Variable weather n changing climate gateway2 part1


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part 1 sec 3 elective geog gateway 2

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  • Sunspot vid NASA (2min)
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  • Variable weather n changing climate gateway2 part1

    1. 1. Chapter 2 Gateway 2 What is happening to the Earth’s climate?
    2. 2. Global Climate Change • The variation in global climate • Changes in the climatic patterns in the long term • General trend has been an irregular but significant increase in global temperature.
    3. 3. Global Warming • Process where global temperatures increase over a long period of time.
    4. 4. Global Cooling • Process where global temperature decrease over a long period of time.
    5. 5. Changes since 1880 • Drastic fluctuations on annual basis. • 5-year mean still fluctuates. • Over 120 years, mean has risen significantly. • Increase in temperature is more obvious in Africa, Parts of Asia and the Arctic.
    6. 6. Natural Causes of Climate Change • There are some natural phenomena that will cause climate change. 1. Variations in Solar Output 2. Volcanic Eruptions
    7. 7. Variations in Solar Output • Solar radiation changes as the magnetic field of the sun changes. • Increase in magnetic activity will lead to increase in solar radiation. • Sunspot activity leads to more solar radiation emitted. • Solar activity cycle is linked with earth’s cycle of high and low global temperature. – High activity leads to spikes in temperature.
    8. 8. What are Sunspots?
    9. 9. Volcanic Eruptions • During eruptions, cabon dioxide, water vapour, sulphur dioxide, dust and ash are released into the environment. • Sulphur dioxide reacts with water to form sulphur-based particles in the atmosphere. • These work with the dust and ash to reflect solar energy back into space, causing global dimming.
    10. 10. Global Dimming • The gradual reduction in the amount of sunlight reaching the earth’s surface. • Causes temporary cooling of the earth. • Eruption of Mt Pinatubo, 1991, lead to lowering of temperatures in the northern hemisphere by as much as 0.6°C. • Effect can last several years.
    11. 11. Greenhouse Effect
    12. 12. What is greenhouse effect? • Process that sustains habitable temperature on earth. • Shortwave radiation from the sun reaches earth as visible light. • Longwave radiation is heat from the heated surface of the earth. – Earth’s surface is heated by the shortwave radiation from the sun.
    13. 13. Process of greenhouse effect • Shortwave radiation comes from the sun. • Some of it is reflected and trapped in the atmosphere by greenhouse gases. • Some of it passes through and heats up the earth’s surface. • The earth’s heated surface emits (gives off) longwave radiation. • Some longwave radiation is reflected back by the atmosphere layer while some escapes. • The reflected radiation continues to heat up the earth’s surface. • This maintains the optimal temperatures on earth for life to exist.
    14. 14. What is enhanced greenhouse effect? • When greenhouse gases in the atmosphere increase, the amount of radiation trapped increases. • This causes the heat on Earth’s surface to increase. • Key greenhouse gases are nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4).
    15. 15. Who causes this spike? Burning of Fossil Fuels • Industries and modern fossil-fuel burning machines have accounted for the spike in greenhouse gases. • Intense spike in all 3 tracked gases since 1500 to date (due to the onset of the Industrial Revolution and rapid human population growth)
    16. 16. Deforestation • Loss of forests due to removal and clearance of tress. • Commercial value of timber • Enhance need for agricultural / residential / commercial land • Loss of carbon lungs of the earth. • South America and Southeast Asia are the 2 highest areas of forest loss.
    17. 17. Reforestation • Process where trees are planted to replace lost forest areas. • China, India, Vietnam, USA has large scale reforestation programs. – When you need to reforest it means that you had previously done deforestation. – Reforestation levels often fall short of deforestation levels. – Reforestation also tends to be of lesser variety compared to the original lost species.
    18. 18. Changing land use Agriculture • Global increase in meat consumption leads to increased livestocks reared. • Argentina is one of the world’s largest beef producers. • Methane gas emitted from lifestock account for 30% of Argentina’s total greenhouse gas emissions. • Widespread use of machines in agriculture release additional CO2 into the atmosphere.