The International North Greenland Eemian Ice Drilling NEEM project results indicate that melting of Antarctic ice sheet may have contributed more to sea level rise than melting of the Greenland ice sheet some , years ago. This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts. A new study that provides surprising details on changes in Earth’s climate from more than , years ago indicates that the last interglacial–the period between “ice ages”–was warmer than previously thought and may be a good analog for future climate, as greenhouse gases increase in the atmosphere and global temperatures rise. The research findings also indicate that melting of the massive West Antarctic ice sheet may have contributed more to sea-level rise at that time than melting of the Greenland ice sheet. Members of the research team noted that they were working in Greenland during the summer of during a rare modern melt event similar to those discussed in the paper. While this was an extreme event, the present warming over Greenland makes surface melt more likely, and the predicted warming over Greenland in the next years will potentially have Eemian-like climate conditions. The research published this week shows that during the Eemian interglacial, the climate in North Greenland was about 8 degrees Celsius warmer than at present.
Based on an early Greenland ice core record produced back in , versions of the graph have, variously, mislabeled the x-axis, excluded the modern observational temperature record and conflated a single location in Greenland with the whole world. More recently, researchers have drilled numerous additional ice cores throughout Greenland and produced an updated estimate past Greenland temperatures. This modern temperature reconstruction, combined with observational records over the past century, shows that current temperatures in Greenland are warmer than any period in the past 2, years.
North Greenland Ice Core Project Members (): 50 year means of oxygen isotope data NGRIP * Latitude: * Longitude: * Date/Time.
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Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. A year — chronological record of environmental perchlorate, reconstructed from high-resolution analysis of a central Greenland ice core, shows that perchlorate levels in the post atm were two-to-three times those of the pre environment.
While this confirms recent reports of increased perchlorate in Arctic snow since compared with the levels for the prior decades — , the longer Greenland record demonstrates that the Industrial Revolution and other human activities, which emitted large quantities of pollutants and contaminants, did not significantly impact environmental perchlorate, as perchlorate levels remained stable throughout the 18 th , 19 th , and much of the 20 th centuries.
The increased levels since likely result from enhanced atmospheric perchlorate production, rather than from direct release from perchlorate manufacturing and applications. The enhancement is probably influenced by the emission of organic chlorine compounds in the last several decades. Prior to , no significant long-term temporal trends in perchlorate concentration are observed. It appears that atmospheric perchlorate production is impacted by large eruptions in both high- and low-latitudes, but not by small eruptions and nonexplosive degassing.
A synchronized dating of three Greenland ice cores throughout the Holocene
Guest commentary from Jonny McAneney. You heard it here first …. Back in February, we wrote a post suggesting that Greenland ice cores may have been incorrectly dated in prior to AD This was based on research by Baillie and McAneney which compared the spacing between frost ring events physical scarring of living growth rings by prolonged sub-zero temperatures in the bristlecone pine tree ring chronology, and spacing between prominent acids in a suite of ice cores from both Greenland and Antarctica.
GISP2. Ice Core. The GISP2 ice core in Greenland was drilled as deep as 2 miles. Ice cores provide excellent seasonal markers allowing very accurate dating.
During the Holocene and the previous interglacial period Eemian the dust record was dominated by coarse particles consistent with rock samples from central East Greenland. From the coarse particle concentration record we infer the East Greenland ice sheet margin advanced from These findings constrain the possible response of the Greenland ice sheet to climate forcings. Although ice cores are geographical point measurements, they represent a record of air, water and aerosols transported to the ice over regional or even hemispheric scales.
In contrast, reconstructions of past ice sheet limits are typically limited to the locations of the individual measurements 1 , 2.
Ice Cores, Antarctica And Greenland
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Hence there are large dating uncertainties regarding glacial advance after the Eemian. Ice core dust records may complement this research.
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Register new account. East Greenland Ice-core Project. General Organisation. University of Copenhagen.
East Greenland ice core dust record reveals timing of Greenland ice sheet advance and retreat
Vinther, H. Clausen, S. Johnsen, S.
The International North Greenland Eemian Ice Drilling (NEEM) project Telephone numbers or other contact information may be out of date;.
Ice consists of water molecules made of atoms that come in versions with slightly different mass, so-called isotopes. Variations in the abundance of the heavy isotopes relative to the most common isotopes can be measured and are found to reflect the temperature variations through the year. The graph below shows how the isotopes correlate with the local temperature over a few years in the early s at the GRIP drill site:. The dashed lines indicate the winter layers and define the annual layers.
How far back in time the annual layers can be identified depends on the thickness of the layers, which again depends on the amount of annual snowfall, the accumulation, and how deep the layers have moved into the ice sheet. As the ice layers get older, the isotopes slowly move around and gradually weaken the annual signal.
Data from DRI ice core lab shows rapid melting of Greenland ice sheet
Research article 20 Nov Correspondence : Florian Adolphi adolphi climate. During the last glacial period Northern Hemisphere climate was characterized by extreme and abrupt climate changes, so-called Dansgaard—Oeschger DO events. Most clearly observed as temperature changes in Greenland ice-core records, their climatic imprint was geographically widespread. However, the temporal relation between DO events in Greenland and other regions is uncertain due to the chronological uncertainties of each archive, limiting our ability to test hypotheses of synchronous change.
In contrast, the assumption of direct synchrony of climate changes forms the basis of many timescales.
A difficulty in ice core dating is that gases can diffuse through firn, so the ice at of a Greenland core (for example) with an Antarctic core.
Previous studies have utilized satellite observations, which only go back to The detailed DRI measurements of more than 20 elements and chemical species in both the D5 and NU ice cores enabled precise dating of the records that underpin the new findings. Recovering an ice core from west Greenland. The study provides new evidence of the impacts of climate change on Arctic melting and global sea level rise.
Meltwater lakes on the Greenland ice sheet. Ice loss from Greenland is one of the key drivers of global sea level rise. Icebergs calving into the ocean from the edge of glaciers represent one component of water re-entering the ocean and raising sea levels. But more than half of the ice-sheet water entering the ocean comes from runoff from melted snow and glacial ice atop the ice sheet.
To determine how intensely Greenland ice has melted in past centuries, the research team used a drill the size of a traffic light pole to extract ice cores from the ice sheet itself and an adjacent coastal ice cap, at sites more than 6, feet above sea level. During warm summer days in Greenland, melting occurs across much of the ice sheet surface. At lower elevations, where melting is the most intense, meltwater runs off the ice sheet and contributes to sea level rise, but no record of the melt remains.
At higher elevations, however, the summer meltwater quickly refreezes from contact with the below-freezing snowpack sitting underneath. This prevents it from escaping the ice sheet in the form of runoff. Instead, it forms distinct icy bands that stack up in layers of densely packed ice over time.
How are ice cores dated?
It is not uncommon to read that ice cores from the polar regions contain records of climatic change from the distant past. Research teams from the United States, the Soviet Union, Denmark, and France have bored holes over a mile deep into the ice near the poles and removed samples for analysis in their laboratories. Based on flow models, the variation of oxygen isotopes, the concentration of carbon dioxide in trapped air bubbles, the presence of oxygen isotopes, acid concentrations, and particulates, they believe the lowest layers of the ice sheets were laid down over , years ago.
So far, no melt record exists for eastern Greenland, as ice cores are thick annual layers are beneficial for layer counting and dating, but. 5.
Always quote above citation when using data! You can download the citation in several formats below. View dataset as HTML shows only first rows. Two deep ice cores from central Greenland, drilled in the s, have played a key role in climate reconstructions of the Northern Hemisphere, but the oldest sections of the cores were disturbed in chronology owing to ice folding near the bedrock.
Here we present an undisturbed climate record from a North Greenland ice core, which extends back to , years before the present, within the last interglacial period. We find unexpectedly large temperature differences between our new record from northern Greenland and the undisturbed sections of the cores from central Greenland, suggesting that the extent of ice in the Northern Hemisphere modulated the latitudinal temperature gradients in Greenland.
Ice core dating using stable isotope data
Polar ice results from the progressive densification of snow deposited at the surface of the ice sheet. The transformation of snow into ice generally occurs within the first meters and takes from decades to millennia, depending on temperature and accumulation rate, to be completed. During the first stage of densification, recrystallization of the snow grains occurs until the closest dense packing stage is reached at relative densities of about 0.
Then plastic deformation becomes the dominant process and the pores progressively become isolated from the surface atmosphere. The end product of this huge natural sintering experiment is ice, an airtight material.
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 based on GRIP core dating. Isochrons observed in radio echo.
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers for shallow holes or powered drills; they can reach depths of over two miles 3.
The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures , and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide. Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past.
These data can be combined to find the climate model that best fits all the available data. Impurities in ice cores may depend on location. Coastal areas are more likely to include material of marine origin, such as sea salt ions. Greenland ice cores contain layers of wind-blown dust that correlate with cold, dry periods in the past, when cold deserts were scoured by wind. Radioactive elements, either of natural origin or created by nuclear testing , can be used to date the layers of ice.
Some volcanic events that were sufficiently powerful to send material around the globe have left a signature in many different cores that can be used to synchronise their time scales. Ice cores have been studied since the early 20th century, and several cores were drilled as a result of the International Geophysical Year —