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Pulse-like carbon dioxide release to the atmosphere on centennial time scales has only been identified for the most recent glacial and deglacial periods and is thought to be absent during warmer climate conditions. Here, we present a high-resolution carbon dioxide record from 330,000 to 450,000 years before present, revealing pronounced carbon dioxide jumps (CDJ) under cold and warm climate conditions. CDJ come in two varieties that we attribute to invigoration or weakening of the Atlantic meridional overturning circulation (AMOC) and associated northward and southward shifts of the intertropical convergence zone, respectively. We find that CDJ are pervasive features of the carbon cycle that can occur during interglacial climate conditions if land ice masses are sufficiently extended to be able to disturb the AMOC by freshwater input. [ABSTRACT FROM AUTHOR]

The timing of sea-level change provides important constraints on the mechanisms driving Earth's climate between glacial and interglacial states. Fossil corals constrain the timing of past sea level by their suitability for dating and their growth position close to sea level. The coral-derived age for the last deglaciation is consistent with climate change forced by Northern Hemisphere summer insolation (NHI), but the timing of the penultimate deglaciation is more controversial. We found, means of uranium/thorium dating of fossil corals, that sea level during the penultimate deglaciation had risen to ∼85 meters below the present sea level by 137,000 years ago, and that it fluctuated on a millennial time scale during deglaciation. This indicates that the penultimate deglaciation occurred earlier with respect to NHI than the last deglacial, beginning when NHI was at a minimum. [ABSTRACT FROM AUTHOR]

Whether cooling occurred in the Southern Hemisphere during the Younger Dryas (YD) is key to understanding mechanisms of millennial climate change. Although Southern Hemisphere records do not reveal a distinct climate reversal during the late glacial period, many mountain glaciers readvanced. We show that the Puerto Bandera moraine (5005), which records a readvance of the Southern Patagonian Icefield (SPI), formed at, or shortly after, the end of the YD. The exposure age (10.8 ± 0.5 thousand years ago) is contemporaneous with the highest shoreline of Lago Cardiel (49°S), which records peak precipitation east of the Andes since 13 thousand years ago. Absent similar moraines west of the Andes, these data indicate an SPI response to increased amounts of easterly-sourced precipitation—reflecting changes in the Southern Westerly circulation—rather than regional cooling. [ABSTRACT FROM AUTHOR]

Long-term variations in Northern Hemisphere summer insolation are generally thought to control glaciation. But the intensity of summer insolation is primarily controlled by 20,000-year cycles in the precession of the equinoxes, whereas early Pleistocene glacial cycles occur at 40,000-year intervals, matching the period of changes in Earth's obliquity. The resolution of this 40,000-year problem is that glaciers are sensitive to insolation integrated over the duration of the summer. The integrated summer insolation is primarily controlled by obliquity and not precession because, by Kepler's second law, the duration of the summer is inversely proportional to Earth's distance from the Sun. [ABSTRACT FROM AUTHOR]

We propose that from ∼3 to 1 million years ago, ice volume changes occurred in both the Northern and Southern Hemispheres, each controlled by local summer insolation. Because Earth's orbital precession is out of phase between hemispheres, 23,000-year changes in ice volume in each hemisphere cancel out in globally integrated proxies such as ocean δ18O or sea level, leaving the in-phase obliquity (41,000 years) component of insolation to dominate those records. Only a modest ice mass change in Antarctica is required to effectively cancel out a much larger northern ice volume signal. At the mid-Pleistocene transition, we propose that marine-based ice sheet margins replaced terrestrial ice margins around the perimeter of East Antarctica, resulting in a shift to in-phase behavior of northern and southern ice sheets as well as the strengthening of 23,000-year cyclicity in the marine δ18O record. [ABSTRACT FROM AUTHOR]

Two hypotheses have been put forward to explain the large and abrupt climate changes that punctuated glacial time. One attributes such changes to reorganizations of the ocean's thermohaline circulation and the other to changes in tropical atmosphere-ocean dynamics. In an attempt to distinguish between these hypotheses, two lines of evidence are examined. The first involves the timing of the freshwater injections to the northern Atlantic that have been suggested as triggers for the global impacts associated with the Younger Dryas and Heinrich events. The second has to do with evidence for precursory events associated with the Heinrich ice-rafted debris layers in the northern Atlantic and with the abrupt Dansgaard-Oeschger warmings recorded in the Santa Barbara Basin. [ABSTRACT FROM AUTHOR]

Discusses the extension of a precise relative chronology for Greenland and West Antarctic paleotemperature to 90,000 years ago, based on correlation of atmospheric methane records from the Greenland Ice Sheet Project 2 and Byrd ice cores. Climate change during the last Glacial Period; Oceanic teleconnection between the hemispheres on millennial time scales.

Documents climate shifts during the last deglaciation using carbon 14 time scales from the Cariaco Basin in Venezuela. Hydrography of the Cariaco Basin; Increase and decline of carbon 14 during the Younger Dryas; Forcing mechanisms corresponding to carbon 14 variations; Climate effect of solar irradiance.

Presents a report on the variations in atmospheric nitrous oxide (N2O) concentration during abrupt climatic changes. Records covering the last glacial-interglacial transition and a fast climatic change during the last ice age showing that the N2O concentration changed in parallel with fast temperature variations in the Northern hemisphere; Information about the response of the environment to global climatic changes.

Discusses climatic changes during the Glacial Age. Period of southwest monsoon intensification; Teleconnections in the evolution of monsoonal and high-latitude climates; Frequency of monsoonal climate variability.

Explores glacial surface temperatures of the Southeast Atlantic ocean. Discussion of the presence on brisk cyclonic currents; Use of marine records in identifying long-term cooling in the Last Glacial Maximum; Documentation of Cape Basin records in terms of substantial temperature ocean warming.

The article explores how the Antarctic ice sheet has changed in recent years by tracking mass changes. The methods for measuring mass changes mentioned in the article include subtracting the melt and ice flow from the total snowfall, sensing changes in the strength of gravity using pairs of satellites, and repeat mapping of surface elevations from satellites. A study cited in this article, which applied the repeated mapping method, showed that a correction must be made for changes in the density of the firn layer on the ice sheet surface.

The article discusses the causes of glacial cycle in earth. It has been stated according to the Milankovitch theory that the changes of insolation is the cause of ice age cycle. Insolation is described as the exposure of the earth's surface to the rays of the sun. It varies on time scales of thousands of years as a result of regular changes in earth's orbit around the sun, in the tilt of earth's axis, and in the direction of earths axis of rotation. An example has been cited that between 3 and 1 million years before present, glacial oscillations follows a 41,000-year cycle and that these oscillations correspond to insolation changes driven by obliquity changes. Other information related to the topic are discoursed in the paper.

Focuses on the factors affecting biological diversity. Impact of glacial-interglacial cycles on biodiversity; Effects of climatic changes on geographic distribution of species; Importance of southern refugia on the survival of biodiversity.

The article focuses on the deglaciation during Pleistocene epoch. A compiled evidence suggests that the sea levels would fluctuate by 30 to 40 meters during the start of warm intervals. This occurrence will confirm the variability of relative elevations of deposits in Greek shoreline. Information to determine the sample ages using U/Th dating found out that the sea level will drop twice precipitously between 136,000 and 135, 000 years in Red Sea and Papua, New Guinea. These results will constrain the timing of sea-level rise during the penultimate deglaciation.

The article focuses on the impact of environmental changes on civilization. Anthropological archaeologists have examined the significance of environmental influences, such as climate patterns and shoreline movements due to shifting sea level. They compared local climatic and geographical changes with concurrent societal developments in specific regions of the Persian Gulf between 15,000 and 6000 years ago. They found that early societal development was shaped by the formation of productive estuaries, the availability of ample fresh water, and the ability to transport goods over water. Climatic changes particularly the increase in aridity between 6000 and 5000 years ago play an important role in fostering the consolidation of settlements. They found that the emergence of highly organized urban society was the result of the glacial-inter-glacial cycle and related climate changes.

This article presents views of paleoclimatologists about Earth's climate. Indeed, the revival of the Snowball Earth hypothesis almost 7 years ago has bogged down of late, as paleoclimatologists have failed to turn up unequivocal evidence that ice enrobed the planet. A group of geochemists offers a new snowball marker: the element iridium, which continually rains down on us from space. They say they found so much iridium deposited at the end of a glaciation 635 million years ago that the planet must have been frozen pretty much solid for 12 million years straight.

Examines the importance of atmospheric mineral dust on global climate change. Effect of atmospheric mineral dust on the heat budget of Earth; Role of dust on the formation of carbon dioxide concentration; Influence of glacial cycles to the concentration of atmospheric dust.