This is one of the most feared tipping points. There is a delicate threshold where a slight rise in the Earth’s temperature can cause a dramatic change in the environment by triggering a huge and instantaneous increase in global temperature. See Footprints #3.
This melting is an irreversible ecological landslide – a vicious circular feedback that is becoming stronger and stronger, and is doing so more quickly with every passing summer.
Once started extreme global warming would be irreversible.
A significant part of the heat gained during the summer is held within the peat by the autumn snow that acts like a blanket to keep it warm, and thus the heat gained is incremental. This is why the present passion for carbon trading will make no difference to the outcome.
When we start heating these natural systems, the process quickly becomes unstoppable. We do not have any technological brakes we can apply. This is enormously important because we can’t put the permafrost back once it’s gone. The gasses stored there have the potential to raise temperatures even more than all of our past emissions.
Since the bogs were formed they have been generating methane, most of which has been trapped within the permafrost itself, in ice-like clathrates.
It is estimated that the west Siberian bog alone contains some 70 billion tonnes of methane, a quarter of all the methane stored on the land surface of the world. This is equivalent to emitting 1.7 trillion tons of CO2, which is more greenhouse gas than has been emitted by humans in the past 200 years.
There are already impacts on roads and buildings which are collapsing as the ice-held foundations melt. In addition, once the bog dries out deep sub-surface fires ignited by lightning will themselves create more CO2 to add into the air.
Alarmingly, it has just been reported by Wetlands International that huge areas of wet peatland forests are being drained and logged in Indonesia and Malaysia. Along with the ensuing peat fires this contributes 2 billion tons of CO2, making South-East Asia the third largest polluter in the world behind the US and China.
We CAN reduce our CO2 emissions from fossil fuels but we COULD NOT reduce methane emissions once they get started. These huge natural forces would take over and change our world in double-quick time.