Week 2 - Intro To Environmental Change Flashcards
Concept of reconstructing environmental change
Why study past climate change?
Understanding the past helps us understand how the climate works - climate models, computer programs can predict how it’s going to change in the future
What are Direct Societal Benefits and Academic Benefits of studying past climate change?
Direct - understanding the climate will help us predict future climate change
Academic - how climate influences, such as human evolution and civilisations collapses
Name an example of Analogues for the future in terms of studying past climates.
How high did temperatures reach in the past the last time CO2 levels were this high?
How do we benchmark climate models?
Run climate models backwards to see if they accurately predict past climate change (and how that compares to our palaeolimate reconstructions)
Why do grain harvest records infer climate?
A certain type of climate gets more grain in a year
What are proxies?
Physical, chemical or biological records that respond to changes in temperature or precipitation- in order to ‘reconstruct’ past climate change
What is an archive and name an example.
Something that accumulates material over time
Sediments at the bottom of the lake, accumulation of sediment
Tree rings
Ice cores
In a tree, what is the archive and what is the proxy?
The tree is the archive and the ring is the proxy (how wide it is could tell us about the climate at the time)
Name 5 examples of archives (geological and biological material)
Ocean sediments
Ice cores
Lake sediments
Bog sediments
Trees
Name 4 examples of proxies
Stable isotopes (18O, 13C)
Pollen
Diatom
Tree ring width
What is paleolimnology?
The study of lake sediments
How can a closed lake (one that has no flow of water) help us reconstruct past environmental change?
The lake level goes up if it gets ‘wetter’ (less evaporation and/or more precipitation) and goes down if it gets ‘drier’ (more evaporation and/or less precipitation).
In lake sediments there is a light layer and dark layer forming every year. What are they?
Light layer is calcium carbonate
Dark layer is algae
Though they have the same number of protons, what does Oxygen-18 have that Oxygen-16 does not have?
2 more neutrons
In a lake, what does a change in the ratio of O18 and O16 indicate?
Changes in lake level - caused by how wet or dry the climate is
What are Peatlands?
A mixture of more or less decomposed plant (humus) material
Accumulates in a water saturated environment
Absence of oxygen (anaerobic)
Why does material not completely decompose in peatlands?
Because of anaerobic conditions as a result of no oxygen
What are the two types of peatlands?
Ombrotrophic peatlands (bogs)
Minerotrophic peatlands (fens)
What are ombrotrophic peatlands?
Receive water solely/mostly from mineral-poor precipitation falling onto their surface
Minerotrophic peatlands (fens)
Influenced by mineral-rich groundwater from outside their own limits. Can turn into bogs
What can ombrotrophic peatlands tell us about past environmental changes?
As they get most of their moisture from precipitation, any change in the hydrology of the bog (how much water there is) can tell us about precipitation and temperature
What is Troels-Smith classification when analysing peat cores?
Visually identify stratigraphic units/layers (dark, lighter)
Mark the boundaries on the section/core
Record depth and nature of upper boundaries (sharp or diffuse)
Describe the physical components of each peat unit
What are the 4 different peat components?
Turfa herbacea (stringy)
Turfa bryophytica (spongy)
Turfa lignosa (woody remains)
Substantia humosa (highly decomposed)
What are the 3 components of Munsell Colour?
Munsell Hue (red, green, blue)
Munsell Value (light, dark)
Munsell Chroma (bright, vibrant)
