 |
| ...exploding methane hole |
All over the semi frozen parts
of the globe, as temperatures keep rising, massive, unquantified amounts
of methane are being released. We're still increasing CO2 levels in the
atmosphere.. but in all probability, it will be methane that 'flips the
switch.'
Methane concentrations up till 2011
Methane, a greenhouse gas more than 30-100 times more potent than CO2, is released from previously frozen soils when organic matter thaws and decomposes under anaerobic conditions (that is, without oxygen present).
The concentration of methane in Earth's atmosphere has increased by 150% since 1750, and now accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. According to NOAA the atmospheric methane concentration is now above 1820ppb.. largely due to the arctic (and antarctic) methane releases from melting methane clathrates. Atmospheric methane concentration has not been this high for over 420,000 years.. and correlates to 9 °C average Earth temperature increase.
Arctic permafrost where the accumulation of organic matter in frozen soils covers about 24% of northern hemisphere continents is estimated to contain more than 900 billion tons of carbon. The Siberian permafrost is in particular danger. A large region of the frozen underground (called the Yedoma), will undergo runaway decomposition once it starts to melt.. evidence showing that this process has in fact already begun.
Already measurements along the Siberian shelf uncover enhanced methane release. In 2010 a Russian marine survey conducted more than 5,000 observations of dissolved methane showing that more than 80% of East Siberian shelf bottom waters and more than 50% of surface waters are supersaturated with methane. Atmospheric methane levels (during glacial periods were 300–400 parts per billion, and during interglacial periods were 600–700ppb). And they have recently reached 1850ppb.. the highest level in 400,000 years!!
Most of the current permafrost formed during or since the last ice age and can extend down to depths of more than 700 meters in parts of northern Siberia and Canada.
None of this thawing of part of the permafrost [and methane release] has yet to be accounted for in any climate projections.
Earth’s history shows that releasing these stores could set off a series of events with calamitous consequences... global climates only slightly warmer than today are sufficient to continue the thawing of extensive regions of permafrost.
Arctic air temperatures are expected to increase at roughly twice the global rate. A global temperature increase of 3C means a 6C rise in the Arctic, resulting in an irreversible loss of anywhere between 30 to 85% of near-surface permafrost.
Looking to the future.. foreseeing a worse case scenario... the onset of a hyperthermal (a huge release of carbon) such as happened 55 million years ago, during the Paleocene-Eocene period.. with an attendant mass extinction of most all planet species is not an outlandish impossibility.
