Have We Reached the Tipping Point?
Siberian Fires from Earth Observatory
A massive, unexpected thaw that covers an area of Siberia the size of France
and Germany combined is now releasing billions of tons of the super global
warming gas methane into the atmosphere. This will cause the kind of methane
spike that preceded the last period of extreme warming 15,000 years ago,
which was followed by a violent change to a much different climate. This is
poised to happen again.
Methane is 20 times as good at holding heat close to the earth as carbon
dioxide, and the greatest 'methane sink' in the world is the Siberian
permafrost. For years, scientists have warned that, if it melts suddenly,
there will be a climate catastrophe. Such a melting process is taking place
now, and if it extends into the autumn and is repeated with greater
intensity in coming summers, the effects will be severe in just a very few
Unfortunately, the fact that Siberia is outgassing massive quantities of
methane at this time means that the atmosphere is going to heat up much
faster than climate scientists anticipated, and it is likely that future
summer melts will be more intense, and will extend into the permafrost
beneath the American arctic. Environmental scientists have long dreaded the
day when Arctic permafrost would begin to melt seriously, and that day is
now at hand. From geologic records, we know that the last great ice age
began with a huge release of methane, but no one knows where all that
methane came from. It could have come from the ocean floor or from a peat
bog just like this one.
Climate scientist Stephen Sitch says that western Siberia is heating up
faster than anywhere else in the world. US climatologist Larry Smith warns
that the Siberian peat bog could release 70 billion tons of methane, which
is one-fourth of all the methane stored in the ground around the world.
Smith has thought the Siberian permafrost would thaw gradually, so it will
not release its methane into the atmosphere in a single burst. However, a
great deal of methane was released into the atmosphere all at once in the
distant past, so it could happen again, and the unprecedented situation that
is happening now is an indication that the melt will be fast and extensive.
Climatologist David Viner says that even if the methane gradually seeped out
of the permafrost over the next 100 years, it would still lead to a 10 to
25% increase in global warming. 700 billion tons is about the same amount
that is now released annually from agriculture around the world, so the
amount of greenhouse gas in the atmosphere would double.
Siberia's peat bogs formed around 11,000 years ago, when the last ice age
ended. They've been generating methane from rotting vegetation ever since,
but it's been harmlessly trapped beneath the frozen permafrostâuntil now.
Climate researcher Karen Frey says if the bogs dry out as they get warmer,
the methane will oxidize and be generated into the atmosphere as carbon
dioxide. But if the bogs remain wet, the methane itself will be released
straight into the atmosphere. While both CO2 and methane are greenhouse
gasses, methane is 20 better at trapping heat than carbon dioxideâwhich is
much worse for the future of the Earth.