Causes of disasters
Climate change will create new hazards such as glacier melting, sea level
rise and extreme weather events in proportions never seen before. This will
aggravate the existing disaster risks and vulnerabilities and expose millions of
people never affected before around the world.
In its Fourth Assessment Report, the Intergovernmental Panel on Climate
Change (IPCC) predicted that by 2100:
• Global average surface warming will increase by between 1.1°C and
• Sea level will rise by between 18cm and 59cm; sea-level rise, coupled
with coastal storms, will increase the risks of flooding and threaten
• Oceans will become more acidic and warmer.
• Extreme heatwaves and heavy rainfalls will become more frequent.
• More heatwaves will increase death rates among the elderly, very young,
chronically ill and socially isolated.
• Higher latitudes will experience more precipitation; subtropical land
areas will become more arid.
• Tropical cyclones (including typhoons and hurricanes) will become more
intense, with higher peak wind speeds and heavier precipitation, as
tropical sea surface temperatures increase.
• Regions hardest hit will include the Arctic, sub-Saharan Africa, small
islands, developing states, Asian deltas and coastal zones.
• Increased drought in some regions will lead to land degradation, crop
damage and reduced yields; livestock deaths and wildfire risks will
increase, and people dependent on agriculture will face food and water
shortages, malnutrition and increased disease, with many being forced to migrate.
• Greater rainfall in some areas will trigger more floods and landslides, with
consequent disruption to agriculture, urban settlements, commerce and
• Increases in the number and intensity of powerful cyclones will affect coastal
regions and threaten very large additional losses of life and property.
• As temperatures rise, glaciers melt, increasing the risk of lake bursts and
disastrous floods; as mountain glaciers recede, farmers and towns downstream
that depend in the summer months on glacial melt water will increasingly be at risk.
What can be done?
• Make disaster risk reduction a national and local priority, with strong institutions
to implement decisions.
• Set up early warning systems that reach all people, in time for appropriate
action, and accompany the warnings with helpful advice.
• Incorporate climate risk in all urban planning and water and forest management
• Maintain and strengthen coastal wave barriers, river levees, flood ways and
• Have adequate drainage systems to avoid flooding.
• Incorporate climate risks in infrastructure projects, especially in hospitals,
schools and water supplies.
• Support diversification, including new sources of income, new crops and
agricultural techniques, and new ways to improve water uptake and reduce
• Build mechanisms that will get people out of harm’s way in a hazard and
prepare shelters to protect them when they are forced to move.
Rapid and unplanned urbanization
The rapid growth of cities, combined with climate change and the urban
population explosion, will create new stresses for urban settlements and make
city dwellers increasingly vulnerable.
• One out of every two people now lives in a city; this proportion will go on
rising; by 2030, 5 billion of the planet’s expected 8.1 billion population will
• One in three of the urban population lives in marginal settlements or
crowded slums with inadequate access to clean water, sanitation, schools,
transport and other public services
• One city dweller in four lives in absolute poverty; by 2030, two-thirds of
humankind will live in cities and three billion in slums.
• Eight of the 10 most populous cities on the planet are vulnerable to
earthquakes; 6 of the 10 are vulnerable to floods, storm surges and tsunamis.
• Ineffective land-use planning, inadequate enforcement of building codes
and faulty construction standards put millions at risk.
• By 2015, 33 cities will have at least 8 million residents; of these, 21 are in
coastal areas and particularly vulnerable to meteorological hazard driven
by climate change (e.g. Dhaka, Shanghai, Manila, Jakarta, and Mumbai).
Cities with weak governance and small and medium-sized urban areas are
more vulnerable to disasters as they have weaker capacities to manage
urban growth, deforestation and destruction of coastal systems.
According to UN-HABITAT, up to 3,351 cities around the world are located in
low-lying coastal zones that may be affected by rising sea levels. Six out of the
10 largest cities are also located along seismic fault lines.
What can be done?
• Have national and local budgets to systematically integrate disaster risk
reduction in all aspect of urban planning
• Plan urbanization and avoid building in risk areas.
• Avoid the development of slums, offering safe lands to low-income families.
• Have safer schools, hospitals, roads, bridges than can withstand any type
• Identify high-risk areas, build disaster risk reduction into development
programmes and implement effective disaster recovery policies.
• Integrate seismic risk assessment in the construction of buildings in areas
exposed to earthquakes.
• Involve people at risk by educating them on disaster risk reduction and in
making their own neighborhoods safer; this effectively empowers people
and increases their capacity to respond to disaster.
• Protect communities by installing early warning systems.
• Make warnings more effective with regular drills and increase community
ability to foresee, prepare for and cope with disasters.
• Give poor communities access to financial mechanisms to protect houses
Making Cities Resilient
UNISDR launched a worldwide campaign in 2010 to make cities more
resilient. The campaign proposes a checklist of Ten Essentials for Making
Cities Resilient that can be implemented by mayors and local governments.
The checklist is derived from the five priorities of the Hyogo Framework
for Action 2005-2015: Building the Resilience of Nations and Communities
to Disasters, a key instrument for implementing disaster risk reduction.
Achieving all, or even some, of these Ten Essentials will help cities to
become more resilient.
Poverty and socio-economic inequalities are aggravating disaster factors. They
not only make poor people more vulnerable to disasters but they trap them in a
vicious circle of poverty.
• Disasters hit poor people the hardest. It is not only true in developing
countries but also in developed countries. Levels of vulnerabilities are
highly dependent upon the economic status of individuals, communities
and nations. The most affected people during the Katrina hurricane in the
United States were the poor communities. During the hurricane season
in 2008, Haiti was the hardest hit among the Caribbean states.
• Fifty-three per cent of affected people by disasters live in developing
countries while 1.8 per cent lives in developed countries. Over 95 per
cent of the people killed by disasters lived in middle and low-income
countries, using World Bank classification based on gross national
income (GNI) per capita.
• Disasters affect poor countries and poor communities disproportionately.
The World Bank reports that: “This disproportionate effect on developing
countries has many explanations. Lack of development itself contributes
to disaster impacts, both because the quality of construction often is low
and building codes, and registration processes, and other regulatory
mechanisms are lacking, as well as numerous other development
priorities displace attention from the risks presented by natural events” (
Hazards of Nature, Risks to Development, World Bank 2006).
• A country’s level of development has a direct impact on the damage
natural hazards inflict on populations. Less-developed countries suffer
most, as they are more frequently hit and more severely affected. Their
weak infrastructure and limited capacity for prevention makes them more
vulnerable than wealthy, industrialized nations.
One half of the world population is vulnerable to disasters because of
their social living conditions. Slums and poor urban settlements are the
most exposed to disasters.
• An estimated 1 billion people worldwide live in slums and shanty towns,
which are vulnerable to disasters.
• Extensive research shows the poor are more likely to occupy dangerous,
less desirable locations, such as flood plains, river banks, steep slopes
and reclaimed land because the price is cheaper.
• Poor people tend to live in poorly built and unprotected building that will be
the first to collapse in any disaster.
• Losses from disasters are most devastating to the poorest people.
• Disasters have long-term consequences on poor people as they have less
means to recover. Poor people not only lose their family members, houses,
main source of income and livelihoods when disasters happen but also
become more vulnerable to future disasters.
What can be done?
Establish urban development programmes that reduce the creation of
slums in risk areas and prevent the growth of housing on dangerous
slopes or flood plains.
Provide the poor with access to lands that are safe.
• Involve the poorest communities in building their own capacity to resist
disaster since they have most to lose, and to give them a greater political
stake in the community.
• Give the poorest people full access to early warning systems, preparedness
measures and at the same time access to financial mechanisms that can
help them protect their homes, health and livelihoods
Communities can all too often increase the probability and severity of disasters by
destroying the forests, coral reefs and wetlands that might have protected them.
• Forests once covered 46 per cent of the Earth’s land surface – half of these
have disappeared; only one-fifth of the Earth’s forests remain undisturbed.
• Coral reefs are home to one-fourth of all marine species; 60 per cent of
coral reefs could be lost in the next 20-40 years.
• The expansion of deserts and the degradation of land threaten nearly
one-quarter of the planet’s land surface; more than 250 million are directly
affected by desertification and 1 billion are at risk.
• Global warming could be accompanied by widespread species loss,
ecosystem damage, flooding of human settlements and greater frequency
and severity of other disasters due to vulnerability to natural hazards.
What can be done?
• Undertake land-use planning with an ecosystem approach.
• Recognize the risk reduction function of ecosystems in environmental
policies and legislation.
• Identify and protect natural buffers such as forests, wetlands and coral reefs.
• Restore forests and plant mangroves to shield communities from hazards
such as storm surge, coastal flooding and tropical storms.
• Manage forests to reduce wildfire risk.
Why we should protect the environment
Wetland and forest ecosystems function as natural sponges that absorb and
slowly release surface water, rain, snow melt, groundwater and floodwater.
The destruction of such natural buffers can put tens of thousands at risk.
Mangroves, dunes and reefs, for example, act as natural physical barriers that protect
communities from coastal hazards. As they disappear, communities become at greater
risk of flooding. Likewise, deforestation makes flooding more severe because slopes
stripped of tree cover are less able to hold water. As a result, soil erosion lowers the
productivity of farmland, amplifies drought and eventually leads to desertification.
“The six countries that have best addressed the underlying risk drivers of badly
planned and managed urban development, ecosystem decline and poverty and
which have strong governance are Switzerland, Sweden, Denmark, Ireland,
Norway and Finland. The bottom six countries (Afghanistan, Chad, Haiti,
Somalia, Democratic Republic of Congo and Eritrea) are low-income nations
that are experiencing or have recently experienced conflicts or political crisis.”