- A long-term change in the earth's climate, especially a change due to an increase in teh average atmospheric temperature.
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What is the Quaternary period?
- The period of geological time from about 2.6 million years ago to the present. - In this perod, global temp has shifted between cold glacial periods and warmer glacial periods.
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Ice cores
- Ice sheets are made up of layers of ice (one ice layer formed each yr). - Ice sheets are drilled into to get long cores of ice. - By analysing the gases trapped in the layers of ice, they can tell what the temp. was each yr.
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Sediment cores
- Remains of organisms found in cores taken from ocean sediments can be analysed. - Can extend temp. record back at least 5 million yrs.
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Pollen analysis
-Plant pollen get preserved in sediment, e.g.at bottom of lakes or in peat bogs.-Preserved pollen can be identified+dated to show which species were living at that time.-Preserved pollen from similar plants to now show climate conditions were similar
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Tree rings
- A s a tree grows it forms a new ring each yr - the tree rings are thicker in warm, wet conditions. - Scientists take cores and count the rings to find age of tree. - Thickness of each ring shows what climate was like.
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Temperature records
- Since 1850s globsl temp.s have been measured accurately using thermometers. - Reliable but short-term. - Historical records (e.g. newspaper weather reports+harvest dates) can extend record a bit further back.
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Other cards in this set
Card 2
Front
What is the Quaternary period?
Back
- The period of geological time from about 2.6 million years ago to the present. - In this perod, global temp has shifted between cold glacial periods and warmer glacial periods.
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