The tidal power available for electricity generation from in-stream turbines placed in the Minas Passage of the Bay of Fundy is examined. A previously derived theory is adapted to model the effect of turbine drag on the flow through the Minas Passage and the tidal amplitude in the Minas Basin. The theoretical maximum power production over a tidal cycle is determined by the product of the amplitude of the forcing tide in the Bay of Fundy and the undisturbed volumetric flowrate through the Minas Passage. Although the extraction of the maximum power will reduce the flowrate through the Minas Passage and the tides in the Minas Basin by over 30 per cent, a significant portion of the maximum power can be extracted with little change in tidal amplitude as the initial power generation causes only an increase in the phase lag of the basin tides. Two-dimensional, finite-element, numerical simulations of the Bay of Fundy-Gulf of Maine system agree remarkably well with the theory. The simulations suggest that a maximum of 7 GW of power can be extracted by turbines. They also show that any power extraction in the Minas Passage pushes the Bay of Fundy-Gulf of Maine system closer to resonance with the forcing tides, resulting in increased tidal amplitudes throughout the Gulf of Maine. Although extracting the maximum power produces significant changes, 2.5 GW of power can be extracted with a maximum 5 per cent change in the tidal amplitude at any location. Finally, the simulations suggest that a single turbine fence across the Minas Passage can extract the same power as turbines throughout the passage but that partial turbine fences are less efficient.

Chlorofluorocarbon (CFC) banks from uses such as air conditioners or foams can be emitted after global production stops. Recent reports of unexpected emissions of CFC-11 raise the need to better quantify releases from these banks, and associated impacts on ozone depletion and climate change. Here we develop a Bayesian probabilistic model for CFC-11, 12, and 113 banks and their emissions, incorporating the broadest range of constraints to date. We find that bank sizes of CFC-11 and CFC-12 are larger than recent international scientific assessments suggested, and can account for much of current estimated CFC-11 and 12 emissions (with the exception of increased CFC-11 emissions after 2012). Left unrecovered, these CFC banks could delay Antarctic ozone hole recovery by about six years and contribute 9 billion metric tonnes of equivalent CO 2 emission. Derived CFC-113 emissions are subject to uncertainty, but are much larger than expected, raising questions about its sources.

Water resources planning requires decision-making about infrastructure development under uncertainty in future regional climate conditions. However, uncertainty in climate change projections will evolve over the 100-year lifetime of a dam as new climate observations become available. Flexible strategies in which infrastructure is proactively designed to be changed in the future have the potential to meet water supply needs without expensive over-building. Evaluating tradeoffs between flexible and traditional static planning approaches requires extension of current paradigms for planning under climate change uncertainty which do not assess opportunities to reduce uncertainty in the future. We develop a new planning framework that assesses the potential to learn about regional climate change over time and therefore evaluates the appropriateness of flexible approaches today. We demonstrate it on a reservoir planning problem in Mombasa, Kenya. This approach identifies opportunities to reliably use incremental approaches, enabling adaptation investments to reach more vulnerable communities with fewer resources.

Water resources planning requires making decisions about infrastructuredevelopment under substantial uncertainty in future regional climate conditions.However, uncertainty in climate change projections will evolve overthe 100-year lifetime of a dam as new climate observations become available.Flexible strategies in which infrastructure is proactively designed to bechanged in the future have the potential to meet water supply needs withoutover-building expensive infrastructure. Evaluating tradeoffs between flexibleand traditional robust planning approaches requires extension of currentscenario-based paradigms for water resources planning under climate uncertaintywhich take a static view of uncertainty. We develop a new dynamicplanning framework that assesses the potential to learn about regional climatechange over time and evaluates flexible approaches. We demonstrateit on a reservoir planning problem in Mombasa, Kenya. This approach identifiesopportunities to reliably use flexible, incremental approaches, enablingclimate adaptation investments to reach more vulnerable communities withfewer resources.

Climate change will have potentially significant effects on freshwater quality due to increases in river and lake temperatures, changes in the magnitude and seasonality of river runoff, and more frequent and severe extreme events. These physical impacts will in turn have economic consequences through effects on riparian development, river and reservoir recreation, water treatment, harmful aquatic blooms, and a range of other sectors. In this paper, we analyze the physical and economic effects of changes in freshwater quality across the contiguous U.S. in futures with and without global-scale greenhouse gas mitigation. Using a water allocation and quality model of 2119 river basins, we estimate the impacts of various projected emissions outcomes on several key water quality indicators, and monetize these impacts with a water quality index approach. Under mitigation, we find that water temperatures decrease considerably and that dissolved oxygen levels rise in response. We find that the annual economic impacts on water quality of a high emissions scenario rise from $1.4 billion in 2050 to $4 billion in 2100, leading to present value mitigation benefits, discounted at 3%, of approximately $17.5 billion over the 2015-2100 period.