CLIMATE CHANGE EVIDENCE
- Created by: Charlie Davies
- Created on: 29-05-14 11:45
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- Climate Change- Evidence
- Climate Change is any long term change in weather
- any significant change in the weather of a region over a period of at least several decades
- Climate is constantly changing, it always has and it always will
- Last 2.5million years, global temperatures has shifted between cold glacial periods that last around 100,000years and warmer interglacial periods that last 10,000 years
- we are now in an interglacial period
- 20,000years ago Earth was cold. 15,000 years ago tarted to warm up
- over last 10,000 years climate has been warm with minor fluctuations
- over last 1000 years climate has been fairly constant with small fluctuations in annual temp.
- over last century global temp. as increased rapidly.-Called global warming. Sharp rise in average temp (0.7oC 1900 and 2000)
- Global temps rose steadily from early 2othC until 1940's (13.5oC to 14oC)then dropped.Scientists thought another glacial period but risen even more
- changes in climate over last century are result of human acitivities
- Global temps rose steadily from early 2othC until 1940's (13.5oC to 14oC)then dropped.Scientists thought another glacial period but risen even more
- over last century global temp. as increased rapidly.-Called global warming. Sharp rise in average temp (0.7oC 1900 and 2000)
- over last 1000 years climate has been fairly constant with small fluctuations in annual temp.
- over last 10,000 years climate has been warm with minor fluctuations
- EVIDENCE FOR CLIMATE CHANGE
- OBSERVATIONS
- HISTORICAL RECORDS
- can indirectly show different conditions in the past.
- e.g. agricultural reports showing changing conditions throughout human history
- can indirectly show different conditions in the past.
- WEATHER RECORDS
- details of weather conditions consistently collected since 1861. Used to show detailed cimate changes
- HISTORICAL RECORDS
- PHYSICAL EVIDENCE
- POLLEN ANALYSIS
- pollen is often preserved in sediment
- this pollen can be identified to the plant it came from
- pollen is often preserved in sediment
- COLEPTERA
- these are beetles whose remains are preseved in sediment
- different species live in different climatic conditions
- these are beetles whose remains are preseved in sediment
- TREE RINGS (DENDROCHRONOLOGY)
- as trees grown new tree ring is produced
- rings are thicker in warm, wet conditions
- trees can reliably show date and climate conditions upto 10,000 year ago
- rings are thicker in warm, wet conditions
- as trees grown new tree ring is produced
- POLLEN ANALYSIS
- BIOLOGICAL EVIDENCE
- ICE CORES
- scientist drill deep into ice sheets to extract the cores
- ice sheets made up of layers of ice- one layer is formed every year
- analyse gases trapped
- can tell what temperature was like and how it has changed over time
- high CO2 indicate warm climate at that time
- Oxygen has two main isotopes 0-18 and 0-16
- O-16 is lighter than O-18
- Cold periods less energy for evaporation so water molecules with O-16 evaporate easier and falls as snow
- High levels of O-16 to O-18 = cold climate
- Cold periods less energy for evaporation so water molecules with O-16 evaporate easier and falls as snow
- O-16 is lighter than O-18
- can tell what temperature was like and how it has changed over time
- analyse gases trapped
- ice sheets made up of layers of ice- one layer is formed every year
- scientist drill deep into ice sheets to extract the cores
- SEA FLOOR SEDIMENTS
- sediments deposited on sea floor record chemical composition of seawater when deposited
- like oxygen contain Oxygen isotopes
- during periods of cold climate water molecules O-16 more easily evaporated so ocean becomes rich in O-18
- high levels of O-18= cold period
- during periods of cold climate water molecules O-16 more easily evaporated so ocean becomes rich in O-18
- like oxygen contain Oxygen isotopes
- sediments deposited on sea floor record chemical composition of seawater when deposited
- SEA LEVEL CHANGES
- as climate warms ice caps melt and sea levels rise.
- E.G. POOLE HARBOUR, DORSET
- Shows sea level is higher than it used to be
- RETREATING GLACIERS
- look at historical pics and at deposited rocks
- distance of rocks from current galicer indicates climate change
- If front of glacier miles away from rocks shows temp. increased
- distance of rocks from current galicer indicates climate change
- look at historical pics and at deposited rocks
- ICE CORES
- OBSERVATIONS
- Climate Change is any long term change in weather
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