The reason we are concerned about global warming is due to the so-called greenhouse effect; several gases reflect or trap heat, most importantly CO 2
They trap the heat emitted by the earth, like a blanket around the globe; the basic effect is good, if the atmosphere did not contain greenhouse gases, the average temperature on Earth would be approximately 59 o colder, or a constant -18 o C.
This is by the way the constant temperature above the GHG layer in our atmosphere.
The Greenhouse Effect GHG effect increases with increasing concentrations of CO 2
Permafrost - is soil at or below the freezing point of water for two or more years.
Most permafrost is located in high latitudes (i.e. land in close proximity to the North and South poles
The extent of permafrost can vary as the climate changes. Today, a considerable area of the Arctic is covered by permafrost.
General circulation models predict that, for a doubling of atmospheric concentrations of carbon dioxide due to anthropogenic sources, mean annual air temperatures may rise up to several degrees over much of the Arctic.
In those areas where ground temperatures are within 1-2 degrees of melting, permafrost will likely ultimately disappear as a result of ground thermal changes associated with global climate warming.
Some believe that its release could accelerate global warming in a giant positive feedback where more atmospheric methane causes higher temperatures, leading to further permafrost melting and the release of yet more methane.
There is high agreement and much evidence that with current climate change mitigation policies and related practices , global GHG emissions will continue to grow over the next few decades.
The scenarios are grouped into four scenario families (A1, A2, B1 and B2) that explore alternative development pathways, covering a wide range of demographic, economic and technological driving forces and resulting GHG emissions. Conclusion Source: The Intergovernmental Panel on Climate Change, “Climate Change 2007: Synthesis Report,” 2007 What does it mean?