1. Climate and Change
*Celsius 1 = 33.8 Fahrenheit

2. How and why has climate changed in the past?
To understand that climate has changed in the past through natural causes, on timescales ranging from millions to hundreds of years.
To begin to appreciate the Geological Time Scale
Carbon dioxide and temperature levels over the last 800,000 years
Changes in the Earth’s average temperature & projections.
Sources of evidence for climate change taken from tree, sediment, ice & coral cores.

3. Ice cover in the last Ice Age
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A glacial period (or alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The last glacial period ended about 15,000 years ago; The Holocene epoch is the current interglacial.

4. Normally the Greenhouse Effect is like a blanket – you wouldn’t want to take it off because you would be too cold – however putting another blanket on would make you too hot.
The human-produced greenhouse gases are like this extra blanket, resulting in what is called the Enhanced Greenhouse Effect.
Gasses
% of gas produced
Sources
Warming power compared to carbon dioxide
% increase since 1850
Carbon dioxide
89%
Burning fossil fuels (coal, oil, gas), deforestation which produces carbon dioxide 1
+ 30%
Methane 7%
Gas pipeline leaks, rice in paddy fields, cattle farming.
21 times more powerful
+ 250%
Nitrous oxide 3%
Jet aircraft engines, cars and lorries, fertilisers and sewage farms.
250 times more powerful
+ 16%
Halo-carbons 1%
Used in industry, solvents and cooling equipment.
3000 times more powerful
Not natural
Year
ppm
1800
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
CO2
280
282
283
287
291
295
299
310
323
347
386
Methane
700
713
727
756
796
835
871
980
1430
1656
Nitrous oxide
270
271
275
276
286
290
294
304
311
318

5. What causes changes in climate?
Natural
Human
The Earth’s atmosphere is affected by changes in the lithosphere, as well as by cosmic influences such as; the Sun’s activity (sunspots), variations in the Earth’s orbit (circular to elliptical), and volcano activity (Pinatubo-1991; sunlight reduced 10%, global temperature reduced 0.5o).
GHG: The most abundant greenhouse gas (GHG) is water vapor. Carbon Dioxide is emitted from volcanoes, hot springs, geysers and other places where the earth's crust is thin.
Humans effect changes in climate through the production and transport of coal, natural gas & oil, the decomposition of organic wastes in landfill sites, agricultural and industrial activities & combustion of solid waste & fossil fuels.
Compound
Formula %
Water vapor and clouds
H2O
36 – 72%  
Carbon dioxide
CO2
9 – 26%
Methane
CH4
4 – 9%  
Ozone O3
3 – 7%  

6. 5 Minute Quiz
Describe some of the evidence that tells us climate was different in the past.
What is the length of time between now and the previous warm period of time?...and the one before that…and before that…
Describe the variations in the temperature graph.
Does the Earth warm up faster, or cool down faster?
How closely are temperature and carbon dioxide levels linked?
Look at the map of the ice sheets – Ice cover in the last ice age. Which parts of the land were covered by ice 20,000 years ago, and are now ice free?
Explain the significance of the Quaternary period?
Which of the Greenhouse Gases is most common through natural processes & human activity?
Extrapolation: What is a climatologist?