We examine processes that influence North Pacific sea surface temperature (SST) anomalies including surface heat fluxes, upper ocean mixing, thermocline variability, ocean currents, and tropical-extratropical interactions via the atmo-sphere and ocean. The ocean integrates rapidly varying atmospheric heat flux and wind forcing, and thus a stochastic model of the climate system, where white noise forcing produces a red spectrum, appears to provide a baseline for SST variability even on decadal time scales. However, additional processes influence Pacific climate variability including the “reemergence mechanism, ” where sea-sonal variability in mixed layer depth allows surface temperature anomalies to be stored at depth during summer and return to the surface in the following winter. Wind stress curl anomalies in the central/east Pacific drive thermocline variability that propagates to the west Pacific via baroclinic Rossby waves and influences SST by vertical mixing and the change in strength and position of the ocean gyres. Atmospheric changes associated with the El Niño–Southern Oscillation (ENSO) also influence North Pacific SST anomalies via the “atmospheric bridge. ” The dominant pattern of North Pacific SST anomalies, the Pacific Decadal Oscillation (PDO), exhibits variability on interannual as well as decadal time scales. Unlike ENSO, the PDO does not appear to be a mode of the climate system, but rather it results from several different mechanisms including (1) stochastic heat flux forcing associated with random fluctuations in the Aleutian Low, (2) the atmo-spheric bridge augmented by the reemergence mechanism, and (3) wind-driven changes in the North Pacific gyres. 1.

A systematic study is presented of decadal climate variability in the North Pacific. In particular, the hy-pothesis is addressed that oceanic Rossby basin modes are responsible for enhanced energy at decadal and bidecadal time scales. To this end, a series of statistical analyses are performed on a 500-yr control integration of the Community Climate System Model, version 3 (CCSM3). In particular, a principal oscillation pattern (POP) analysis is performed to identify modal behavior in the subsurface pressure field. It is found that the dominant energy of sea surface temperature (SST) variability at 25 yr (the model equivalent of the Pacific decadal oscillation) cannot be explained by the resonant excitation of an oceanic basin mode. However, significant energy in the subsurface pressure field at time scales of 17 and 10 yr appears to be related to internal ocean oscillations. However, these oscillations lack the characteristics of the classical basin modes, and must either be deformed beyond recognition by the background circulation and in-homogeneous stratification or have another dynamical origin altogether. The 17-yr oscillation projects onto the Pacific decadal oscillation and, if present in the real ocean, has the potential to enhance the predictability of low-frequency climate variability in the North Pacific. 1.

Results are presented from a set of experiments designed to investigate factors that may influence proxy-based reconstructions of large-scale temperature patterns in past centuries. The factors investigated include 1) the method used to assimilate proxy data into a climate reconstruction, 2) the proxy data network used, 3) the target season, and 4) the spatial domain of the reconstruction. Estimates of hemispheric-mean temperature are formed through spatial averaging of reconstructed temperature patterns that are based on either the local calibration of proxy and instrumental data or a more elaborate multivariate climate field reconstruction approach. The experiments compare results based on the global multiproxy dataset used by Mann and coworkers, with results obtained using the extratropical Northern Hemisphere (NH) maximum latewood tree-ring density set used by Briffa and coworkers. Mean temperature reconstructions are compared for the full NH (Tropics and extratropics, land and ocean) and extratropical continents only, with varying target seasons (cold-season half year, warm-season half year, and annual mean). The comparisons demonstrate dependence of reconstructions on seasonal, spatial, and methodological considerations, emphasizing the primary importance of the target region and seasonal window of the reconstruction. The comparisons support the generally robust nature of several previously published estimates of NH mean

Geological Survey (USGS) and other scientists suggest that the region may become drier for the next 2 to 3 decades, in a pattern similar to mid-20th century dry conditions. Because the region’s population has increased rapidly since the mid-1950s, a repeat of such a dry episode could have severe consequences not only for residents but also for the desert’s diverse and fragile ecosystems. Diverse topography, complex geology, and distinctive plant communities characterize the Mojave Desert region. The desert covers 152,000 km 2 of eastern California, southern Nevada, the southwest corner of Utah, and northwest Arizona (fig. 1). On the west and southwest, the Mojave Desert is bounded by the Sierra Nevada and the San Gabriel and San Bernardino Mountains. These imposing mountains alter the prevailing westerly winds and intercept moisture derived from the Pacific Ocean, producing a rain-shadow effect and arid conditions on the lee side of the mountains. The regional climate and topography of the Mojave (Rowlands, 1995) strongly influence the distribution and abundance of its diverse and fragile desert plant communities.

Impacts of climate change on species, populations and communities: palaeobiogeographical insights and frontiers

Who in blazes are we to have the au-dacity to issue 10 commandments? Well, we certainly do not believe that we are Yahweh et al. Rather, because you are reading this, we suspect that the title grabbed you, and so our goal regarding this outrageously grandiose heading is ful-fi lled. In reality, our humble intention is to stimulate much needed discussion re-garding the explicit details of ecosystem-based fi sheries science as a bonafi de new discipline. We perceive a need to bridge the gap between general principles, which are already well-articulated, and specifi c methodologies for full implementation, which is the present challenge and beyond the scope of this article. Our intention is to help ecosystem-based fi sheries science escape the danger of becoming either “quasi-religious ” (sensu Larkin 1996:149) or “surreal ” (sensu Longhurst 2006:108) by proposing tangible action items. Given our collective backgrounds, we address only the natural sciences, yet emphasize the need for ecosystem-based manage-ment to integrate the natural and social sciences (see Commandment 10). Although a marine “ecosystem ” is a hu-man construct that artifi cially delineates a portion of the ocean, and given that the biosphere comprises highly integrated linkage of all such systems, we are con-

Executive Summary 7 3 7 1 5. 1. The North American Region 7 4 1 1 5. 1. 1. Previous Wo r k 7 4 1

Who in blazes are we to have the au-dacity to issue 10 commandments? Well, we certainly do not believe that we are Yahweh et al. Rather, because you are reading this, we suspect that the title grabbed you, and so our goal regarding this outrageously grandiose heading is ful-fi lled. In reality, our humble intention is to stimulate much needed discussion re-garding the explicit details of ecosystem-based fi sheries science as a bonafi de new discipline. We perceive a need to bridge the gap between general principles, which are already well-articulated, and specifi c methodologies for full implementation, which is the present challenge and beyond the scope of this article. Our intention is to help ecosystem-based fi sheries science escape the danger of becoming either “quasi-religious ” (sensu Larkin 1996:149) or “surreal ” (sensu Longhurst 2006:108) by proposing tangible action items. Given our collective backgrounds, we address only the natural sciences, yet emphasize the need for ecosystem-based manage-ment to integrate the natural and social sciences (see Commandment 10). Although a marine “ecosystem ” is a hu-man construct that artifi cially delineates a portion of the ocean, and given that the biosphere comprises highly integrated linkage of all such systems, we are con-

iences, M ntology, tment, B al Scienc the fingerprint of solar activity variations should be strongest in the tropics, but there is also evidence that changes in the ocean heat transport took place during the LIA at high northern latitudes, with possible additional implications for climates of the Southern Hemisphere (SH). 2008 Elsevier Ltd. All rights reserved.

Declines in avian populations are a global concern, particularly for species that migrate between Arctic-temperate and tropical locations. Long-term population studies offer opportunities to detect and document ecological effects attributable to long-term climatic cycles such as the El Ni~no/Southern Oscillation (ENSO). In this study, we report possible population-level effects of such climatic cycles on shorebird species that use two non-breeding season sites in Ecuador (Santa Elena peninsula area, near La Libertad). During our 9-year study period (1991/1992e 1999/2000), there was a particularly strong ENSO warm phase event during 1997/1998. Population trend data for three species of shorebird, Western Sandpipers (Calidris mauri), Semipalmated Sandpipers (C. pusilla), and Least Sandpipers (C. minutilla), indicated abundances gener-ally declined during the 1990s, but there was an increase in the proportion of first-year birds and their abundance in the years following the 1997/ 1998 ENSO warm phase. There was some support for variation in apparent survivorship associated with the onset of the ENSO warm phase event in our population models, based on captureemarkerecapture data. Following the 1997/1998 ENSO event onset, individuals for all three species were significantly lighter during the non-breeding season (F1,3789 6.6, p 0.01). Least-squares mean mass (controlling for size, sex and day of capture) for first-year birds dropped significantly more than for adults following ENSO (first-year mass loss 0.69 0.12 g; adult mass loss 0.34 0.11 g, F1,3789 5.31, p 0.021), and least-squares mean mass dropped most during the period when sandpipers prepare for northward migration by gaining mass and moulting into breeding plumage. Least Sandpipers may have declined the most in mean mass follow-ing ENSO (0.76 0.19 g), whereas Semipalmated Sandpipers were 0.52 0.12 g lighter, and Western Sandpipers 0.40 0.13 g lighter, but