Climate Change

Climate Change

1. Evidence

   • Scientists know from fossil records that there have been fluctuations in temperatures in the last 5.5 million years with a cooling trend.
     • Oxygen trapped in layers of ocean sediments, and water molecules in Antarctic snow can be analysed so calculate temperatures.
       • There has been warming trend since 1970s.
   • Shrinking glaciers and melting ice.
   • Sea levels rising due to- glaciers and ice caps melting- thermal expansion, warm ocean water expands in volume- so low lying land is at risk of flooding.
   • Tree flowering, bird migration and nesting is advancing.

2. Causes

   • Orbital change- eccentricity where the earths orbit goes from circular to elliptical- axial tilt where the tilt of the earths axis moves between 21.5 and 24.5 degrees- precession where the axis wobbles from one extreme to the other.
   • Solar activity- the sun has dark patches called sunspots of reduced temperature and are accompanied by explosive, high energy solar flares and over a period of 11 years increase from a minimum to a maximum and back again.
   • Volcanic activity- ash can block out the sun- sulphur dioxide is also blasted out and converts to droplets of sulphuric acid which can reflect the solar radiation back into space.

3. Greenhouse Effect

   • Keeps the earth naturally warm.
     • Greenhouse gasses like methane and carbon dioxide trap heat.
     • Allows shortwave radiation from the sun through the earth.
     • Traps some of the long wavelength radiation.
   • Human Impact
     • CO2 contributes to 60% and is from burning fossil fuels, transport, farming and deforestation.
     • Methane from livestock, rice, sewage treatment and landfill emissions.

4. Managing Climate Change

   • Alternative energy sources rather than burning fossil fuels like hydroelectric power, nuclear power, solar, wind. Renewable energies that are sustainable.
   • Carbon capture which uses technology to capture CO2. It is then compressed and injected underground fro long term storage.
   • Planting trees that will remove CO2 from the atmosphere by photosynthesis. They also release moisture which can act as a block to solar radiation when its a cloud.
   • International agreements that aim to come up with solutions.
   • Global impacts of climate change include- reduce crop and water supplies- more heat related illness- flooding- changing of ecosystems- more extreme weather- tropical storms- desertification.
     • Farmers need to adapt so that they can- cope with extreme weather- manage water supply- plant trees for shade- change crops and livestock for new conditions.
     • To reduce risk of rising sea levels- build sea walls- raised housing- restoration of mangroves- relocation- artificial islands.