evidence for climate change- lqc 14a Flashcards
correlation
When a change in one variable is associated with a change in another variable
causation
When a change in one variable is responsible for a change in another variable
why is pollen so useful for reconstructing past climates
- Plants produce pollen in vast amounts
- Pollen grains have a tough outer layer that is resistant to decay
- Each species of plant has a distinctive type of pollen – allows plant identification
- Pollen is trapped in peat – the deeper the pollen in peat, the older the pollen
- Each plant species has a particular set of environmental conditions – the type of pollen present indicates the tree and therefore the climate
why are peat bogs so good at preserving organic matter
They are anaerobic (lacking in oxygen) and acidic. These conditions inhibit the growth, survival and multiplication of microorganisms by inhibiting enzyme activity. The decay rate is slowed or stopped altogether.
dendrochronology
tree ring analysis
what type of climate is indicated by wide tree rings
warm and wet because an optimum temperature and an abundance of water is better for tree growth, therefore larger xylem vessels will be created and the tree ring will be wider.
how are ice cores used to indicate past climates
- As water freezes, bubbles of air become trapped within the ice.
2.The ratio of different oxygen isotopes in the trapped air is measured and this gives an estimate of the average temperature when the ice was formed. - The CO2 concentration can also be measured in the bubbles.
Explain how dendrochronology may also be used to provide evidence for climate change.
dendrochronology is the study of tree rings, each year a new tree ring is formed, the size of the ring reflects the growth of the tree that year, size of ring is affected by climate, photosynthesis is affected by climate, number of rings can be used to work out the timescale
