CHANGING CLIMATE

CHANGING CLIMATE

1. past climate change

   • climate is defined as the average weather conditions over 30 years
   • fossils of animals and plants in regions they are not found in today
   • evidence of glaciation in regions that are free of ice now
   • evidence from rocks showing us the climate conditions when those rock were formed
   • evidence from ice cores in Greenland and Antarctica showing use how much carbon dioxide was in the atmosphere wen the ice was formed

2. the causes of change

   • volcanic eruptions
     • large eruptions emit vast quantities of dust and gases such as sulphur dioxide into the atmosphere
     • this blocks out or absorbs incoming solar gradation so earth cools
     • large asteroid collisions have a similar cooling effect as they throw dust and ash into the atmopshere
   • sunspot activity
     • sunspots are darker areas on the sun surface they are a sign of greater solar activity
     • they come and go in cycles of about 11 years
     • however there are longer periods when very few sunspots were observed
   • changes in the earths orbit and rotation
     • the shape of the earths orbit changes over a period of 100 000 years known as orbital eccentricity
     • the earth woles on its axis over a period of 26 000 years known as precession
     • the tilt of te axis varies btween 21 and 24 degress over about 4000 years
     • taken together these effects change the amount of solar energy received at the earths surface

3. little ice age

   • rivers froze over
   • winter was colder and longer reducing growing season by several weeks
   • widespread crop failure and famine
   • remote areas such as Greenland were abandoned by settlers as survival became immpossible
   • the price of grain increased
   • glaciers advanced in the alps

4. the impact on mega fauna

   • plants and animals died out
   • mass extintion
   • humans hunted the animals

5. the uk climate today

   • 5 air masses and jet steams
     • polar maritime
     • artic maritime
     • polar continetal
     • toprical continental
     • tropical maritime
   • prevalling south westerly winds bringing moist air from the atlantic means rain
   • gulf steam means that warmer air

6. the greenhouse effect

   • green houses gases retain heat from the sun so it warms the earth
   • solar energy passes through the atmosphere without having an impact on it
   • radiation is tapped by green hous gasses
   • green house gases
     • carbon dioxde
     • methane
     • nitruos oxide

7. what we do and why we do it

   • deforestation
     • burning forest to clear land produces co2
     • reducing the number of trees lowers the ability of the earth to absorb co2
   • industry
   • energy supply
   • ransport

8. the impact on global temperatures and sea level

   • sea level change
     • thermal expansion
     • melting ice caps and glaciers