icefield. >> today on "earth focus," from monitoring glalacier melt and arctic sea ice to what scientists say cmate changnge may mean for our fufuture, coming up on "earth focus." >> on the edge of the gulf of alaska, straddling the icy border with canada and the coast range mountains, lies the juno icefield. this is the fifth largest expanse of ice covering the planet and is the source area

for hundreds of glaciers. the juno icefield research program, or jirp, has been studying these mighty rivers of ice since 1946 to better understand how our planet's natural environments are changing and what this means to our common future. >> and actually there's a little bitit of complexity as s to whye use glacier ice. >> i came here as a science student 23 years ago and returned to work here this summer as a part-time staff member. like other jirpers, as we call ourselves, this project launched my interest in the natural world and continues to inspire my science reportiting. each year a group of science researchers crosses this vast area like i did, getting a chance to learn how to survive and conduct research in this, one of the most wild classrooms in north america. supported and

staffed by the foundation for glacier and environmental research, the juno icefield research program has some of the longest-rununning glacial climae records in the world and is a treasure trove of valuable data about how our world's climate is changing. i'm here at camp 17 on the juno icefield, and i'm going in to have a quick word with dr. anthony arendt. he's from the university of alaska in fairbanks, and he's one of the guys who designed the latest satellite imagery systems for nasa to understand the mass balance of this icefield. >>glaciers r respond immediately to a any changes in n climate. r riations and their mamass are determined directly by how much snows llls on them in the wintertime anand how much ice ad snow melts away due to warmer temperatures in the summertime. so by monitoring glacier variations, we can understand a

lot about climate systems, and so they're one of the first sost of early hallmamarks of climate change on the planet. >> dr. arendt helps create high-resolution computer models of glaciers like this one using data from satellites, airplanes, and deep snow pits like these to develop a clear picture of our future global climate. 95% of alaskan glaciers are melting at an unnatural and unprecedented pace. >> glacieiers arere really large contributors to changing sea levels. you wantnt to be able to quantify how much water is coming out of these systems every year and then use that information to develop modedels and predict in thehe future to help policymakers plan for potential facts of sea level change in the next 50 or 100 years. >> scientists like dr. arendt come here to conduct research and to share their experience with the young-and-upcoming researchersrs taking g part in e prprogram. to collect the ground

data that sophisticated high-tech science depends on, students have to cross vast distances through the isolated heart of the icefield. in order to traverse the icefield safely, we train them extensively for the dangers of this rugged field experience. here at camp 17, they learn adventure skiing, safe glacier travel on a rope, and how to rescue a colleague from a crevice. the training equips and inspires these students for a career i in extre environmental research, collecting data that the g globl scienentific commununity depends upon t to further r the understandining of our changing worlds. >> it's just a useful tool in itself. >> first off we practice tying knots. that was like the basis of all this, and then from those knots, then we learned different ways to use ththe knots on a ro, whwhich then you learn how t toi with a r rope teteam and what to in case anything bad happens on a rope team, like a fall into a crevice and how to save a team

memember that has fallen. >> yay! >> after science and safety training at camp 17, the participants start their traverse across the icefield, doing field work in geology, glaciology, climate change, and other disciplines. >> well, when these people come out of the icefield and experience thehe glacial environment, by making measurements, they can see how that ecosystem is changing this year and in years before. >> to be on the juno icefield is a fantastic experience for me, and part of a major program that monitors mass balance of an important glacier, and in addition,n, it gives me the opportunity to try and contribute to the scientific development of young scientists. > mass balance indicates the health of a glacier. a positive mass balance means that the glacier is growing. a negative

mass balance means that it is shrinking. the older a mass balance record is the more valuable it becomes. long-running studies provide a historical average against which this year's data can be compared, showing how the climate h has changed and what y happppen in the future.. >> the mass balance data that's been collected by the jirp program is an extremely important record because it goes back as far as 1946, and there are probably only about 30 glaciers in thehe world t that e bebeen monitored for mass balale for 10 or morere yearsrs. >> a glacier exists here because snow that falls in the winter does not melt completely in the summer. the relative amounts of snowfall and melt represent this mass balance. like a positive bank account, a positive mass balance indicates that the glacier is growing. on the flip side, if the glacier has less snowfall and more melt, the glacier becomes smaller. so how

have generations of scientists come to grips with the estimation of the health of this 3,900-square-kilometer ice sheet? they dig. a lot. by digging many pits like these, scientists like dr. jason amundson calculate how much melted ice is flowing into the ocean. >> when the glaciers are actually in retreat, the one thing they y do is they contrtre to sea level rise, but they also affect atmospheric circulation patterns, which propagates downstream. it affects other things. the changes in the amount of freshwater runoff into the ocean, which will affect the ocean properties, which could afaffect the marinine life. >> > the globalal sea levelel ig to rise, and it will rise by varying amounts depending on where you are in the world, and the contribubution from glacie is like to o beignififint.

>> diggining sn pitits s beenen useful for almost 60 years on the juno icefield, but when these snow pits are paired with new ground-breaking technologies, the science becomes even m more successful. salvatore candela is using a powerful ground-penetratating radar, or gpr as it's known, to gett information from the vastt areas between snow pipits using the pits thememselves as a refeference for hihis readings. >> the diggingng of pits and usg ground-penetrtrating radar realy tieses well together. since i''m imaging what's in the ground and they're actually digging in the area i'm imaging, they compliment each other in that if i have a question about what i'm seeing on the radar, i can go jump in a 5-meter-deep hole and actually see what is there. and bybyairing theheir visual observations with what's on the radar, it allows us to o come ta much stronger concnclusion about

whwhere the annual l layer is or where a specificic densi change might be that they're looking for in the mass balance process. >> by dragging his gpr sled, named the bumblebee, and using the pits to calibrate it, candela is helping create a much better understanding of this dynamic glacial system. the researchers also map the movement of the ice with gps and 3-d imagery. >> ...successful? >> i think we're very successful. jerking it around. >> ok, s so i grab it, and i moe it around to that. wow.. >> they even get deep under the ice in vast complexes of subglacial caverns to calculate how the glaciers are melting from the bottom up. the huge llewellyn glacier r in canadadas melting fastst, exposing more of

itits secrets for researarchers brooke stamper and mira dutschke to discover, using photogrammetry and ice lens measurements. as the 2013 field season on the icefield comes to a close, we make our way northeast and walk off the llewellyn glacier through a dangerous crevice field. >> we'e're winding our w way thh the crevivices of t the llewelln glacier. everyone's making their way very carefully here because the glacier gets a littlele bron up, , but it's a beautifulul da, and it looks like we might make it all the way to lake atlin. >> we struggle down through this dusty and blowing newly uncovered ground where the vast llewellyn has melted and finally we make our way down this long valley to lake atlin. here we're picked up by a boat

and startrt deciphering the data and working it into the scientific literature, where researchers around the world can use it to fine tune their climate change predictions. from the glaciological and arctic sciences institute on lake atlin, british columbia, this is jeffrey barbee reporting for link tv. >> glaciers are not the only things melting. so is arctic sea ice. just how fast is the sea ice melting? r research scientit julienne stroeve is working with the national science foundation to find out. i knknow the importance e of snow anand ice in helelping rege the planet's temperature, it's one of the reasons i went intoto studying snow and ice because it's very important to our climate system. and i don't

think it really was until about 2002, 2003 that we started to really start paying attention to what's happening in the arctic, because before that we would have, you know, we'd have low sea ice in the 1990s and then it would be followed by a high sea ice year, but what started happening in 2000 is you'd have a low sea ice year and another low sea ice year, and it just kept happening and happening year after year. and that was the thing we hadn't seen before, at least during the last sort of 50 years o of data collectioion. and then when 2007 happened, where you had 26% drop from the previous september in 2006, and everybody was like, what is going on? 'cause nobody expected that large of a drop. it took everybody by surprise in the science community. the rate of decline right now over the last 3 decades is about 114% perer decade, and this s is actually faster than most of our kind of models are actually capturing today. these projections of ice-free dates of, like, 2050 to sometime beyond 2100, it looks like it ccould happen a bit sosooner, so like 2030 might be a more realiic d datas t to when wee migight see no o sea ice in the

summer in the arctic. you know, basically everything on the planet's connected, and the arctic is sort of the big refrigerator for our planet. it helps keep our planet a lot coololer because, as you know, snow and ice reflect most of the sun's energy that comes in during the summer period, so if you remove the snow and you remove the ice, then the land can absorb that heat from the sun or the ocean can absorb the heat from the sun and warm up further and amplify the warming in the arctic for example. all of our weather systems or large-scale weather patterns are driven by that temperature difference between the equator, which receives most of the sun's energy, and the polar regions, which receive very little of the sun's energy. but if you change that difference in the temperature between the two regions, you change the speed of the large-scale weather systems that move around the planet. as you change the temperature gradient, these weather systems start to move more s slowly through our atmosphere, and you can get more extreme conditions such as droughts and floods that just last longer in a particular region because these weather systems are moving that much

slower. and so there is a connection between what happens in the arctic and weather in the lower latitudes. and we knew that if the planet started to warm and you start melting snow and you start meltlting ice,e, n you'rre gonna a have this s sorf feedback e effect thatat's g goa amplify ththe warming becacause yoyou're g gonna warm m up. youe gonna melt more snow. you're going to melt more ice. it's going to further warm everything up and melt more and more snow and ice, so you have this really vicious positive feedback. so we knew t that the arctic was very sensitive to increases in temperature, and it's responding likike you would d expect it tos the temperatures have warmed, so it is sort of an early-warning system. we did expect changes to happen firstst there before everywhere else in the planet. if you looked at the factors that we tended to use to explain past low sea ice years, and those factors really weren't working anymore, so it wasn't necessarily a certain weather pattern or, you know, a certain temperature pattern that was causing it. there's some sort of background force that was happening on the ice cover that we, you know, were trying to figure out what that was. whwhen i started looking at the climate model and comparing them to the observation, then i

started realizing, well, you know, all of these models would be an own face of natural clilimate variabibilities, so ty could be showing increasases or decreaeases over a period of observation, but they all sw a decrease, and so that's what starts to help implicate greenhouse gases that's forcing the changes that we're seeing today in the ice cover. we can say that about 50%-60% of the loss of sea ice that we're seeing today is a result of greenhouse gases. the other 40%-50% is actuaually natural climate variability, so we know both are acting on the system right now. and right now the results are about 50/50, , i think, on what's happening, what we're seeing today. the planet's going to warm by a certain amount a degrees. the ssea ice is going toto disappean the summertime. the ice is continue to respond, sea level is going to continue to rise, but when we look at things like, well, where are the precipitation patterns going to change? who's going to get more rain? ? who's going to get less rain? what''s going to happen to the american southwest? are theyey going to lose their snowfall? in that sense, there's not a

whole lot of robustness between the model simulations yet, so they give different answers in different regions, and so we don't have a good handle, i think, on how rainfall, for example, is going to change in a warming climate. and that's really i think one of the key things that we need to better understand is where is the water going to be? because a lot of regions depend very strongly, for example, on the glacier, to feed the city and provide all the water for a city like santiago, chile, for example, and so better understanding on how precipitation is going to change and snowfall is going to change is one of the key things that we need to understand. we do s see that ifif you run point-t-litigationon scenariosos and youou reduce the amouount of greeeenhouse ga, tthat you cacan actuallyly brine ice backck. you can n stabilizee amount t of ice lososs. if we we to reducuce our greeeenhouse ga, it's not going to be this runaway effect. we can stop some of these changes that are happppening in the arctic, but that does mean we're going to have to o commit t to reducingne amamount of fossil fuels w we're putting inin the atmtmosere,e, d that's the real challenge.

>> most experts say fossil fuels are the leading cause of climate change. the climate change deniers often associated with the fossil fuel lobby and iindustry-y-supported think tans downplay the connection between fossil fuels and the wararming f our planet. climate scientist michael mann on how a changing climate may affect our future. >> sometimes you'lll hear from the critics. they'll say, "we demand proof that humans arere causing this." anand my response is that proof is reserved for alcoholic beverages and mathematical ththeorems." it doesn't characterize how science woworks. science works through weights of evidence, through likelihoods, through confidence levels, and so we're about as certain that humans are causing global warming as we are about any scientific proposition, but we never say we've proven something inin science because there's always the outside chance ththat we coululd discovr

some new piece of informatition thatat would change our persrspective. it's s absolutely true that critics of sort of the forces of antiscience, those looking to confuse the public about the science will always draw upon that vulnerability, that as scientiststs we're never comfortable in statiting things in absolutes because that's not the way thehe world works, tha's not the way science works. unfortunately our detractors, those looooking to sort of polle the public discoursrse on mattes of s science like global w warmg are more than happypy to state their opinions with absosolute certainty. so it's important to understand t that there is sortf an asymmetry i in the battle ovr informing the public about science. we're at a bit o of a disadvantage a as scientisists becaususe we have to be true to our principles. we have to be honest. and we have to recognize nd describe things in rms of caveats, in terms of layers of uncertainty. there are no absolutes. that having been

said, it's perfectly appropriate fofor a climate scientist to say we are nearly certain that the globe is warming because of us, because of increased greenhouse gas concentrations from fossil fuel burning and other human activities, and if we continue on the course that we're on, we are likely to see very y damagig impacts on us, on our environment. one of the valid, in my view, criticisms of the ipcc is t that in many respects it has been overly conservative in the way it has stated its conclusions, and there's no better example than the e melting of ice, both sea ice, the layers of ice that form seasonally in the arctic, and around antarctica, and land ice, the major ice sheets,s, the continental ice sheets like the greenland ice sheet and the antarctic ice sheet. in both respects, both in terms of the shrinking amount of sea ice, for example, in the arctic at the

end of a summer. the kind of trajectory that we're on leads to the conclusion that within a matter of a couple of decades, we may see ice free conditions in the arctic at the end of the summer. . this is somethining tt the climate models predict shouldn't happen for another 60 years, 'til the end of the 21st century, and indeed nature seems to be on a course that's faster, that's more dramatic than what the climate models predict. we are alreaeady observing and measuring a decrease in the amount of ice in the greenland ice sheet and the west antarctic ice sheet. now, the climate models have predicted that we shouldn't see that for many decades to come, and the key distinction here is if it's a land ice sheet, a land-based ice sheet, then when it melts, it actually contributes to global sea level rise. that's not the case for

sea ice, but it is the case for the continental ice sheets, so the fact that we're already measuring losses of ice from these major continental ice sheets means that they're contributing to sea level rise faster, once again, than climate scicientistprojojected ththem t. there's a credible body of work now that suggests that if we continue witith business-as-usul fossil fuel emissions, than by the end of this century, we could see as much as two meters, 6 feet of global sea level rise. now, that would be catastrophic for many coastal regions. for the u.s. east coast and gulf coast, island nations around the world, some of which will literally be submerged by that amount of sea level rise. the ipcc makes a far more conservative statement. they state an upper bound of about a meteter, about 3 feet, and it's once again an example of where the ipcc arguably has been overly conservative. some as

myself have argued that partly that's just due to the culture of science. scientists tend to bebe reticent. we dodon't like o make strong conclusions that we have to withdraw atat some later time. and there's s also a componenent, i believe, due e to ththe pressure, the outstside pressure, the e critics,s, a vey well-funded and well-organized efforort to literally discredit the science of climate change sometimes by attempting to discredit the s scientists themselves. i myself have been a victim of that. and in the face of all that pressure and those attacks,s, i think to o some ext ththe ipcc has actualllly withdn a bit, a and they've been more guarded, more conservative, more reticent in what they're willing to conclude thahan they realally should be giviven the evidence. and arguguably, you know, if it is indeed the ipcc's role to advise governments on the potential for dangerous anthropogenic interference with

the climate, which is what the ipcc was originally charged w wh as their missionon, arguably you should not downplalay the higher-end scenarios if they're credible, even if f they're loww probabilityty outcomes. if ththr probability i isn't zero, then they should contribute to t the assessment of risk much in the way t that, you know, we buy fie insurance for our homes nott becauause we think our homes are going to bururn down. that's a very rare occurrence. it's very unlikely to happen to o us, but even thohough its probability is very l low, the magnitude of co, the impact on our lives if our house was to o burn down is immeasurable. mitigating climate change, , doing somemething abot our carbonon essioions ia plananetary insurance policy, ,d in guiding the teterms of that insurance policy,y, we need t te focucusing on some of those potentialal more extreme catastrorophic outcocomes. if te

ipcc systematically downplays those e outcomes, then it dodo't serve ththat largeger process of societal risk assessment as it should. qualitatively speaking, if you look at impacts on human health, water availability, human water resources, food resources, land, the global economy, pretty much every sector of our lives, of human civilization, what you see is a business-as-usual fossil fuel burning scenario, by the end of the century gives us highly negatitive impacts across the boards in all those categogories. i forgot to mentin biodiversity, a potentially large-scale extinction of species. some of these we can quantifyfy economicacally or wen try to. some of them we can't even qualify how important they

are. what is the value of the earthth? well, it'ss infinitee because if we destroy the earth's environment, there is no plan "b." there is no planet "b" that we can go to. how do you put a cost on, you know, on the health of the environment? arguably you can't even do so. and in fact it's that principle that it's an infinite cost when we start talking about those sorts of scenarios that leads some people to, you know, conclude that the precautionary principle applies here, that the potential impapact of what we're doing is so potentially harmful to us, to other living things, to the planet that it's almost obvious that we need to mitigate this problem, that we need to take actions now to avert those catastrophic f futures, potentil futures. 8úxúa>fssssssss[[[[[[[[w

nina: our next speaker is someone who has been tirelessly and courageously tackling some of the most--the thorniest, most persistent core contradictions that have roiled our society for centuries andnd that are curreny more hotly contested than everr today. she had done so as an activist, a leader, and a scholar, and is one of the most influential actors and penetrating thinkers on race, gender, immigration, social class, and poverty. you know, all those light-hehearted topics that no one gets t too et