How far into the past can ice-core records go? Scientists have now identified regions in Antarctica they say could store information about Earth’s climate and greenhouse gases extending as far back as 1. By studying the past climate, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere. This, in turn, allows them to make better predictions about how climate will change in the future. Now, an international team of scientists wants to know what happened before that. At the root of their quest is a climate transition that marine-sediment studies reveal happened some 1. Earth’s climate naturally varies between times of warming and periods of extreme cooling ice ages over thousands of years. Before the transition, the period of variation was about 41 thousand years while afterwards it became thousand years.
Picture Climate: What Can We Learn from Ice?
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.
Other ways of dating ice cores include geochemisty, wiggle matching of ice core records Uranium has been used to date the Dome C ice core from Antarctica.
Ice core , long cylinder of glacial ice recovered by drilling through glaciers in Greenland, Antarctica , and high mountains around the world. Scientists retrieve these cores to look for records of climate change over the last , years or more. Ice cores were begun in the s to complement other climatological studies based on deep-sea cores, lake sediments, and tree-ring studies dendrochronology.
Since then, they have revealed previously unknown details of atmospheric composition , temperature, and abrupt changes in climate. Abrupt changes are of great concern for those who model future changes in climate and their potential impacts on society. Ice cores record millennia of ancient snowfalls, which gradually turned to crystalline glacier ice.
In areas of high accumulation, such as low-latitude mountain glaciers and the Greenland Ice Sheet , annual layers of ice representing tens of thousands of years can be seen and counted, often with the unaided eye. The first deep drilling took place in the s as preliminary efforts at Camp Century, Greenland, and Byrd Station, Antarctica. This effort reached a depth of 3, 10, feet. These cores span about , years of relatively stable ice.
A 2-Million-Year-Old Ice Core from Antarctica Reveals Ancient Climate Clues
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.
Figure 1 Scientists measure ice cores from deep drilling sites on the ice sheet near Casey Antarctica is the coldest, windiest, highest and driest continent on Earth. In order to date the ice cores accurately, the annual layers need to be thick.
Ice cores are highly valued in paleoclimate research because they record environmental parameters that range on spatial scales from individual snowflakes to the Earth’s atmosphere and on time scales from hours to hundreds of millennia. Ice cores are our only source of samples of the paleoatmosphere. They are especially valuable for investigating climate forcing and response, because they record many aspects of the climate system in a common, well-dated archive. The main objective of the WAIS West Antarctic Ice Sheet Divide ice core project drilling operations from was to investigate climate from the last glacial period to modern conditions, with greater time resolution than previous Antarctic ice cores.
In addition, the project investigated the dynamics of the West Antarctic Ice Sheet and cryobiology. The distinguishing characteristic of the project was the development of environmental records of the last glacial period and early Holocene, with greater time resolution and dating precision than previous Antarctic ice cores.
This is particularly true for the records of atmospheric gases, water isotopes, and chemistry. Map of West Antarctica. Waesche MW are shown. Ice shelves are shown in gray. Siple Coast and Amundsen Sea ice streams are shown by blue shading. Contour interval is meters. Credit: T. A site in Antarctica was required to provide a Southern Hemisphere equivalent to the deep Greenland ice cores.
Core questions: An introduction to ice cores
Ice cores are cylinders of ice drilled out of an ice sheet or glacier. Most ice core records come from Antarctica and Greenland, and the longest ice cores extend to 3km in depth. The oldest continuous ice core records to date extend , years in Greenland and , years in Antarctica. Ice cores contain information about past temperature, and about many other aspects of the environment. Crucially, the ice encloses small bubbles of air that contain a sample of the atmosphere — from these it is possible to measure directly the past concentration of gases including carbon dioxide and methane in the atmosphere.
However, dating methods are still associated with large uncertainties for ice cores from the East Antarctic plateau where layer counting is not possible. Indeed.
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.
Last month, in an excellent piece of research Sigl et al. The clinching evidence was provided by linking tree-ring chronologies to ice cores through two extraterrestrial events…. In , Miyaki et al.
Eight glacial cycles from an Antarctic ice core
Deep ice core chronologies have been improved over the past years through the addition of new age constraints. However, dating methods are still associated with large uncertainties for ice cores from the East Antarctic plateau where layer counting is not possible. Consequently, we need to enhance the knowledge of this delay to improve ice core chronologies. It is especially marked during Dansgaard-Oeschger 25 where the proposed chronology is 2.
Dating of 30m ice cores drilled by Japanese Antarctic Research Expedition and environmental change study.
Figure 1: New ice core timescale of Greenland ice core NEEM NS1 (top) and Antarctica ice cores (bottom), and the effects of their forcing on a.
Why use ice cores? How do ice cores work? Layers in the ice Information from ice cores Further reading References Comments. Current period is at right. Wikimedia Commons. Ice sheets have one particularly special property. They allow us to go back in time and to sample accumulation, air temperature and air chemistry from another time. Ice core records allow us to generate continuous reconstructions of past climate, going back at least , years.
By looking at past concentrations of greenhouse gasses in layers in ice cores, scientists can calculate how modern amounts of carbon dioxide and methane compare to those of the past, and, essentially, compare past concentrations of greenhouse gasses to temperature. Ice coring has been around since the s. Ice cores have been drilled in ice sheets worldwide, but notably in Greenland and Antarctica[4, 5].
Through analysis of ice cores, scientists learn about glacial-interglacial cycles, changing atmospheric carbon dioxide levels, and climate stability over the last 10, years. Many ice cores have been drilled in Antarctica.
Ice cores and climate change
To support our nonprofit science journalism, please make a tax-deductible gift today. Scientists endured bitter winds to retrieve ancient ice from a blue ice field in the Allan Hills of Antarctica. Scientists announced today that a core drilled in Antarctica has yielded 2. Some models of ancient climate predict that such relatively low levels would be needed to tip Earth into a series of ice ages.
But some proxies gleaned from the fossils of animals that lived in shallow oceans had indicated higher CO 2 levels.
An important link between Antarctic and Greenland ice cores is the prominent geomagnetic excursion known as the Laschamp event that took place approximately.
Selecting the right spot for ice-core drilling is a difficult pursuit. And after three years of searching with radar and on-the-ground sampling, an international team just struck gold: They found a spot on Antarctica where the ice is thick enough to reveal 1. It will take another three years to drill down that far. Ice cores reveal what the climate was like on Earth throughout time. Air bubbles trapped in the ice can be sampled to measure how much carbon, methane, and other gases were in the atmosphere at the moment the ice froze.
A single meter-long piece could contain 10, years of climate history, if selected carefully. And the deeper the ice core, the farther back in time the samples can go. Those cores were taken between and , and reached just over two miles 10, ft, or 3, meters deep into the ice. In some cases, ice that old melts due to the pressure created by the immense layers of ice above it, but Little Dome C is in good shape, according to a press release.
If the European Union approves funding to drill the new cores, they will be taken at 1. The drilling would begin in , and continue for three Antarctic summers.
How are ice cores dated?
I was wondering how ice cores are dated accurately. I know Carbon 14 is one method, but some ice cores go back hundreds of thousands of years. Would other isotopes with longer half-lives be more accurate? Also, how much does it cost to date the core?
We discuss ice core dating, the difficulties connected with trace measurements, and regions of the Greenland and Antarctic ice sheets is strongly influenced by.
E-mails: ufrgs. E-mail: sharon. The study of atmospheric aerosols through polar ice cores is one of the most common and robust tools for the investigation of past changes in the circulation and chemistry of the atmosphere. Only a few subannual resolution records are available for the development of paleochemical and environmental interpretations.
Here, we report the ionic content record for the period of A. The ion concentrations found in the core were determined by ion chromatography on more than 2, samples and the basic statistics were calculated for major inorganic and organic ions. Significant aerosol input events were identified and grouped considering the ions present, their provenance and the season. The chemical investigation of polar ice cores is an excellent tool in paleoclimatology, especially due to its wide environmental representation when compared to other existing paleoclimatic techniques.
An ice core is a reliable local record of past atmospheric conditions that may be representative for a region. Moreover, it can be especially useful for regions with limited instrumental records. While glaciochemical information for central West Antarctica remains scarce Steig et al.
Siple Dome Core Date from Measurement of the d18O of Paleoatmospheric Oxygen, Version 1
Figure 1 Scientists measure ice cores from deep drilling sites on the ice sheet near Casey station Photo by M. Antarctica is the coldest, windiest, highest and driest continent on Earth. That’s right – the driest! Antarctica is a desert. The annual precipitation of snow, averaged across the continent, is about 30 centimetres, which is equivalent to about 10 centimetres of water.
In some locations as little as 2 centimetres water equivalent is recorded.
Any groups that have been impacted by the tour shutdown will be prioritized when we resume tour operations. Thank you for your patience and understanding. Glaciers form as layers of snow accumulate on top of each other. Each layer of snow is different in chemistry and texture, summer snow differing from winter snow. Over time, the buried snow compresses under the weight of the snow above it, forming ice.
Particulates and dissolved chemicals that were captured by the falling snow become a part of the ice, as do bubbles of trapped air. Layers of ice accumulate over seasons and years, creating a record of the climate conditions at the time of formation, including snow accumulation, local temperature, the chemical composition of the atmosphere including greenhouse gas concentrations, volcanic activity, and solar activity.
Ice cores are cylinders of ice drilled from ice sheets and glaciers. They are essentially frozen time capsules that allow scientists to reconstruct climate far into the past. Layers in ice cores correspond to years and seasons, with the youngest ice at the top and the oldest ice at the bottom of the core. By drilling down into the ice sheet or glacier and recovering ice from ancient times, scientists are able to determine the past composition and behavior of the atmosphere, what the climate was like when the snow fell, and how the size of ice sheets and glaciers have changed in the past in response to different climate conditions.
Ice cores have provided climate and ice dynamics information over many hundred thousand years in very high, sometimes seasonal, resolution. This information allows scientists to determine how and why climate changed in the past. By understanding how and why climate changed in the past, scientists are able to improve predictions of how climate will change in the future.
Ice Cores and the Age of the Earth
Scientist Ed Brook holds an ice core dating back 2 million years. Oregon State University. Analyzing the oldest ice core ever retrieved in Antarctica, U. The core, drilled in an area miles from the U.
Dating blue ice is a “key difficulty” in ice core analysis, given its jumbled stratigraphy, said John Moore, a climate scientist at the University of.
When archaeologists want to learn about the history of an ancient civilization, they dig deeply into the soil, searching for tools and artifacts to complete the story. The samples they collect from the ice, called ice cores, hold a record of what our planet was like hundreds of thousands of years ago. But where do ice cores come from, and what do they tell us about climate change? In some areas, these layers result in ice sheets that are several miles several kilometers thick.
Researchers drill ice cores from deep sometimes more than a mile, or more than 1. They collect ice cores in many locations around Earth to study regional climate variability and compare and differentiate that variability from global climate signals. Each layer of ice tells a story about what Earth was like when that layer of snow fell.
For example, LeGrande says, as snow deposits onto a growing glacier, the temperature of the air imprints onto the water molecules. The icy layers also hold particles—aerosols such as dust, ash, pollen, trace elements and sea salts—that were in the atmosphere at that time. These particles remain in the ice thousands of years later, providing physical evidence of past global events, such as major volcanic eruptions. Additionally, as the ice compacts over time, tiny bubbles of the atmosphere—including greenhouse gases like carbon dioxide and methane—press inside the ice.
A climate model is like a laboratory inside a computer, LeGrande said. Scientists build all of the existing knowledge about how the atmosphere, ocean, land and ice work into this special laboratory. However, predicting the climate of the future is a bit more complicated these days, she said.