NOT FINISHED - Glaciers EQ1 - How has climate change influenced glaciated landscapes?

Explain the 2 forms which earths climate has shifted between

Greenhouse conditions

• Relatively warm causing glaciers and ice sheets to retreat or disappear

• There are no continental glaciers

Icehouse conditions

• Climate cools - continental ice sheets expand from the poles

Is earth currently experiencing icehouse or greenhouse conditions?

Earth is currently experiencing icehouse conditions but is currently in an interglacial period

What is the Quaterny period?

The most recent period of geological time - covers the time from 2 million years ago until the present - includes both the pleistocene and the holocene

What is the pleistocene epoch?

The first epoch of the Quaternary which lasted from about 2 million years ago to 11,700 years ago

During the pleistocene there were fluctuations in global temperatures - colder glacial periods interspersed with warmer interglacial periods

What is the difference between a glacial and an interglacial?

A glacial is a colder period of an ice age with extensive ice sheets whereas an interglacial is warmer periods of an ice age with reduced ice cover

• Glacials are longer than interglacials

• The change into an interglacial is rapid whereas the change into a glacial is much slower

What is an interglacial?

Warmer periods similar to the present when glacier ice retreats

What are stadials and interstadials?

An interstadial is a warm period within an interglacial period

A stadial is a colder period within an interglacial period

What triggered the pleistocene?

The tectonic movement causing North America and South America to join - meaning that warmer water was forced north allowing the air to carry more moisture - this causes greater snow in the northern regions

What are the long-term causes of climate change?

• Changes in the Earths orbit- Milankovitch cycles

• Tectonic movement and ocean currents (not associated with glacials and interglacials)

What are the 3 cycles that Milankovitch said varied the earths surface temperature?

• Eccentricity cycle (orbits)

• Obliquity cycle (tilt)

• Axial precessions (wobble)

Explain how changes in eccentricity cycles varies earths temperatures

Over time the shape of the earths orbit changes from circular to more elliptical (around every 100,000 years, which closely matches the glacial-interglacial cycle) - this changes the amount of solar radiation that the earth recieves

The earth is relatively further from the sun when the orbit is more circular (meaning it receives less solar radiation) causing a glacial period to occur

Explain how changes in Obliquity varies the earths temperatures

The tile of the earths axis changes on a 41,000 year cycle between 22.1 and 24.5 degrees

When the tilt is 22.1 there is a smaller climatic difference between summer and winter meaning snow and ice is more likely to last the summer season leading to a build up over time - at 24.5 the temperature range will be greater

Explain how the axial precession varies earths temperatures

The earth goes through long cycles of ‘wobbles’ on its axis meaning different parts of the earth go through phases of facing towards or away from the sun - these cycles last 26000 years

This causes the seasons to last different lengths of time, the longer the winter lasts the more snow and ice remain on the earths surface

What are the short term causes of climate change?

• Changes in solar ouptut

• Volcanic eruptions

How do volcanic eruptions impact earths temperatures?

Large volcanic eruptions like Mt Tambora causes billions of tonnes of gas/debris into the atmosphere - ash can reach the most stable part of the atmosphere (stratosphere) and therefore stay suspended for long periods of time - this results in less incoming solar radiation reaching earths surface - this can trigger periods of cooling and the onset of a cold period

After mount Tambora erupted there was a ‘year without a summer’

How do changes in solar output vary earths temperatures?

The sun does not always give out the same amount of energy - called sunspot cycles - darker spots on the sun are called ‘sun spots’ which emit above average amounts of solar radiation known as solar flares

At periods of time the sun has more sun spots (cycle every 11 years) therefore more solar output

What was the little ice age and what caused it ?

The little ice age occurred between 1300 and 1850 across most of Europe and North America - the average temp during this time was between 0.5-1 cooler than it has been since 1900

Believed to have been caused by sunspot activity and volcanic activity

Thames froze over

What was the loch lomond stadial and what caused it?

Around 12,700 years ago ice age conditions returned to some parts of the UK for about 1000 years

Caused by abrupt atmospheric cooling in the northern hemisphere which causes ice caps in mountainous regions to grow quickly

What % of current glacier ice is in the Antarctic?

85%

Why are higher latitudes colder?

They recieve less solar radiation as the suns rays hit the earths surface at a less direct angle than the equator - it heats a larger area and therefore has a weakened effect on surface temperatures making them colder