Unit 2 - Extreme Weather Case Studies

Key Information/Causes

The hottest summer across Europe since at least 1540, summer temperatures were raised 15-20% higher than the seasonal average. This extreme weather was caused by a blocking anti-cyclone, with warm, Meditteranean air firmly anchored over the western European land mass holding back the rain-bearing depressions that usually enter the continent from the Atlantic ocean.

Impacts (Social/Economic/Environmental)

• More than 40,000 people died during the heat wave. Over 2,000 in the UK.
• The UK rail transport was disrupted by speed limits set due to the buckling of the rails caused by the heat.
• France lost 20% of its wheat crops through the drought caused by the heat wave. The UK lost 13%. The total EU production of wheat was down by 10 million tonnes, 10%.
• Potato and wine production were also seriously affected. The fodder deficit varied from 30% ( Germany, Austria and Spain) to 40% (Italy) and 60% in France.
• Wildfires in Portugal caused the loss of 215,000 hectares of forestry.
• The anomalous overheating affecting the atmosphere also created anomalies on sea surface stratification in the Mediterranean Sea and on the surface currents as well.

Key Information/Causes

The decrease in average temperatures were caused by a weather cycle, caused by a low pressure zone in the Baltics and a high pressure zone over Greenland, which started in southern Scandinavia, moving through central Europe before hitting the UK on the 25th November. Coldest temperatures recorded were -17.3C in Llysdinam, Wales. Cold conditions returned on the 16th December, with a cold front reintroducing a cold, arctic airstream.

Impacts (Social/Economic/Environmental)

• Over 8000 schools were closed and 5000 homes in Sussex were left without electricity.
• A total of 19 deaths were recorded in the UK & Ireland due to the cold conditions.
• Retailers suffered a 20% decrease in footfall at their stores compared to the previous year, with as much as 30% in the West Midlands and South East, the location of many of the UK’s biggest retail centres.
• It was estimated that the cold spell cost the UK economy up to £1.2 billion a day. In total, the cold spell cost the nation’s economy an estimated £13 billion.
• In the UK it was the coldest December ever, since Met Office records began in 1910, with a mean temperature of -1°C. It broke the previous record of 0.1°C in December 1981.
• The coldest winter for England and Wales since 1978-1979

Key Information/Causes - In El Nino years, trade winds reverse, this caused Australia to experience very high pressure. The moist air had been felt by South America which usually would have come to Australia. This change between normal years and El Nino years is called the South Oscillation Index.

Impacts (Social/Economic/Environmental)

• On 7th February 2009, temperatures in the country reached 46.4C. This led to over 2000 houses burning to the ground and a death toll of over 170 people. The media branded this day ‘Black Saturday’.
• Drinking water supplies where also affected in Sydney. Its largest reservoir is now 40% full and many small rural towns in east Australia faced shortages within a month.
• 40,000 jobs had been lost as a direct impact of the drought.
• The drought knocked one percentage point off Australia's growth rate last year, by the government's reckoning. It is paying out $1.7m a day in drought-relief to farmers.
• During Black Saturday, the total sheep population halved, from just over 100 million to about 50 million.
• Grassland turned into scrubland.

Key Information/Causes - Warm air picking up moisture travelled towards Cornwall, these winds experienced a strong up-drafting force thus causing internal moisture to reach the atmosphere, and consequently cool as a string of storm clouds. The rain was very localised, which was thought to be an extreme example of what has become known as the ‘Brown Willy’ effect. Caused by a "blocking high".

Impacts (Social/Economic/Environmental)

• Possessions belonging to more than 1,000 people were swept away. 
• 75 cars, 5 caravans, 6 buildings and several boats were washed into the sea.
• The town was closed to tourists after the flood, causing a massive loss to revenue, as the town relies on tourism, accounting for 30% of Cornwall’s GDP. This caused a major loss to the potential £1bn spent by tourists in the county.
• The damage of properties by the flood was at an average of £15,000-30,000 per property.
• Many trees were destroyed as well as other vegetation.
• Much of the village’s open land, including gardens and the village green, has been covered with fresh beds of alluvial silt. 

Key Information/Causes - Strongest hurricane of the 2005 season. Formed as a tropical depression off the coast of the Bahamas, crossed Florida as a category 1 hurricane and strengthened to a category 5 storm in the Gulf of Mexico before reaching Louisiana as a category 3 storm. The main cause for the substaintal flooding was the failing of the levee system.

Impacts (Social/Economic/Environmental)

• At least 1,833 people died in the hurricane and subsequent floods.
• The extensive flooding stranded many residents, who remained stranded long after Hurricane Katrina had passed.
• Total property damage was estimated at $81 billion, nearly triple the damage brought by Hurricane Andrew in 1992.
• The labour force fell and wages decreased, with an estimated loss of 70,000 jobs.
• The storm surge caused substantial beach erosion, in some cases completely devastating coastal areas.
• The storm caused oil spills from 44 facilities throughout southeastern Louisiana, which resulted in over 7 million gallons of oil being leaked.