Challenges for the Planet

1. Over the last 10,000 years temperature has increased by 5 degrees celsius, within this general trend there have been fluctuations after last ice age the temperature rapidly rose for following 2000 years.
2. Between approx 6000 and 9000 years ago two warm periods interrupted by colder spell, another warm spell happened between the years AD800 and AD1200 known as the medieval warm period. Then followed by Little Ice Age where temp were below the long-term for six hundred years ending in the late 1800's. In past 100 year the temps has begun to rise steadily, with greater increases since the 1960s. Temperature projected to increase much more rapidly in the coming years being 1 degree warmer in 2100 than now.

1. External
   1. Solar Output
      1. Energy comes from the sun changes overtime in 1980's showed total amount of solar energy reaching Earth has decreased by 0.1% if continues for 100 yrs could influence global climate. 1% change could make the temp rise or fall between 0.5 and 1.0c. Also affected by sunspot activity
   2. Orbital geometry
      1. Shape of Earth's orbit around the sun varies from near circular (cold) to elliptical (warmer back to circular every 95,000 yrs.
      2. Tilt of the Earth's axis varies overtime from 21.5 to 24.5 occurs over 41,000 year time span greater the angle hotter summers and colder winters
2. Internal
   1. Volcanic activity
      1. Volcanic eruptions release large amounts of sulphur dioxide and ash into the atmosphere act as cloak and reduce amount of solar energy reaching the Earth's surface.
   2. Surface reflection
      1. During cooler periods when there is a larger amount of snow and ice on the Earth, global temperature will drop due to the snow and ice reflecting back to space
   3. Change in atmospheric gas
      1. Clear relation between the amount of C02 in the atmosphere and temperature variations. Keep heat within the Earth's atmosphere by absorbing longwave radiation without there would be 3c decrease in avg global temperature
   4. Tectonic activity
      1. Movement of continents caused by plate tectonics affects the global pattern of atmospheric and ocean circulation; and the changing shape of the Earth's surface causes winds and ocean currents to change has affect over span of 10,000 yrs

1. Fossil fuels, carbon dioxide, and methane
   1. Fossil fuel are fuel produced from coal, oil and natural gas fuels are used to produce energy in power stations and to supply fuel to vehicles, in China 75% of energy produced from coal, when fossil fuels are burnt gases are released which build upp in the atmosphere one of the gases is carbon dioxide which contributes to the greenhouse effect causing the climate to change. Generation of power accounts for 25% of global carbon dioxide emissions. Methane is a greenhouse gas; can trap heat within the Earth's atmosphere, makes up 20% of the greenhouse gases in the atmosphere and is 20 times more potent, stronger chemical effect, than carbon dioxide. Comes from organisms alive many years ago recently dead rotting organisms and those alive today. Fossil methane that provides approx 30% of methane released into the atmosphere was formed undergournd many years ago, comes to the surface when fossil fuels are mined.
2. Modern methane sources
   1. Wetlands including marshes and swamps, growing of rice, landfills containing rotting vegetable matter, burning vegetation, bowels of animals.
      1. Levels of methane have been rising in the atmosphere by 1.5% for past decade
         1. Increase in the mining of fossil fuels, rising temp which causes increase in bacteria emissions from wetlands, increase in rice production due to the growing population in rice producing countries, increase in the number of cattle and sheep for meat reflecting increase in Western-style diets

1. Changing pattern of crop yields
   1. Countries closest to equator liikely to suffer as crop yields will decrease. Africa Tanzania longer peroids of drought and shorter growing seasons could lose almost a third of their maize crop. Forecast in India will be 50% decrease in the amount of land available to grow wheat due to hotter and drier weather.
2. Rising sea levels
   1. between 1993 and 2006 sea levels rose 3.3mm a year lead to an 88cm rise in sea levels by end of centuary threaten large cities such as London, New York and Tokyo Two kiribati island in pacific are now covered with sea water
3. Retreating glaciers
   1. Vast majority of world's glaciers are retreating due to increase in temperature 90% of glaciers in Antartica are retreating believed that melting ice in the Artic could cause the Gulf Stream to be diverted further south owing to colder temps in western Europe, matching temp across Atlantic in Labrador at present time. Temps are frequently below 0 degrees in winter with avg of 8-10 degrees in July, 10 degrees cooler than average UK summer temp.

Attachments:

• Greenhouse effect