The Earth’s Energy Balance:

**Shortwave radiation** from the Sun enters the surface-atmosphere system of the Earth and is ultimately returned to space aslongwave radiation (because the Earth is cooler than the Sun). A basic necessity of this energy interchange is that incoming solar insolation and outgoing radiation be equal in quantity. (From PhysicalGeography.net)

Factors Affecting the Balance Between Incoming and Outgoing Radiation:

Albedo

The reflectivity or albedo of the Earth’s surface varies with the type of material that covers it. For example, fresh snow can reflect up to 95% of the insolation that reaches it surface. Some other surface type reflectivities are:

Dry sand 35 to 45%
Broadleaf deciduous forest 5 to 10%
Needleleaf confierous forest 10 to 20%
Grass type vegetation 15 to 25%

Reflectivity of the surface is often described by the term surface albedo. The Earth’s average albedo, reflectance from both the atmosphere and the surface, is about 30%. (From PhysicalGeography.net)

Human Influence on Albedo:

The main human activities that change the reflectivity of the earth’s surface and atmosphere are:

Fossil fuel combustion; industrial processes; and biomass burning release aerosols and other pollutants into the atmosphere, changing its capacity to reflect or absorb solar radiation. These aerosols may also be deposited onto the land surface and cause changes to the surface albedo.

Deforestation, agricultural practices and urbanisation change the reflectivity of the earth’s surface. (from www.aph.gov.au)

Other factors affecting the energy balance include;

Desertification

Melting Ice Caps

Particulates (Pollution) in the Atmosphere (Global Dimming and Global Brightenning)

Volcanic Activity

Cloud Cover

Solar Activity

Deforestation

Greenhouse gasses (GHG): Any gas that absorbs and emits radiation in the thermal infrared range. The gases include: Carbon monoxide, carbon dioxide, methane, sulphur dioxide, Nitrous Oxide, water vapour and ozone.

Sources of greenhouse gases include:

Transport (cars and planes)
Animals (cow release large amounts of methane)
Burning fossils fuels (especially oil and coal)
Melting Permafrost (methane is released when permafrost melts)
Industry
Domestic use (wood fires)

Exam Style Questions:

Describe the energy balance between solar and long wave radiation in the atmospheric system [5 Marks]
Explain the changes in the balance between solar and long wave radiation due to external forcing [5 Marks]
Explain the changes in solar and long wave radiation due changes in the albedo of the atmosphere [5 Marks]

Climate Change: The Causes

To what extent are the causes of global climate change natural? 15 Marks + 4 Marks (from Geographyalltheway)

The Environmental Consequences of Climate Change:

polar bear.jpg

Describe and explain the environmental consequences of global climate change [15 Marks]

Use the links below to answer this question as an IB Exam essay style question.

A UN panel has released the most comprehensive assessment yet of the effects of climate change on our planet. Members of the Intergovernmental Panel on Climate Change (IPCC) say the “summary for policymakers” provides overwhelming evidence of the scale of these impacts. The BBC News website’s science editor Paul Rincon breaks down the key findings.”In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans.”

Atmosphere and Change