Research methods

Question 2

What methods can we use to research past conditions on Earth?

Answer 2

Boreholes
Ice cores
Pollen
Insects
Paleo modelling
Paleo oceans
Caves
Lakes
Coral
Fauna
Historical
Plant Macros

Question 3

What data can we use to research the past conditions on Earth?

Answer 3

Proxy data
Direct data

Question 4

What is Proxy data?

Answer 4

Preserved physical characteristics of the environment that can stand in for direct evidence of past climates
- stuff that is inferred from evidence

Question 5

What is direct data?

Answer 5

Data that is gathered from an original first hand source
- stuff that is recorded

Question 6

Give examples of proxy data

Answer 6

Animal and plant fossils
C12-C14 isotope ratio
O16-O18 isotope ratio
Mg-Ca in calcite deposits
Rock deposits
Air bubbles in ice cores

Question 7

Give examples of direct data

Answer 7

Written accounts
Historical record (meteorological)

Question 8

What does the strength of a record depend on?

Answer 8

The timescale (Length of time and resolution)
The geographical area
The ability to accurately record an event

Question 9

What happens to raw proxy data?

Answer 9

Gets calibrated against modern record climate data. If there isn’t any, it gets more qualitative than quantative

Question 10

What are ice cores? What can they show us?

Answer 10

A cylinder of glacial ice made up of layers that preserve climate evidence from the past.

• Accumulation rate
• air temperature
• summer temperatures
• atmospheric gas concentration
• volcanic activity
• sea ice concentration
• atmospheric circulation
• solar activity

Question 11

How do ice cores show accumulation rate?

Answer 11

thickness of layer = rate of precipitation
more thick = more snow
more snow = warmer temp

Question 12

How do ice cores show summer temperatures?

Give example

Answer 12

melt layers = layers without gas in

more melt layers = warmer summer because the water melts, dispelling gas

e.g. trends in melt layers of ice in NE Antarctic Peninsula

Question 13

How do ice cores show us atmospheric gas concentrations?

Answer 13

bubbles in ice can be shaved, melted or crushed to release gas. Gas can then be tested

Question 14

How can ice cores show us air temperatures?

Answer 14

Analyse the gas concentrations. More greenhouse gases = warmer because they would have insulated more.

Analyse the water isotope ratio. More O-18 than O-16 means warmer because it requires more energy to evaporate O-18 = heavier.

Question 15

How can ice cores show us volcanic activity?

Answer 15

Layers of ash in the ice = volcanic activity

Tephra can spread a long way. If geochemically identical ice is found in two separate places, we can find the extent of the eruption

Test for acidity - more acid, more volcanic. Run electric current because acid is conductive

Question 16

How can ice cores show us sea ice concentration?

Answer 16

Test salinity. More salinity = more sea ice because sea ice is made from frozen sea water (-1.8) rather than freshwater.

Can be used to predict extent by comparing different places.

Question 17

How can ice cores show us atmospheric circulation?

Answer 17

Aerosols carried in air currents get deposited on glaciers e.g. dust from storms.
- the more aerosols found mean better circulation because dust storms do not start in icy places

Can also be used to predict climate changes in other parts of globe - conditions such as drought needed to start the storm

Question 18

How do ice cores show us solar activity?

Answer 18

Beryllium-10 is made by Beryllium reacting with cosmic rays near surface of earth. More Beryllium-10 means more cosmic rays, means anomalies in solar radiation e.g. solar wind or Milankovitch theories of orbit. (eccentricity)

INDIRECT

Question 19

Pros of ice cores

Answer 19

• will reliably give evidence
• gives huge range of proxy data in a small sample
• hundreds/thousand of years
• relatively easy to collect/access

Question 20

Cons of ice cores

Answer 20

• EXPENSIVE
• demanding (-36)
• permanent/semi permanent camps
• drills can malfunction
• kerosene
• gas can diffuse

Question 21

What is radioisotope analysis?

Answer 21

Using radiation given off by C-14 to determine the movement of elements through natural systems

Question 22

How does radio isotope analysis work?

Answer 22

• Living organisms absorb C-14 into their tissue
• when they die, C-14 decays into other atoms
• when they decay they release gamma rays
• these strike RIIDs and convert it to an electrical signal

Question 23

What is radioisotope analysis used for?

Answer 23

• what plants and animals lived where and how long ago
• how much carbon in atmosphere when animal was alive
• temperature ranges can be found by comparing it to the dead animals temperature preferences
• trophic levels and food chains/webs
• how plants and animals spread after glacial retreat

Question 24

Pros of radioisotope analysis

Answer 24

• samples can be moved to examination site
• gains info that cannot be gained any way else
• dates ancient materials
• pretty accurate
• small samples
• 63,000YA is a while ago

Question 25

Cons of radioisotope analysis

Answer 25

- radioactive samples need to be shielded - radiation damage to humans - sample has to contain C-14 to be studied - half life = 5000 years. Some stuff e.g. rocks just too old - expensive - sample is destroyed - sample can be contaminated

Question 26

What is oxygen isotope analysis?

Answer 26

Method using the ratio of oxygen isotopes in a sample to gather information about past environmental conditions such as past temperatures, rainfall, and water quantity in ice sheets O-16 and O-18 are analysed

Question 27

How does oxygen isotope analysis work?

Answer 27

The mass of O-16 and O-18 in a sample are taken and then the ratio of these masses are calculated More O-16 means temps were cooler - it is lighter and therefore condenses last More O-18 means temps were warmer - it is heavier and therefore evaporates last.

Question 28

Pros of oxygen isotope analysis

Answer 28

- available anywhere that water chemistry has been preserved - not limited by age - good understanding of natural climate cycles changing over time and the human impact - accurate

Question 29

Cons of oxygen isotope analysis

Answer 29

- expensive - complicated - ratios can be influenced by other factors - marginal seas may not represent the big picture - cannot be applied below CCD

Question 30

What are magnesium/calcium ratios?

Answer 30

Using the magnesium/calcium ratio in samples such as foraminifera, water and soil to determine past conditions

Question 31

How does the Mg/Ca ratio in foraminifera show past conditions?

Answer 31

Mg/Ca ratio in shells tells us about temperature. - Warm temperatures = more Mg. Expends energy to use Mg but it'll be okay in warm temps

Question 32

How does the Mg/Ca ratio in water show past conditions?

Answer 32

Shows alteration in water chemistry and trends can be used to predict past and future data - ratio increased over past 10s of millions of years. Triggered changes in organisms that build massive CaCO3 reefs - ratio identifies processes that alter the oceans physiochemical properties

Question 33

What physiochemical properties can Mg/Ca ratios influence? Why are they important?

Answer 33

- physical properties e.g. freezing/boiling point - solvation properties - molecular properties e.g. size/shape/volume - amino acid properties e.g. acidity Allows scientists to understand a substance's behaviour and predict hazards. How to help environment.

Question 34

How can the Mg/Ca ratios in soil show past conditions?

Answer 34

- good soil structure has Mg/Ca ratio of 1:2 - any less is instable, and more than 10:1 is a deficiency. Bad because: - poor aeration (bad gas exchange and harmful pathogens) - bad plant growth (bad roots and mineral uptake) - bad plant health (bacteria/viruses) - bad crop yields Identifying these in a sample can point to bad soil quality in the past, so we can predict condition that could have lead to it.

Question 35

How has life on earth influenced transpiration?

Answer 35

- plants evolve and colonise land - transpiration returns water vapour to the atmosphere which increases rainfall in other areas and can make new plants grow, which build up the stream