Global trends show that reported natural disasters have significantly risen since the 1960s due to factors like population growth, urbanization, and climate change. Some hazards like floods and wind storms show clearer increasing trends, while others like earthquakes are more stable. Though death tolls from disasters are falling due to better disaster management, economic costs and numbers of people affected continue to rise as populations grow in hazardous areas. Reducing vulnerability and building resilience is an ongoing challenge.

1. World at risk Global Disaster
Trends

2. Hazard trends (1)

3. Hazard trends (2)
•The graph on the last slide shows that the number of reported disasters has
risen significantly in recent years.
•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 (3)
Number of natural disasters by type, 1970–2005

5. Hazard trends (4)
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• Some types of disaster show clearer trends thanothers.
• 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 ofhazardous
events.
It could be the result of global climate change and/or other environmental
changes.

6. Hazard trends (5)
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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.
There is a rising trend in the number
of people affected (see table). Notice
that 8 of the top 10 eruptions have
occurred since 1990.
This reflects growing population
density in the developing world.
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. Hurricane trends (1)
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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.

8. Hurricane trends (2)
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One certain trend is the rise in the number of people living on the UScoast.
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.

9. Global warming (1)

10. Global warming (2)
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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 30–35 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 thedecline
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.

11. Flood disaster trends (1)
Reported global flood disasters and death tolls, 1977–2007

12. Flood disaster trends (2)
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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.
• Separating the climate change signal from the human factors that increase flood
risk is a real challenge.

13. El Niño/La Niña
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As well as global warming, the El Niño/La Niña cycle is known to haveclimatic
consequences on a global scale.
• Changes in Pacific Ocean circulation have knock-on weather effects in otherparts
of the world through teleconnections.
• 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 layerof
complexity to the calculation of hazardrisk.

14. Summer 2007 UK floods
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In summer 2007, many areas in theUK
received over 100 mm of rainfall in 24
hours, causing widespread flooding.
The media were quick to link the
unprecedented flooding (50,000 homes
and 7,000 businesses flooded, total cost
£3 billion+) to global warming.
The basic cause of the flooding was a
southerly jet stream, meaning low
pressure and rain over the UK at a time
when high pressure was to be expected.
Many meteorologists have linked this
situation to La Niña conditions in the
Pacific.
Rainfall pattern, summer 2007

15. Human trends (1)
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Some trends among the human population add to increasingrisk.
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 tocope
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 (2)
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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 areremoved.
• With no vegetation to intercept rain, flash-flood risk rises.
• Without the evapotranspiration provided by trees, rainfall becomes more variable
and aridity increases.
Occasional flash floods can produce a cocktail of increased hazard risk and falling
food and water security.

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 (1)
Disaster management cycle
Falling death tolls suggest
improvements in disaster
management.

19. Disaster management (2)
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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 todisasters.
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.