Deposits of sediment left by these glaciers are present over large areas of North America and Eurasia. Proxies for global temperature show gradual cooling as the ice sheets form, and then very rapid warming as the ice sheets melt back.
The brief periods of warm temperatures between glaciations are called interglacials. Past interglacials have lasted only about twenty thousand years. Humankind developed civilization only within the very last interglacial-and you are still in it! Skip to main content. K-5 GeoSource. PDF version. An ice core is a long cylinder of ice that is removed from a glacier or ice sheet using specialized equipment. Ice cores have been collected from every continent, but most of them come from Greenland and Antarctica.
To extract an ice core, researchers set up drilling equipment on the surface of a glacier or ice sheet, and drill down hundreds and even thousands of meters with a special drill that leaves a cylinder of ice undisturbed as it goes through. The longest ice cores collected were over 3 km 2 miles long! Drilling into the ice allows scientists a glimpse into the climate of the past.
Yu, and J. Lowe, Quaternary Science Reviews , 27 1 : Wolff, and M. Curran, A review of sea ice proxy information from polar ice cores. Quaternary Science Reviews , 79 0 : Fischer, H. Fundel, U. Ruth, B. Twarloh, A. Wegner, R. Udisti, S. Becagli, E. Castellano, A. Morganti, and M. Severi, Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica.
Earth and Planetary Science Letters , 1 : What kind of crushing and grinding does ice undergo over thousands of years?
When bubbles are analyzed and you get your values, what exactly do those values represent? What about temperature, for instance? Does the data gathered represent the average for the entire year? What is the margin for error? What is the sampling rate for the graphs shown above? How many years of separation between the samples? Could years of data have been lost to melting or sublimation? And it does. I saw a report on , years of Vostok ice cores. They had a graph that also showed CO2.
Of course the deniers will then tell you that every one of the hundreds of science academies and organizations as well as so many tens of thousands of scientists and researchers are ALL in a massive conspiracy.
That means there is a bit of uncertainty around the exact age of the samples of atmospheric gas contained in the bubbles, as the upper few tens of meters of snow and firn is essentially open to the atmosphere. It also means that the ice surrounding the bubbles is older than the air inside.
This is a primary area of research in ice core science. This really does allow close matching between modern measurements and old air trapped in the firn and ice below.
An Australian group did this quite nicely at a place called Law Dome, on the coast of East Antarctica. You are right to be careful assuming that the carbon dioxide, methane, or other gases inside the bubbles might not be perfectly preserved. It turns out that they are quite well preserved, especially in Antarctica. These bubbles in ice are the ONLY way that actual samples of the ancient atmosphere are preserved. For instance, since the Greenland Ice Sheet is in the Northern Hemisphere with most of the exposed land on Earth, the ice there contains high amounts of dust.
Minerals in that dust do interact with gases preserved in the icy air bubbles, so much so that carbon dioxide records from Greenland ice cores are very difficult to develop. Antarctica preserves much cleaner, clearer gas records because it is very isolated from any of the few Southern Hemisphere land masses and thus isolated from dust sources.
Ice core sites are picked very carefully to avoid too much complex ice flow at great depths, but there is always some.
It is quite common that the bottom few hundred meters of deep ice cores m long cores are not included in climate records.
Another relevant process occurs at depths greater than about m. Other things you mention are worth considering, and are considered by us icy scientists often. And, yes, especially in East Antarctica where snowfall is very low less than 5 cm per year , wind scouring and sublimation can remove snow from the surface, resulting in probably short discontinuities in the data.
In, fact, data from most of these ice cores are archived in a few places. I remember when the Artic not Antarctic was being researched thru ice core samples. I think you human penguin guess at alot of data that you research. Without precipitation how would or could you even guess at what a year would be. Oh well theres a sucker born every minute i suspect.
Many thanks for your comment. Precipitation was occurring throughout the last ice age and certainly throughout the Holocene last 11, years. You cannot build an ice sheet without precipitation! It was drier in places, such as around the margins of the ice sheets, but there was still precipitation. Although archives of precipitation are generally more complex than temperature, thicknesses of annual layers in ice cores provide some good information on precipitation. In places like the UK, lake and peat bog cores include microfossils which also provide information on past precipitation.
Please clarify. In Antarctica, there is a growing body of evidence that suggests the West Antarctic Ice Sheet has collapsed in the past. Please forgive me if this was answered in the article. Earlier I read another article on ice cores going back , years. Given your comments about evidence of ice fields collapsing, hope do you rule out total melt-off of an ice sheet? Would that not extend the time frame of the , bands, and add millennia to the core?
Secondly, the question was raised about the necessity of precipitation to create the bands. Is it not a stretch to think that an , year core might have a significant number of years without precipitation? Ice cores are taken generally from areas with the slowest-moving ice, such as at the ice divide.
Even here, it is difficult to find very old ice. However, there are now programmes underway to core ice that may be many millions of years old in the Dry Valleys e. Which they do, and which can be correlated to other geological records such as sediments. I want to add it to my data ime drilling him with.
Ive seen it in the past, its one of the easiest to understand for most people. Ive studied a lot of data, but most find it very hard going. Most graphs need a decent understanding of the science that not many people have. You have to keep things as simple as possible for most people. Ime arguing with my brother about manmade climate change. Hes no dummy[nor am i]. Its coming!! Any idea where i can find that graph??
The population of Europe years ago was estimated to be about million. They were burning massive amounts of fossil fuels back then. Our current uses of fossil fuels are about 10x more efficient than theirs. Why is it only the past 50 years of fossil fuels that are a problem? Another point to consider is that every doubling of CO2 in the atmosphere is supposed to add the same amount of heat to our atmosphere. Then we need to burn 4 times as much for an additional 1 degree.
Professor Carl Otto Weiss, advisor to the German Climate Board, has conducted a Fourier Analysis on all the European temperature data from to the present time and also the Vostok ice core proxy temperatures going back hundreds of thousands of years.
He found that 6 recurring cycles, but predominately 2 cycles one 28 year and one year cycle account for all the anual temperature fluctuations. Since CO2 has basically trended continuously downward it does not figure in the data as a driver of temperature. The level of CO2 in the atmosphere has increased from 0. This is a minuscule amount of a weak greenhouse gas and is perhaps a fifth or tenth of what it was when plants evolved.
Is it not reasonable to suggest that our CO2 production is actually saving the planet? Seems a bit of a stretch that million people burning fires at night emitted more carbon than 7. Generally, gloves and googles are worn when opening the cores, to avoid contaminating the insides, but this PPE should also provide protection for the scientist.
A Harvard University study included several other institutions recently concluded that air pollution had caused million deaths. Seems like there is more reason than just climate change to not pour accumulating greenhouse gases into the atmosphere. Other locations on the planet remarked similarly. Hi I am doing environment studies for building at Unitec Mt Albert Auckland NZ, just would like to know if the ice core samples that have been recorded are from the same altitude around the planet.
The atmospheres would change the density of the samples and would like to know what the out come of the samples would return at different altitudes. Ice cores are generally taken where the ice is thickest, meaning the top is the highest around and the bottom is the lowest they can find.
Here the ice flow is slowest and the ice is ideally the oldest. That means it will be about two miles high in Antarctica, and over a mile high in Greenland. What the researches are interested in is the content of the bubbles—not their size or quantity. They are assumed to retain the relative gas ratios of the atmosphere that they trapped, as well as the isotope ratios. The current time — i. Current period is at left. The isotopic record of past climate recorded by the bottom layer of the ice core is determined by the age of the ice.
The age of the bottom layer of the ice core is determined by the depth to which the ice-core is drilled, and the thickness that one annual layer represents. Notably missing is a mention of the temporal relationship between CO2 concentrations and the derived temperature.
Cross correlating the two from the Vostok data set reveals a quite variable delay between local minimums and maximums of CO2 and temperature, with CO2 lagging by up to years. The DomeC data is more precise and definitive about the delay, which is on the order of a couple of hundred years, although slightly asymmetric.
The delay can only be indicative of biology catching up with a more favorable climate as it takes time for CO2 to accumulate up to a large enough level to support a larger biomass.
Similarly, on the down slope, the extra CO2 temporarily sustains a more robust biomass as the planet cools. Also missing is any mention of the strong correlation between the Earths variable precession, orbit and axis and the temperatures extracted from ice cores, especially DomeC whose temporal positioning of ancient samples is far more accurate than Vostok.
CO2 is very soluble in water, but its solublility decreases inversely with temperature. Also, as the earth warms, most of that energy is absorbed by the oceans. Early in a warming cycle, atmospheric CO2 increases modestly, because much of it dissolves in the ocean.
As the ocean warms more slowly than the atmosphere due to its high specific heat it stops absorbing the CO2, and atmospheric CO2 increases more rapidly. If current conditions were due entirely to Milankovitch cycles, global climate should be cooling slowly for another few thousand years, just as it has for the past or so. Here are some informative plots.
They show a metric congruent with the probability that given a change in some variable for example, temperature that in N years K in these plots the same variable autocorrelation or a different variable cross correlate will be changing in the same direction positive values or in the opposite direction negative values.
A value of zero means that there is an equal probability that the variable will be changing in either direction. Results from both Vostok and DomeC shown. The peak in the green is at the delay where changes in CO2 are most correlated to changes in temperature. The green line consistently above the magenta line shows that changes in CO2 concentrations are always more correlated to past temperature than future temperatures.
Note that for the DomeC data, with better temporal positioning, future temperatures are nearly completely uncorrelated to past CO2 levels. This next plot adds CH4, showing that it is delayed by even more and is another unambiguous biological marker.
These autocorrelation tests of temperature data show the strong correlation with various periodic orbital attributes. Correlation to the precession of perihelion is shown here around 20K years although also present is the strong correlation to the period of axial tilt variability. This last one shows the temperature variability plotted along with the axial tilt and variable eccentricity. The smoothing applies is averaging around center and is used to 1 normalize the sample period between recent samples and ancient samples, 2 normalize the sample period between variables with different temporal resolution and 3 to act as a low pass filter to remove short term correlations to reveal longer period correlations.
I should have provided enough information to replicate these results, but if more is required, more is available. Why does Vostok temperature from the Deuterium and 18O proxies disagree so much? The plot you linked to shows delta-Deuterium dD in blue, which is the ratio of H2 to H3 called deuterium in H2O water.
This is a very important distinction. So the orange curve represents the isotopic composition of atmospheric oxygen measured in air bubbles trapped in the ice cores, versus the blue curve of the isotopic composition of water a. This proxy is representative of global ice volume, because the size of the ice sheets determines the d18O and dD composition of seawater, which in turn sets the isotopic baseline of the global hydrologic cycle.
There are very small, useful differences in how O and H fractionate in water which can tell us a bit about where the moisture that falls as snow on the ice sheets comes from.
Whew, looks like I posted too fast! Apologies for my confused response. Question for those knowledgeable about the actual data. I looked at a handful of datasets on the NOAA ice core website which are for periods of over k years.
They generally have a resolution in the hundreds of years with some exceptions of higher resolution. When looking at a trend over hundreds of thousands of years, plotting data points every couple hundred years makes plenty of sense.
But I am curious about whether there is higher resolution data for the specific historical periods during which there are rapid increases in CO2 levels, specifically k, k, and k years. I had the same question. Also, to what degree has each ice core data set been cross-referenced to each corresponding data set by location and researcher ie do we have a list by year of all of the available ice core data for that year to achieve a reasonable average?
If not, which is considered definitive? Lastly, how well does ice core data from different locations correlate? I am studying to be a science teacher and have been assigned to ask an expert about the project I am doing for class. The project is making a poster about ice core sampling. Is there anyone on this site who could refer me to an expert or is an expert? That would be quite helpful.
Specifically I would like to ask an expert 1 is there ice core data that shows the very recent exponential rise of CO2 to over ppm in the last few years, and 2 about the controversy of why the CO2 levels have historically appeared to follow the temperature. I have to cite the expert so I will need more info about your expertise see above.
For the first, some of the best ice core CO2 data that overlaps with modern measurements comes from a place called Law Dome in East Antarctica. David Etheridge from Australia is the expert on this, and there is a very detailed article about his work here:. As for the second question, natural fluctuations of temperature in the past have indeed led CO2.
Rather than citing a conversation in the comments here, even if I am an expert, I would encourage you to cite credible information you can find on these topics.
The links I have provided are for very reliable sources which can confidently be cited. Ice cores are collected from the oldest ice in the interior of ice sheets. The ice contains isotopes that vary with climate. Approximately how many years of time is covered by each CO2 reading from an ice core? Comparing CO2 measurements which may represent the average conc. You would miss any large spikes or dips that may occur due to natural forces.
In the upper parts of the ice core last few hundred years , annual laminations in the ice allow us to derive annual CO2 and isotopic variations.
As the ice is compressed deeper in the core, the annual layers are lost so several not s of years may be amalgamated. Specifically, in the EPICA core, how many years make up a data point at kyr, kyr and kyr ago. Although the language and material in this summary is still at a relatively high level, you can still gain a lot by just looking at the figures. Figure TS. Solar variability has at least a 15x smaller effect on RF than CO2!
Greenhouse gases are really the primary drivers of warming by a significant margin, importantly with relatively small uncertainty. There is an year cycle in sunspot numbers, which has been observed for several hundred years you can see these data in the top box of figure TS. Hope that helps in some small way.
There is a lot of technical information in the IPCC reports, and it can sometimes be a bit overwhelming, but it represents fairly well the entirety of our understanding of the Earth system as compiled by the expert authors and editors as well as thorough peer review.
The ice-cores give a recording of variations of temperatures at the site, but only at the site of the cores. CO2 would be the same around the globe. How do those temperature variations relate to those at other parts of the globe? For example, how does a Vostok ice-core record of a change of say 9C translate to other latitudes?
This is a very insightful question. You are correct that CO2 would be the same around the globe, as it is a well-mixed greenhouse gas GHG.
Methane records in particular are used to synchronize deep ice core records. The easiest way to explore this question of how Antarctic temperatures relate to the rest of the world is to look at what Greenland ice core temperature records look like.
Here is a great article on RealClimate. You can think of deltaO basically as temperature, but calculating exact degrees-celsius from this proxy is more involved than I am able to go into!
Briefly it involves measuring the physical temperature of the ice sheet using the borehole created by the ice core, which then helps better get an estimate of true temperature change through some interesting math and physics. You can see in the first figure in the RealClimate.
This has to do with the geography of these places, and energy heat transport through slow ocean circulation processes. Consider that Antarctica is a large continental ice sheet surrounded by the Southern Ocean and from this alone it makes sense that temperature changes will be more gradual in the Antarctic.
It takes a long time to get an entire ocean to warm or cool, or for ocean currents to transport water warmed in the North Atlantic all the way to Antarctica—around years, based on this new data from WAIS Divide.
That really only partly answered your question, but I wanted to be able to point you to freely available data so you can see the difference between Antarctic and Greenland ice core temperature proxy data. We also know that polar amplification causes more rapid warming at high-latitudes due to dominant pole-ward circulation and thus heat transport. So from the Volume change data above Ice Age Temperature Change figure , I would estimate that the earth will possibly start a new ice age in 1K to 5K years from now.
We have been in a melting phase for about the last 15K to 20K years. This is cyclic. So, given the talk about methane, CO2, H2O yes water is a green house gas too , sun activity, magnetic field of earth, volcanic activity under Greenland and the Antarctic, cows farting and adding to the methane part of green house gases yes a farming factor , plus industry and the growth of cities, plant growth when CO2 builds up in the atmosphere, plants actually thrive , the earth wobbling influence, etc….
I am focused on the cyclic nature of the ice volume. Hi there, although I myself am not at OSU, I can provide some perspective from a faculty member there and his co-authors. They argue that this longer-term framing of past and future climate change better informs decision-makers and the public that anthropogenic global warming is not just going to be a problem on the timescale of the 20th and 21st centuries. We usually only look at years of historical temperature measurements to establish that the climate is warming, for instance.
Sun activity, magnetic field, volcanic activity are lesser terms. The answer is that NO we are not going to have another ice age, and this article takes it further to really demonstrate what we are going to face instead.
Based on policy decisions about GHG emissions in the coming decades, we are committing ourselves to possibly having anywhere from 10 m to 20 m of sea level rise over the next 10, years. We were required to quote UncertInty of Measurement within a stated Confidence Interval for our tests. I would like to see this information for data on carbon dioxide and other gases in ice cores, particularly for oxygen isotopes at extremely low concentrations. I note that this information dates back many years.
Surely more modern measurements would have lower uncertainty. Also what about the uncertainty of temperature measurement in past centuries. There are a number of factors affecting the precision and accuracy of ice core measurements, which are very carefully documented and presented in the literature.
In many cases, with the progression of technology, the biggest limiting factors are no longer in the instruments used i.
That statement applies to the more routine measurements made, including CO2 concentration of ancient air trapped in bubbles in the ice, and oxygen isotopes in the ice itself which provides a temperature proxy. More advanced techniques, for instance breaking down the carbon isotopic composition of that CO2 to name just one, still have relatively large analytical uncertainties.
One is the development of ice core timescales, which are a combination of annual layer counts, absolute dating of volcanic horizons, ice-flow models, and gas chronology matching. There is also uncertainty in diffusion of chemical signals in the snowpack, which essentially averages these signals on depth scales controlled by site temperature and snow accumulation rate. Diffusion is studied and documented so scientists know the minimum resolution at which they can interpret actual climatic or environmental signals rather than meaningless noise.
There is also uncertainty of the spatial coherence of chemical signals in the snow i. Some of these sources of uncertainty are briefly discussed here by Eric Steig of the University of Washington full disclosure, Eric was my M. For an example of the state-of-the-art of ice core dating including uncertainty, check out two papers on the WAIS Divide ice core timescale.
This is the highest-resolution Antarctic ice core record spanning the last 68, years. This is a lot of information to digest, but I will emphasize that these sorts of detailed presentations of uncertainty associated with ice cores are published for all major ice core projects.
All scientific journals require such presentation of uncertainties associated with all presented data. Additionally, as an international community, the International Partnerships in Ice Core Sciences works to maintain high standards for presenting uncertainties affecting these valuable data.
Is the current rise in global temperatures statistically significantly greater than the natural variation in Greenland ice core temperature variation seen over the last 10, years? From graphs that I have seen, the current rise in global temperatures is well within normal variation where as the CO2 rise is obviously a dramatic new change.
If this dramatic rise in CO2 has not caused any statistically significant abnormal rise in temperature when compared to a 10, year record, it is unclear how much an effect this rise in CO2 is having. I guess the only answer is that the rise in temperature is lagging the rise in CO2. I would like to understand how the Greenland data show no abnormal significant rise in current temps.
Thanks for any insights! Fred, I suspect you may have seen mislabeled Greenland ice-core graphs based on Alley and the Cuffey and Clow papers. They are all over the internet, typically found on blogs that try to refute anthropogenic global warming. The last data point from these ice-core studies was , years ago, however the graphs are mislabeled labeled as current or present.
Your framing of this question is great, very clearly set out. You are right that we have dramatically increased CO2 concentration in the atmosphere, from about ppm before the early s to about ppm today which we know from, guess what…. Despite this noise, we are indeed seeing anthropogenic warming emerge from natural variability.
A very detailed demonstration of this, unsurprisingly, comes from the Intergovernmental Panel on Climate Change. You can see from the blue AOGCM results, that you cannot produce the 20th century warming trend without including anthropogenic forcing, which includes greenhouse gases and also aerosols and other pollutants—which actually have a cooling effect. We understand very well what is going on! There is still some rather unpredictable natural variability, but the budget-keeping adds up.
In the case of Greenland temperatures specifically, we are seeing the trend begin to emerge out of natural variability. Events like the summer melt event which spanned the entire Greenland Ice Sheet are rare but not unprecedented—a similar event occurred in the 19th century.
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