Projecting the Risk of Future Climate Regime Shifts


Recent research has pointed to the existence of natural, generation-scale (15-40 year) climate phases, or regimes, related to the influence of the Atlantic and Pacific Oceans [1-9]. These decadal-to-multidecadal (D2M) swings in ocean temperatures have had significant impacts on air temperature, rainfall and severe storms in North America, Europe and Africa [10-16]. Most importantly, D2M climate regimes have impacted the frequency of extreme events, such as droughts [12], floods, hurricanes [16] and environmentally linked health problems. In Florida, D2M climate regimes are associated with a 40% change in the water supply for Lake Okeechobee, which is the main reservoir for South Florida (Figure 1). The natural D2M climate regimes have alternately camouflaged and exaggerated the effects of anthropogenic climate change [10], and are being studied, among other things, in order to reduce the uncertainty in the magnitude of the anthropogenic influence. Modern computer models used for D2M studies - unlike those used for the more short-lived El Niño - are not yet capable of predicting future shifts in the D2M climate regimes. However, thanks to recent tree-ring reconstructions of past D2M regime shifts over a half-millennium or more [17,18], we now have the ability to project the probability of future regime shifts with useful accuracy. With further collaboration between climate scientists and risk managers, such as water management engineers, we hope this new area of study will lead to the development of an increasingly useful suite of decision support tools for water, health, agriculture and disaster mitigation. In this project we aim to develop such tools for a specific area of high priority for NOAA and the nation: water supply management.