The atmosphere is changing and so are climates. Click on the Guardian stories below for recent news about our changing climate:
Aims:
- To be able to describe the functioning of the atmospheric system in terms of the energy balance between solar and long wave radiation.
- To be able to explain the changes in this balance due to external forcing – changes in solar radiation, changes in the albedo of the atmosphere and changes in the longwave radiation returned to space.
University of Arizona – Basic climate concepts
The diagram above shows the Earth-Atmosphere energy balance.
4% of insolation is reflected from the Earth’s surface. This is is known as the Planetary Albedo. Find out the albedo values for forests, snow/ice, cities and water. Use this link.
Use figures from the table below to describe how the albedo of the ground surface can change the amount of long wave radiation emitted by the earth.
The atmosphere is largely heated from below as outgoing long-wave radiation is trapped by greenhouse gases like carbon di-oxide (see diagram below). Without the greenhouse effect (see diagram below) the average Earth temperature would be 33 degrees C colder (-18 degrees instead of 15 degrees centigrade).
The greenhouse effect – Energy flows in the greenhouse effect.
The ‘enhanced greenhouse effect’ results from additional greenhouse gases entering the atmosphere due to the actions of people.
Climate change
NASA climate change site – Very informative.
Royal Meteorological Society website – A detailed overview of the climate change issue from a trusted source.
Causes
External forcings (natural causes) – These are non-human factors that can lead to changes in climate. Examples include: 1. Changes in solar radiation (e.g. due to sun-spot activity – see this youtube video); 2. Small changes to the Earth’s orbital path around the sun; 3. Volcanic eruptions; 4. Changes to the planetary albedo due to desertification, ice melting and changes in cloud cover (though these may also be linked to human activity). See camelclimatechange.org for more detailed info about how external forcings can influence the balance between insolation and long wave radiation, which can lead to changes in climate.
Anthropogenic forcings (human causes) – Increased emissions of greenhouse gases (Carbon Dioxide – burning fossil fuels and wood from forest clearance, Methane – released from livestock and rice crops, Nitrous oxides – released from vehicle emissions and industry, and others).
Consequences
Many and complex. Examples include; gradual poleward shift of vegetation types, rising sea level due to melting of glaciers and thermal expansion of sea-water, Loss of bio-diversity, expansion of deserts, More extreme weather patterns, melting of ice sheets/glaciers, Cooling of oceans if large-scale melting of ice – disruption of ocean currents, bleaching of coral reefs etc……
| Sinking islands – The Guardian | Lost lake in Bolivia – The Guardian |
Coral bleaching in the Great Barrier Reef, Australia. |
Climate change resources
ipcc.ch – website of the Inter-Governmental Policy – Report on impacts, adaptation & vulnerability
The Guardian – climate change website
NASA – website on climate change
epa.gov – US government website
Time.org – How climate change is increasing migration from Syria to Europe
Typical questions you are likely to see in an IB examination:
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]
More information available here: LINK