Climate Variability and Climate Models

Key Terms
GCMs, AGCMs, OGCMs, CGCMs, uncertainty, predictability

Review Questions

  • Is climate chaotic? It the chaotic behavior limited in the atmosphere only? Or is it also in other elements of the climate system, such as the oceans and cryosphere? Will the  chaotic behavior be amplified when the atmosphere is coupled together with the oceans and cryosphere? Is there is a limit to our ability to predict climate beyond a certain time range? To what extent, a climate model can be simplified to produce the chaotic behavior? 
  • Natural Variability. Will a chaotic system always have a well defined attractor, i.e., a well defined distribution describing the probability of occurrence of various climates? Does the natural variability of climate arise from the climate system's chaotic elements? Will the distribution itself be predictable beyond the limit of deterministic predictability? Is the natural variability of the climate system on time scales of decades and longer dependent on oceanic and cryospheric processes only? How much do we understand this natural variability based on paleoclimatic evidence?
  • Errors in Initial Conditions. To what extent does the ability to predict future behavior depend on the accuracy of the knowledge of the system's initial state? How does the ability differ for a chaotic or a non-chaotic system?  Do we know how accurately we need to know the temperatures of the deep ocean today in order to make a prediction of climate of a given accuracy, say, fifty years in the future?  Given the long time scales of the deep ocean circulations, the climate trends of the coming decades may be crucially dependent on the history of climate during the last few centuries. What is the extent of this dependence?
  • Model Errors. Would our climate predictions be hampered by the imperfect state of current climate models even if the above factors did not introduce limits on our ability to predict climate? Are there any coupled atmosphere-ocean general circulation models which are able to reproduce a climate equilibrium like the current climate without introducing artificial sources of heat, moisture, and/or momentum at the interface between the atmosphere and the oceans (i.e., "flux corrections")? Do we know the source or sources of these errors? Why do you think the potential sources include inadequate resolution of oceanic currents and eddies, and inadequate representations of subgrid scale processes such as moist convection and clouds in the atmosphere? The need to parameterize subgrid scale processes may introduce severe limitations on our ability to represent these processes and their impact on climate change, and we need to understand these limitations and the resulting uncertainty.
  • Can we trust what the climate models tell us and why?
Additional Readings:
Other readings:


Last updated on 12/08/09 02:52 PM by Zong-Liang Yang