CLIMATE CHANGE

CLIMATE CHANGE

1. Causes of short term

   • Volcanic Eruptions
   • Solar Energy Variation (Sunspots)
   • El Nino La Nina

2. Human activity

   • Agriculture 14%
   • Transport 14%
   • Deforestation 17%
   • Electricity 24%

3. Causes of long term

   • Ocean Currents (Thermohaline circulation)
   • Milankovitch theories on Orbit, Tilt and Wobble
     • Orbit/eccentricity is the path of Earth which changes from a perfect circle to an ellipse and back again every 96,000 years
     • Tilt; Earth is tilted at an angle on its axis as it orbits the Sun. Changes between 21.8 to 24.4 degrees in a cycle of 41,000 years. Changes amount of solar energy different latitudes receive. When tilt greater, larger areas will receive more energy (tropics more temperate less). When tilt smaller, smaller areas receive more.

4. Issues resulting from climate change

   • Changing biomes:
     • Coniferous forests- will expand into tundra areas (Yukon in Canada). However WWF predicts that Southern Canada will lose 45% (700km retreat) of its habitat and boreal conifer forest as tempreture increases and grassland takes over. Studies in Europe show a Northward push of coniferous forests by 120km in the last century. Over 60 species of butterflies have been recorded to move northwards with this trend. Polygonia butterfly is spreading northward at 10km a year in the UK.
     • Tundra- face threats such as melting of permafrost (nearly 75% of Tundra permafrost) due to enhanced global warming; reducing amount of water available to local wildlife as lakes disappear as water infiltrates through the unfrozen ground; rivers and the sea erode land more quickly as soil exposed; destroying river bed for salmon; newly exposed bogs release methane from the decaying organic matter which was trapped under the ice (the amount of methane trapped in Siberia is thought to be 100 times what we release each year from BFF.
   • Increasing levels of extreme weather and the impacts on human activities
     • Drought: Murray-Darling basic Australia 2000-2010 drought. Reduced agricultural output by 60% causing farmers to become bankrupt and even increasing figures of suicide and migration. Bush fires in Australia caused 120 deaths near Melbourne in 2009 destroying homes and businesses.
       • The Murray–Darling basin is a large geographical area in the interior of southeastern Australia, whose name is derived from its two major rivers, the Murray River and the Darling River.
     • Tropical storms: will increase like the 2005 season in USA. Hurricane Katrina caused an increase in petrol cost globally as destroyed oil rigs. 1,500 killed and out-migration mean New Orleans lost 40% of its population. Property damage estimated at $81 billion.
   • Melting glaciers, rising sea levels and their impact on people
     • Increased erosion: by the ocean (hydraulic action, corrosion and abrasion) will affect a larger area as more of the cliffs and land will be exposed to the sea at high tide. Thus increasing the cost of sea defences such as sea walls and groynes. Loss of income and jobs from tourism as beaches moved by long shore drift and loss of industrial areas near low lying ports.
     • Bleaching of coral reefs: as sea levels rise and coral reef is too deep for photosynthesis. 70% of all fish live in the coral reefs and it is very important for food web. Decrease tourism and food for locals.
     • Salination: rising sea levels means salt intrusion into the groundwater so contaminating the drinking water supply. This decreases agricultural yields as people cant grow crops in salty soil. Kiribati's 32 atolls and one raised coral island have an average height above sea level of just two metres and may be flooded in 30 years time.
   • Impacts on society
     • Food supply: will increase as more carbon dioxide increases photosynthesis and high temperatures means different crops like olives can be grown in UK. Africa will see less output due to failing rains and increased extreme weather (floods and droughts).
     • Health: Increased malnutrition as less yield of healthy crops. Increased deaths due to severe weather events e.g. Katrina 2005 (1,500 deaths), increased occurence of diarrhoeal diseases (cholera) as spreads quicker in warmer climates. Increased cardio-respiratory diseases due to polluted humid air. 290 million more people exposed to malaria by 2080 with China most at risk.