2.4 Global Climate and Sea Level Change Flashcards
Which way has the British area moved throughout time?
Northward
What would the climate have been like in the British Isles in carboniferous times?
Warm - equatorial climate
What would the climate have been like in the British Isles in Permian and Triassic times?
Hot desert climate
What kind of rocks were formed in the lower Paleozoic era? (15-30° south of equator)
- greywacke (sandstone)
- shale
- granite
- gneiss
- slate
- schist
Where was the British Isles positioned in the lower Paleozoic era?
15-30° south of the equator
Rock formed in the Lower Carboniferous era?
Shelly limestone
Where was the British Isles positioned in the Lower Carboniferous era?
0-5° South of the equator (shallow marine)
Rocks formed in the Upper Carboniferous era?
- shale
- sandstone
- coal
- fossil plants
Where was the British Isles positioned in the Upper Paleozoic era?
5° North of the equator
Rocks formed in the Permian era?
- desert sandstone
- halite
- breccia
Where was the British Isles positioned in the Permian era?
15° North of the equator - desert
Rocks formed in the Jurassic era?
- shelly limestone
* oolitic limestone
Where was the British Isles positioned in the Jurassic era?
30° North of the equator (Mediterranean type sea and few land areas)
Rock formed in the Cretaceous era?
Chalk
Where was the British Isles positioned in the Cretaceous era?
40° North of the equator (covered in sea due to sea level rise)
Rock formed in the Cenozoic era?
Basalt
Where was the British Isles positioned in the Cenozoic era?
45°N - mainly land
Rock formed in the Quaternary era?
Breccia
Where was the British Isles positioned in the Quaternary era?
British isles in present position
Who put forward the idea of natural selection?
Charles Darwin and Alfred Wallace
What shows that there used to be little oxygen in the oceans?
In Australia - ancient banded ironstones
Approximately, when did the oxygen in the oceans and atmosphere begin to rise?
2 billion years ago
What does the Burgess Shale show?
That 520 million years ago all major categories of modern animals had evolved and food chains had developed
When did Pangaea develop?
250 million years ago
Why did the development of Pangaea kill off 90% of marine life?
Reducing the coastline - drop in sea level
Examples of evidence for global climate change throughout geological time?
- deposition of glacial deposits in regions close to equator (Carboniferous tillites)
- deposition of limestone in areas outside the Tropics (Cretaceous limestones/chalk)
What evidence is there that there has been changes in sea level over geological time?
Drowned forests
What is greenhouse earth?
When Earth is warmer than usual
What is icehouse earth?
When Earth is cooler than usual
How does an increase in ice coverage affect global temperature in an icehouse phase?
Increases the drop in global temperatures by increasing albedo
Are we in an icehouse or greenhouse period?
Icehouse - continental ice sheet sheets at both poles
Why does greenhouse earth happen?
An increase in solar radiation or change in concentration of gases in the atmosphere
Was chalk created in an icehouse or greenhouse earth in Britain?
Greenhouse during Cretaceous
Factors that can change global average temperatures?
- atmosphere composition
- position of continents and oceans
- earths orbit - (goes from circular to elliptical in a cycle of 95000 years)
What evidence can be used for average global temperatures in the past?
Fossils, sedimentary rocks and ice cores
Why might melting glaciers result in a lower sea level rise than expected?
As more polar ice melts, weight of water could push down on crust
What is the evidence for the greenhouse effect?
Ice cores
How do ice cores provide evidence for the greenhouse effect?
Ice traps CO2 as it freezes, with older deeper ice allowing us to go back in time and measure previous CO2 levels
How can the natural controls of CO2 in the atmosphere be categorised?
- positive - ↑ CO2 in atmosphere
* negative - ↓ CO2 in atmosphere
What is the main positive control of CO2 in the atmosphere?
Albedo effect - snow reflects sunlight, cooling earth. However if areas of ice and snow ↓ then less sunlight reflected and earth will warm - this can lead to build up of CO2
What are the negative controls of CO2 in the atmosphere?
- dissolving of CO2 into seawater
- absorption of CO2 by marine organisms to form their skeletons
- formation of rocks e.g. limestone
Natural sources of CO2 in the atmosphere?
- volcanic outgassing
- natural burning of organic matter
- respiration processes of living organisms
Man-made sources of CO2 in the atmosphere?
- burning fossil fuels
* industrial processes e.g. cement making
What are the most attractive CCS (carbon capture) sites?
Deep saline aquifers, coal seams, and oil and gas reservoirs
What are the main problems with CCS?
Where to store the gas, and how to transport the gas
What would be the most economic way of transporting CO2 for CCS?
Along pipelines
How might seismic activity affect CCS?
May undo the sequestration and cause leakage
What can happen if landfill holes are not capped?
Rainwater filters in and dissolves toxic materials forming a leachate - if rocks are permeable, this can flow into the water table
What is commonly used for landfill?
Old brick pits as the clay has low permeability
Solutions to contaminated groundwater (before regulations were put into place)?
- dilute leachates in the water table by adding groundwater - so when it reached the surface the pollution had become dilute enough
- waste placed in impermeable areas - e.g. line with impermeable clay liners or membranes (sheets of plastic)
How is methane produced?
Through decay of organic matter
Solutions to production of methane by decomposition of organic matter?
- collect methane and pipe it to where it can be burnt safely
- use methane as fuel
How can landfill sites be monitored?
- check permeability of rocks and amount of groundwater flow
- decide on suitability of site as either: low, moderate or highly toxic waste
- find best method of confining waste and lowering leakage
- checking hydrogeology to detect any leakage
What is the best way to dispose of radioactive waste in Britain?
Encase the waste, then deep burial in an impermeable, crystalline rock e.g. granite
Why might soil be contaminated?
- leakage from underground storage tanks
- pesticides
- seepage from contaminated surface water
- oil and fuel dumping
- leaching of waste from landfills
- direct discharge of industrial waste
How can soil be uncontaminated?
Soil cleaning - requires permeable soil - grains in soil washed and scrubbed mechanically - removing organic material
