Terrestrial archives Flashcards
What are terrestrial archives? Give examples
Archives found on land e.g. lake sediments, tree rings, peatlands etc.
Why do terrestrial archives not go as far back as ocean archives?
They do not survive as long because they dry out.
Why are terrestrial archives important?
They provide regional climate records, humans live on land (not oceans!) and they are of a high resolution.
What proxies are associated with lake sediments?
18O Carbonate, pollen, algae etc.
What proxies are associated with peatlands?
Pollen and other microfossils e.g. vegetation.
What proxies are associated with tree rings?
18O and ring width.
What is palynology?
The study of pollen and other microfossils e.g. fungal spores.
What do changes in pollen show?
Changes in vegetation growing in that region which can be associated with changing climates.
What causes pollen changes?
Climate, human activity e.g. chopping down trees.
Name some advantages of pollen as a proxy.
They are easy to identify, have a high resolution and are very resistant to decay.
Is pollen always representative of the climate where it was found?
No as wind can carry pollen for tens to hundreds of miles away from where it came from
What can pollen tell us about past climates?
If there is more tree pollen it indicates wetter conditions, if there is more grass/shrub pollen it indicates drier conditions (Moore & Waddington, 2015).
What does glacial refugia refer to?
Small populations of trees that survive the glacial periods. This depends on moisture availability and topographic variability (shelter)
What is the Holocene and when did it begin?
The Holocene is the current interglacial period. It began around 11,700 years ago.
Why do pollen proxies show slower climatic changes than e.g. lake sediments?
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.
In what way are modern pollen-climate relationships modelled?
Numerically.
Name some advantages of using tree rings as a proxy.
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).
Name some disadvantages of using tree rings as a proxy.
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).
What is dendrochronology?
Dendrochronology is the study of data from tree ring growth (Li et al., 2016).
Name some advantages of measuring borehole temperatures:
Temperature-depth profiles of boreholes contains records of surface temperatures due to thermal diffusion (used to estimate past climates) - (Li et al., 2016).
Name some disadvantages to borehole temperatures:
Only retains long-term trends, past climate temperatures become harder to recover the further back you go (Li et al., 2016).
Why are multi-proxy climate apporches useful?
They reduce the number of uncertainties - if multiple proxies suggest the same climate then interpretations are likely correct (Li et al., 2016).
