Last minute Glaciation revision:
EQ1: How has climate change influenced the formation of glaciated landscapes?
• Understanding the factors leading to climate change
• Milankovitch Cycle - This is a cycle based on Orbital forcing and it takes 3 main
characteristics into account. i) Eccentricity - this is the changing of the earths orbit from
being more elliptical to more circular over a period of 100,000 years. It changed the
amount of solar radiation received from the sun. ii) Axial Tilt - this varies from 21.1° to
24.4° over 41,000 years. This affects the ammonite of sunlight reaching the earth’s surface
and its intensity, thus affecting the seasonality of the earth’s climate. The greater the tilt,
the greater the distance between summer and winter. iii) Wobble - The earth wobbles on
its axis, changing the point in the year at which the earth is closest to the sun. This
happens over a 21,000 period. It causes long term changed to when certain seasons
occur along the earth’s seasonal orbital path.
• Solar forcing - Sunspots can vary the amount of solar energy emitted from the sun. There
are a number of cycles of varying length, including the 11 year cycle. A Longer period of
time with no sunspot activity is called the Maunder Minimum which occurred between
1645 and 1715, during the little ice age. The problem is, that sunspots alone aren’t enough
to explain fluctuations in the earth’s climate.
• Volcanic causes - Volcanic eruptions with a high volcanic explosivity index can alter global
climate. Eruptions with high explosivity eject lots of ash, sulphur dioxide and CO2 into the
atmosphere. In Tambora, Indonesia in 1815, a volcano erupted and ejected 200m tonnes
of sulphur dioxide into the atmosphere. For the following 2/3 years, rapid global cooling
was seen. This is because the volcanic gasses add to the cloud sky and they don’t let as
much solar energy in to heat up the earth.
• Characteristics & Causes of the Loch Lomand Stadial and the Little ice age
• Loch Lomand Stadial - Around 12,000 years ago, temperatures plummeted back down to
glacial conditions, with temperatures roughly 7°c lower. This led to the re-advance of many
glaciers, including those in the scottish highlands. Greenland’s ice core data shows that
when temperatures rose again, after the event. There was a corresponding increase in
sea levels.
• Little Ice Age - This occurred between 1550 and 1750. It had many impacts such as the
widespread abandonment of farms in upland Scandinavia and Iceland, as well as the
freezing of the River Thames and New York Harbour. Glaciers also re-advanced in
mainland Europe.
• Understand the differences between ice sheets, ice caps, cirques, valley glaciers and ice
fields
• Ice sheet - This is the complete submergence of regional topography and it creates a gently
sloping dome of ice sever KM thick in the middle.
• Ice cap - This is a smaller version of an ice sheet, typically occupying an upland area.
• Piedmont Glacier - This is a glacier which extends beyond the end of the mountain valley
into a flatter expanse.
• Cirques - Smaller glaciers occupying a hollow on the mountain side. These can carve out a
corrie or cirque which are sometimes known as niche glaciers.
• valley glaciers - A glacier which is confined between two valley walls and it terminates in a
narrow tongue.
• Ice Field - This is ice covering an upland area but it’s not thick enough to cover the
topography.
• Describe the distribution of past and present periglacial landscapes
• During the pleistocene, glacial conditions were much more widespread than they are today,
with roughly 33% of the world’s landmass experiencing these conditions, at much lower