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Global climate and the atmospheric partial pressure of carbon dioxide () are correlated over recent glacial cycles, with lower during ice ages, but the causes of the changes are unknown. The modern Southern Ocean releases deeply sequestered CO2 to the atmosphere. Growing evidence suggests that the Southern Ocean CO2 ‘leak’ was stemmed during ice ages, increasing ocean CO2 storage. Such a change would also have made the global ocean more alkaline, driving additional ocean CO2 uptake. This explanation for lower ice-age , if correct, has much to teach us about the controls on current ocean processes. [ABSTRACT FROM AUTHOR]

Dust can affect the radiative balance of the atmosphere by absorbing or reflecting incoming solar radiation; it can also be a source of micronutrients, such as iron, to the ocean. It has been suggested that production, transport and deposition of dust is influenced by climatic changes on glacial-interglacial timescales. Here we present a high-resolution record of aeolian dust from the EPICA Dome C ice core in East Antarctica, which provides an undisturbed climate sequence over the past eight climatic cycles. We find that there is a significant correlation between dust flux and temperature records during glacial periods that is absent during interglacial periods. Our data suggest that dust flux is increasingly correlated with Antarctic temperature as the climate becomes colder. We interpret this as progressive coupling of the climates of Antarctic and lower latitudes. Limited changes in glacial-interglacial atmospheric transport time suggest that the sources and lifetime of dust are the main factors controlling the high glacial dust input. We propose that the observed ∼25-fold increase in glacial dust flux over all eight glacial periods can be attributed to a strengthening of South American dust sources, together with a longer lifetime for atmospheric dust particles in the upper troposphere resulting from a reduced hydrological cycle during the ice ages. [ABSTRACT FROM AUTHOR]

Massive iceberg discharges from the Northern Hemisphere ice sheets,‘Heinrich events’, coincided with the coldest periods of the last ice age. There is widespread evidence for Heinrich events and their profound impact on the climate and circulation of the North Atlantic Ocean, but their influence beyond that region remains uncertain. Here we use a combination of molecular fingerprints of algal productivity and radioisotope tracers of sedimentation to document eight periods of increased productivity in the subpolar Southern Ocean during the past 70,000 years that occurred within 1,000-2,000 years of a Northern Hemisphere Heinrich event. We discuss possible causes for such a link, including increased supply of iron from upwelling and increased stratification during the growing season, which imply an alteration of the global ocean circulation during Heinrich events. The mechanisms linking North Atlantic iceberg discharges with subantarctic productivity remain unclear at this point. We suggest that understanding how the Southern Ocean was altered during these extreme climate perturbations is critical to understanding the role of the ocean in climate change. [ABSTRACT FROM AUTHOR]

Dates the penultimate deglaciation in a record from the Bahamas using a uranium-thorium isochron technique. Theory on the cause of Ice Age climate cycles; June Northern hemisphere insolation; Potential alternative driving mechanisms for the Ice Age cycles.

Presents research which showed that millennial-scale oscillations in climate occurred over one million years ago. Records of variations in the Earth's climate; Possible tie of climate shifts to alterations in the mode of ocean thermohaline circulation; Nature of climate conditions one million years ago; Climate instability a long-term and pervasive trait of Earth's climate.

The article focuses on the research on ocean circulation in a warming climate. Accordingly, findings show that the Last Glacial Maximum (LGM) had stronger winds which fit to the common observation that it is windier in the winter than in the summer because there is greater thermal contrast within the atmosphere in the winter hemisphere. Moreover, the paper cited several observations that predict that oceans' circulation will weaken in response to global warming, but the warming at the end of the last ice age suggests a different outcome. However, by studying these observations, it is clear that large circulation changes took place and it seems unlikely that circulation changes of this magnitude could have happened without substantial changes in the wind forcing.

Focuses on the reconstruction of temperatures in the Atlantic Ocean during the last age which is 21,000 years prior to 2003. Factors influencing climate changes; Mechanisms of global change; Magnitude and direction of ice-age temperatures; Dynamics of air-sea interaction in the tropics; Sensitivity of global system to changing greenhouse gases.

Discusses what causes ice ages, and other episodes of violent climate change, according to a report by T. Blunier et al in the same issue. Their efforts to cross-date isotope records in ice cores from Greenland and Antarctica to within a few centuries; How they took advantage of the rapid and large swings in the methane concentration of the atmosphere during the last glacial period.