Climate Change Flashcards
What has happened to Earths climate over last 100 million years?
Fluctuated between greenhouse and icehouse conditions
What are greenhouse conditions?
- Carbon dioxide in atmosphere high
- High global temps
- Eustatic sea level rises
What are icehouse conditions?
- Carbon dioxide in atmosphere low
- Low global temperatures
- Eustatic sea level fall
What are the 6 major periods of change?
- Mid-cretaceous
- Paleocene
- Oligocene
- Quaternary
- Holocene
- Anthropocene
When was the mid cretaceous period?
100 million years ago
When was the Palaeocene period?
55 million years ago
When was the Oligocene period?
35 million years ago
When was the Quaternary period?
2.6 million years ago
When was the Holocene period?
Last 11700 years
When was the Anthropocene period?
The present
In what period did the glaciation of Antartica form?
Oligocene
What was the Mid-Cretaceous period like?
- Avg temp 6-8 degrees higher than today
- No polar ice caps
- Sub-tropical conditions extend from Antartica to Alaska
- Greenhouse conditions 5x higher than today
- 10s of millions of years
- Oceanic circulation impended by continents
What was the Oligocene like?
- Icehouse conditions (lasted till today)
- Glaciation of Antartica
4 reasons why the glaciation of Antartica occurred:
- Decrease in CO2
- Continental drift
- Circumpolar current
- South Sandwich Island Arc
What was the drop in carbon levels during the Oligocene
1100 —> 550ppm
What was the Quaternary period like?
- Cyclical changes of climate
- Long period of glacial conditions (100k years)
- Short interglacial periods (15k years)
- Overall icehouse period
- 1km thick glaciers covered majority of N England + Scotland
Why was the Holocene like?
- Major decline of ice-sheets + glaciers
- Steady warming
—> some short periods of cooling (6000 years)
—> little ice age (1550-1850) - Climate was in equilibrium
What was the Anthropocene like?
- Atmospheric carbon dioxide —> 420ppm
- Raised avg global temp by 1.3 degrees celsius
How much solar power radiation is reflected back to space in the NGE?
- 30%
( Clouds 25%, ice sheets 2.5%, deserts 2.5%)
What is it called when light surfaces reflect solar radiation?
The Albedo effect
How much solar radiation is absorbed by the atmosphere in the NGE?
- 70%
( Atmosphere 23%, surface 48%)
What happens when solar radiation is absorbed by the atmosphere?
- Re-emitted as long wave/infrared/terrestrial radiation (heat)
—> some leaves Earth’s system, into space
—> some absorbed by gases, these GHG then re-emit heat, warming the Earth
What are external factors causing climate change?
In space
Name the external factors causing climate change
- Milankovitch cycles
- Solar output
