World at Risk: Global Hazard Trends

  • Created by: Sophie
  • Created on: 30-03-15 13:14

Why Question Data Obtained?

  • There is no universally accepted definition of a disaster or a threshold number for classifying an event as a disaster eg 25 or 100 deaths, 1% population affected or 1% annual GDP lost or a combination of these.
  • Reporting of death numbers depends on whether direct (primary) deaths only or indirect (secondary) deaths from subsequent hazards or associated diseases are counted.
  • Location – Events in remote locations are frequently under recorded as they are not in the media spotlight.  About 10% of data is even missing from CRED.
  • Declaration of disaster deaths and casualties may be subject to political influences.  Eg After the 2004 tsunami the impact was ignored by the Myanmar (Burma) government but initially overstated and then played down by the Thai government (to protect the tourist industry).
  • Statistics are hard to collect in remote regions, like the Kashmir earthquake of 2005 or in densely populated areas like shanty towns where the exact population is not known.   
  • Time-trend analysis – means looking at historical data to produce trends.  But the interval selected can influence the pattern seen.  Also whether the means of data collection has stayed the same.  Trends can be upset by a cluster of mega disasters eg 2005-6
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Changing Nature of Hazards

Are they becoming more frequent?

Actual numbers are increasing
Decreasing no. of deaths due to improved mitigation
Capacity to cope is increasing
Cost of hazards increasing as there are more things in the way
Deforestation and damaging coral
More people affected-harder to evacuate, gridlock in cities.

Many people moved to big cities near water.

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Trend in no. of reported hazards

Hydro-meteorological: Increase in floods and storms, and more recently in droughts is responsible for driving the overall trends. Floods and storms together accounted for 70% of all disasters globally in the last 40 years. Of the total 197 million people affected by disasters in 2007, 164 million were affected by floods.

Geophysical: Earthquakes and volcanoes have increased slightly since the 70s, possible as a result of more people reporting disasters and the rising number of vulnerable populations living in hazard prone areas. In general, the trend fluctuates. Indonesia is a hotspot for tectonic activity and has two very active volcanoes. It has experienced five major earthquakes and several tsunamis since 2005, where the Indian plate is subducted beneath the Burma plate

Biological: Also shown an upward trend from a low base, often numerically exceeding geophysical hazards. May be linked to global warming which leads to more pests and diseases.

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Physical Factors towards rising trends


Rising temperatures lead to warmer oceans, spawning more hurricanes, and causing stronger convectional cells, yet again creating more hurricanes. 
Rising temperatures increases evaporation, in turn increasing rainfall and more flooding.

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A Normal Year

Trade winds move warm surface water towards the western pacific, warm moist air rises, cools and condenses, forming rain clouds.

Cold water wells up along the west coast of South America.

Low air pressure in Australia, high air pressure in South America.

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El Nino

Every 3-4 years, may last 12-18 months

Air pressure over the west coast of South America becomes unusually low and that over northern Australia particularly high
The normal east to west trade winds over the Pacific are disrupted and warm water sloshes eastwards
Upwelling of cold water on the South American coast is suppressed

South America 1997-98
High evaporation and precipitation, for each of 12 days in early March Peru got 6 months of normal rain. Flash floods killed 292, injured more than 16,000, destroyed 13,200 homes and wrecked roads and farmland. Economic disaster to the Peruvian fisheries. Some plants blooms for the first time in 100 years in the Atacama desert.
Indonesia and Australia 1997-98
Droughts in Australia which caused a water shortage. Lake Eyre in Australia dried up. Indonesian forest fires caused severe haze over several countries.

Severe coastal storms, heavy rainfall, flooding and mud slides on the west coast of US, California. Droughts in Mexico and C. America= forest fires. Later arrival of monsoon in Indian.

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La Nina

Occurs less frequently so less easy to predict

Essentially an increase in normal conditions

Air pressure is unusually high over the west coast of South America and low over Northern Australia

The easterly trade winds are more intense than normal

More warm water is pushed to the west of the Pacific Ocean

Rainfall increases over South East Asia and Australia
Drought happens in South America
Could be linked to greater hurricane activity in the Caribbean
Interrupts the jet stream by the mid latitudes, like the UK, giving stormier, wetter and cooler conditions

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Human Factors towards rising trends

Land Pressure
Leads to clearance of mangroves which protect coast from tsunamis and storm surges

Economic Development
Leads to land degradation, deforestation for timber and farming beyond the margin lead to desertification, soil degradation and increased pollution

Population Growth & Change
More people means more vulnerable people, especially the elderly and young. Increasing pressure at coasts with 40% of the world's population living in the coastal zone.

Political Change
Corrupt governments at war can exert extra pressure on land and lead to desperate responses by rural migrants. They can also mismanage disaster relief efforts.

Rapid Urbanisation and Growth of Megacities
Leads to mny people living in squatter settlements at high risk from flooding or landslides.

Economic Growth
Increases value of property and infrastructure, increasing economic impacts.

Means many LDCs cannot afford disaster management and support for vulnerable people

Technological Innovation
Controls hazards but does not protect against major disasters, can encourage people to build in danger zones

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Social and Economic Impacts of Disasters

"Deaths are falling, whereas the number of people affected by disasters is rising and economic losses are escalating. LDCs experience more deaths (social costs) and MDCs experience more damage (economic costs)"

The number of people reported killed by natural disasters dropped dramatically before the 70s, but has levelled off in recent years. Mostly due to better disaster management.

Better mitigation (use of hazard proof/climate proof structures) and improved disaster preparedness using education, community training and high technology warning systems. Earthquake proof buildings. Radon gas levels measured. Emergency drills, emergency rations.

Emergency responses have improved, with local participation in effective disaster relief programmes.

Recovery programmes better coordinated. More international aid available.

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Current Examples

For Vanuata and other Pacific Island nations, Cyclone Pam has been the worst-case scenario: in Port Vila, Vanuatu’s capital, 90% of the housing has been badly damaged; kids have nowhere to go to school, and the town’s hospital was left with no power. In the country’s outer islands, where most people live, about a quarter of a million people had little or no protection from the cyclone’s 160mph winds. And if people cannot get clean water and at least temporary toilets very soon, a “second emergency” could follow from water-borne diseases.

One in six UK homes at risk from flooding, says MPs report

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