What state are we currently in?
Icehouse state
What are the conditions of an greenhouse state?
The must be no continental glaciers on the planet.
How old is the world?
4.6 billion years old
In what state has the world mostly been in?
Greenhouse state, for 90% of the Earth’s history
How long do icehouse states last for?
Few million years
What age are we in?
An ice age, however a warmer period.
This is called an interglacial stage.
What was the last glacial and when did it end?
Pleistocene - around 12,000 years ago
In the quaternary period
What is the interglacial we are currently in called?
Holocene - began around 12,000
In the quaternary period
What is a stadial?
A short-lived pulse of ice advance during a glacial period.
What is an interstadial?
A warm period of retreat still during the glacial period
What is the Devensian?
Last glacial maximum (advance) occurring around 18,000 years ago.
What is the Loch Lomond Stadial?
Last glacial advance which occurred between 12,000 and 10,000 years ago.
What was the Little Ice Age?
A stage where very little sunspot activity led to low levels of solar radiation. This caused lower average temperatures in Europe and North America.
What are short-term causes of climate?
•Volcanic emissions:
- Large volumes of sulphur dioxide being emitted into the atmosphere
- This will then create sulphur aerosols, which are highly reflective.
- Therefore, less radiation reaching the Earth’s surface, lowering Earth’s temperature.
- Sulfur dioxide can remain in the Earth’s atmosphere for as long as 3 years, causing short term climate change.
• Sunspots:
- Sun has increased levels of energy in certain areas, leading to increased levels of energy in certain areas.
- This can be seen during 1650-1750, where a lack of sunspot led to cooling, finally caused Little Ice Age
What are the long term causes of climate change.
• Milankovitch’s theory: Axis tilt, eccentricity and wobble all have limited impact, but all combine over 100,000 year cycles, causing major temperature changes.
- Glaciers seem to have occurred at 100,000 year intervals, supporting Milankovitch’s theory.
- To explain larger temperature changes of up to 5 degrees, a positive climate feedback must be in place. This is due to the lower temperature causing more snow, and therefore more reflection. This process is repeated, which leads to the higher changes in temperatures, due to enhanced effect.
Describe the cause of the Loch Lomond Stadial?
- The drainage of the Lake Agassiz disrupted the THC (Thermohaline circulation).
- This cut off the poleward heat transport from the Gulf Stream, lowering global temperature by 6-7 degrees.
- The cooling in area led to ice formation. This lead to glaciers re-advancing.
Describe the characteristics of Loch Lomond Stadial
11,500 years ago, temperatures fell dramatically, leading to the advance of the Loch Lomond. This took place along the West of Scotland. Advanced for 200km, travelling South.
Describe the cause the Little Ice Age
- Widespread abandonment of upland farms in Scandinavia and Iceland.
- Many glaciers in Europe re-advanced down valleys.
- Volcanic activity
- Low levels of solar radiation (lack of sunspot activity)
Describe the characteristics of Little Ice Age?
- Cold winters took place: canals and rivers such as British Isles and Netherlands freezing over (so much so that ice skating could take place).
- Farms and villages were destroyed as glaciers advanced e.g. Swiss Alps.
- Sea extended: including 1 mile in every direction off Greenland.
- Crops failed across Europe leading to famine.
(Researchers argued that a new Stadial was prevented by the industrial revolution - fired by coal)
