One concern about global climate change is the idea that re-enforcing loops can be triggered that accelerate system changes that aggravate a trend.  Global warming could have that effect by warming the planet to the point that refrigerated methane could be released causing more global warming which will release more methane.

When we think of methane, known as natural gas, we usually associate it with visible biological waste processes like feed lots (manure) or old landfills.  Methane, however, is ubiquitous in nature and is trapped in large quantities underground where we drill to fill our pipelines to support our natural gas demand worldwide.  We use it to heat our homes, cook our food and support our electrical grids.

Geologists have known for a long time that large quantities of ancient methane also generated as waste from biological processes is trapped in  permafrost regions around the top of the planet both on land and under the sea in the form of methane hydrates.  Methane hydrates are methane molecules enclosed in icy cages.

This article tells us that our polar regions are warming enough that these hydrate structures are collapsing (melting) under water and the methane is being released at increasing rates into the atmosphere. Methane is a "greenhouse gas" which is 20 times more powerful than carbon dioxide. This means that methane is 20 times more effective at trapping heat in the atmosphere than carbon dioxide. However, the residence time of methane in the atmosphere is only about 10-15 years compared to carbon dioxide which can remain in the atmosphere for centuries or more. We know that the poles are warming much faster than the temperate zones because high elevation winds (Hadley cells combine with the Coriolis effect) cast off heat from the equatorial regions toward the poles. In addition, ocean currents (thermohaline Conveyor belt) pump warm waters northward warming the oceans along the way.  Shedding this heat to the North will induce accelerated warming in regions of the world remote from us but we will be captured in this network of re-enforcing loops as the total planet warms. 

More warmth is coming to a neighborhood near you sooner than you would like.

http://weatherhead.case.edu/fowler/
www.vaportrailsthenovel.com