Climate Change (Methods Used To Provide Evidence For Past Climate Change) (1a)

Question 1

What is proxy data?

Answer 1

Information that is a substitute for direct observations of Earth’s climate

Question 2

Tree rings/dendrochronology (proxy data)

Answer 2

-Each ring represents 1 year
-Grow thicker in warm + wet climates
-Up to 10000 years ago

Question 3

Ice cores (proxy data)

Answer 3

-Bubbles contain levels of atmospheric gases at time of when the ice was deposited
-Measure ghgs and oxygen isotopes
-Allows us to go back 1 million years ago

Question 4

Ice cores (cold climate)

Answer 4

-Less energy
-Only O16 evaporates (lightest)
-No O18 found in snow - > only O16 found

Question 5

Ice cores (warm climate)

Answer 5

-More energy
-Both O16 and O18 evaporate and are deposited in snow

Question 6

Oceanic sediments + fossils (proxy data)

Answer 6

-Microfossils called forominifia
~ single celled organisms whose skeletal remains built up in layers on ocean floor, millions of years ago
-Different species prefer different climatic conditions
-Exoskeleton is made from calcium carbonate so composition in shells can indicate temperatures

Question 7

Lake sediments + pollen fossils (proxy data)

Answer 7

-Micropollen + microfossils
-Species can help identify conditions of climate at time of deposition
-VARVES
~tiny layers of lake sediment, light + dark bands
~light = coarse sediment, high energy, melt water in summer + spring = warmer
~dark = finer sediment, less energy, = cold winter