Proxies

Question 1

What is plant microfossil data?

Answer 1

Plant remains. (Lowe and Walker, 2015).

Question 2

Name some advantages of plant microfossil data:

Answer 2

Provide regional data, can identify species that pollen records fail to show. (Lowe and Walker, 2015).

Question 3

Name some disadvantages to plant microfossil data.

Answer 3

Some microfossils e.g. mosses are more resistant to decay than others e.g. small seeds - makes identified species distribution uncertain.

Large samples often required to receive a few fragments of microfossil data.

Difficult to identify plant microfossils when they are particularly small. (Lowe and Walker, 2015).

Question 4

Name some advantages of diatoms.

Answer 4

Found in practically every body of water.

Good indicators of local habitat changes. (Lowe and Walker, 2015).

Question 5

Name some disadvantages of diatoms.

Answer 5

Often difficult to classify.

They do not always represent the location they’re found in as wind blows them across long distances e.g. from freshwaters to the sea. (Lowe and Walker, 2015).

Question 6

Where are fossil insect remains found?

Answer 6

Lake archives, peats and any other archive that preserves plant debris. (Lowe and Walker, 2015).

Question 7

What type of fossil insect remain is most commonly used to reconstruct climates? Why?

Answer 7

Coleoptera (Beetles) because they are the most diverse and abundant group. (Lowe and Walker, 2015).

Question 8

Name some advantages of fossil insect remains/Coleoptera:

Answer 8

They occupy a huge range of environments and each have a preference for a specific environment (makes identifying climates easier).

They are sensitive to climatic changes which helps researchers identify more subtle changes in climate. (Lowe and Walker, 2015).

Question 9

Name a disadvantage of fossil insect remains.

Answer 9

Fossils that are not Coleoptera are often very difficult to identify. (Lowe and Walker, 2015).

Question 10

What are ostracod’s?

Answer 10

Mussel shrimps that identify climates for most aquatic environments. (Lowe and Walker, 2015).

Question 11

Name some advantages of ostracods:

Answer 11

Some have limited ecological preferences which makes them useful palaeoenvironmental indicators.

Their fossil records are well documented - began in 1700s - useful for showing long-term changes.

Tell us about salinity, temperature, hydroclimate, oxidisation levels, nutrient availability etc. (Lowe and Walker, 2015).

Question 12

Name a disadvantage of using Ostracods:

Answer 12

It is not always clear what factor caused their distribution to change e.g. it could have been temperature or salinity or both etc (Lowe and Walker, 2015).

Question 13

What proxies are associated with lake sediments?

Answer 13

18O Carbonate, pollen, algae etc.

Question 14

What proxies are associated with peatlands?

Answer 14

Pollen and other microfossils e.g. vegetation.

Question 15

What proxies are associated with tree rings?

Answer 15

18O and ring width.

Question 16

What do changes in pollen show?

Answer 16

Changes in vegetation growing in that region which can be associated with changing climates.

Question 17

What causes pollen changes?

Answer 17

Climate, human activity e.g. chopping down trees.

Question 18

Name some advantages of pollen as a proxy:

Answer 18

They are easy to identify, have a high resolution and are very resistant to decay.

Question 19

Is pollen always representative of the climate where it was found?

Answer 19

No as wind can carry pollen for tens to hundreds of miles away from where it came from

Question 20

What can pollen tell us about past climates?

Answer 20

If there is more tree pollen it indicates wetter conditions, if there is more grass/shrub pollen it indicates drier conditions (Moore & Waddington, 2015).

Question 21

Why do pollen proxies show slower climatic changes than e.g. lake sediments?

Answer 21

Because if a species hasn’t been in an area for a while they will not come back immediately – tree/plan species take time to spread back from their refugia.

Question 22

Name some advantages of using tree rings as a proxy.

Answer 22

Most widely distributed and used proxy (lots of other data to compare with), high resolution, dating tree rings is effectively absolute (Li et al., 2016).

Question 23

Name some disadvantages of using tree rings as a proxy.

Answer 23

Limited ability of capturing slow climate change variability, sometimes trees ‘miss a year’ meaning there is a ring missing for that year which impacts interpretations (Li et al., 2016).

Question 24

Name some advantages of measuring borehole temperatures:

Answer 24

Temperature-depth profiles of boreholes contains records of surface temperatures due to thermal diffusion (used to estimate past climates) - (Li et al., 2016).

Question 25

Name some disadvantages to borehole temperatures:

Answer 25

Only retains long-term trends, past climate temperatures become harder to recover the further back you go (Li et al., 2016).

Question 26

Why are multi-proxy climate approaches useful?

Answer 26

They reduce the number of uncertainties - if multiple proxies suggest the same climate then interpretations are likely correct (Li et al., 2016).

Question 27

Name as many proxies as you can:

Answer 27

Pollen, tree ring width, isotopes e.g oxygen, plant and insect microfossils, algae, diatoms, foraminifera, borehole temperatures, ostracods etc.