tectonics and climate

Question 1

Supervolcanic events

Answer 1

e.g. Toba, 74000YA, Yellowstone, 2.1MYA
- ejects much higher into atmosphere, so global effects on climate are much longer (but short term in geological time scales) than smaller scale volcanic events
- sends huge amounts of particulates into the atmosphere (sulphur dioxide, carbon dioxide and dust)
- increases albedo, reducing the solar radiation reaching Earth’s surface
- reduction in worldwide temperature

Question 2

rain shadow

Answer 2

• mountains create a low pressure area
• clouds and rain form windward side as warm and moist air rises to meet the low pressure area and expands, cooling down, meaning the relative humidity rises until it hits 100%, forming strong rainfall
• non windward side very dry as the descending air has no moisture left

Question 3

high plateaux areas

Answer 3

• high and flat, can interfere with jet streams and disrupt atmospheric circulation by forcing air up and over them and deflecting the weather system around them
• colder in winter, creates anti-cyclonic areas of high pressure above them
• reversed in summer, creates cyclonic low pressure areas as they are heated up more, so air above them rises, driving monsoons

Question 4

Latitudinal arrangement of continents, tropical ring world model

Answer 4

• landmasses only around the equator
• heat dissipates away from the equator towards the poles
• no ice build up at poles as wind created from convection would push ice formed towards equator
• limited temperature gradient of ~30C

Question 5

Latitudinal arrangement of continents, polar cap world model

Answer 5

• landmasses only at poles
• temperature gradient >35C
• if cold air and water forms permanent ice caps, temperature gradient increases up to 60C

Question 6

reality of latitudinal arrangement of continents

Answer 6

• northern hemisphere similar to polar cap world model, no permanent ice cap over landmass
• southern hemisphere similar to polar cap world with ice caps model

Question 7

Longitudinal arrangement of continents, double-slice world model

Answer 7

• 2 landmasses running north to south
• double gyre system each hemisphere from the coriolis force
• similar seen in North Atlantic and North Pacific today

Question 8

Longitudinal arrangement of continents, double slice model with a low latitude seaway

Answer 8

• double gyre system in north and south hemisphere
• dominated by strong westward equatorial current
• seen during the cretaceous period, the Tethys sea

Question 9

Longitudinal arrangement of continents, double slice model with high latitude seaways

Answer 9

• single gyre system in north and south hemisphere
• strong easterly circumpolar currents at high latitudes
• seen in Antarctic circumpolar current today in southern hemisphere

Question 10

Longitudinal arrangement of continents, reality

Answer 10

• 3 major bands of continent with ocean basins in between

Question 11

tectonic changes driving climate in last 100 million years

Answer 11

• 100-50MYA = Cretaceous period, green Antarctica separates from Pangea and starts to move south
• 50MYA = Palaeocene/Ecocene thermal maximum. No ice caps at poles, Indian and Eurasian plate collide
• 35-30MYA = opening of Drake Passage, formation of circumpolar current in Southern Ocean around Antarctica draws heat away from Antarctica, ice sheet forms
• 10MYA, further global cooling from erosion of silicate Himalayas, transfers carbon to marine organisms and deep sea sediment stores
• 6MYA = Messinian salinity crisis, strait of Gibraltar closes, Gulf stream slows down from lack of saline input from Mediterranean, Atlantic much colder and Mediterranean dries up
• 5.3MYA = strait of Gibraltar reopens, Gulf stream intensifies, increasing humidity in North Atlantic forming Greenland ice cap
• 4.5-2MYA = closing of Isthmus of Panama, less input of Pacific water into Caribbean, increasing salinity in North Altanic. Gulf stream intensifies, Greenland ice sheet increases