Climate surprise
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A climate surprise is used by the IPCC as a synonym for abrupt climate change, and defined by:
- The nonlinearity of the climate system may lead to abrupt climate change, sometimes called rapid climate change, abrupt events or even surprises. The term abrupt often refers to time scales faster than the typical time scale of the responsible forcing. However, not all abrupt climate changes need be externally forced. Some possible abrupt events that have been proposed include a dramatic reorganisation of the thermohaline circulation, rapid deglaciation and massive melting of permafrost or increases in soil respiration leading to fast changes in the carbon cycle. Others may be truly unexpected, resulting from a strong, rapidly changing forcing of a nonlinear system. [1]
Climate surprises are low-probability, high-consequence extreme events, such as a collapse of the "conveyor belt" thermohaline circulation in the North Atlantic Ocean or rapid deglaciation of polar ice sheets. Because the global climate is made up of a number of complex subsystems which interact in complex and chaotic ways, climate change may lead to relatively few changes up to a tipping point, beyond which the system may tip into a new equilibrium.
Because of the high uncertainty regarding climate surprises, they are typically excluded from standard climate change scenarios. According to the International Climate Change Taskforce [2]the risks of surprises may increase above a 2°C temperature rise compared to the pre-industrial level, of which 0.8°C has already taken place and another 0.5 is already committed [3].
The 2°C rise is typically associated in climate models with a carbon dioxide concentration of 400ppm; as of March 2008, the current level is 386ppm [4], and rising at approximately 2ppm annually. (The 2°C rise would not happen immediately, but would effectively be inevitable.)
Towards the end of the last ice age, the Younger Dryas saw rapid shifts in the earths climate.
[edit] See also
[edit] External links
- Stephen H. Schneider (2004), "Abrupt non-linear climate change, irreversibility and surprise", Global Environmental Change 14 (2004) 245–258
- Michael D. Mastrandrea and Stephen H. Schneider (2004), "Probabilistic Integrated Assessment of "Dangerous" Climate Change", Science, Volume 304, pages 571-575
- "Meeting the climate challenge: Recommendations of the International Climate Change Taskforce", January 2005
- "Tipping points in the Earth System", An introductory article by Professor Timothy M. Lenton of the School of Environmental Sciences, University of East Anglia, Norwich
