A mid-Holocene shift in Arctic sea-ice variability on the East Greenland Shelf

From this was recovered the deepest ice core record to date. Comparative data between these two deep cores have allowed scientists to develop an ice core-derived paleoenvironmental record dating back greater than , years BP BP means “before present” and “BP” is defined as In other words, the ice has been confirmed to be as old as the collective measurements indicate. These data alone destroy the core doctrine of the theory of Young Earth Creationism that the Earth is only about 6, years old. In addition to the actual age of the ice at any given depth in the core, scientists can also determine the mean temperature of the Earth’s past climate for different times and ages by measuring the ratio of the isotopes of oxygen O16 and O18 gas present in the CO2. Secular critics of Young Earth Creationism cite the very existence of the Greenland Ice Sheet and the paleoenvironmental record it contains as well as the data found in ice cores from the glaciers on Kilimanjaro in Africa and Huascaran in Peru as absolute proof that the Earth is older than 6, years and that Noah’s flood did not occur, since there are no indications of a flood in the ice core layers.

8 – Last Glacial Interglacial Transition & Holocene Environments

Advanced Search Abstract Oscillations in the time series of insoluble microparticle characteristics between 0. Elevated values in microparticle number and mass, especially during the Younger Dryas, are related to Northern Hemisphere aridity and the subsequent increase in dust available for long-range transport to Greenland. This scenario occurs with the colder climatic conditions that result from a more expanded spatially and temporally polar vortex.

Peaks in mean grain size based on number mean number diameter are a proxy for increased strength in zonal winds westerlies. Highs in mean number diameter in the earlier part of the record often coincide with number and mass peaks reflecting the increased temperature and pressure gradients with an expanded polar vortex. Highs in mean grain size based on mass mean mass diameter reflect greater deposition of the coarser size fraction, and thus are a proxy for increased storminess associated with better developed synoptic-scale pressure systems in the northernmost Atlantic region.

Figure 1). From the ice cores, many variables, such as oxygen isotopes, physical stratigraphy, and various ions, during the ice age and the Holocene part after the ice age.3 The S04 2-‘ ion, from the GISP2 Greenland ice core and implications for the volcano-climate system. Science,

Here, we investigate the regional footprints of the North Atlantic weather regimes on Greenland isotope and climate variability, using a compilation of 22 different shallow ice-cores and the atmospheric pressure conditions from the twentieth century reanalysis 20CR. Likewise, the Scandinavian blocking and the Atlantic ridge also show remarkable imprints on isotopic composition over the region. To assess the robustness and model dependency of our findings, a second isotope simulation from the isotopic model is also explored.

This study opens the possibility for reconstructing past changes in the frequencies of occurrence of the weather regimes, which would rely on the sensitive regions identified here, and the use of additional proxies over the North Atlantic region. We would also like to thank two anonymous reviewers for their constructive comments that helped to improve the final version of the manuscript. J Geophys Res Geophys Res Lett Mon Weather Rev Q J R Meteorol Soc Bull Am Meteorol Soc

Dansgaard–Oeschger event

By Eryn Brown Jul 10, 3: A team reported Wednesday that it had used such ice cores to eliminate discrepancies in scientists’ understanding of the timing of volcanic eruptions — and subsequent climate effects — over the last 2, years. Olivia Maselli A new method of analyzing ice cores has allowed scientists to more precisely determine when volcanic eruptions occurred on Earth over the last 2, years.

A multidisciplinary team of scientists melted down giant ice cores drilled from sites in Greenland and Antarctica and painstakingly analyzed sulfate deposits in the ice as they went.

Walton, Mariah H., “Holocene Reconstruction of the West Greenland Current and the Greenland Ice Sheet Margin Near Disko Bay Using Foraminiferal Assemblages” (). Atmospheric & Oceanic Sciences Graduate Theses & Dissertations.

Under a Creative Commons license open access Abstract Due to their outstanding resolution and well-constrained chronologies, Greenland ice-core records provide a master record of past climatic changes throughout the Last Interglacial—Glacial cycle in the North Atlantic region. A key element of these protocols has been the formal definition and ordinal numbering of the sequence of Greenland Stadials GS and Greenland Interstadials GI within the most recent glacial period.

The GS and GI periods are the Greenland expressions of the characteristic Dansgaard—Oeschger events that represent cold and warm phases of the North Atlantic region, respectively. The data not only resolve the well-known sequence of Dansgaard—Oeschger events that were first defined and numbered in the ice-core records more than two decades ago, but also better resolve a number of short-lived climatic oscillations, some defined here for the first time. Using this revised scheme, we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the Last Glacial period that are represented in the Greenland ice records.

The final product constitutes an extended and better resolved Greenland stratotype sequence, against which other proxy records can be compared and correlated. It also provides a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations. Previous article in issue.

Wild Ice-Core Interpretations by Uniformitarian Scientists

Location map and Agassiz proxy temperature records: A Map showing the study area with the names and locations of ice core borehole sites mentioned in the text. Each record is referenced to its preindustrial temperature value at CE. The two time series were remarkably similar, leading the authors to adopt a spatially homogeneous change in air temperature across the region spanned by these two ice caps.

These so-called thinning curves provide a valuable constraint on model reconstructions of the Greenland ice sheet 5.

A synchronized dating of three Greenland ice cores throughout the Holocene. B. M. Vinther. E-mail address layer thickness in each core section confirms that the new synchronized dating is consistent for all three cores. The data used for the main annual layer counting of the past years are the DYE‐3, GRIP, and NGRIP stable isotope.

Climate at the core: Amy Dusto Like a prehistoric fly trapped in amber during dinosaurs’ days, airborne relics of Earth’s earlier climate—including dust, air bubbles, sea salts, volcanic ash, and soot from forest fires—can end up trapped in glacial ice for eons. To climate scientists, those relics tell a story about how our planet’s climate and atmosphere have changed over thousands of years. The embedded pebbles and dingy ice tell researchers that this portion of the ice core is from the bottom of the glacier, right above bedrock.

This chunk comes from the first ice core drilled at Mt. Hunter, Alaska; the core’s total length was feet. Photo by Mike Waszkiewicz. What they find out could have an impact on worldwide civilization within a few generations—especially in coastal regions. Ice cores may reveal whether Antarctica’s western ice sheet melted fully the last time Earth’s climate warmed to the temperatures the planet is predicted to reach in the next two centuries.

9,400 years of cosmic radiation and solar activity from ice cores and tree rings

But the planet bears the scars of only a few hundred of these impacts because of weathering processes like erosion. Through analysis of crater size and sediments from the crater, they estimate that the asteroid that slammed into Earth was more than a kilometer in diameter, composed mainly of iron. This discovery suggests that Earth may harbor more signs of its tumultuous history beneath its glaciers and ice sheets.

They were using archival measurements of the Greenland Ice Sheet to study its ice flows and underlying bedrock. But when a group of Danish researchers noticed a circular depression in the bedrock at the northwest edge of the ice sheet, under Hiawatha Glacier, their curiosity was piqued.

Stable isotopes and climate history from polar ice cores-Stable isotopes of oxygen and hydrogen and their use in ice core studies-Paleoclimate studies on Greenland ice cores over the last 40 years-Antarctic records of climate history-Correlation of Greenland and Antarctic recordsUH Winter School Talk # 26 Thorsteinn Thorsteinsson.

Their data indicated that after the termination of the glacial period, temperatures steadily rose to a maximum of 2. After the Little Ice Age, they report that temperatures once again rose, but that they had “decreased during the last decades,” thereby indicating that the MWP in this part of the Arctic was significantly warmer than it was just before the turn of the century. Wagner and Melles also worked on Greenland, where they extracted a 3.

Key to the study were biogeochemical data, which, in the words of the two researchers, reflect “variations in seabird breeding colonies in the catchment which influence nutrient and cadmium supply to the lake. And after that “medieval warm period,” their data suggested another absence of birds during what they called “a subsequent Little Ice Age,” which they said was “the coldest period since the early Holocene in East Greenland. However, values of the most recent measurements of seabird numbers were not as great as those inferred for the earlier Medieval Warm Period, which result indicates that higher temperatures prevailed during much of the period from to years BP than those that had been observed over the most recent hundred years.

A third Greenland study was conducted by Kaplan et al. This work revealed that the interval from to years BP was marked by warmth and stability, but that the climate cooled thereafter until its culmination in the Little Ice Age. From years BP, however, there was a partial amelioration during the Medieval Warm Period, which was associated with an approximate 1.

Enormous Impact Crater Spotted in Greenland Under Glacial Ice

Evidence[ edit ] The best evidence for Dansgaard—Oeschger events remains in the Greenland ice cores , which only go back to the end of the last interglacial, the Eemian interglacial. Ice core evidence from Antarctic cores suggests that the Dansgaard—Oeschger events are related to the so-called Antarctic Isotope Maxima by means of a coupling of the climate of the two hemispheres, the Bi-polar Seesaw.

Unfortunately, current ice core records from Greenland extend only through the last most recent glacial period so direct evidence of D-O events in earlier glacial periods from Greenland ice is unavailable. However, work by Stephen Barker and colleagues has shown that the existing Greenland record can be reconstructed by deriving the Antarctic ice core record.

But even during the last glacial there are clear anti-correlations between the three ice cores, even between the two Greenland ice cores on a scale of thousands of years. Therefore his failure to show a comparison of GISP2 and Vostok over the period of the Holocene with sufficient resolution is .

For a—e, the dashed red curve is the calcium carbonate content at the respective sub cores of BC after It was necessary to switch to the more sensitive Finnigan for the stable isotope analyses in the LIA samples where the benthic foram abundance was minimal because of higher clay and silt fluxes. Isotopic results show good agreement between the two instruments see Fig. If these data accurately reflect bottom water nutrient levels, then during the LIA NADW was nearly completely replaced by nutrient-rich circumpolar water in the deep western North Atlantic.

This increase is driven by samples in only the upper 2 cm of the cores, and is markedly less than what would be expected from a 0. The two tracers cannot both be reflecting deep ocean nutrient levels accurately. Although neither proxy is perfect, we do not presently have enough information to determine which is more reliable. Box core tops are sometimes disturbed in the recovery process, and the core is bioturbated, but those processes should influence the trace metal and isotopic data equally.

Carbon isotope ratios are also known to be influenced by the rain rate of organic carbon 29 , 30 , but those problems are thought to be of greatest concern in upwelling regions, not the centers of subtropical circulation like the Sargasso Sea. If we were to calculate the mass accumulation rate of organic carbon, there would be a large spike during the LIA because the rate of sedimentation spikes 20 , but that artifact would not be preserved in the sedimentary record as the percent organic carbon decreases to a steady state value.

One test of our Bermuda Rise observations is to study shallower locations where the potential for carbonate dissolution is not so great. Unfortunately, at present only a few open marine locations are known to resolve the LIA, and shallower sites might not be as sensitive to changes in the densest components of NADW. Furthermore, although both the ice-rafted debris episodes and the grainsize changes may have similar periodicities in their respective cores, there is not an exact match between every ice-rafted debris event and every grainsize event.

In fact, there is surprisingly little agreement among the proxy data in Fig.