Q: How far back in time (millions of years) have ice cores been dated, and at that time what was living on Earth?
Michael Spinos, Clermont, Florida
Lonnie Thompson and Ellen Mosley-Thompson: Mr. Spinos,
The oldest ice to be drilled from a glacier or ice sheet is about 800,000 years old. This ice core is from a place called Dome Concordia (or Dome C for short) in East Antarctica. Over this 800,000 year history, Earth experienced eight cycles of glaciation and deglaciation. This means that large continental ice sheets expanded (grew) and contracted (shrank) eight times. We live in Ohio, and 20,000 years ago Columbus was covered by an ice sheet estimated to have been about a mile thick. As to what plants and animals were living on the planet 800,000 years ago, we have suggested some additional references / websites below. However, many of the same plants and animals present on Earth today were present then, but they lived in different locations. We know that some mammals (such as the mammoth, mastodon, and ground sloth) present 20,000 years ago are now extinct. Modern humans, like us, were not present 800,000 years ago, but our ancestors were present. We are not anthropologists or biologists, but paleoclimatologists, so for more specific information you might do more research. We have suggested some starting points below.
If you are interested in reading more about this oldest ice core we suggest:
1) A paper in the general science journal called Nature that was published in the June 10, 2004 issue called "Eight glacial cycles from an Antarctic ice core" by the EPICA community members.
2) This is the EPICA website (http://www.esf.org/index.php?id=855) and from here you can go to the Concordia website and select English.
As for the nature of animals that lived during the last glaciation (~20,000 years ago) you might see this website for the Illinois State Museum.
Also, from the Encyclopedia Britannica you can read more about the Pleistocene Epoch that covers roughly the last two million years and during which ice sheets waxed and waned many times.
As for the nature of humans at this time, there are many resources discussing human evolution. For a quick overview you might check the evolution timeline below, but remember that Wikipedia is not a peer-reviewed resource.
Q: Lonnie and Ellen,
Thank you for your work. I believe the climate models and the implications of manmade CO2 emissions. But when I discuss it with many people, including intelligent and otherwise rational people, I get strong reactions of denial—without any seeming basis for it other than sound bytes, or shout bytes, provided by political entities. Do you have any advice for connecting people with the facts and the science of climate change? I can use some help. Thanks again for your work.
P.S.: I became convinced after hearing a Stanford geology professor tell his firsthand account of 20+ years of study of Antarctic ice cores.
Don Bain, Devon, Pennsylvania
Thompson & Mosley-Thompson: Hello Mr. Bain,
Thank you for sending your question. We also have the same experience even with well educated friends who remain unconvinced. Many very well educated people have not had the benefit of in-depth science training or an introduction to the basics of climate science.
It is important to remember that it is good to be initially skeptical about the information we receive. Science moves forward because scientists are naturally skeptical. Scientists use the scientific method such that questions are posed, data are collected, hypotheses are formed, these are further tested, and eventually if a hypothesis can't be disproven it may become a law (for example, Newton's Laws of Motion). The crux of the anthropogenic climate change issue is whether human activities such as the emission of greenhouse gases, the removal of vegetation such as forests, and the resulting positive (amplifying) feedback effects are responsible in part for the recent (last 60 years) and rapid warming of Earth's globally averaged temperature.
The observational record confirms that Earth's globally averaged temperature has increased roughly 0.75 °C since 1900. To put this in perspective, it is estimated that the globally averaged temperature was 6 °C cooler 20,000 years ago at the height of the last glaciation (see question 1 from Mr. Spinos above). So the difference between an ice age type world and today is roughly a 6 °C change in Earth's globally averaged temperature. This puts the recent warming into a perspective that is easy to grasp.
The most important thing that you can do is educate yourself regarding global climate change (GCC) so that you can educate others. Below we have provided a number of resources that are electronically available for this purpose. You should share these with your friends and encourage them to read even more widely. With that in mind, remember that any information can be placed on websites, so you must be a critical consumer of the available information. The gold standard for scientific information remains the peer-reviewed literature (the general science journals called Science and Nature are examples). The abstracts of papers published in most journals are free (websites are listed below), but the full papers may be available only to subscribers.
The National Academy of Sciences has an excellent piece written for the general public (see link below) and the Intergovernmental Panel of Climate Change (IPCC) provides the most authoritative statements on GCC based on our current knowledge. The IPCC's fourth assessment reports and Technical Summary are not written with the general public as the intended audience. Recognizing this, the IPCC produced a Summary for Policy Markers that is understandable to the general reader. A comment regarding the information available from websites is needed: Be sure that you know who or what organization is maintaining the content on any website you visit. There is an active group of global climate change contrarians, some funded by special interest groups for their activities, who post non-peer reviewed information designed to promote the idea that (1) the science of global climate change is poorly understood and (2) that the scientific community is strongly divided on this issue. Both are false statements. Websites that can generally be trusted would end in (.gov) and would be maintained by such agencies as NASA, NOAA, DOE, etc.
With those comments in mind, the following information is provided for those who wish to learn more about this issue. Share these with your friends, family and colleagues. This list is not exhaustive but provides a starting point for your self-directed inquiry to this topic.
These materials are organized from the most basic information to more complex issues. Included are a number of the international and national assessments that represent the general scientific consensus on specific topics. Remember that scientists are naturally skeptical and constantly test and retest their hypotheses as more observations are obtained and as knowledge advances. Climate science, like all the sciences, builds on current knowledge to generate deeper and broader understanding.
Science Magazine (www.sciencemag.org)
Nature Magazine (www.nature.org)
Note that Science had two special issues in 2003 entitled "State of the Planet" and "Tragedy of the Commons." The full papers are freely available at http://www.sciencemag.org/sciext/sotp/
Reports for the general public:
1) National Academy of Sciences: Understanding and Responding to Climate Change available at http://americasclimatechoices.org/basics.shtml
2) The Pew Center provides well balanced information available at http://www.pewclimate.org/
3) After gaining some background you might review the most authoritative documents on the issue of global climate change that are regularly produced by the Intergovernmental Panel on Climate Change (called the IPCC). The full reports are available at http://www.ipcc.ch but as mentioned above, we recommend the Summary for Policy Makers for the three different Working Groups (WG): WG1 (The Physical Science Basis), WG2 (Impacts, Adaptation and Vulnerability) and WG3 (Mitigation of Climate Change). These summaries are written for the nonscientist and are available at http://www.ipcc.ch.
4) The U.S. Global Change Research Program (USGCRP) has been combined with the President's Climate Change Science Initiative and is now called the Climate Change Science Program (CCSP) available at http://www.climatescience.gov/default.php.
5) The U.S. Climate Change Science Initiative also includes the Climate Change Technology Program available at http://www.climatetechnology.gov.
Major assessment reports that are more regional:
1) Scientific Assessment of the Effects of Global Climate change on the United States (NRC, 2008)
http://www.ostp.gov/galleries/NSTC Reports/Scientific Assessment of the Effects of Global Change on the United States.pdf and http://www.ostp.gov/galleries/NSTC Reports/Scientific Assessment FULL Report.pdf
2) The effects of climate change on agriculture, land resources, water resources, and biodiversity in the United States, Final Report, Synthesis and Assessment Product 4.3
3) Arctic Climate Impact Assessment (ACIA): Impacts of a Warming Arctic: Arctic Climate Impact Assessment. Overview and Policymaker's Summary: http://www.acia.uaf.edu/
4) The State of the Arctic Report (released Nov 2006):
A few more focused reports and websites:
1) The Yale School of Forestry and Environmental Studies' website has excellent content, including economic information, available at http://environment.yale.edu/topics/policy_economics_and_law/
2) The New Scientist has posted an article entitled: Climate change: A guide for the perplexed. May 16, 2007 at http://environment.newscientist.com/channel/earth/dn11462. This reviews 26 of the most commons myths and misconceptions about climate change.
3) The National Academy of Sciences has published an excellent overview of energy: What you need to know about energy, available free at http://www7.nationalacademies.org/energy/energy_booklet_pdf.pdf
4) One issue of concern in the climate community has been the differences between the surface-based temperature observations and those made from satellite-borne sensors. Those differences largely disappeared when the satellite records were properly corrected. The most recent report addressing these issues was issued in 2006 by the U.S. Climate Change Science Program (CCSP) and is available at http://templatelab.com/climatescience-sap1-final-report/
Finally, if you like to follow discussions on GCC via a blog you can periodically visit www.realclimate.org
After watching PBS, I almost feel like a proud mother (like your mother). I graduated in 1970 (first year for Braxton) then from MU 1974. Now a railroader, as I'm sure you can relate to being from Gassaway. I lived down the hill across from my grandfather's service station (Lertie Keener). I can remember getting on the bus with you and especially Regina (a sad day for Braxton and MU). Actually, I've kept up with [your career] thru newspapers, Internet, and TV. Keep up the outstanding work and hope it can resonate with all (primarily US). Hey, Gassaway is proud.
James V. Keener, Jr., Davis Grade School, Gassaway, West Virginia
Thompson: Hello Jim,
I remember you well. Thank you for your interest in this important topic and for your kind comments. We visit Gassaway several times a year and should renew our acquaintance. Gassaway was a great place to grow up in those days before the Internet and video games because we were always outside entertaining ourselves and interacting with nature. There was no "nature deprivation syndrome" for our generation in Gassaway, was there?
Q: How do you manage to keep the ice cores frozen all the way from a distant glacier to your laboratory in Ohio?
Thompson & Mosley-Thompson: Dear Anonymous,
Keeping the cores frozen all the way back to Ohio State University is a major challenge. Regardless of where we drill the cores, they are cut into roughly 100 cm (1 meter) long pieces that are placed in plastic tubing that is marked with cataloging information. This plastic tube of ice core is then placed into a cardboard tube that is slightly longer than a meter, and then six of these ice core tubes are placed in a thermally insulated "ice core box."
Returning these ice core boxes to Ohio State can be fairly easy to exceedingly challenging. The Antarctic and Greenland ice sheets are the easiest places from which to return ice cores. This is because the National Science Foundation's Office of Polar Program's has excellent logistical support systems in place. From Greenland the core boxes are flown in an unheated LC-130 aircraft stationed at the Air Force Base in Schenectady, New York. Once at the airbase, the boxes are placed in a freezer truck that is waiting to deliver them to Ohio State and other institutions whose scientists may have collected cores in Greenland that year. The core boxes from Antarctica are placed into freezer vans at McMurdo Station (Antarctica) that are then placed into the hold of one of the ships returning from Antarctica to Port Hueneme, California. Once back in Port Hueneme, the ice core boxes are placed into a freezer truck that drives across the country delivering ice core boxes to all the institutions whose scientists drilled cores there that year. As a safeguard, the truck carrying the ice cores is accompanied by a second empty freezer truck.
Returning cores from places like Mount Kilimanjaro, the Andes Mountains in South America, and the Himalayas of southern Asia is more challenging because we do not have the luxury of many available freezer facilities. In most cases we rent a freezer truck from a larger city (Lhasa or Lima) to park at the base camp. This is usually at the end of the road or as far as the truck can travel up the mountain. We then use porters and pack animals (yaks in China; horses and mules in Peru) to bring the cores down from the drill site to the freezer van. Here the cardboard tubes filled with the ice cores are placed six to a box, and the insulated box is placed in the freezer. Once all the cores have been collected, the freezer truck drives to the nearest large town with a freezer facility and an airport. In China that hub is usually Lhasa, and in Peru that hub is Lima. Here the cores will sit in the freezer facility until arrangements can be made to return the ice cores to Chicago by air. In Chicago, a freezer truck meets the shipment and the boxes are placed in the truck that brings them to the freezer facility at The Ohio State University.
I hope this is helpful. Here is the link to a brief article discussing our ice core team and showing two core boxes strapped to a yak. (This was in the Himalayas).
Q: Why do so many quote-or-unquote experts always only use temperature as the single measure of global warming when specific heat for air, water, and ground in total store heat and accumulate heat in various ways where air changes differently, but the heat can be actually containing more energy even if the air temperature is lower? Humidity being lower is sometimes talked about, but that ignores sea surface storage of heat that only fractionally heats air; the heat can be retained in all these places. How can your ice cores show specific heat stored in air, water, and soils so we stop missing this by focusing too much on air temperature and eliminating all components for global warming potentials?
Also, my hope is you can use your paleogeology to help uncover when man discovers fire and date that more precisely or even potentially locate through some kind of triangulation from your core samples several instances of man's history and paleogeologic phenomena, like volcanic evidence of super volcanic eruptions or Holocene impacts like Burckle Crater in the Indian Ocean.
D. R. Arthur, Des Moines, Iowa
Thompson & Mosley-Thompson: D.R. Arthur,
You actually have one complex question and several comments. Jumping to the comments regarding when humans first used fire, it is very unlikely that any definitive information about this will come from the ice cores. Our community is very interested in identifying specific chemical compounds that can serve as a proxy (or indicator) of biomass burning. The chemical compound or biomarker must be unique to biomass burning to provide a useful signature. Although work on these biomarkers is underway with some promising results, there are very few ice cores that extend back to the "approximate" time when humans first used fire. This is not our area of expertise but we believe the time of first use of fire lies somewhere between 800,000 and 400,000 years ago. Only one ice core today extends back 800,000 years, and because Antarctica is so remote from the centers of early human development and the amount of emissions would have been very low, there is little chance that any of the emissions would be carried to Antarctica. Thus, pinning down the first use of fire will come from other evidence but not ice cores.
The second comment deals with using ice cores to learn more about large volcanic events or impacts. The sulfate concentrations in polar ice cores have been used for decades to learn more about past volcanoes. There is a rich literature on this and an excellent summary paper was published a few years ago by Dr. Alan Robock (Rutgers). Below is the reference to the paper, which is available on his excellent website (also included). More recently, ice cores have been analyzed for concentrations of elements known be to associated with impacts. One of these is Iridium, which is considered a very clear marker for material of extraterrestrial origin. The problem has been development of analytical equipment and sample preparation techniques that can measure the very small abundances preserved in ice cores. Significant progress has been made in the last few years and in the near term there will be more applications of ice core chemistry to reconstructing impact histories.
Reference to Robock et al. paper:
Robock, Alan, 2000: Volcanic eruptions and climate. Rev. Geophys., 38, 191-219.
http://climate.envsci.rutgers.edu/pdf/ROG2000.pdf with the correction http://climate.envsci.rutgers.edu/pdf/ROGcorrection2007RG000232.pdf
Alan Robcock's website (paper above is linked here).
His section on volcanic activity and climate
Finally, to your question as to why the focus is primarily on temperature in the discussions of global climate change and why there is much less discussion of the specific heat of the different components of the Earth system. We have not thought about this and are sure others might be able to offer a more elaborate answer. First, we wonder how many members of the general public or our policymakers would know the definition of specific heat (SH), which is the amount of energy needed to raise the temperature of a specific amount of a substance by one degree C. The SH is different for each material—water, air, soil, metals, etc. Water has one of the highest specific heat values for common substances. Climate models do incorporate the SH of different materials and the heat storage in the different components of the Earth system is considered by most coupled ocean-atmosphere-land surface models (now called climate system models). Although no model is comprehensive and every substance is not included in the heat transfers and storage tracked by the model, the major components of the system—water, air, soil—are included. Models do consider the heat storage of the oceans for example. The high SH of water makes it critical to understand the role of water (liquid and vapor) in modulating Earth's temperature, including the details of the water vapor feedback processes.
We do not think that discussions of "specific heat" and "heat storage" would be meaningful or productive for most general discussions of global climate change. But you can be sure that those concerned with understanding and modeling the processes that govern and modulate air and ocean temperatures are cognizant of their importance.
Q: Could bacteria and viruses imprisoned in ice samples from long ago cause health problems to present-day life if they were re-introduced into the environment, either by accident or when the ice melts?
Louis Massey, Kingston, Ontario, Canada
Thompson & Mosley-Thompson: Mr. Massey,
This is fairly far outside our range of expertise. We were involved in some of the earliest research efforts to determine whether microorganisms preserved in ice cores could be resuscitated. Our role was to provide ice samples from around the world and to design a system that could extract uncontaminated liquid samples from the interior of an ice core. Dr. Zagorodnov of our group at OSU designed this sampling system and Brent Christner, then a Ph.D. student in the Microbiology Department, and Dr. John Reeve, then the Chair of Microbiology, conducted the resuscitation studies. These early studies were successful and led to these conclusions: (1) more microorganisms were found in the ice cores located in the lower latitudes where the glaciers were in closer proximity to land surface where dust (such as soil particles) could be lofted into the atmosphere in large quantities. The microorganisms tend to "hitch a ride" on the dust particles; (2) the older the ice core sample, the longer it takes for resuscitation to occur; here the thinking is that it takes longer for the organisms to repair any cell damage; (3) microorganisms were resuscitated from 40,000 year old ice; and most of the organisms were bacteria and most were already identified.
As to whether these might cause health problems if reintroduced, we would suspect that the chances of this are very, very low, but maybe not zero. This is not our area of expertise and we suggest that you contact experts in this area. We have included some links below to the websites of several colleagues working in this area.
Dr. Brent Christner
Dr. John Priscu
Q: Hi Lonnie,
I watched your story with admiration and a little sadness. You are only 10 years older than me, and your life has been so much grander than mine, and it's because of what was explained at the start of the story. The death of your sister and father made you focused at a very young age—focused and determined to do something with that energy. I never had or was able to see the need for that motivation and drive. I still don't. I mean, I can see it, but it is not intrinsic to me. I have something in me that is a fear of acting; it's almost like a shyness.
It makes me look back and think that focus and drive are two hugely important and still overlooked things we should impart to our youth.
My question is the age-old one, nature versus nurture. What I describe seems to be all learned, at first glance, but I wonder if genes, heredity, plays as much or even a much stronger part in a young person's ability to develop strong and determined motivations. Have you thought about this question at all? Have you come up with any considered opinions?
Darrell Marcy, Syracuse, New York
Thompson & Mosley-Thompson: Mr. Marcy,
This is clearly not our area of specialty and thus we can offer only our opinion. There are many factors that conspire to help an individual succeed in his or her chosen endeavors. Key ingredients include curiosity, preparation (education), opportunity, persistence, and good old hard work. We recently read an excellent book entitled "Outliers" by Malcolm Gladwell (it has been #1 on the non-fiction list for weeks). This book examines the different factors that explain why some people exceed far beyond expectation while others do not. It is very important to be passionate about your chosen endeavor—find a something that excites you and focus your time and effort there.
Q: Dear Drs. Lonnie and Ellen,
You both have been on many expeditions into high-latitude and high-altitude regions. It must be both exhilarating to visit such places and wrenching to see the ice archives you work so hard to collect vanishing before your eyes.
My question is: Is there anything we humans can do to protect these fast-disappearing archives before they're gone forever? Like putting giant tarps over portions (obviously you can't cover the whole thing) of glaciers that you haven't yet sampled? Or perhaps installing reflectors that would lower the temperature just enough to slow the melt? These are probably crazy ideas, but just wondering.
Thank you, and keep up the important work you do.
Thompson & Mosley-Thompson: Dear Anonymous,
These schemes such as covering glaciers with reflective materials will not work. There has been no successful proof of concept demonstration project with the potential of long-term viability. Anthropogenic climate change is very likely to be with us for quite a while. Also, the general scientific consensus (see IPCC discussion in our answer to Mr. Bain's question above) is that the Earth system will continue to warm at least another 0.5 °C even if all greenhouse gas (GHG) emissions stopped tomorrow. It is our educated opinion, based on years of observations and basic glaciological principles, that if the globally averaged temperature of the planet continues to increase, the smallest glaciers will go first, followed in due course by larger glaciers. Numerous mountain glaciers around the world are in decline (see several links below). Larger glaciers may persist longer, and the polar ice sheets will be with us for hundreds of years or longer. However, the Greenland ice sheet is now losing mass (ice) along many of its coastal areas. The ice is discharging into the ocean. In the Antarctic Peninsula (an area that is warming faster than the global average) and along the margin of West Antarctica there are areas where ice is now discharging more rapidly into the ocean (this means sea level rise).
So is it too late? No one knows for sure, but it appears that time is running out quickly for smaller glaciers in the high mountains. The additional warming already resident in the Earth system likely means there is nothing we can do but watch them disappear. For the largest glaciers and the polar ice sheets there may still be time to avoid their demise, but action needs to be taken sooner rather than later.
World Glacier Monitoring Service:
World glacier inventory:
Q: Do ice core studies reveal the time relationship of increase of CO2 and the increase of climate temperatures? I have geologist friends who cite studies that state that CO2 increase LAGS BEHIND global warming by 200-800 years.
R. M. Swerdfeger, Grand Junction, Colorado
Thompson & Mosley-Thompson: Mr. Swerdfeger,
The problem with using the example you mention above is the conflicting time scales (length of time) associated with glacial-interglacial changes and the current time scales associated with contemporary global climate change. Also, the above statement assumes that CO2 is the only driver of climate change and does not consider the many feedbacks in the system. Rather than summarize the work of others on this important topic, we point you to an excellent discussion of this point by Professor Severinghaus at Scripps Oceanographic Institution. He is one of a group of scientists working on the extraction of CO2 (and other gases) from ice cores, understanding how these records are produced and preserved, and examining the leads and lags in the system between CO2 (and other gases) and Earth's temperature response.
To read his excellent discussion, visit his comments on the real climate blog. This is a moderated blog site, so it is important to review the training and credentials of the scientists providing the comments. Note that the discussions provide links to peer-reviewed papers and definitions to help the reader.
Be sure to also see the 2007 update to this topic at http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/
Q: Is there any doubt scientifically among reputable climate scientists that climate change is happening now, is serious, and is human-induced?
Is there a list or source for the most reputable information on global warming?
Kyle Schmierer, Phoenix, Arizona
Thompson & Mosley-Thompson: Mr. Schmierer,
For the second question, please see the answer we provided to Mr. Bain above. Here you will see an abundance of sources providing the most reputable information available. Also, in this response we noted that it is good to be initially skeptical about the information we receive and that science moves forward because scientists are naturally skeptical and they constantly test and retest their hypotheses as more observations are obtained and as knowledge advances. Climate science, like all the sciences, builds on current knowledge to generate deeper and broader understanding. Listed in this response are a number of the international and national assessments that represent the general scientific consensus on specific topics. Two key summary statements from the IPCC are (1) the warming of the climate system is unequivocal and (2) that most of the observed increase in globally averaged temperatures since the mid-20th century is very likely* due to the observed increase in anthropogenic greenhouse gas concentrations. Here * means with 90 percent confidence.
It is likely no surprise that we consider ourselves reputable scientists. Further, our research and observations support the IPCC summary statement #1. It is our educated opinion that the climate modeling results that underpin the summary statement #2 encapsulate the most comprehensive scientific understanding of global climate change available. Are the models perfect? No, much more basic research and model improvements are needed, but these model results do strongly suggest that human activities are playing an important role in the warming of the last 60 years. So the quick answers to your first question are: It is our educated opinion that change is happening now, some of the consequences are likely to be serious, and it is highly likely that much of the recent warming (and other related climate changes) are human-induced.
Q: Being a husband-and-wife team working in the same field, what do you talk about around the dinner table? Is it all ice cores and climate change? Or are those subjects the LAST thing you want to talk about?!
Thompson & Mosley-Thompson: Dinner table conversation ranges from daily household topics (yard work, for example), family topics (our daughter and her activities; our dogs and their issues), and of course what happened at work that day and what remains to be done. We confess that work-related discussions do occur with every meal, but they are not first on the priority list of topics. It is important to maintain a balanced life and keep the highest priority items, such as family and friends, in perspective.