Scientists say they have developed a means of accurately dating Earth’s oldest and densest polar ice by analyzing the composition of krypton gas trapped within ancient air bubbles. Advertisement “The oldest ice found in drilled cores is around , years old, and with this new technique we think we can look in other regions and successfully date polar ice back as far as 1. Potential uses, Buizert and his colleagues say, are dating meteorites recovered in Antarctic ice, and studying the Earth’s climate and its cycle of ice ages. Krypton is a noble gas that is present in the atmosphere at extremely low levels, or about one part per million. In the upper atmosphere, exposure to cosmic rays can transform a stable krypton isotope into a slow-decaying radioactive isotope. Using krypton to gauge the age of ancient ice Scientists say that air bubbles in polar ice will contain some of these radioisotopes. By comparing the radioisotope’s state of decay to stable krypton isotopes, researchers can determine how long the gas has been trapped in the ice. That’s essentially how scientists use carbon techniques to date ice, but that method is only accurate back to about 50, years.
Detailed information on air temperature and CO2 levels is trapped in these specimens. Current polar records show an intimate connection between atmospheric carbon dioxide and temperature in the natural world. In essence, when one goes up, the other one follows. There is, however, still a degree of uncertainty about which came first—a spike in temperature or CO2. The data, covering the end of the last ice age, between 20, and 10, years ago, show that CO2 levels could have lagged behind rising global temperatures by as much as 1, years.
Unfortunately, annual layers become harder to see deeper in the ice core. Other ways of dating ice cores include geochemisty, layers of ash (tephra), electrical conductivity, and using numerical flow models to understand age-depth relationships.
See Article History 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. Core sites 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.
Ice-core evidence of abrupt climate changes
Ice Cores Introduction Ice cores are long cylinders of ice drilled from glaciers and ice sheets. They provide a detailed picture of how global and regional climates and levels of certain pollutants have changed over long periods of time, in some cases up to , years before the present. When snow falls, it captures samples of the atmosphere, along with its current concentrations of dust, ions, and important global climate forcing agents such as the greenhouse gases carbon dioxide CO2 and methane.
At high latitudes and altitudes where it is too cold for frequent melting, snow compresses into layer upon layer of ice, preserving these air bubbles for centuries to hundreds of millennia. The mix of isotopes atoms of the same element that have different atomic weights of oxygen and hydrogen in this ice indicates past temperatures and how they varied over long periods of time.
Diffusion: The limit to δ 18 O-based ice core dating Snow is slowly compressed into ice in the upper 80 meters of an ice sheet (read more about the process here). During this process, water vapour can move relative to the ice in the open pores between the snow grains, .
The basis for palaeoclimatic interpretations of variations in the stable isotope content of water molecules is that the vapour pressure of H 2 16O is higher than that of H 2 18O. Evaporation from a water body thus results in a vapour which is poorer in 18O than the initial water; conversely, the remaining water is enriched in 18O. During condensation, the lower vapour pressure of the H 2 18O ensures that it passes more readily into the liquid state than water vapour made up of the lighter oxygen isotope Dansgaard, During the poleward transportation of water vapour, such isotope fractionation continues this preferential removal of the heavier isotope, leaving the water vapour increasingly depleted in H 2 18O.
Because condensation is the result of cooling, the greater the fall in temperature, the lower the heavy isotope concentration will be. Isotope concentration in the condensate can thus be considered as a function of the temperature at which condensation occurs. Water from polar snow will thus be found to be most depleted in H 2 18O. This temperature dependency allows the oxygen isotope content of a ice core to provide a proxy climate record. For most palaeoclimate reconstructions, typical values for 18O obtained from ice cores range between and Morgan, Similar palaeoclimatic studies can be carried out using isotopes of hydrogen 1H and 2H Deuterium , but these are rarer in nature and the laboratory techniques involved are more complex.
Using krypton gas to date the age of ancient ice cores
Why is studying ice cores important? Air bubbles in ice trap whatever was in the air at the time the ice froze. By looking at ice core samples, we can tell what the atmosphere was like thousands of years ago. There are also layers of volcanic ash that record eruption times..
How are ice cores dated? I was wondering how ice cores are dated accurately. Other ways of dating ice cores include geochemisty, wiggle matching of ice core records to insolation time Typical CPL cut plan for a large multi-investigator ice coring project such as the WAIS Divide Ice Core project. —Credit: NICL-Science Management Office.
Drilling Ice Cores Introduction Ice cores are drilled in glaciers and on ice sheets on all of Earth’s continents. Most ice cores, however, come from Antarctica and Greenland, where the longest ice cores extend to 3 km—over 2 miles—or more in depth. Ice cores from the cold interior regions of polar ice sheets provide exceptionally well-preserved and detailed climate records.
This is because the lack of melt at these locations does not corrupt the record of trapped gases or blur the record of other impurities. The oldest continuous ice core records extend to , years in Greenland, and , years in Antarctica. Ice cores are typically drilled by means of either a mechanical or thermal drill. Both types of drills incise an annulus, or circle, around a central, vertical core. A mechanical drill is simply a rotating pipe, or drill barrel, with cutters at the head.
When the drill barrel is rotated, the cutters incise a circle around the ice to be cored until the barrel is filled with ice. The cuttings—also referred to as chips—are transported to a chip chamber in the drill. The drill barrel is rotated by either physical force, as in the case with simple hand augers, or with an electromechanical motor drive, as in the case with sophisticated electromechanical drills.
Thermal drills, in contrast, use a ring-shaped heating element to melt an annulus around the ice to be cored and the melt water is stored in a tank in the drill. At sites where the ice is well below freezing, such as the interiors of the polar ice sheets, mechanical drills must be used. In contrast, thermal drills are particularly effective at coring through warmer ice e.
Do Ice Cores Show Many Tens of Thousands of Years?
This lesson will explain what glacial moraine is, and describe the various types of glacial moraine, both those that remain after a glacier recedes and those that don’t. A short quiz will follow. What is Glacial Moraine? Let’s say you’re eating a hard cookie, but for some reason you like to eat your cookies with a fork. In the process of pulling apart the cookie and pushing it around your plate, it’s unavoidable that there will be certain collateral damage.
Radioactive isotope in ice core record reflects solar activity over years Air samples taken in previous studies near forest fires have contained cesium, says Wotawa, but this is the first time that scientists have detected long-range redistribution of the radioactive isotope.
How do ice cores work? Current period is at right. From bottom to top: Milankovitch cycles connected to 18O. From top to bottom: Ice sheets have one particularly special property.
The Most Popular Ice Cream Flavors, Power Ranked
I have reproduced the article here so that I can respond to it in context. First of all, thank you for the link to it. Before I begin, I want to mention that the dating and the article are done with the presupposition of both long ages and not only uniformitarianism but gradualism. Understanding that I do not accept these presuppositions and will be looking at the evidence presented from the standpoint of recent creation and catastrophic interruptions in history, I will approach the article from a “devil’s advocate” point of view as far as evolutionists are concerned.
The quoted article is in italics. Antarctica is the coldest, windiest, highest and driest continent on Earth.
From , the European Greenland Ice Core Drilling Project drilled in central Greenland at coordinates 72° 35′ N, 37° 38′ W. The ices in that core were years old at a depth of m, 40, years old at m, and , years old or more at m bedrock.
Accuracy International Ice core dating accuracy international, i. Ice cores can be dated using counting of annual layers in their uppermost layers. The Vostok Ice-Core To demonstrate the methods used in dating ice-cores I will use the Vostok ice-core as an example because I found plenty of literature on it and because it is an Antarctic ice-core which was what the original post was about. It is more difficult to connect the timescales in different hemispheres.
Counting of Annual Layers 1. Ice Core Dating Definition A section of the graph of delta value and hydrogen peroxide is shown in Figure 4, along with the year.