Higher Geography - Atmosphere: Global Climate Change
Uploaded by
knoxgeographyHigher Geography - Atmosphere: Global Climate Change
Uploaded by
knoxgeographyHigher Geography - Atmosphere
GLOBAL CLIMATE CHANGE
Note 4 -the y axis does not show Note 1actualgraph shows also been Note-2 - since 1860 this-temperature in the temperature steady rise theNote 3 - There have ait shows cooler only been about 1C global temperature. therise has than average years. difference from the average!
GLOBAL CLIMATE CHANGE
Physical Factors Solar variation Volcanic activity Ocean currents Milankovitch cycles Human Factors Burning fossil fuels Increased output of methane etc. Deforestation
PHYSICAL 1-SOLAR VARIATION
The suns output varies slightly from time to time - its size is even known to change by a fraction as it expands and contracts.
PHYSICAL 1 - SOLAR VARIATION
Sunspots: an increase
in sunspot activity may lead to a very slight increase in the suns output and a temporary warming of the earth. Sunspot activity follows 11 and 22 year cycles. The Little Ice Age of 1450-1700 may have been linked to periods of very low sunspot activity.
PHYSICAL 2 - VOLCANIC ERUPTIONS
Eruptions of volcanoes can throw millions of tonnes of ash,dust and sulphur dioxide into the atmosphere. This produces aerosols that can reduce the amount of sunlight reaching the earth. This can lead to a temporary cooling of the earth.
VOLCANIC ERUPTIONS 2 Major eruptions in the past which have been linked to short periods of global cooling include Tambora (1815), Krakatoa (1883), Mt. St Helens (1980) and Pinatubo (1991)
When Mt. Pinatubo erupted in 1991 an estimated 22 million tons of ash was thrown into the atmosphere, cooling the worlds climate by about 1C.
When Tambora erupted in 1815 it led to 1816 being called the year without summer, when summer frosts and other major weather problems were experienced. It cooled the global climate by 3C.
PHYSICAL 3 - MILANKOVITCH CYCLES
Stretch, Wobble and Roll!!!
Milankovitch cycles are three variations in the earths orbit. Although they may be linked to very long term changes in the climate, their effect would not be noticed on a scale of a few hundred years.
PHYSICAL 4 - OCEAN CURRENTS Changes in the pattern and strength of ocean currents may lead to changes in the distribution of heat around the planet. A short term example would be El Nio, which appears every few years. A longer term example would be the North Atlantic Drift, which may change position every few thousand years.
ENSO - the El Nio Southern Oscillation
The normal conditions, with cool surface water off the coast of Peru. Every 2-7 years the western Pacific becomes much warmer, disrupting weather patterns - possibly on a global scale.
A La Nia year
An El Nio year
One theory suggests that global warming will increase the number of icebergs in the Atlantic, cooling the sea and switching off the North Atlantic Drift / Atlantic Conveyor system. This would be bad news for us!
The Atlantic Conveyor system is part of a global circulation of water and heat energy.
GLOBAL CLIMATE CHANGE - HUMAN FACTORS 1 - THE ENHANCED GREENHOUSE EFFECT.
HUMAN 1 - BURNING FOSSIL FUELS
The fossil fuels are: COAL OIL NATURAL GAS They are called fossil fuels because they are formed from the remains of ancient plants (coal) and marine animals (oil).
BURNING FOSSIL FUELS
There has been an enormous increase in these greenhouse gases since the Industrial Revolution began about 200 years ago.
When we burn these fuels, we release millions of tonnes of Carbon Dioxide (CO2) into the atmosphere.
BURNING FOSSIL FUELS
Power stations are one of the main producers of greenhouse gases such as Carbon Dioxide.
Environmental campaigners all over the world are demanding cuts in CO2 emissions. Here Greenpeace uses a light display to get its message across.
HUMAN 1 - VEHICLE EXHAUSTS
Vehicle exhausts are the main source of Nitrous Oxides.
BURNING FOSSIL FUELS
Photo chemical smog in Beijing, China.
HUMAN 2 - INCREASED METHANE
The huge increase in world population and in the area of land given over to crops in general and to rice production in particular, has led to a rapid rise in global methane production. Farmland for rice has doubled in 45 years.
I am a ruminant - when I digest grass, I produce methane - lots of it!
HUMAN 2 - INCREASED METHANE A cow can burp / fart about a quarter of a kg. of methane a day. The number of cattle has doubled in the past 40 years. Sheep, goats and camels are also ruminants. There are now 1.3 billion cattle, each burping / farting methane several times a minute! The New Zealand government is proposing to bring in a flatulence tax on cattle farms.
HUMAN 3 - DEFORESTATION
Forests absorb CO2 and release oxygen:
...if they are cut down, atmospheric levels of CO2 must rise as a consequence.
HUMAN 3 - DEFORESTATION
Clearing forest by burning releases huge amounts of stored CO2 back into the atmosphere. The smoke from the fires also adds to global air pollution.
GLOBAL CLIMATE CHANGE - REVIEW OF MAIN POINTS
Physical Factors Solar variation Volcanic activity Ocean currents Milankovitch cycles
Human Factors Burning fossil fuels Increased output of methane Deforestation
KEY TERMS TO REMEMBER Solar variation / Sunspots Volcanic eruptions /Sulphur dioxide /Aerosols Milankovitch cycles El Nio Enhanced Greenhouse effect Carbon Dioxide / Methane / Nitrous Oxides The Industrial Revolution / burning fossil fuels Paddy fields / cattle / methane production Deforestation
Exam questions and advice.
2001 Paper 1
Note the narrow band of temperature variation - less than 1C overall.
Note the overall trend is towards warmer temperatures, but there have also been several cooler than average years.
Note the timescale - only 140 years.
1997 Paper 1
Again, note the narrow temperature range.
This is not 0C - it shows the difference between these years and the average.
No clues in the wording, so remember both physical and human factors. (c) Suggest reasons for the variations in global temperatures shown on the diagram. (4)
1992 Paper 1
Note the similarities in the wording and graphics with other years. Again, remember the narrow temperature range above and below the average.
Dont forget to describeeasy marks if you mention the upward trend and the occasional high and low points.