I have often spent time thinking about the danger of a tipping point into runaway climate change – particularly about the ways in which the concept can be conveyed to non-experts in a comprehensible manner. This eleven minute video does a good job. The script, with peer-reviewed references and additional information is at wakeupfreakout.org.
Here are some related prior posts:
- Equilibrium ruminations
- Methane clathrates and runaway warming
- Ethics among the doomed
- GHG stocks, flows, and climate change
- Tundra dangers
- Hansen on 350ppm
- Permafrost and climatic precariousness
- The Great Dying
I discovered the video linked above through this Gristmill post.
[Update: 4 February 2009] Here is a post on the danger of self-amplifying, runaway climate change: Is runaway climate change possible? Hansen’s take.
I like the sad violin-playing polar bear.
Will natural methane emissions enhance
man made emissions?
Substantial quantities of methane are emitted
naturally from wetlands, and this emission is
expected to change as wetlands change. Changing
rainfall patterns will cause some wetland areas to
increase in extent, others to decrease, and increases
in temperature will act to increase emissions from
wetlands. One version of the Hadley Centre climate
model includes a description of wetland methane,
and this predicts an increase in natural wetland
emissions by the end of the century equivalent to
the amount of man-made emissions projected for
that time, thus leading to a more rapid rise in
methane concentrations, and hence warming.
On the other hand, the chemical reactions in the
atmosphere which destroy methane are expected to
become more efficient in future, largely as a result
of increased water vapour. This will act as a
negative feedback on methane amounts.
Methane is also stored in permafrost, and it is likely
that some of this will be released as surface warming
extends into the permafrost and begins to melt it.
Finally, huge amounts of methane are locked up in
methane hydrates (methane clathrates) in the oceans.
They are currently at high enough pressures and
temperatures to make them very stable. However,
penetration of greenhouse effect heating into the
oceans may destabilise them and allow some of the
methane to escape into the atmosphere. The
potential for this to happen is very poorly understood.
There is concern that this may be another positive
feedback not yet included in models, although there
is little evidence for this from the behaviour of
methane during the large temperature swings
between ice ages and interglacials, and in particular
over the last 50,000 years.
Climate change and the greenhouse effect
A briefing from the Hadley Centre
December 2005