Climate Change

Question 1

What are some examples of how man is changing the surface of the Earth?

Answer 1

Example 1: Bolivia

1975: Area adjacent to Rio Grande o Guapay river was dense rainforest
2003: Area had been transformed into a major agricultural area
2003: Area had been transformed into agricultural area

Example 2: Lake Chad

1972: One of largest lakes in Africa
1987: Extensive irrigation projects, the encroaching desert + increasingly dry climate= Shrunk to 5% of its former size

Question 2

What is the Earth’s greenhouse effect?

Answer 2

One of the interacting factors determining the receipt and fate of solar energy across the Earth’s surface

Incoming solar radiation: Some are reflected back to space and some are diffused, but most reach the Earth’s surface

The surface then cools by radiating heat energy upwards but some are trapped

The more heat is trapped in the atmosphere, the higher the temperatures

Question 3

What is ocean thermohaline circulation?

Answer 3

3D circulation, involving deep and intermediate water currents

Driven by water’s density which is controlled by temperature and salinity

• In polar regions: Ocean water is very cold= Sea ice
• Result: Surrounding sea water gets saltier as salt is left behind when it forms sea ice
• Seawater gets saltier= Density increases= starts to sink
• Surface water is pulled in to replace the sinking water= Becomes very cold and salty= Sinks
• Result= Deep ocean currents driving the global conveyer belt as the surface water keeps replacing the sinking water

Question 4

How could climate change affect THC?

Answer 4

Changes in ocean circulation are implicated as at least part of the mechanism of many rapid climatic changes

Question 5

What other natural phenomena can modify the atmosphere on a large scale?

Answer 5

Fires
Volcanic activity
Smoke and dust particles can be ejected to high altitude= Can spread around regions or whole globe and impact both incoming short- wave and outgoing long-wave radiation
Alters energy balance

Example: Mount Pinatubo, Philippines= Eruption in 1991 released 20 million tons SO2 injected into the atmosphere
Dispersal of gas/particulates cloud around the world= Caused global temperatures to drop by around 0.5 degrees celsius

Question 6

What are some factors which affect the Earth’s climate so that it has not been the same through the ages? (Milankovitch Cycles)

Answer 6

1) Gravitational effects of the larger planets such as Jupiter and Saturn= Affects surface temperature
Also have 3 aspects of the Earth’s orbit which are important in relation to global climate:
1) Eccentricity: Shape of Earth’s orbit
Measure of how elliptical an orbit is
Periphelion= Earth is closely to the sun
Aphelion= Earth is the furtherest distance from the sun
The larger the eccentricity, the greater the difference in solar radiation that reaches the Earth
Shorter distance= Hotter
Over long term, changes in eccentricity can affect the Earth’s climate

2) Obliquity: Tilt of its axis
December: Axis is tilted away from sun= Cold
June: Axis is tilted towards the sun= Hotter
Northern Hemisphere: Receives energy from the sun at more oblique angles= Winter weather
Northern Hemisphere receives energy from sun at less oblique angles= Summer weather
Tilt= Seasons

3) Precession: Direction of its axis
Changes the direction of tilt of the Earth’s axis relative to Eccentricity
Northern Hemisphere: Winter when the Earth is closest to the sun

Milankovitch cycles= Result in long term fluctuations in the energy that reaches the Earth

Question 7

How are humans affecting the carbon cycle?

Answer 7

Fossil fuel emissions
Land clearing= No plants to take in CO2 during photosynthesis

Increasing partial pressure of CO2 should favour carboxylation over oxygenation in rubisco BUT: often when leaves are exposed to CO2 enrichment for a long period, the initial enhancement in photosynthesis is not maintained= Plants do not respond linearly to changes in CO2