Climate Changes

Introduction

In this section you will learn
  • Why polar regions play such an important role in climate change.
  • How various physical properties affect climate change.
    •
Polar regions are important to climate change because
  1. Processes in polar regions influence the climate at all latitudes.
  2. Anthropogenic (caused by man) warming is expected to be first observed in polar regions.
    3.
The primary reason that polar regions are thought to be particularly sensitive to climate change is the snow/ice - surface albedo feedback effect. A feedback is defined by Webster's Dictionary as "the return to the input of part of the output." A positive feedback causes an amplification of any perturbation. A negative feedback causes the damping of any perturbation.
 
The snow/ice - surface albedo feedback works in either of the following ways.
Warming Loop Cooling Loop
 
  1. Something causes warmer conditions.
  2. As a result, some snow and ice melts.
  3. This lowers the surface albedo.
  4. Lower albedo causes more solar radiation to be absorbed at the surface.
  5. More absorption of solar radiation causes warmer conditions.
  6. Go back to Step 2.
    7.
  1. Something causes colder conditions.
  2. As a result, some more snow and ice forms on the surface.
  3. This raises the surface albedo.
  4. Higher albedo causes less solar radiation to be absorbed at the surface.
  5. Less absorption of solar radiation causes cooler conditions.
  6. Go back to Step 2.
    7.

In either case, the loop is a positive feedback because the initial pertubation (Step 1) is amplified by the feedback process. This particular feedback is highly non-linear because when the temperature is well above or well below freezing, small perturbations do not cause much change in snow/ice coverage. But when the temperature is close to freezing, small perturbations can cause large changes in snow/ice coverage. Because land and ocean albedos are much lower than snow or sea ice albedos, changes in snow/ice coverage have a huge effect on the surface energy budget and, therefore, surface temperature.
 
Because most of Earth's snow and ice are in polar regions, these areas are expected to be the most affected by the snow/ice - surface albedo feedback effect. Therefore, if increased atmospheric CO2 concentration causes global warming, then polar regions should warm faster than other locations on Earth.
 
Climate change is a complicated problem; a full analysis is beyond the scope of this web module. Detailed information is available in many books, articles and at various web sites.
 
For this module, you will use an interactive web climate model called 'FASTCLIMATE'. FASTCLIMATE simulates the most important physical processes that control global climate. With FASTCLIMATE you will be able adjust these physical processes and see how sensitive the climate is to changes in these processes. At the end of this module are some links to web resources on the relation between polar processes and climate change.

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Last update: 4/8/2005
Please send all comments and suggestions to the author/instructor, Peter Guest.