Geography - Challenges For the Planet

Geography - Challenges For the Planet

1. Why has the world's climate changed since the last ice age?

   • World's Climate
     • Solar Output
       • This is the energy that comes from the sun
       • Readings from 1980s show solar energy reaching earth has decreased by 0.1%
       • Activity of sunspots on earths surface affects their output. Reduced activity between 1645 & 1715 -Cause of ice age
     • Change in atmospheric gases
       • Clear relationship between amount of Co2 in atmoshpere and temperature variations.
       • Co2 important gas, responsible for greenhouse effect. Greenhouse effect keeps heat within earth by absorbing longwave radiation.
       • Without greenhouse effect global temp fo earth will be -18 degrees rather than present 15 degress
     • Volcanic Activity
       • Eruptions release large amounts of sulphur dioxide and ash to atmoshpere
       • Act as a cloak and reduce amount of solar energy reaching earths surface
       • 1815 - Mt Tambora erupted. Following year unusually cold over much of the world , Europe having heavy snowfalls and frost throughout the summer.
     • Orbital Geometry
       • Earth orbit around the sun varies from nearly circular to epilliptical and back to circular again every 95,000 years
       • Many conflicting views on what happens to temperature as Earths orbit shape changes.
       • Circular - During cold periods Elliptical - Warmer periods

2. Causes of current climate change

   • Fossil Fuels
     • Coal, oil & gas burnt - Produce Co2, contributes to greenhouse effect
       • Increase in burning fossil fuels to produce energy. China - 75% coal burnt, developing rapidly and using coal to fuel this development
       • Increase in global car ownership, more oil used, in turn increases amount of Co2 in the atmoshpere
       • Drilling for oil releases methane in the form of natural gas
   • Methane
     • Makes up 20% of greenhouse gases in the atmosphere, also 20X more potent than Carbon Dioxide.
       • Amount of methane has risen by 1.5% per year in past decade.
         • Why?
           • Increase in bacteria emissions from wetlands because of rising temperatures
           • Increase growing of rice because of growing populations in rice producing countries
           • Increase in the number of cattle, They produce methane as they ruminate their food.

3. Negative effect of climate change

   • Crop Yields
     • Tanzania experiencing longer periods of drought. Farmers will lose a third of their maize crop
     • India - 50% decrease in amount of land available to grow wheat. Due to hotter & drier weather.
   • Glaciers
     • Glacier National Park, Montana, USA - created in 1910. At this time there were 150 glaciers. Decreased to 30 after this. Predicted that withing 30 years all glaciers will dissapers.
     • Antartcic - 90% of glaciers are retreating

4. Response to Climate Change - Global Scale

   • December 1997 - Kyoto Confrence
     • The Kyoto protocol was signed, came into force in February 2005