4.1: The cause of longer and short-term climate change

Question 1

Where is there identifiable evidence of glaciation within Europe?

Answer 1

The North European Plain

Question 2

How can ice cores be used to determine past climate events?

And what does their contents indicate?

Answer 2

Air bubbles trapped within the ice contain atmospheric carbon dioxide and the ice itself proves a record of oxygen isotopes - low contractions of carbon occur during glacial periods whereas much higher ones indicate an interglacial period.

Question 3

When did the Quaternary period begin?

Answer 3

2 million years ago

Question 4

Why did the tertiary period end?

Answer 4

there was an onset of global cooling and ice-house conditions

Question 5

What is a glacial period?

Answer 5

cold, ice-house period within the Pleistocene

Question 6

what is an Interglacial

Answer 6

Warner periods similar to the present, i.e greenhouse periods

Question 7

what are Ice-house conditions?

Answer 7

very cold gacial conditions

Question 8

what are Green-house conditions

Answer 8

much warmer interglacial conditions

Question 9

Quaternary period is divided into 2 epochs of geological time. Name them.

Answer 9

Pleistocene and Holocene

Question 10

Describe the span of the Pleistocene period

Answer 10

covers the time span from the Quaternary to 11,500 years ago when the most recent continental glacial ended

Question 11

Describe the Holocene period

Answer 11

interglacial period (we are living in now) is similar climatically to previous interglacials, but is distinctive a it is noted for the growth of human civilisation

Question 12

Glaciers and their meltwater to create erosional and depositional features. But can these be changed over time?

And how does this affect scientists ability to understand glacial process’

Answer 12

landforms produced have been changed by later glaciations and post-glacial geomorphic processes making reconstructing past patterns of glaciation challenging.

Question 13

Define what a Stadial is

Answer 13

colder periods that lead to ice re-advancement

Question 14

Define what an Interstadial is

Answer 14

short term fluctuations within in ice-house-greenhouse conditions

Question 15

Name the three elements of the Milankovitch cycles

Answer 15

1. Eccentricity
2. Axial Tilt
3. Axial Precession

Question 16

Explain Eccentricity and the timescale in which it happens

state how this affects global temperature

Answer 16

The orbit of the earth changes from elliptical to circular and back again over a period of 100,000 years. This changes the amount of radiation received from the sun to the earth due to the changes in distance between them

Question 17

Explain Axil Tilt and the timescale in which it happens

state how this affects global temperature

Answer 17

It varies from 21.8 to 24.4 degrees (currently the earth is tilted at 23.5) over 41,000 years. This changes the intensity of sunlight received at the poles and, therefore, the seasonality of the earth’s climate. The greater the tilt the greater the difference between summer and winter.

Question 18

Explain Axil Precession and the timescale in which it happens

state how this affects global temperature

Answer 18

The earth wobbles on its axis changing the point in the year at which the Earth is closest to the sun over 21,000 years. This causes long-term changes to when different seasons occur along the earth’s orbital path.

Question 19

Change in orbit are impactful to global climate however by how much do these changes change global temperature?

Answer 19

0.5 to 1 degrees

Question 20

What are climate feedback mechanisms?

Describe them both and what affect they have

Answer 20

Feedback effects are those that can either amplify a small change and make it larger (positive feedback) or diminish the change and make it smaller (negative feedback)

Question 21

Does positive feedback increase or decrease warming or cooling rates?

Answer 21

Increase

Question 22

Does negative feedback increase or decrease warming or cooling rates?

Answer 22

Decreasing

Question 23

Explain 2 factors of positive feedback and their effects

Hint: to do with snow and ice cover

Answer 23

1. Increase in snow and ice cover
   Small increases in snow/ice cover raise surface albedo (reflectivity) so more solar energy is reflected back into space leading to further cooling, which can lead to further snow and ice cover
2. Melting of snow and ice cover
   The melting of snow and ice covered by CO2 emissions decreases albedo. Methane is emitted as permafrost melts and warming seas lead to calving of ice sheets, which all lead to loss of snow/ice cover and surface albedo decreasing reflectivity and accelerating further warming

Question 24

Explain 2 factors of negative feedback and their effects

Hint: to do with snow and ice cover

Answer 24

1. Global dimming
   Increase in global warming leads to more evaporation and, over time, pollution from industrialization adds to global cloud cover. Increaly cloudy skies could reflect more solar energy back to space and diminish the effect of global warming - so may become less intense because of this global dimming
2. Thermohaline Circulation
   Ice sheet dynamics can disrupt the thermohaline circulation (THC). warming water in the arctic disrupts ocean currents; less warm water from the gulf stream is drawn north, which could lead to cooling in europe - therefore slowing down the effects of global warming

Question 25

What is the thermohaline circulation system?

Answer 25

a global system of surface and deepwater ocean currents driven by differences in temperature (thermo) and salinity (haline) between areas of oceans. Sometimes called the ocean conveyor.

Question 26

How do solar sunspots affect global temperatures?

Answer 26

The amount of energy emitted by the sun varies as a result of the number and density of sunspots (dark spots on the sun’s surface caused by intense magnetic stores). The more sunspots there are and the more intense they are the greater the rise in global temperature

Question 27

2 historical examples of the impacts of solar sunspot

Answer 27

1. A longer period with no sunspot activity, the Maunder Minimum, occurred between 1645 and 1715, at the height of the Little Ice Age
2. The proceeding mediaeval warm period has been linked to more intense sunspot activity

Question 28

How does Volcanic Activity affect global temperatures?

Answer 28

Violent volcanic activity can alter global climate.
Eruptions with high volcanic explosivity index (VEI) eject huge volumes of ash, sulphur dioxide, water vapour and carbon dioxide into the atmosphere (volcanic aerosols), which high level winds distribute around the globe

Question 29

2 historical examples of the impacts of volcanic activity affecting global temperatures

Answer 29

1. In 1815 Tambora in Indonesia ejected 200 million tonnes of sulphur dioxide into the atmosphere and for the following three years, temperature were recorded 0.4-0.7 degrees lower - so short lived global cooling occurred
2. Laki Fissure eruption in Iceland from 1783-84. The size of volcanic aerosol and length of the eruption were linked to the exceptionally cold winter in the northern hemisphere in 1785 - (which contributed toward the French revolution)

Question 30

Describe the Loch Lomond Stadial

State when it happened, the change in temperature it caused, its effects and what caused it?

Answer 30

1. Around 11,500 years ago glacial conditions occurred
2. Temps 6-7 degrees lower
3. Glacial re-advancement occurred in many parts of the world; formation of ice caps in the Scottish highlands, from which cirque and valley glaciers flowed. Smaller areas of cirque glaciers formed in the lake district and north wales
4. One possible cause was the drainage of the huge proglacial lake Agassiz disrupted the THC, thus cutting off the poleward heat transportation from the gulf stream

Question 31

Describe the Little Ice Age

State when it happened, the change in temperature it caused, its effects and what caused it?

Answer 31

1. Between 1350 and 1900 conditions were slightly colder - on average 1 - 2 degrees - than at present
2. Between 1550 and 1750 there was a low trough of very cold conditions causing the little ice age
3. Widespread abandonment of upland farms in scandinavia and iceland

Arctic ice sea spread further south with polar bears frequently seen in Iceland

Rivers in the UK, lowland europe and the New York Harbour froze over

Researchers argue that the little ice age could have developed into a stadial but this was prevented by the industrial revolution, fired by coal. The release of C02 triggered climate warming, which halted the cold period.