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2 Glaciated Landscapes and Change > EQ1 - How has climate change influenced the formation of glaciated landscapes? > Flashcards

EQ1 - How has climate change influenced the formation of glaciated landscapes? Flashcards

1
Q

In what epoch was the most recent major ice age?

A

Pleistocene epoch

  • spanned from 2.5m to 11,700 years ago
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2
Q

What is a glacial period?

A

Where colder temperatures cause glacial advances

  • sea levels fall
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3
Q

What is an interglacial period?

A

Where warmer temperatures cause glacial retreats

  • sea levels rise
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4
Q

What was the name of the most recent period of glacial advance (around 21,000 years ago) ?

A

Last Glacial Maximum

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5
Q

During the last Glacial Maximum, a large area of the northern hemisphere was covered by ice sheets (including the UK)

True or False?

A

True

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6
Q

The world is currently in a glacial period - naturally, over time temperatures will drop and glaciers will advance.

True or False?

A

False - we are in an Interglacial period

  • temperatures are higher and most glaciers are retreating
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7
Q

What can be used to evidence temperature fluctuations during glacial/interglacial periods in the past?

A

Ice Cores

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8
Q

How do ice cores show temperature fluctuations?

A

They reveal atmospheric gas concentrations over time

  • this can be used to determine atmospheric composition and temperature
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9
Q

What is the name of the epoch that began 11,700 years ago?

A

Holocene epoch

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10
Q

Define an ‘Icehouse’ phase

A

Period of long-term cooling and presence of polar ice

  • as experienced in the Pleistocene
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11
Q

Define a ‘greenhouse’ phase

A

Period of higher global temperatures where ice is minimal

e.g during Cretaceous period

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12
Q

What is the most significant long-term driver of climate change?

A

Milankovitch cycles

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13
Q

What are Milankovitch cycles?

A

Changes in the earth’s orbit and axial positioning, affecting the distribution of solar energy across the planet

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14
Q

Name the 3 components (types) of Milankovitch cycles

A
  1. Eccentricity
  2. Axial tilt
  3. Precession (wobble)
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15
Q

In ice cores, what does low concentrations of carbon dioxide suggest?

A

A glacial period

  • interglacial usually high CO2 (much warmer)
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16
Q

Though the Pleistocene is considered a ‘single ice age’, there were actually multiple periods of glacials/interglacials within it

True or False?

A

True

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17
Q

What are stadials and interstadials?

A

Short-term fluctuations within ice-house/greenhouse conditions

  • stadials are intense cold
  • interstadials are relative warmth
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18
Q

What is eccentricity?

A

The variation in the path of the earths orbit

  • either more elliptical or more circular
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19
Q

How long do cycles of eccentricity typically last?

A

Around 100,000 years

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20
Q

How does Eccentricity affect global climate?

A

Changes the amount of solar radiation received by the Earth

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21
Q

What is Axial tilt?

A

The angle in which the earth rotates on

22
Q

What is the range of which axial tilt varies?

A

Between 21.8 - 23.4 degrees

23
Q

How does axial tilt affect climate?

A

Changes the intensity of sunlight received at the poles

This affects seasonality of climate - (greater the tilt, greater the difference between winter and summer)

24
Q

What is Precession (wobble)?

A

How the earth wobbles on it’s axis (like a spinning top)

25
Q

How does precession affect climate?

A

The wobble of the earth on it’s axis changes the point at which it is closest to the sun

  • this can cause long term changes to when different seasons occur along the Earth’s orbital path
26
Q

How long does a cycle of Eccentricity last?

A

100,000 years

27
Q

How long does a cycle of Axial tilt last?

A

41,000 years

28
Q

How long does a cycle of Precession (wobble) last?

A

21,000 years

29
Q

What occurence seems to support Milankovitch’s theory that orbital variation heavily impacts solar radiation/climate?

A

Glacials seem to have occurred at regular intervals of 100,000 years

(the same length as each eccentricity cycle)

30
Q

What is the actual impact, in Degrees Celsius (‘C), that Milankovitch cycles have on global temperatures?

A

Only change temperatures by 0.5-1’C

31
Q

What mechanism is used to explain large temperature changes (more than +/- 5’C) in history?

A

Climate Feedback Mechanisms

32
Q

Many scientists see Milankovitch cycles as a possible ‘trigger’ for major glacial/interglacial periods, but NOT as the driving factor.

True or False?

A

True - it is climate feedback mechanisms which sustain the process

33
Q

Explain positive and negative feedback effects?

A

Where a small change is either amplified (positive) or diminished (negative)

34
Q

What effect does an increase in snow/ice have on the Earth’s surface albedo (reflectivity)?

A

Raises surface albedo (reflectivity), so more solar energy reflected back into space

35
Q

Is the albedo effect an example of positive or negative feedback?

A

POSITIVE Feedback - more solar energy reflected leads to further cooling

36
Q

How does the melting of snow/ice due to CO2 emissions create a positive feedback loop?

A

It decreases albedo effect + releases methane from melted permafrost

37
Q

How do increasing global temperatures affect evaporation and cloud cover? (negative feedback)

A

More evaporation leads to more cloud cover

Cloud cover reflects solar energy back to space, diminishing warming

  • This process is known as global dimming
38
Q

How do ice sheet dynamics affect thermohaline circulation (THC) and global temperatures?

A

Warming water in the Arctic disrupts ocean currents, reducing the flow of warm water from Gulf Stream to Northern Europe

  • Potentially leading to cooling in this region
39
Q

What is ‘calving’?

A

The breaking up of chunks of ice at the glacier snout/ice sheet to form icebergs

  • Occurs as the glacier reaches a lake or ocean
40
Q

What is the Thermohaline Circulation?

A

Global system of surface and deep-water currents

  • known as the ‘ocean conveyor’
41
Q

What are currents in the Thermohaline circulation driven by?

A

Differences in temperature (thermo) and salinity (haline), between areas of the oceans

42
Q

What 2 factors have been responsible for short-term fluctuations in climate?

A
  1. Solar Forcing
  2. Volcanic Activity
43
Q

What causes the amount of energy emitted by the Sun to vary?

A

The number/density of Sunspots

44
Q

What are Sunspots?

A

Dark spots on the surface of the sun

  • they affect the amount of energy emitted by the Sun
  • Caused by intense magnetic storms
45
Q

What was the ‘Maunder Minimum’ (1645-1715), coinciding with the height of the Little Ice Age?

A

A long period with no Sunspot activity

46
Q

Despite the ‘Maunder Minimum’ phenomenon, what is the actual % variation in solar radiation caused by Sunspot activity?

A

0.1%

  • Suggests that sunspots alone are insufficient to explain climate fluctuations
47
Q

What % of 20th century global warming do scientists attribute to solar output variation (sunspots)?

A

20%

48
Q

How do large volcanic eruptions impact global climate?

A

Released substances such as ash, sulphur dioxide and CO2 are recirculated globally by high-level winds

49
Q

What was the decrease in global temperature in the 2-3 years following an eruption releasing 200m tonnes of sulphur dioxide in Indonesia, 1815?

A

Temperatures dropped by 0.4-0.7’C

  • caused short-lived global cooling
50
Q
A

2 Glaciated Landscapes and Change (4 decks)

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