A large amount of methane gas on our planet is stored as clathrates under oceans and land bogs. They are stable only in the cold or under high pressure.
Clathrates under the name of gas hydrates were discovered in 1810 by Sir Humphrey Davy, (inventor of the mining safety lamp), and were considered to be a laboratory curiosity until the 1930s when clathrate formation turned out to be a major problem by clogging gas pipelines in very cold weather. Clathrates are crystalline solids which look like ice, and occur when water molecules form around smaller ‘guest molecules’.
The most common guest molecule is methane. If one cubic metre of methane clathrates is brought to the surface in an uncontrolled state it will releases164 cubic metres into the atmosphere as a highly potent greenhouse gas, 24 times greater than CO2.
Estimates suggest that methane hydrate deposits are a potential reserve twice the size of the combined total for coal, oil and conventional natural gas.
This realization of huge reservoirs of methane has led to some exploration, mainly by oil-poor countries seeking an alternative energy fuel. The methane gas might be recovered through injection of hot water or depressurisation, but the process has so far turned out to be technically difficult and expensive. There is also a danger of creating instability within the clathrate zone causing landslips and tsunamis.
A vast expanse of permafrost in Siberia and Alaska has started to thaw for the first time since it formed 11,000 years ago. It is caused by the recent rise in local temperature over the past 40 years – more than four times the global average. Peat bogs cover an area of a million square miles (or almost a quarter of the earth’s land surface) to a depth of 25 meters. Those in Siberia are the world’s largest and thawing of the permafrost has led to ‘burping’ of methane into the atmosphere as a greenhouse gas.
This is one of the most feared tipping point. 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 through an uncontrollable release of methane gas.
Methane, evolved through melting of methane hydrate, has been proposed for a sudden change of climate and surge in global temperature following end of the last ‘ice age’ some 200,000 years ago. A major underwater ‘slumping’ occurred resulting in the Storrega submarine landslide off Norway when 5600 km3 of sediment slid down a slope for about 800 km. It is possible there was also a massive tsunami.
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.
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. Once methane gas escapes in large quantities into the ozone layer extreme global warming is likely to be irreversible.
There was a little ‘ice age’ at the beginning of the 14th century after the huge loss of population from the Black Death when the North Atlantic cooled until the mid-19th century. This period brought severe winters, sudden climatic shifts, and profound agricultural, economic, and political impacts to Europe. It was marked by persistent crop failures, famine, disease, and population migration, perhaps most dramatically felt by the Norsemen. Famine caused tens of thousands of deaths.
We are indeed fortunate that we are living in one of the warmest periods for the past million years and under conditions that must be under the optimum for human life to flourish. Any dramatic change should therefore be viewed with apprehension.