World at risk (Lesson 11-15)

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  • Created on: 11-03-11 16:37
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Lesson 11.
Not been an eruption since 19 15 ­ Lassen Park.
Are being monitored for potential eruptions e.g. Lassen Park, Mammoth Lakes.
Coastal floods linked to storm surges every year from winter storms ­ Long Beach recently
devastated ­ whole of Californian coast is suffering coastal subsidence to increase risk.
Flash floods (October ­ January) ­ encouraged by steep relief of drainage basins &
deforestation e.g. Sierra Nevada and Coastal Range. LA experiences flash floods and
associated debris flows every year ­ 1995 worst on record.
1995 ­ heavier snowfalls due to climate change and El Nino ­ led to minor avalanches and
huge surges in spring months due to meltwater. Set to continue.
1995 ­ 8 deaths ­ LA to San Francisco highway washed away, 38 counties designated
emergency areas.
Rivers have been heavily channelized to try to avoid flooding.
Caused by anticyclones = dry air = dry weather.
Also caused by La Nina event.
Winds from Arizona desert = dry air, no moisture = no precipitation.
Overuse of water in naturally dry climate due to population pressure.
2003 ­ drought for two years, accelerated by high Santa Ana winds = fire threat.
Dead / dry vegetation as fuel source = fire spreads fast.
15 deaths, ½ million hectares burned, almost 1000 homes.
October 2007 ­ 1300 homes destroyed & 22 people killed.
Geomorphic Hazards: Landslides.
Earthquake induced along all of West Coast.
Steep unstable hillsides above LA surround it like a bowl ­ destabilised by winter rainstorms
adding lubrication.
Geology ­ loosely consolidated sands and gravels and impermeable clays around Santa
Building on steep slopes = further hazard increase.
2003 ­ Campsite disasters outside LA. Series of landslides kills 16. Wildfires had removed
vegetation = unstable slopes. Worst rainfall for 20 years.
Consequence: Severs key local roads and prevents search for survivors ­ federal aid and
disaster classification.
Similarities and Differences between the Philippines and California.
California. Philippines.
% Population affected. About 70%. About 100%.
Number of natural 6. 6.

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Why effects so bad? Santa Andrea's fault & Ring of fire & coastal area,
coastal area. also have a weak capacity to
Damage caused. With a majority high capacity The country can't develop
to cope means that there are economically unless it was to
quick responses. be cleared of debt caused
every year by these
Lesson 12.
El Nino Southern Oscillation & La Nina.
`The most catastrophic weather phenomenon's on earth'.…read more

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It is effectively the exact / extreme opposite of El Nino.
· Sea temperatures off Peru fall below normal = high pressure & dryer than normal conditions
= extreme drought.
· Low pressure = heavy rain & flooding in Indonesia & Australia.
· Warmer winter temperatures in S.E. USA.
· Colder winter temperatures from N.W. Pacific to the Great Lakes.
· Unsettled winters in N.E. & mid Atlantic U.S. states.
· Increase in Hurricanes in Caribbean & Southern USA.…read more

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Queensland was a disaster-zone.
Livestock drowned.
Thousands evacuated.
35 dead & 9 still missing.
Damage of approximately £30,000,000,000.
Barely been affected by recession, but now mines have been flooded (price gone up).
70 towns affected.
Approximately 200,000 people directly affected.
Roads & railways damaged (infrastructure).
Trade from North to South completely stopped.
Brisbon River flooded 3,000 homes.
At least 180,000 homes were without electricity.
Responses are continuous.
Extra police needed to prevent looting.
200km waterways have been searched for bodies.
Military have helped.…read more

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Measuring long term climate change.
Ice Cores.
The best evidence comes from Ice cores taken from the Antarctic and Greenland ice sheets.
Air bubbles in the core show C levels (parts per million) in the ice.
Glacial periods have low C ppm.
Interglacial periods have higher C ppm.
Carbon levels in the ice today are higher than at any other time in history.
Pollen Analysis.
Pollen from plants in preserved in sediment.…read more

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Arctic ocean could be ice free by 2060 if the melting continues.
Glaciers worldwide melting & retreating e.g. Greenland ice sheet lost 239km³ in 2006.
Other natural drivers of climate change
Astronomical forcing: a Serbian, Milutin Milankovitch developed the theory of climate
forcing in 1924. He believed the earth's temperature changes as it wobbles and tilts on its
axis ­ the bigger the tilt or wobble the bigger the climate change = ice ages.…read more


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