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Water Whiplash in Mediterranean Regions of the World
Get PDFThe presence of weather and water whiplash in Mediterranean regions of the world is analyzed using historical streamflow records from 1926 to 2023, depending on the region. Streamflow from the United States (California), Italy, Australia, Chile, and South Africa is analyzed using publicly available databases. Water whiplash—or the rapid shift of wet and dry periods—are compared. Wet and dry periods are defined based on annual deviations from the historical record average, and whiplash occurs when there is an abrupt change that overcomes an accommodated deficit or surplus. Of all the stations, there are more dry years (56%) than wet years (44%) in these regions, along with similarities in the variances and shifts in extremes (i.e., whiplash). On average, 35% of the years were defined as water whiplash years in all countries, with the highest levels in the US (California), where 42–53% of the years were whiplash years. The influence of the El Niño–Southern Oscillation (ENSO) influences Chile and South Africa strongest during the first quarter of the year. This study found that smaller extreme wet periods and larger and less extreme dry periods are prevalent in Mediterranean regions. This has implications for water management as adaptation to climate change is considered
Permafrost Carbon: Progress on Understanding Stocks and Fluxes Across Northern Terrestrial Ecosystems
Get PDFSignificant progress in permafrost carbon science made over the past decades include the identification of vast permafrost carbon stocks, the development of new pan-Arctic permafrost maps, an increase in terrestrial measurement sites for CO2 and methane fluxes, and important factors affecting carbon cycling, including vegetation changes, periods of soil freezing and thawing, wildfire, and other disturbance events. Process-based modeling studies now include key elements of permafrost carbon cycling and advances in statistical modeling and inverse modeling enhance understanding of permafrost region C budgets. By combining existing data syntheses and model outputs, the permafrost region is likely a wetland methane source and small terrestrial ecosystem CO2 sink with lower net CO2 uptake toward higher latitudes, excluding wildfire emissions. For 2002–2014, the strongest CO2 sink was located in western Canada (median: −52 g C m−2 y−1) and smallest sinks in Alaska, Canadian tundra, and Siberian tundra (medians: −5 to −9 g C m−2 y−1). Eurasian regions had the largest median wetland methane fluxes (16–18 g CH4 m−2 y−1). Quantifying the regional scale carbon balance remains challenging because of high spatial and temporal variability and relatively low density of observations. More accurate permafrost region carbon fluxes require: (a) the development of better maps characterizing wetlands and dynamics of vegetation and disturbances, including abrupt permafrost thaw; (b) the establishment of new year-round CO2 and methane flux sites in underrepresented areas; and (c) improved models that better represent important permafrost carbon cycle dynamics, including non-growing season emissions and disturbance effects
Ambiguity, Cognitive Reflection, and Strategic Complexity across Auctions
Get PDFThis paper bridges large but separate literatures on decision-making under ambiguity, the dual system framework of behavioral economics, and market design. We characterize behavior under ambiguity arising from dual system preferences. Rational System 2 satisfies the subjective expected utility axioms while behavioral System 1 satisfies the obvious dominance axiom from mechanism design. Our axioms provide a novel foundation for the popular NEO-EU ambiguity model and allow for source dependent ambiguity perceptions. Our approach also provides an explanation as to how behavioral differences arise between obviously strategy-proof mechanisms (e.g. English auctions) and other mechanisms. Empirically, we find ambiguity perceptions are lower for individuals who engage in reflective System 2 reasoning. Further, ambiguity perceptions regarding auction prices increase with the mechanism’s strategic complexity (lowest for obviously strategy-proof English auctions, intermediate for strategy-proof second-price auctions, highest for non-strategy proof first-price and Dutch auctions). However, ambiguity attitudes, representing preferences, are stable across auction formats