Climate and Change

Climate and Change

1. Natural causes of Climate Change

   • Orbital Change- Long term
     • Changes in how the earth moves around the Sun are believed to cause ice ages. Every 100,00 years the Earth's orbit changes how much sunlight we recieve. The Earth's axis also "wobbles" every 41,000 years and this also affects how much sunlight we recieve.
   • Sunspot theory- Medium term
     • The Sun's output does not always stay the same. The more sunspots there are, the more solar output we recieve. These cycles last about 11 years.
   • Volcanic Activity- Short term
     • Major volcanic eruptions lead to a brief period of global cooling, due to ash and dust particles from the eruption blanketing the Earth. Following the Mount Pinatubo eruption in 1991 sunlight reaching the Eart was reduced by 10%

2. Climate change in the past and its effetcs.

   • The last Ice Age was appoximately 1.8 million years ago- this is called the Pleistocene era. The warm period we are in now is called the Holocene and this started 10,000 years ago.
   • The Little Ice Age
     • A time when Europe's climate cooled between 1550 and 1800, leading to long, cold and snowy winters.
     • Evidence- Tree ring growth in houses bulit at the time, art and books (Dickens) from the time that described winter landscapes. Farming records showed shorter growing seasons across Europe- evidence such as grape harvests especially.
     • Effects- Vikings in Greenland. The little ice age meant that as the temperatures plummented the vikings couldn't grow as much food. The Vikings also deforested many trees meainging that soil erosion occurred. They also could no longer trade with Iceland and Norway as the sea ice froze.
     • Other Effects- Changes in ecosystems and animal populations- e.g. seal populations fell due to a fall in their fish supply
   • Extinction of Megafauna
     • Megafauna are large animals that becane extinct at the end of the last ice age (Pleistocene). These animals lived in North America and Europe (including the UK). These aniamals included woolly mammoths, sabre-toothed tigers, large wolves and large beavers. As many as 135 species became extinct.

3. Greenhouse Gases

   • Mixture of Chloroflurocarbons, Nitrous oxide, Methane and Carbon Dioxide. The gases provide a kind of blanket, letting heat in, but preventing most heat from escaping.
   • Enhanced Greenhouse effects
     • In 2008, world carbon dioxide concentrations passed 380ppm (parts per million). In 1800, it was just 280ppm. This figure grows by 2ppm per year. This is despite efforts made by people and governments world wide.
     • Increased wealth in Asia has seen an increase in the amount of methane produced. This is because there is an increasing demand for meat and dairy in diets. The IPCC (intergovernmental Panel on Climate Change) believes that greenhouse gases need to be below 550ppm.

4. UK climate

   • Air Masses influnce the UK climate.
   • The climate of the UK appears to be changing as a result of global changes caused by human activity.
   • Ocean Currents
     • Moving currents of warm water from the Caribbean transfer warm water across the Atlantic towards the UK. This results in mild, wet winters and cool summers.
   • Jet Streams
     • The wet summer of 2012 and cold winter of 2012/2013 has been caused by a shift in the Jet Stream above the UK. Scientists believe this shift may be related to global warming.

5. Case Study- MEDC- UK

   • Advantages
     • Heating costs would decrease
     • Tourism in the UK could become more popular
     • Fewer deaths of old people from the cold
     • New crops might mean new sale opportunities for farmers.
     • More land could be farmed at higher altitudes
   • Disadvantages
     • Water shortages in the south of England
     • Some plant or animal species might become extinct in the UK
     • Farmers would need to change types of crops grown
     • Road surfaces and railways damaged by heat
     • More cases of sun stroke and skin cancer
     • Increased pressure on resources due to increased immigration.

6. Case Study- LEDC- Bangladesh

   • Population- 150m (7th largest)
   • Development- 10th poorest (Income £1/Day)
   • Causes
     • Bangladesh is vulnerable to flloding as the majority of its population live on low lying flat land that regularly gloods. Climate Change is increasing the risk of flooding.
       • Sea level is rising
       • Melting glaciers in the Himalayas in the north of the country
       • Warmer global temperatures will make tropical stoms stronger bringing more rain and flooding to the area
   • Effects
     • Every time that Bangladesh experiences major flooding it sets it back on the road to development
       • Destroying farms and crops so that people struggle for food
       • Destruction of infrastructure such as roads and railways
       • Interrupted schooling- safeguarding education is vital if Bangladesh is to lift itself out of poverty
   • Other LEDC's at risk of gloal warming
     • The Maldives- chain of islands in the Indian Ocean that are very low lying (less than 10m) and are due to be submerged
     • Tuvalu- Island in the Pacific Ocean also under threat
   • What are governments trying to do to help?
     • Research
       • In 2005 Sir Nicholas Stern write a report on global warming and its impacts. He recommended that they spend 2% of our GDP in reducing greehouse gases emissions
     • Inernational Agreements
       • To reduce greenhouse emissions- The kyoto Protocol in 1997 dd this and resulted in countries cutting their emissions. UK achieved this by introducing recycling programmes and cleaning up our emissions