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How anthropogenic climate change will affect hydroclimate in the arid regions of southwestern North America has implications for the allocation of water resources and the course of regional development. Here we show that there is a broad consensus among climate models that this region will dry in the 21st century and that the transition to a more arid(More)
The causes of persistent droughts and wet periods, or pluvials, over western North America are examined in model simulations of the period from 1856 to 2000. The simulations used either (i) global sea surface temperature data as a lower boundary condition or (ii) observed data in just the tropical Pacific and computed the surface ocean temperature elsewhere(More)
Numerical experiments are performed to examine the causes of variability of Atlantic Ocean SST during the period covered by the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis (1958–98). Three ocean models are used. Two are mixed layer models: one with a 75-m-deep mixed layer and the other with a(More)
The possible role that tropical Pacific SSTs played in driving the megadroughts over North America during the medieval period is addressed. Fossil coral records from the Palmyra Atoll are used to derive tropical Pacific SSTs for the period from A.D. 1320 to A.D. 1462 and show overall colder conditions as well as extended multidecadal La Niña–like states.(More)
SUMMARY Is the transport of heat northward by the Gulf Stream and North Atlantic Drift, and its subsequent release into the midlatitude westerlies, the reason why Europe's winters are so much milder than those of eastern North America and other places at the same latitude? Here, it is shown that the principal cause of this temperature difference is(More)
Could the Dust Bowl drought of the 1930s have been predicted in advance if the SST anomalies of the 1930s had been foreknown? Ensembles of model simulations forced with historical observed SSTs in the global ocean, and also separately in the tropical Pacific and Atlantic Oceans, are compared with an ensemble begun in January 1929 with modeled atmosphere and(More)
Ocean models are used to investigate how variations in surface heat fluxes and ocean heat transports contribute to variations of tropical Atlantic SSTs on decadal timescales. The observed patterns of variability, deduced from reanalyses of the National Centers for Environmental Prediction (NCEP), are found to involve the ocean's response to variations in(More)
The response of the Atlantic Ocean to North Atlantic Oscillation (NAO)-like wind forcing has been investigated using an ocean-only general circulation model coupled to an atmospheric boundary layer model. A series of idealized experiments was performed to investigate the interannual to multi-decadal frequency response of the ocean to a winter wind anomaly(More)
The mechanisms of changes in the large scale hydrological cycle projected by 15 models participating in the Coupled Model Intercomparison Project 3 and used for the Intergovernmental Panel on Climate Change Assessment Report Four are analyzed by computing differences between 2046-65 and 1961-2000. The contributions to changes in precipitation minus(More)