funding for this program is provided by... narrator: the human species is engaging in a vast global experiment in climate change.

each day, more greenhouse gases are being added to the atmosphere with unknown consequences. clues for what the future may hold are frozen deep within ice on the world's highest mountains. lonnie thompson and his team have been risking their lives for over three decades drilling into mountain glaciers -- ice that has remained frozen for thousands of years. the ice cores they retrieve contain a perfectly preserved record of the earth's past climate. looking toward the future, chris field has created a time machine in a northern california grassland. the jasper ridge global change experiment is subjecting an entire ecosystem to the predicted climate conditions possible 50 to 75 years in the future.

both research programs -- one looking into the past and the other toward the future -- will ultimately provide us with better ways to predict and cope with earth's changing climate. [ wind whipping ] man: ie climbed a t of mountains and i've been told that i hold the world's record for the amount of time a human being has spent above 18,000 feet, which is 3 1/2 years of my life. but i've always had a purpose for going up there. and unlike mountaineers, i am always looking for the simplest, safest way we can get our crew up there and all of our equipment 'cause we have to move 6 tons of equipment to these mountaintops.

and unlike a mountaineer we set up camp and we live there for six weeks or two months, and we bring four tons of frozen ice back down. and the reason we drill at such high elevations is that we're trying to get to the coldest place in those ice fields. and if you go up to where the temperature is below freezing, no melting occurs, and you have the best archive of the parameters that we want to measure. narrator: lonnie thompson is a glaciologist who researches the earth's climate history by reading information trapped in ice. he drills ice cores hundreds of feet deep all the way to bedrock at elevations above 18,000 feet -- places where the air is very thin and extremely cold. even in the tropics, the temperature at this altitude remains below freezing year-round

so the snow that fell centuries ago has never melted and is buried under newer layers. when the ice is drilled out, it can be read back in time, much like the rings of a tree. here. here. here. thompson: the beauty of the ice is it records anything that's in the atmosphere at the time that that snow falls. if you're at the top of the himalayas you can see the development of industry in india. you can see when lead was put into gasoline. you can see when legislation was passed to remove it. anything that's in the air gets recorded. and perhaps, with the ice cores probably the thing that really makes them unique is that they record the history of the earth's atmosphere. and you can see how the earth's atmosphere has changed through time. and our limitations is just interpreting how that recorder is working.

when i came to ohio state university i was prettyonvinced i was going to become a coal geologist. because, having grown up in west virginia, i could see -- one of the reasons of going to college was to get a job. and i could see the application there. in my first quarter here i got a little note in my mailbox that said, "how would you like to work for a research program "in the institute of polar studies looking at ice cores?" and so i took this position. it took me about a year, year and a half, to really start to realize what was archived in those ice cores or the potential. and at that time all the work was being done in the polar regions. narrator: during the 1950s and '60s, ambitious drilling programs in the remote ice caps of antarctica and greenland provided an impressive record of past climate, such as ice ages and warming events going back hundreds of thousands of years. but these records only provided part of the climate's history.

as a young man thompson's interests lay outside the arctic. he set a goal -- to drill ice where no one had ever drilled before. in the polar regions at the time, there was a lot of competition and no one was looking anywhere else. and so i'm thinking, "well here's the rest of the world. why not?" and then, of course, if you start thinking about it you realize that we got 6.5 billion people on the planet. 70% of them live in the tropics. and then you also realize a lot of the big weather phenomena that impact people -- el niño, monsoons -- those are tropical phenomena. and if you really wanted to look at the history of those, you need records from that part of the world. and i will never forget a rebuff when we proposed to drill the quelccaya ice cap. and it basically said, "the ice cap is too high for human beings and the technology does not exist to drill it."

and toward the end of the season, i got a telex from the program manager. he said that he had funded all of his real science projects and he had $7,000 left -- what could we do on that tropical glacier for $7,000? and i remember telexing back and saying "i think we can get there." the idea was to bring a drill from antarctica and fly this thing up to the summit drill the core put the cores in a helicopter, fly it out. this helicopter -- we'd be flying along at 19,000 feet and it would just fall like a rock. i mean, it's clear air. and the pilot's eyes were big. i'm sure ours were, too. after two attempts, they said, "there's no way. we can't even get close to the ice cap." you just couldn't do it. so we failed in our mission to drill the ice field. and that's when we came up with the idea of solar power. the beauty of that is that they're panels. and you can put six panels to a horse and you can transport your power

supply to the edge of the ice, carry it up on the summit, assemble the array and power your drill. turned out that that solar power was just beautiful. the fact is, we actually drilled not one but two cores to bedrock using that solar-powered drill. and we couldn't have chosen a better ice field on earth to do this because the record was so straightforward. quelccaya was annually layered. you could see it. and you could see it in the dust measurements. it was -- couldn't have made a better choice. narrator: the ice cores lonnie's team recovered on the quelccaya ice cap became a major step forward in climate history research because their annual layers could be dated so accurately. the tropics have alternating wet and dry seasons every year and these alternating seasons are clearly marked in the ice, containing vital information about the weather in the region, such as monsoons, droughts and el niño.

each year, the wet season brings a thick snow layer followed by a darker layer created by dry-season dust carried by winds up the mountain. these alternating wet and dry layers can then be linked to historic atmospheric events such as volcanic eruptions giving a precise annual record. thompson: and so that gives you your calendar. you can see it on the margin of the ice cap and you can see it in the ice cores when you drill, and you can see it in the analysis when it's done in the lab. and if you want to talk about rates of change, you need that annual calendar. and we now know, probably 25 years later, that that ice cap contains the highest resolution the longest annual record, that we will ever find in the tropics. narrator: the peruvian expeditions were the beginning of an ambitious worldwide drilling program. over the next 30 years

lonnie and his team continued to make technical improvements to better retrieve high-resolution ice cores from extreme locations. to create a global archive of past climate, lonnie has made more than 50 expeditions to africa, antarctica, bolivia china, greenland, peru, russia and the united states. at the end of every expedition the ice is rushed back to the cold room at ohio state university where it is preserved in a frozen library, waiting to be deciphered. th ompson: and we now have 7,000 meters of core we store at minus 30. and it turns out now that it's the only tropical archive of ice cores on earth. narrator: these cores are crucial links in the history of climate, connecting the polar regions to the tropics. by analyzing this archive and comparing it to other climate records

a global understanding of past climate is emerging. woman: what we want to do is get it back to the lab and start working on it as quickly as possible because everybody's really curious to see what kind of information it has. as a matter of fact, as we're drilling this we're often talking about what information this record might hold and how it might fit in with all the other records. it's another piece of a global puzzle and we feel that every one of these pieces is critical. narrator: in the lab, lonnie's team analyzes the ice cores. oxygen isotope ratios provide a proxy for the temperature when the ice was formed. these records are consistent with other studies that reveal going back 1,000 years a long-term warming trend, beginning about 150 years ago -- the dawn of the industge.

carbon dioxide measurements taken directly from bubbles trapped in the ice reveal ever-increasing concentrations of co2 over this same time period. adding to this wealth of information lonnie's team can detect droughts by measuring chemical traces in the ice blown in from dry lake beds. dr. davis: well, that's what i was just wondering about. one of the easiest historic records to track in an ice core are drought events. so anywhere you see sulfates indicate that the environment got very dry. here it is. right here was a drought. in calcium, there was an increase here in the '60s. and then you go down. here's another increase in the '30s. it was contemporaneous with our dust bowl period. actually you know what that is?

that's these. thompson: we're now finding that the real story of climate change is not in the science or nature paper that comes from the single site but it's in the connection putting these records together that you see things that you could have never found in one or two sites. narrator: connecting lonnie's tropical ice-core data with cores taken from the polar regions a record of the earth's temperature and carbon dioxide levels can be established going back 650,000 years into the past. over this time period, each rise in carbon dioxide levels is accompanied by a rise in temperature. in the most recent period, carbon dioxide levels have been rising to an all-time high. thompson: having that record now that goes back 650,000 years and knowing that co2 in the natural world has varied between 180, 190 parts per million by volume

during the cold periods when we have lots of ice on the earth to 280, 290 parts per million by volume when these glaciers retreat and during the warm periods, and we're now at 380 parts per million by volume -- there is no analogue in 650,000 years. and the co2 is rising at 2 parts per million by volume each year -- and not be concerned about that. narrator: ice-core data is persuasive on its own but lonnie has witnessed the clearest evidence of a warming planet with his own eyes. the tropical glaciers are melting. this evidence is critical because the tropics, unlike the rest of the planet, naturally experience very little temperature variation. glaciers -- they don't have a political agenda. they just kind of sum up what's going on out there, and they respond to it. and they are giving us a very strong signal

that the planet is warming. and the glaciers are disappearing. like looking at an area like this. you may have known where you were, but... we first went to kilimanjaro in 1999. and in 2000, we had aerial photographs -- flown -- so that we could make a map of the ice on the mountain in 2000. and it's when we started comparing the results of that map with all the other maps that had been made from the mountain, going back to 1912 that you could really see the loss of ice that has occurred there. and some of the skeptics will look at a mountain like kilimanjaro, and they say "well, how do you know that it's not land-use changes, "changes in moisture supply -- droughts and the like?" and the answer to that is that it's not just kilimanjaro. it's mount kenya. it's the ruwenzoris. it's all the glaciers in the andes of south america and throughout the himalayas that are giving the same message. so the confidence comes from this

large scale evidence that all points in the same direction. to me -- and particularly the tropical glaciers are kind of our canaries in a coal mine. so the fact that every tropical glacier is retreating, i think is our warning that the system is changing. it's in looking at this huge system and having the opportunity to work in 15 different countries and observe the glaciers -- and many times on an annual basis -- to see how rapidly that change is taking place, that i think you have to be concerned about what you see. narrator: while thompson's work is documenting the global climate change that is already well underway, one of the great unknowns is what will be the effects of these changes on ecosystems. outdoor carbon dioxide enrichment experiments

around the world are subjecting ecosystems to the kind of vironmtal coitions that scientis predict 50 to 75 years in the future. a stone's throw from stanford university's main campus, chris field's jasper ridge global change experiment is one of the longest-running and most comprehensive of these stues. global change imposes a wide range of stresses on the future. that actually looks just about right. everything we know at this point indicates that those stresses are likely to be of major importance. they are likely to fundamentally alter the range of opportunities that our children and their children encounter. we staedhe jasper ridge global change periment to project these grasslands into the future. we would hope that as you walk into the plots you basically are seeing visions of california for 2075.

narrator: in the future, one of the most prominent of global change conditions will be increased greenhouse gas levels. over the last 50 years carbon dioxide concentrations have increased every year. if this trend continues, carbon dioxide levels may reach twice what they are today by the year 2100. field: we know that plants grow by removing carbon dioxide from the atmosphere. they use the energy from sunlight to convert carbon dioxide into carbohydrates -- into plant. and ecosystems on land are taking up a relatively large amount of the carbon that's emitted by human actions, essentially providing a subsidy. d what we'd like to know is, e into thfuture will that carbon uptake -- that subsidy -- increase? will it decrse? will it go away and turn froa subsidy into an trburden on the atmosphere? but we don't have very good models that address the full sets of things that occur in real ecosystems.

and the jasper ridge experiment allows us the opportunity to get at that in a very precise way that lets us use it as a model system for understanding the controls on carbon balance in other ecosystems. narrator: the primary goal of this elaborate outdoor laboratory is to see how these future conditions will affect the ability of ecosystems to store carbon dioxide. as these plants grow they pull carbon dioxide out of the atmosphere and transform it into plant structure, or biomass. the more these plants grow, the more carbon dioxide they store. earlier experiments, done in controlled environments, show that increased co2 levels led to more abundant plant growth. but the only factor these experiments accounted for was increased carbon dioxide. would plant productivity increase in real ecosystems when other climate-change factors -- water, heat, and nitrogen -- are also taken into account?

field: by the time we started this experiment in the fall of 1997 there was a lot of controversy about the magnitude of growth responses to elevated atmospheric co2. most plants increase the instantaneous rate of co2 uptake -- the instantaneous rate of growth -- when they're exposed to elevated atmospheric co2. but there were a range of different results about plant growth. individual plants in pots or individual plants separated, in the ground tended to grow much faster under elevated atmospheric co2 and the data from ecosystems were quite mixed. we realized over a period of years that there were lots of artifacts that were introduced by growing plants in isolation or in these controlled-growth cabinets and we've moved progressively toward more and more sophisticated designs to get it closer to the way that natural ecosystems work. in order to create a realistic possible future environment for these grasslands

we're manipulating four environmental factors. narrator: the jasper ridge experiment is carefully designed so that not just carbon dioxide but the other factors predicted in climate-change models can be manipulated. the field consists of 32 circular plots each 2 meters in diameter. each plot is cut into quarters making a total of 128 different treatment areas with each of the possible combinations of the four factors... each plot combination is duplicated eight times. the factor of extra carbon dioxide is delivered with tubing that surrounds half the plots. co2 levels are controlled by sensors that keep the enrichment to double current atmospheric levels. the system was designed so that, as a function of wind direction, some emitters could be turned off

that would be on the downwind side of the plot. so only releasing co2 on the upwind side and then having the wind carry it across the plot. narrator: the next factor -- increased temperature -- is delivered to half of the plots with heat lamps. dr. chiariello: birds like to perch on these heaters and bird droppings have a lot of nutrients in them. so one of the concerns that we had was to make sure that we had a control on unintended effects of the heaters. only half of the plots of course, have heat. but in designing the experiment, we recognized that it was important to have this infrastructure present in all of the plots. narrator: the final two factors -- additional nitrogen -- in a form similar to that expected from increased air pollution -- and water are added to plots individually. dr. chiariello: the prediction for california for the next century is that rainfall should increase. the option that we chose was to supplement each major rainfall

by about 50%. narrator: over the growing season, the researchers allow the plants to grow to maturity. then they carefully harvest 10-centimeter squares of plant material. dr. chiariello: the first cut at understanding whether or not plants are responding to elevated co2 or to any of these other factors is to see how much plant biomass there is at the end of a growing season. the plant biomass is partlovound. it's what we see in terms of leaves and flowers and stems. d part of it is below ground in the form of roots and chemicals that have leaked intohe soil around the roots. narrator: once the plots are harvested the samples are dried and then weighed to calculate the amount of carbon the plants removed from the atmosphere each year. this key measure, known as the net primary production is used in computer models that predict climate change effects on other ecosystems.

yeah. after eight years of conducting this experiment, chris and his team's meticulous fieldwork has begun to produce some startling results. field: one of the most unexpected results from the jasper ridge global change experiment is that we found that, under a wide range of conditions, plant growth wasn't increased by elevated atmospheric co2. in fact, under many conditions elevated atmospheric co2 actually prevents plants from taking full advantage of other resources that are available in the environment. this has quite profound implications for our understanding of ecosystem responses to global change and for future climate change. if plants, in fact don't grow more under elevated carbon dioxide, it means that atmospheric co2 is likely to grow faster in the future than we have been anticipating. basically, what it means is that we can't continue to depend on ecosystems to subsidize our emissions of co2 from fossil-fuel combustion. narrator: the results from the jasper ridge global change experiment indicate that some of the projections

for future carbon dioxide concentrations may, in fact, be too low. but we couldn't be confident in our answers unless we had collaborators in many other parts of the world who were doing experiments that are similar in se respects. we have collaborators at the university of minnesota who just found the same resas us -- that you didn't se bigrth response elevated atmospheric co2 unless you also provided nitrogen. a group working on a pine forest in north carolina recently published almost the same result. a group in nevada found that even though elevated co2 increased plant growth it increased the growth of an invasive species that tended to bring wildfire into desert habitats that weren't flammable otherwise. i think that across the community what we're seeing is that the responses to global changes tend to be complicated they tend to be pushing ecosystems in the direction that tends to make them more disturbance-prone and they tend to not be providing the additional carbon storage that we had hoped for

when we took the most simpleminded approach to this kind of experiment. narrator: chris field and his many collaborators at the jasper ridge global change experiment are expanding the scope of their research to look deeper into the mechanisms that limit plant growth. in years to come these projects will provide a wealth of information about how ecosystems respond as a whole to human-induced climate change. field: these studies are ongoing. there are a number of details that we're still trying to understand. we think of the jasper ridge global change experiment as something more like a laboratory than something like an experiment. we all work together to say, "what are the big goals we'd like to accomplish?" but then we encourage individual initiative in order to figure out how the pieces fit together. for the future it's clear that decisions that we make collectively as theuman species determine what the future looks like.

aggressive efforts to limit the emissions of carbon dioxide and other heat-trapping gases to the atmosphere will lead to a world that is hopefully not too different, one that still provides, essentially, consistent goods and services. with a business-as-usual approach where there's aggressive exploitation of fossil-fuel resources and uncontrolled emission of other heat-trapping gases i think we're looking at a future that's much bleaker, where we're looking at temperatures that are warmer than the planet has seen for the last several million years where there are critical shortages of water and other essential services that are provided by ecosystems, and where stresses on people and ecosystems and the global habitat are unlike the stresses that we've encountered ever as a species.

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