Global Warming

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  • Created by: zooandroo
  • Created on: 24-02-14 11:52
When was the most recent Ice Age?
22,000 years ago and was called the Last Glacial Maximum.
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How often do periods of glaciation occur?
Approx every 100,000 years, and they last between 100,000 and 150,000 years. They are characterised by temperatures of up to 8C less than current temperatures.
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What is the current interglacial period called?
The Holocene. It began around 9,000 years ago and global temperatures increased by 4C.
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When did the UN earth summit take place? What happened in it?
It took place in 1992, and it lead to the Kyoto Protocol, when 200 countries made an agreement to tackle climate change.
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Climate
The average condition of precipitation, temperature, pressure and wind over a 30 year period.
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Climate change
Any significant long term trend (of at least several decades) or shift in the average value for any climatic event (eg rainfall, drought, storminess).
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Ice cores for CO2 and O2 - what are they?
Scientists drill deep into ice sheets in Greenland and Antarctica. Ice sheets are made up of layers of ice- one layer is formed every year. They can analyse gases trapped in air bubbles in the ice to work out temperatures/ concentrations of CO2/O2.
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Carbon analysis- what is it?
Air bubbles in the ice contain atmospheric CO2. Cold glacial periods= low concentration, and interglacial periods=high concentration of CO2. They show that levels have varied between 180-280ppm in the last 800,000 years (in 2007 they were 380ppm).
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Reliability of ice cores?
They number of CO2 sequences that correlate well with each other suggest that it's quite reliable.
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Oxygen analysis- what is it?
The ice contains oxygen isotopes- 18O and 16O. The ratio correlates with water temperatures. When there was a low 18O concentration, there was more glacial ice. When there was a high 18O concentration, temperatures were higher.
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Reliability of oxygen analysis from ice cores?
The CO2 and O2 isotope records correlate well. When CO2 levels were low, so were the 18O levels. They broadly agree on sea level change.
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Pollen sequencing
Pollen is often preserved in bogs and lakes. The pollen can be identified and compared to similar pollen now so see differences. The pollen can tell us about atmospheric conditions at the time they were preserved.
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Reliability of pollen analysis?
They rely on good pollen preservation, and long pollen sequences are rare. Also, vegetation may lag behind climate change.
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Retreating Glaciers
Glaciers shrink and grow in response to the climate. Changes can be tracked by looking at old records, maps or photos (most reliable after 1880). They show that most glaciers reached their largest in 1850, and have retreated since then.
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Carbon Dioxide
Only makes up 0.04% of the Earth's atmosphere, yet is a major greenhouse gas. It is given off when carbon-based fuels are burned, eg coal and oil. Fossil fuels have increase atmospheric CO2 by 25%.
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Nitrous Oxide
Agricultural fertilisers, fossil fuels and production of synthetic chemicals (eg nylon) release N2O. N2O traps infrared radiation, changing to nitric oxide which destroys ozone.
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Chlorofluorocarbons (CFCs)
First used in the 1960s as propellants in sprays. CFCs absorb solar radiation and contribute to global warming. In the 1980s, UK scientists discovered thinning in the ozone layer 10-25km above Antarctica, caused by CFCs.
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Ozone
Found mostly in the troposphere (10-25km above Earth). It acts like a greenhouse gas, but disperses harmful UV rays. The warming effect of ozone is greatest at 12km, where most aircraft fly and where N2O pollution is greatest.
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Methane
A minor gas, but very effective in retaining heat. Since 1950, annual emissions have increased 4 times faster than CO2 increase. Causes include rice farming, burning vegetation, coal mining, and cow farts.
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Other cards in this set

Card 2

Front

Approx every 100,000 years, and they last between 100,000 and 150,000 years. They are characterised by temperatures of up to 8C less than current temperatures.

Back

How often do periods of glaciation occur?

Card 3

Front

The Holocene. It began around 9,000 years ago and global temperatures increased by 4C.

Back

Preview of the back of card 3

Card 4

Front

It took place in 1992, and it lead to the Kyoto Protocol, when 200 countries made an agreement to tackle climate change.

Back

Preview of the back of card 4

Card 5

Front

The average condition of precipitation, temperature, pressure and wind over a 30 year period.

Back

Preview of the back of card 5
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