1a. The earths climate is dynamic

Question 1

What is the quaternary period?

Answer 1

• A period spanning the last 2.6 million years.
• Characterised by cyclical changes to the climate.
• Cold periods = glacials
• Warm periods = inter glacials
• Glacial/interglacial last around 100,00 yrs

Question 2

What was The Younger Dryas period?

Answer 2

• A rapid shift in the climate
  -Suden fall then rise in temperature
• Occurred approx 12,00 yrs ago (recent)

Question 3

What was the Holocene Period?

Answer 3

• A gradual warming period
  -Occurred at the END of the Pleistocene
• its the current epoch were experiencing!
  Examples:
  Medieval warming period
  Little ice age

Question 4

Reconstructing past climates: Marine Sediment

Answer 4

• Millions of tonnes of sediment and biological material gets deposited at the ocean floor fossilises and is preserved
• Drilling cores into this can show a sequence of climate change over the years
• Identifies previous:
  ocean temperatures,
  salinity levels,
  river flows

Question 5

Reconstructing past climates: Fossils

Answer 5

• Preserve key characteristics of organisms
• Rock that surrounds the fossil can identify when it fossilised
• Overtime, fossils can change which can let us see if the changes were abrupt or gradual

Question 6

Reconstructing past climates: Ice Cores

Answer 6

• Cores are taken from the ice via drilling and are collected in 1m long samples
• Layers of snow show years of accumulation
• Analysis of the isotopes in each layer let us measure the temperature at the time the snow fell
• Gas bubbles in the ice can show the level of GHG’s in the atmosphere at the time

Question 7

Reconstructing past climates: Dendrochronology (Tree rings)

Answer 7

• Each year a tree gets wider and taller which causes it to form a new ring
• Rings = Cambrian layer = layer of cells between the wood and bark
• Size of the rings depends on the temperature and the wet/dry seasons

Question 8

Reconstructing past climates: Pollen & Beetles

Answer 8

• Plants produce pollen + spores that can show past climates as their outer shell allows them to be preserved and identified as they all look different
• Plants adapt differently to climates which lets us look at the type of climate they would’ve lived in the the type of rock there fossil in also helps
• The rock beetles are fossilised in lets us look how long ago they lived and how long for and in what climates they survived

Question 9

What are Milankovitch Cycles

Answer 9

The distribution + amount of solar radiation the earth receives

Question 10

Eccentricity cycle

Answer 10

Eccentricity = Orbit ( 100,000 years)

• The more elliptical the orbit, the colder the climate becomes as the sun is further away from the earth. This would occur during periods of a glacial advance

Question 11

Obliquity cycle

Answer 11

Obliquity = Tilt (41,000yrs)

• Earths axis tilt perpendicular to its orbital plane, caring between 22 - 24 degrees
• Title at 22 degrees = seasonal temps decrease and summers are cooler and winters are warmer

Question 12

Precession cycle

Answer 12

Precession = direction of the earths tilt (22,000 years)

• Affects the point in the year that the earths closest to the sun and when its furthest away during the northern hemisphere summer (cold)

Question 13

Plate Tectonics: Continental Drift

Answer 13

• Continents broke up from the super continent, Pangea 250 million years ago
• They gradually drifted north, to higher latitudes, where temperatures were cooler
• Snow accumulation increased over centuries = development of large ice sheets
• This increase albedo, causing increase sun rays to be re-radiated = cooling affect

Question 14

Plate Tectonics: Ocean Currents

Answer 14

• Shifting contents changed the circulation of heat and moisture
• 5 Million yrs ago, N & S America joined, closing the circulation between the Atlantic & pacific oceans
  This caused the Gulf Stream to from which warmed NW Europe to warm which triggered the quaternary ice age

Question 15

Plate Tectonics: Volcanic Eruptions

Answer 15

Example: Laki, Iceland

Immediate impacts :
- Destroyed land + agriculture
- Killed livestock
- 1/4 of Icelands population died from famine & starvation

Long term impacts:
- Most of the N Hemisphere was covered by a large sulphur cloud which blocked out sunlight
- Load became infertile
- Intense heat
- Changes in weather patters
- Starvation, food poverty = start of French Revolution and the revolt of the peasants

Question 16

Natural Greenhouse effect

Answer 16

• Solar energy enters the earths atmosphere
• SMALL amount of short wave radiation is absorbed in the atmosphere
• This heats the earths surface which then radiates long wave energy back into the earths atmosphere
• Long wave (heat) energy is easily absorbed by naturally occurring GHG’s in the atmosphere (CO2 = most abundant)
• This continues to further heat the planet
• Only a bit of long wave energy spaces the atmosphere and re-enters space

Question 17

Sun Spots + Faculae

Answer 17

• Sunspots = Dark
• Faculae = white
• As solar radiation increases every 11 years, sunspots + faculae increase in numbers
• During a solar minimum number of sunspots varies between 20 or less per year
  During a solar maximum, sunspots range between 100-150

Question 18

Earths major warming + cooling periods

Answer 18

• Temperatures have fluctuated over the last 4000+ years
• During the little ice age, >90 major eruptions occurred which prevented light exerting earth due to large gas clouds
• Increased cold temperatures during this period