Why is deeper ice older

Park Passes. Technical Announcements. Employees in the News. Emergency Management. Survey Manual. Glacier ice is blue because the red long wavelengths part of white light is absorbed by ice and the blue short wavelengths light is transmitted and scattered. The longer the path light travels in ice, the more blue it appears. In the other 10 chapters, each of which concerns a specific glacierized region of Earth, the authors used remotely Fifty years of U. Geological Survey USGS research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States.

These long periods of record provide clues to the climate shifts that may be driving glacier change. Between and , optimum satellite images were distributed to a team of 70 scientists, representing 25 nations and 45 institutions, who agreed to author sections of the Professional Paper concerning either Every year a layer of snow accumulates on glaciers, like a page in a history book, and eventually turns to ice.

Like reading the pages of a history book, analyzing the layers in a glacial ice core for specific chemical and physical components is The warming climate has dramatically reduced the size of 39 glaciers in Montana since , some by as much as 85 percent, according to data released by the U.

Geological Survey and Portland State University. Frozen bodies of ice cover nearly 10 percent of the state of Alaska, but the influence of glaciers on the environment, tourism, fisheries, hydropower, and other important Alaska resources is rarely discussed. The persistence of an already rare aquatic insect, the western glacier stonefly, is being imperiled by the loss of glaciers and increased stream temperatures due to climate warming in mountain ecosystems, according to a new study released in Freshwater Science.

Photograph of the Juneau icefields of southeastern Alaska that contain more than glaciers which extend over 1, square miles 3, square km. The iceberg has just broken free from under the water and shot to the surface, spinning towards the ice face.

The ice cliff here is about 70 m Icebergs are calved as stress fractures in the glacier merge, eventually resulting in a piece of ice cracking off and falling into. Note the icebergs in the ship's wake in the lower right side of the photograph. Skip to main content. 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. To test the climate models under these very different environmental conditions, scientists test the models by simulating past climates. Ice core records are an essential part of creating and checking these simulations.

These differences create annual layers in the ice that can be used to count the age of the ice, just like rings inside a tree. However, the more the ice compacts and the less that snow accumulates, the harder it is to see these annual layers.

To analyze the age of the deepest layers, scientists use a variety of methods, including measurements of the chemical composition and electrical conductivity of the ice. It has been the work of many other climate scientists to demonstrate with high confidence that most of these greenhouse gases are emitted by human activity. I find this data presentation by Bloomberg of all places to be one of the best illustrations of just how big a role human greenhouse gas emissions have played in warming since the s.

It breaks down the individual climate drivers adding up to the observed upward global temperature trend. Unfortunately the article is framed as an argument against skeptics, which makes it somewhat adversarial, but this is the state of discourse in the United States. As far as action, you are correct that this requires significant action as quickly as possible.

You bring up thoughts of equity between developed and developing nations, which plays a large role in international UN negotiations towards action. This all has to be taken into account to reach agreements such as the Paris Climate Agreement. As an American scientist I have certainly been reflecting more on advocacy in recent months. My most simplest point: we must support international action towards reducing GHG emissions, and the Paris agreement begins to do this.

It is not enforceable enough, nor strong enough, but it is the framework built thus far and must continue. We do need to get out in our communities and get this message across. Typically how long do interglacial periods last? The last ice age ended about 11, years ago. Are we entering an ice age period or are we already in one? We are currently in an interglacial period, which we call the Holocene. Stable, warm climates are really helpful to grow a population and develop agriculture, languages, etc.!

If we had not emitted so much carbon, we would be on our way back to an ice age in a few thousand years. The added heat trapped by these and other greenhouse gases will now combine with the natural changes in solar forcing from orbital changes. Hello and thanks for an informative web site. I found answers to a lot of questions here, but not the one I was looking for and I hope you can help me satisfy my curiosity.

I see that the core samples contain melt and freeze layers, but how do we know that layers of ice has not melted completely and disappeared from record in warmer periods? If this was the case then the sample of historic greenhouse gas and temperatures would be censored, that is warm periods with a lot of carbon in the atmosphere would not show up in the core samples. One way we can tell whether or not there were out-of-the-ordinary melt events during past warm periods is to measure the oxygen content of the ice.

We do this for a number of reasons, one being that the oxygen content gives you some idea of the elevation of the ice sheet surface there is less oxygen the higher you go in the atmosphere; why it is so hard to climb Mt.

Everest without supplemental oxygen tanks! The other benefit is that melted and refrozen snow has fewer bubbles than normal glacier ice that began as snow and was compressed into ice with air bubbles. Where there are melt layers, one can expect lower oxygen content.

Actually in the surface of the Greenland Ice Sheet experienced nearly total melt, producing a rare melt layer even at the summit of the ice sheet. Another way we can double-check that we are not missing things in the past that may have melted away is to compare with other paleoclimate archives.

We can also look at speleothem—cave stalagmite records—to similarly check. Peter Neff. You need Oxy when climbing high mountains or flying high because of lower pressure. Our lungs need the pressure to absorb the Oxy. How precise are the dates gathered from ice-core. In some of the science involved in establishing dates in ice core, this would say that the planes have been there for 36, years. How recent can we read ice core data?

Well, according to the first graph, we can read ice cores for about 10, years into the FUTURE, when it will be the year We can read most ice core data right up to the present. We study both the air trapped in the ice past atmospheric composition and the ice itself water stable isotopes for temperature estimates and impurities in the ice dust, salts, black carbon.

For the ice itself, we can study right up to the present snow surface, and we usually do high resolution snow pit studies in the soft topmost few meters hard to drill a snow core! The primary limitations are for the gases trapped as bubbles in the ice, because—as Harold correctly guessed—this trapping process takes decades to centuries as snowfall slowly accumulates and compresses the air space between snowflakes enough to fully seal bubbles off from the atmosphere.

At a place like Vostok, Antarctica or Dome C, Antarctica where the oldest records come from , and , years, respectively , there is very little snowfall—hence so many layers squeezed into the m thick ice sheet—it takes a long time several centuries to fully trap bubbles of atmospheric air.

In order to get younger gas records, scientists have gone to higher snowfall areas, especially Law Dome, Antarctica, where gases are trapped much more recently. This allows the ice core gas record to be connected with modern atmospheric measurements more on that below. Often, another fundamental constraint is how quickly you can go from drilling your ice core to publishing! It sometimes takes years to get the cores, sample them, analyze the samples, interpret the results, write it up and get them published!

In the case of deep ice cores, it takes up to 5 years or more to drill through the entire ice sheet before the full results can be worked on and presented. Thank you for this forum. What is the total uncertainty of the temperature measurements generated from analysis of ice core data? I realize it probably varies, but what is a ballpark number: plus or minus X degrees C? Optional bonus question: And how does this uncertainty compare to the temperature measurements of early thermometers, or modern thermometers?

Questions: 1 How did you come to the conclusion that Milankovitch cycles are causing fluctuations in the CO2 and CH4 levels? Or is it still a suggestion? How do we know the age of air in the bubbles in the ice? I could see the air in the bubbles being hundreds of years older than the ice it is found in, or mixed with newer air to the point of not representing anything.

When low pressure is over a glacier, the air moves in the ice, up and out. When high-pressure is over the a glacier, air moves down and is pressed into the ice. Ice is not airtight until one or two hundred meter thick. So atmospheric air is clearly being gradually mixt in to the sample in question for at least some hundreds even thousands of years.

I think it is likely that the ice core of CO2 measurements is at best hundred years average. Which means that a 10 year average could be much higher than the current ppm and the annual average could easily be up to thousands. Hello, It is great that you take the time to answer questions from non-scientists. Thank you for that. I see comparisons between current climate data and climate data from various other time spans.

For instance the greatest rise in temperature occurring in the past years. I look at the , year data, and it looks like at the start of all past intergalcial periods CO2 levels shot up rather rapidly as well, and nearly as high. Granted, not to ppmv, but at least in one case to ppmv. What caused those spikes in CO2? It has been proven that there is a correlation between CO2 and Temperature. Sometimes with Temperature leading, and recently with CO2 leading.

But, I have not seen anything proving causation. Could there be another or even several other variables acting on both Temperature and CO2 levels causing them to rise and fall? This is maby allready answerd and sorry to revive an old thread but I have a question about icecores.

Lets say that during a 50 year period Would you be able to detect this or would it thru the eons bleed of into the surrounding layers of ice due to the massive pressure from above? I do not deny we are heating up the earth but could you detect if so was made before? If atmospheric CO2 rises after the temperature rises, then CO2 cannot possibly cause warming. Conversely, if CO2 is lower, biomass will suffer as CO2 is plant food.

If biomass falls due to coldness, then the rise in CO2 surely must correlate with the lower absorption of that gas by the reduced biomass.

The likely probability is that current rising CO2 is being driven by deforestation b man an a massive scale. The answer surely is reforestation on a massive scale. Your information saying only Isreal has more trees in the last years is not correct.

Wealthy, mostly western countries in particular with increasing fossil fuel use have decreased and reversed deforestation. Deforestation continues where coal or gas power is not used for cheap effective fuel. Between and , the area covered by forests and woodlands increased by 90, square kilometres — an area roughly the size of Portugal.

Ice age nett CO2 in the air reduces biomass, plants cannot live on ice. Plants absorb CO2 to make more plant. Currently we are at the tail end of the last ice age, so naturally the globe is warming.

You are spouting a narrative rather than the data. The CO2 increase is increasing biomass. Anyone who has understands carbon chemistry would know this is the expected outcome. Molecular biologist with over 20 years of research experience here.

The only way you can prove this method has any merit is by comparing the CO2 in the bubbles to actual air samples from k years ago which is impossible. A lot of chemical reactions can happen over k years, affecting the CO2 concentrations. Not buying it. Can you inform me how you correct for the compression of the snow into solid ice sheets? We know that very little of the precipitation particularly in the Antarctic is anything other than crystalline ice so this is very loosely packed.

This therefore would require enough of a build-up over time to collapse it down into solid ice. This would also require the proper weather conditions. I would think that you could determine large scale timing by matching dust particles with geological evens such as extreme volcanic or meteoric events but small scales may be important.

Once you get a few hundred meters deep, the ice becomes very glassy and more homogeneous to look at, in my experience, but under the right light conditions, experts can still see the layers.

The likely probability is that current rising CO2 is being driven by deforestation b man and a massive scale. So, since natural CO2 reduction cannot possibly reduce CO2 back to where it was when I was a kid natural CO2 reduction recently reduced it a massive ppmv over just 47,, years then unless you intend to be much more of a big eater and a fatty than me as kid almost impossible it is a non issue for a few thousand years at least so I consider it low priority.

Are your priorities to start by worrying about the possible problems starting in a few thousand years? None of this would be detected in the air you analyze. Many other potential chemical reactions could take place that change the CO2 concentration in the enclosed air. Furthermore, microorganisms such as algae or anaerobic bacteria enclosed in the ice could metabolize CO2, resulting in lower CO2 levels as well.

As a matter of fact, they still metabolize. Under lab conditions, cryopreserved cells at much lower temperatures already go bad after after 10 years, now compare this to k years. The cells would lyse and you would be unable to detect them.

Even if some were still some alive, their numbers would be much lower than initially and the impact of these microorganisms on CO2 levels in the bubbles would be underestimated.

Taken together, this would result in CO2 concentrations that are closer to the surface. Furthermore, your posted Vostok ice core figure is laughable. The last data point on your graph is still within normal range relative to the previous measurements on the left. Then the graph suddenly reaches new heights, going from ca.

I doubt ice core data less than 15 years old is comparable to ice core data k years old. These are two entirely different methods and, no matter what climate or ice core scientists claim, their results will not, never ever, align properly or can be directly compared since you derived them using two entirely different methods.

This is like a molecular biologist measuring a protein concentration using ELISA and then appends these results to protein concentration measured by the Bradford assay. The math seems very off to me. I understand climate change, we go through warming and cooling periods. Can you explain how you get the avg. Thank you Bethan Davies and all of the other researchers and scientists for this very very interesting article. I have so many questions, this article has opened up my mind to Climate change.

Thank you for posting this. Unfortunately you misinterpreted the data and may not of read all the information. The Ice core samples show that temperature increases, then CO2 increases about years later. CO2 does not lead temperature up, it lags it. So the conclusion you should come away with is CO2 does not cause global warming. Petit et all — analysed , years of Vostok, and found that as the world cools into an ice age, the delay before carbon falls is several thousand years.

Fischer et al — described a lag of plus or minus years as the world warms up from an ice age. He says he has visited a few ice core facilities and has seen this; and contends that the cores need to be stored extremely cold to have any accuracy.

While I understand what he is saying, and even acceding that perhaps some cores were stored incorrectly, I cannot believe at this point in climate change studies that this would be a significant factor. There must be hundreds of core studies by different trusted research facilities and institutions which properly store the samples so that we can have confidence in the data being shared such as your graph showing the rise of CO2.

Can you help me address his points or point me in the right direction? I was wondering what the expected Margin of error is when measuring previous years temperatures through ice cores? Davies, you have said that air bubbles trapped in ice cores have been communicating with air for years, even years. I do not know if the greenhouse gas model is correct enough for a long time of many hundreds of thousands of years to determine the temperature through the presence of some gases.

Could you please explain to me more clearly how does the information obtained from the ice core give a claim about the sea level? Here are some thoughts on lag time: It is very challenging to put CO2 records from ice cores on the same timescale as temperature records from those same ice cores, due to the time delay in trapping the atmosphere as the snow is compressed into ice. It is my understanding that the ice at any time will always be older than the gas bubbles it encloses, and the age difference is inherently uncertain.

I understand that Skeptics argue that since CO2 lags temperature, so CO2 rise is a response to temperature change and not the cause of it. It does seem odd that when CO2 levels are at the highest, temperatures start to fall and Earth eventually has advancing glaciers. I understand that at the beginning of an interglacial, the Milankovitch Cycles along with CO2, albedo, and other feedback loops nudge the Earth out of an Ice Age into an interglacial? Does the same thing happen in reverse at the end of an interglacial?

CO2 is not a primary driver of temperature, it is a bit player. As CO2 increases it has less warming effect. Once the concentration of CO2 in the atmosphere gets past about ppm has barely any effect on temperature. Other climate drivers overwhelm the effect of CO2s role, so CO2 can be at ppm and the planet will still cool due to changes in obliquity and other factors.

Hi Nick, Good question. We know that layers are annual as there is typically a change between summer and winter ice, which we can visibly see and count. In addition to this, we can use marker horizons such as tephra layers. Most of these have a known date of deposition, therefore we can calibrate our counting. I hope this helps, Laura. Hi Leah, Thanks for that question, it is really interesting. The ice flow is constant so it acts to close up the hole quickly.

I cannot read very good, and have problems understanding every thing said, Can someone please help me to understand the following. Is there any layers of thick ice with a cyclical periods and if so how thick is the thickest ice and how often do they occur? Could you please email me an answer as this is the only way I can learn and receive understanding with the hep of others, Thank you.

Do I take it that the vertical time resolution is one year? Can one distinguish layers in the Vostok core, which spans some years? Hi Bethan Thanks for the site information. This is important work. Although the cores show helpful relative temperature and CO2 measurements. Would you agree that the ice core samples provide a lack of fidelity and smoothing of gas concentration measurements compared to plant stomata proxies? By the gradual melting of the glacial ice, due to global warming, some countries are falling into loss, while for others it is very beneficial, like Russia.

Most of the seas around Russia are frozen, and it is almost impossible for Russia to keep on its trade all through the year. But now, there is hope for Russia, of opening these seas for international trade. If we review all the glacial ages, the temperature did not remain the same all through the glacial age. At a stage of a peak, the temperature had fallen to an alarming point, but as the large part of the glacial age passed, the temperature became optimum.

I think the recent era is the time of optimum temperature, which can be beneficial for all countries, even for the northernmost and southernmost. Save my name, email, and website in this browser for the next time I comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed. Antarctic ice core drill sites with depth and record duration. This photograph shows an ice core sample being taken from a drill. This picture shows a traversing field camp from December The team were travelling across the West Antarctic Ice Sheet to study snow accumulation.

They spent two nights at each site, first collecting radar data and secondly collecting a 15 m shallow ice core. References 1. Layers in the ice are analyzed for clues to past climates.

The new project aims to drill 1. Deeper ice layers at this site reach back to Eemian times — the most recent period that, like now, was between ice ages. Understanding that event will help guide our understanding of how quickly sea level may rise in the future due to ongoing anthropogenic climate change.

Hercules Dome is a gradual rise on a flat part of the ice sheet, out of view of the nearby Transantarctic Mountains. The UW team is believed to be only the second research group to visit this remote site. The Hercules Dome site, remote even by Antarctic standards, lies near a mountain range that divides East and West Antarctica. UW researchers visited the site in early to survey potential locations for drilling.