World at Risk
1 Global hazards
Hazard – A Hazard is something that has the potential to threaten human life and property
Disaster = A natural hazard becomes a disaster when it has a severe impact of a human population
Risk = the likelihood that humans will be seriously affected by hazards
Vulnerability = How susceptible a population is to the damage caused by hazards
Risk = Hazard x Vulnerability Capacity to cope
Benefits vs Costs fertile soils on flood plain in Bangladesh and the side of Mount Vesuvius
Without the greenhouse effect the earth would be -18OC
2 Global hazard trends
Floods have increased since 1980 e.g. Mississippi floods 2011and are due to extreme rainfall, mid-latitude depressions and linked to tropical cyclones
Coastal flooding due to storm surges form Hurricane Katerina was driven by cyclones and low pressure
Cyclones – ocean surface temperatures have increase by 0.6OC increasing evaporation and El Nino supressed tropical cyclone activity in the North Atlantic Caribbean but La Nina like in 2005 creates favourable conditions for hurricanes
Droughts = prolonged periods of abnormally low rainfall and in the Sahal region of Africa it causes famine, desertification as well as seasonally arid regions like central North America
By 2050 70% of people will live in urban areas putting pressure on land and there
Increasing world population from 7 to 9.3billion in 2050 and 95% of growth will be in the developing world means more people will be living in areas more at risk
Increasing vulnerable population 23% of people live in poverty and lower capacity to cope
Corrupt governments like Myanmar in 2004 after the Tsunami prevented aid
Hurricane in Haiti 2004 caused more damage due to deforestation for charcoal
Anthropogenic global warming has increased the number of hazards
270ppm of carbon in the atmosphere in 1800 now 390ppm

3 Global hazard patterns
Cyclones develop between 5oC and 30oC north and south of the Equator and the surface temperature must be 26.5 oC and move east-west wind e.g. trade winds
In the Sahal, droughts occur due to persistent anticyclones that block the passage of depressions
The area’s most at risk are densely populated and urbanised flood plains like the Mississippi and deforestation accelerates surface run off
Earthquakes and volcanos our along plate boundaries due to convection currents in the mantle Nazca plate is forced under the South American Plate.
Landslides and avalanches occur between 30 and 45O and occur in regions of fold mountains
4 Climate change and its causes
Emissions have drastically increased since 1750 at the start of the industrial revolution
Long term – fluctuations between glacial lasting 100,000 years and interglacial lasting 10,000 years
Medium term – 13,000 years ago there was 1,000 years of cool conditions
Dendrochronology can reliably go back 10,000 years
Short term - risen rapidly since 1970s
Weather records stared in 1861
Milankovich Cycles
Over 41,000 years the earth’s orbit fluctuates between 22 and 24.5 vary the amount of energy latitudes receives
Over 96,000 years Eccentricity of the earth’s orbit varies from near circular to elliptical changing the amount of energy the earth receives precession of the equinoxes changes over 22,000 years the intensity of the seasons7

Sunspots are darker areas on that increase solar output and occur in 11 year cycles
Krakatoa in 1883 led to a 1OC drop in global temperatures as dust acts as a condensation nuclei
5 Impacts of global warming
The tipping point = a critical threshold in a natural system that once exceeded will trigger abrupt and irreversible changes
It will cause eustatic sea level rise which is where the volume of water in the sea increases
If all the Ice sheets melted the sea would rise by 60-80m
The sea by rise 1m by 2100
It will threaten places like Tuvalu and Micronesia in the South Pacific increasing the intensity and frequency of tropical storm and threaten food production