ABSTRACT
Up until relatively recently, water management and planning processes, including planning for extreme events such as droughts and floods, were largely based on the assumption of a stationary climate-that is, the assumption that the historical record (of climate and streamflow) is representative of current and future conditions. More specifically, as described by Milly et al. (2008), stationarity implies:
Traditionally, planning processes for ensuring reliable water supplies and an effective response to drought and floods were progressively developed based on this assumption. This approach does not account for potential nonstationarity in the physical climatological mechanisms that actually deliver rainfall and, in particular, climate extremes. As acknowledged by Milly et al. (2008), “low-frequency, internal variability (e.g., the Atlantic multi-decadal oscillation) enhanced by the slow
2.1 Introduction .................................................................................................... 31 2.1.1 Definitions........................................................................................... 32
2.2 Factors Responsible for Natural Climate Variability and Change ................. 33 2.2.1 Ocean-Atmospheric Circulations and Interactions ............................ 33 2.2.2 Earth-Sun-Moon Interactions ...........................................................46 2.2.3 Atmospheric Chemistry, Aerosols, and Volcanic Eruptions .............. 49 2.2.4 Geological Drivers of Climate Change .............................................. 52
2.3 Factors Responsible for Anthropogenic Climate Change ..............................54 2.3.1 Human-Induced Increases to Greenhouse Gases
and the Enhanced Greenhouse Effect ................................................54 2.3.2 Human-Induced Increases to Aerosols and Other Pollutants .............54 2.3.3 Land-Use Change (Including Urbanization) ...................................... 58
2.4 Summary ........................................................................................................ 59 References ................................................................................................................60
dynamics of the oceans and ice sheets pose a challenge to the assumption of stationarity.” Other examples include the Pacific decadal oscillation (PDO), which is also known as the interdecadal Pacific oscillation (IPO) and is associated with lowfrequency hydroclimatic variability and has been shown to affect the likelihood of extreme events (e.g., Franks and Kuczera 2002; Kiem et al. 2003).
