls are reduced when populations are prepared for a possible
hazard.
• Some hazards can be predicted, e.g. floods, hurricanes, drought and
volcanic eruptions.
• Prediction allows for warning, and, when possible, evacuation. This
can save lives, but is unlikely to reduce economic losses.
• After a disaster, immediate rescue and relief is essential.
• ‘Rapid response’ has improved considerably over the last few
decades. International relief efforts now occur quickly in response to
disasters.
• This saves lives but the numbers affected and the economic losses
are still high.
The challenge is to ‘disaster proof’ communities using appropriate
building techniques, land-use zoning, education and developing
prevention technology. These responses are longer term, costly
and beyond the reach of many in the developing world.