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Broccoli and Klein argue for additional diagnostics to better assess the simulation of cloud feedbacks in climate models. We agree, and here provide additional analysis of two climate models that reveals where model deficiencies in cloud simulation in the Northeast Pacific may occur. Cloud diagnostics from the forthcoming Climate Model Intercomparison Project 5 should make such additional analyses possible for a large number of climate models.

Blues Holes in the Bahamas are solution collapse features which formed in the Bahamas during the repeated sea-level changes which have occurred over the past 2 million years. Not only were these Blue Holes repositories of well preserved organisms which found their ways into their anoxic waters and therefore have been very well preserved, but the sediments also record a legacy of anthropogenic activities in the area during the Pleistocene. Perhaps the most intriguing aspects of the Blue Holes are the multiple generations of stalagmites which record variations in sea-level, temperature, and precipitation during the numerous sea-level low stands. During these periods the caves were located within the vadose zone and freshwater leached the overlying carbonate. As the waters trickled into the caves

I am pleased and honored to cite Amy Clement for the 2007 James B. Macelwane Medal. Amy's work has introduced new ways of thinking that altered research strategies; that is, she is an intellectual leader. Not everyone agrees with her ideas, but no paleoclimate scientist ignores them. Amy's work has been instrumental in changing the way paleoclimatologists think about the tropics and their influence on global climate. The ocean-atmosphere dynamics concepts that she introduced to paleoclimate are now widely used.

Recent studies indicate that the tropical freshwater budget of the Atlantic is modulated by changes in El Nine-Southern Oscillation (ENSO). If anomalies of the Atlantic freshwater balance persist on the order of decades, these might have a large influence on the North Atlantic thermohaline circulation (THC). Here we present a sensitivity study in which we use a model scenario for ENSO behavior during the last 120 kyr to force a simplified model of the THC with corresponding freshwater exchange between the tropical Atlantic and Pacific. If the steady state strength of the North Atlantic THC is similar to the present-day, its response to the forcing is of the order of 1-3 Sv (1 Sv = 10 6 m 3 s - 1 ). No mode changes of the THC are simulated for reasonable values of the coupling constant between freshwater exchange and ENSO. If, on the other hand, the steady state overturning is significantly weaker, a collapse of the THC occurs due to forcing from the tropics. The modeled THC variation due to tropical freshwater perturbations are compared to those resulting from middle- and high-latitude freshwater forcing due to long-term growth and decay of Northern Hemisphere ice sheets. It is found that both forcings are of similar amplitude except during the deglaciation when high latitude forcing dominates. A possible out-of-phase relationship between deep water formation in the North Pacific and North Atlantic is also explored.

Analysis of mollusks from archaeological sites on the north and central coasts of Peru indicates that between ca. 5800 and 3200–2800 cal yr B.P., El Nino events were less frequent than today, with modern, rapid recurrence intervals achieved only after that time. For several millennia prior to 5.8 ka, El Nino events had been absent or very different from today. The phenomena called El Nino have had severe consequences for the modern and colonial (historically recorded) inhabitants of Peru, and El Nino events also influenced prehistoric cultural development: the onset of El Nino events at 5.8 ka correlates temporally with the beginning of monumental temple construction on the Peruvian coast, and the increase in El Nino frequency after 3.2–2.8 ka correlates with the abandonment of monumental temples in the same region.

Acoustic Doppler current profiler (ADCP) data referenced to Global Positioning System navigation were obtained in May 1993 from the Royal Research Ship Discovery within the Benguela Current as part of the Benguela Source and Transport (BEST) project. These data are used in combination with hydrographic data collected during the cruise to investigate the absolute geostrophic velocities in the Benguela Current and the transient eddies. Four anticyclonic eddies were encountered during the cruise, of which three were determined to be Agulhas Retroflection eddies of various ages and one was determined to be an eddy derived from the Brazil Current. ADCP velocities averaged between conductivity-temperature-depth stations have a high linear correlation with geostrophic velocities derived from the hydrographic data (correlation coefficient of 0.93) along the entire cruise track. The magnitudes of the two velocity estimates, however, were notably different within the eddies. It was determined that these discrepancies are probably due to a significant barotropic component of the flow near the eddy center. As much as 50% of the total flow in the eddy is barotropic. The horizontal length scale (radius of maximum velocity) of this eddy determined from both the ADCP data and the thermal field was found to be approximately 60 km, considerably smaller than previous estimates, which are about 120 km. The barotropic component in Agulhas eddies leads to an equal partitioning of total mechanical energy between available potential and kinetic energy. It is also expected to have a significant effect on the climatically important exchange of mass between the Indian and South Atlantic Oceans. Total geostrophic velocities were computed for the Benguela Current usine the averaged ADCP at 250 m as a reference. The ADCP referenced geostrophic transport across 30°S of water warmer than 9°C in the Benguela Current was found to be 17 Sv (1 Sv= 106 m3 s−1) to the north and that of the upper kilometer was 25 Sv to the north. These values are largely consistent with previous estimates, suggesting that the upper layer flow across this section is dominated by the baroclinic field.