Climate Change: Complexity, Chaos and Order

Abstract

The climate system constantly changes due to internal variability and natural external perturbation. Anthropogenic climate change (due to human caused emissions of greenhouse gases) must be distinguished and characterized from this constantly changing background. Controlled experiments of the actual climate system are not possible but controlled simulation experiments using representative models examine how the natural system will respond. Observations and models together detected a novel change in climate over the past century and attribute that change as likely due to human activities. Analysis and prediction of climate system phenomena often depend on particular spatial or temporal scales. The short term fluctuations in weather are heavily influenced by changes in irregular internal processes and small-scale interactions (e.g. between the ocean and atmosphere). Chaotic responses result, which precludes long-term forecasts in the absence of perfect observations and formulations that perfectly predict atmospheric dynamics. In contrast, longer-term climate characteris tics such as the seasonal cycle are primarily determined by regular periodic forcing (e.g. the earth’s orbit) and are generally predictable. However, interactions between sub-units of the climate system (e.g. ocean, atmosphere, cryosphere, and biosphere) do sometimes lead to complex behavior not evident when each sub-unit is viewed in isolation. Such ‘emer gent properties’ include the occurrence of abrupt changes and multiple equilibria.KeywordsClimate SystemMultiple EquilibriumAnthropogenic Climate ChangeThermohaline CirculationNorth Atlantic Deep WaterThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.