 Hi, I'm Isabella Velicogna. I work at the University of California, Irvine, and I work on satellite geology. I study the mass balance of the ice sheets using satellite data and they impact the 7C level. It's a very neat satellite. So we have two satellites that are orbiting around the Earth and they're on freefall. It means they're just there. And we know at every very accurate distance between the two satellites. We have a microwave link and we can know the change in distance with the better accuracy of the micron per second, which is better than the size of the blood cell or the size of your hair. And what happens is that when there is more mass in all land, you say there is a mountain. The first satellite is attractive because there's a gravitational pull and so it goes faster and the distance between the two becomes smaller and becomes bigger. And then once the second one gets closer, it gets attracted, accelerated, and the distance becomes shorter. So measuring those changes, you know, we have basically, every 30 days we have a map of the entire globe. What we can see, we can see what changed from one month to the other and the mountain is there, one month in the other. What changes, you think, is that, you know, water in a river basin, mass in the ocean, and the ice on the ice sheets and on the mountain glacier. And, you know, we, there are some techniques that do much better job in looking at the smaller scale. So we have like a big footprint. We got an average of an area that is a few hundred kilometers radius, so it's a big area. But it's nice because every month, you know, now I have data through October. So I can see what happened, you know. I can somehow, you can imagine, you can just wait for the ice sheets and you can see, you don't know what is the absolute weight. You don't know what is, you know, eye weight, I don't know, 160 pounds, you know. I don't know how much it is, but we can say, oh, look, it's getting, you know, heavier in winter and less in summer. So you can see all those changes. And, you know, it's pretty amazing from up there. In the start of like a few hundred kilometers up, you know, in altitude and they've been doing a great job. And I think that, you know, the cryosphere and really the ice sheet is really one of the important application of this data set. And there are many others. They're like in looking at water storage, you know, for the first time, you can monitor groundwater, depletion, which is something that, especially in remote region, you know, is not easy. But for the ice sheet has been, you know, when we just were able to say, oh, we look at the entire Antarctic ice sheet and we look at the mass change and look, it's changing and it's going down. It's decreasing. You know, there were a lot of other techniques. They were seeing some region changing. They knew that a lot of parts of Antarctica were changing. But then maybe someone could say, oh, well, but you don't have a shot at the same time of everything. So that's why it's great. I think for the data set that we have, you know, we have a point in which we have a very good set of data set, you know, in the satellite, especially for study, the ice sheets are really helpful because, you know, Antarctica is so remote and it's so big that if you have to go and measure it up and down, it's hard. And now we have different measurements. They are very complementary and they all are more sensitive to different processes so we can get a good picture. What I was referring to now was talking about measurement of mass balance. So measuring the change, look at the change in mass. And they're mainly, you know, three satellite, you know, technique that you can use. So one is grays, gravitational, so you just literally measure the change in mass of, you know, the ice. And then if one is a direct measurement and then it has to be corrected by, you know, underneath the ice sheet across uplift, subside as a response to the last deglaculation. And so we have to remove that effect. But once we have that, you know, we just can basically directly measuring the change in mass. Then there is the mass budget method. I use a combination of that interferometry data to look out the ice flow. And then we have information. If we know where is the section, you know, the glacier, then we can say how much is the ice flows out. So we know how much is discharged. And then we can get the input. And this we get it from some regional climate model. Those days are the ones that provide the best, you know, they are doing a great job. And so you combine the two pieces and you have the total mass, mass balance of the ice sheets. And then the resultimetry, which doesn't really directly measure the change in mass, it measures changes in elevation. And so it's very accurate to tell you how the surface of the ice sheets. But then if you want to convert this in mass, you have to assume, you know, okay, is the mass change, this elevation change, what density occur? Or the ice or what does not? And so, you know, in some region, you know, it's tricky because, you know, there's a big difference. It's like you can have almost a factor two, you know, like density of ice goes between, you know, 0.9 and then you can have until maybe, you know, if it's less dense ice, you know, but density of snow is between 0.3 and 0.6. So if you multiply by one another, you can have a different change in mass. But on the other hand, you get a very accurate information about the elevation. So those are the three techniques that now we have. The ice sheets are losing mass at a very significant rate. Greenland is losing mass faster. You know, if you look over the last ten years, one to ten decimal from grace, because I have it off the top of my head, but, you know, from 2002 to 2002 now, you know, you have a mass loss is about 270 gigaton per year, which is the equivalent of about a little bit less than 0.8 millimeter of sea level equivalent. And the thing, so this is like if you measure an average loss. And then, you know, if you look, but the fact is that the mass is not, it doesn't change every year the same way. It's increasing with time. And we see a big acceleration in the mass loss. It means that every year it's melting more. And so, and all the other techniques agree that, you know, Greenland is significantly contributing to sea level. With grace, we have 12 years of data. Then if you can extend the record, you know, other techniques, both ultimately, particularly the mass budget, we can have longer time series so we can get measured from the 60, estimate from the 1960. And so then you get, you know, ten years for the story of the ice sheets, you know. It's like when you talk about climate, climate usage is an average over 30 years, so ten years, especially because how we see, like, you know, is this representative of the long-term variability, but now we have a, we can combine, you know, all the measurements, the fact that they are in good agreement also, you know, somehow tell us that oh, we're looking, you know, giving more confidence in all of them so then we can look at those extended time series and it shows that since the 60, the ice sheets, you know, Greenland is, looks like it's losing mass and, you know, the mass loss may be changing. We can also see from this that we cannot look at a short period. We really have to look at the longer record to have a clear picture. For Antarctica, we're seeing the, the mass loss is increasing and we're seeing, for sure, like West Antarctica, the mass loss is accelerating, is increasing with time, especially, you know, there's some, the Alans and Sea sector and that, you know, we just had actually a paper in which we look at this region combining all the different techniques and looking at how the mass is changing in respect, you know, to the 20-year period and we found that, you know, in the last 10 years, the mass loss increases three times faster than over the average of the last 20 years and, you know, so things are happening fast, you know, and I think that, you know, is exciting for us to study but I think that, you know, we should just be, it's a big signal between the Antarctic and Greenland, you can, you get more than a second just between the top of my head but, you know, a millimeter of sea level rise just, you know, has hit a year. There are, like, a lot of studies that shows, you know, especially, but, you know, in the Arctic, I mean, there's a clear agreement that, you know, the Arctic is warming and things are changing very fast, the ocean is warming and there is, like, and the Arctic, for Greenland, the mass change is a good portion, you know, between 50 and 60 percent is driven by surface mass balance, which is very sensitive to, you know, climate, you know, precipitation and runoff and so all the studies show that, you know, there is, you know, the connection because of this warming that things look like they're happening fast. In Antarctica, there are studies that have been showing that there is, you know, it's like there are very dramatic changes that are observed. There is an increase in temperature. They have been observing increased, you know, change in warming in the ocean and a change in the ocean wind. And there are some studies that relate the fact of, you know, those changes in ocean wind are related and all those are changes to the warming and the change in wind, there are some studies that show that, you know, bring more water closer to the glacier and once, you know, the warm water come, the ice, there is the ice sheet, more the ice shelf, which is like basically the slab of ice, just still attached to the ice where it's floating, is very sensitive to change in the temperature of the ocean because those ice shelves, you see a little slab on top, but they're very, very deep down in the ocean. Basically see only 10% now, so they can be like, you know, hundreds of meters and what happens at that is that the melting point of ice is lower. It means that you take, you need a smaller change in temperature because the pressure is higher to melt ice at that. And so if even a smaller change in temperature at that can have a big effect melting portion of the ice shelf. And once the ice shelf, you know, if those ice shelf melt and the weakness has been shown, as in the case, for example, of Larsonby, the, you know, you basically, the ice shelf works a little bit like a, is like if you have a cork in a bottle of champagne, you know, as I can stop in the champagne, you break the ice shelf and the champagne comes out. And so the glacier has been observed to, once the ice shelf, you know, collapse and it breaks up in pieces, they have been observed flowing faster in the ocean. So these are all things that, you know, so and there is a lot of, you know, new research, especially in the last few years and trying to understand the interaction between ocean and ice sheet and ice dynamic, the ice sheets, because, you know, we are trying to put together all the pieces that we are serving in changing. All the water that is used, like in LA County, for example, for doing everything, industry, you know, agriculture water in one year, you know, and this LA County, so it's big, you know, like and there are people, they water a lot, they are, I'm joking. It's about, it's a little bit more than a gigaton a year. So this, this is like every year, it's like more than 270 times that. So it's a lot of water. The GRACE is a NASA, a German, a DLR, German Space Agency mission, and actually the GRACE follow-on one also, it's going to be a combination, you know, sponsored by both this agency, but they are scientists everywhere in the world. I think it's a great tool, you know, data are posted, you know, a few months after on the web, so every one, you know, can download them and look, in theory, you can just sit down and download and see what's happening with Greenland. Now you have to do, you know, you can have a first look and actually, you know, really, you know, just get the data and have a preliminary idea, then of course, you know, to get the number right and everything, you have to just do more processing. But I think that more and more scientists are using it. I think that, you know, there are different communities that are appreciating the importance, you know. I think the cryosphere, it was pretty obvious, you know, that was an important piece of information, despite, you know, the big food trend in hydrology, also I think they are like more and more student, because it's one of the, you know, it's basically, it's the only way that we have to close the water cycle, so it's very important monitoring drought, and despite the fact that, you know, model is not necessarily so obvious how to assimilate this data, you know, in models, because the model is a very core scale and it's very complicated to just, but still you have a data set that, you know, otherwise the only other option is like go in and put wells everywhere, which, you know, you can maybe do it in the US, but there are some other places where it's hard, you know, like in India. So it's been very, very useful in monitoring drought and also has been used in looking at how vegetation changes, correlated to changing water storage. So it has a lot of application and there are people, you know, all over, I think, all over the world, you know, like, I think people in India, for example, we get a lot of, you know, they are really interested because they care about groundwater. Groundwater is really a very important, you know, resource there and it's very vital, you know, the fact that they exchange their depletion, depletion too much makes a big difference for the population, for the agriculture. So they are more and more interested in trying to use whatever's there. So it was launched in 2002 and it's still a collective measurement. It was a three to five year mission, so now we have 12 years of data, and it's doing well, but, you know, of course, there is no any redundant part, but in principle, so far as energy and consumption, everything goes well. We should be able to get to 2017 where there should be the launch on a graceful one in August 2017. But then again, now what they are starting to do, they are now taking measures every month, so maybe they skip some months, they save energy and that we can just extend the lifetime because it's important to have overlap before continuity. But it's doing still great. We're also working and thinking a way to eventually, if that happened, how you can just establish continuity so that we can just bridge, you know, because grace doesn't measure the total mass, it may measure changes in mass, and so it's relative to, you know, a mean as an anomaly. You have a gap, you have to figure out how to, you know, you don't want to have, you know, you have to shift the right way. I try to do, you know, what I can. I appreciate it when, you know, people ask me to do it because sometimes, you know, you have so much to do that you don't make it as your first priority, but if there is an occasion, it's a good thing. And I think that it's very important to make people aware of how things are and what is happening because I do think that a lot of the misconception that, you know, outside they have is because science is moving very fast in this. You know, we have so many more data sets. We have longer time series. We have more reliable record. And I think that sometime the scientists know, but then, you know, the scientists are busy and don't necessarily, you know, where do I go to tell people, you know, you write your article, but your article is in a technical journal, so my grandmother doesn't hear that or whatever. So I think that a big part of a lot of the misconception is because, you know, the flux of information, you know, and it's normal, but things have really changed, you know, very, very fast in a few years. If you think the IP, two IPCC ago, I think it was like before 2006, the IPCC was saying that we expect Antarctica to grow in a warming climate because of the increase in precipitation. And the IPCC, the last IPCC says what we're seeing in Antarctica is, you know, the West Antarctica is losing mass and there are like two techniques that show that overall, you know, the ice sheets is losing mass. So it's a big change, and it's not because the scientists didn't know what was going on before. It's because we have more data set, we have longer time series, and so we can make better analysis. That's now easy. You know, they are like, I do different things. I think there are a lot of different good scientific questions. I think that it's very interesting and try to understand what is the, how the ice-ocean interaction, you know, affect the ice sheet. I think that there is a big question, which is now, I do some work related to looking at the Antarctic. Now the water side, the vegetation is changing as it comes with the warming and how water and temperature control affect changes in vegetation. And I think that that's a very complicated question and it's a good question, you know, how the ecosystem is going to respond, you know, to the warming and how, you know, how, because things are happening in a different way with respect to what we were expecting. We were expecting the always warming, the Arctic is going to be all warm, longer growing season, and the plants are going to go crazy, you know, photosynthesis are going to go and it's going to act as a carbon sink. And in the last few years, they start to observe that there are some places where they're actually, you know, the plants are suffering. There's a decrease in productivity. And so, you know, things are occurring differently than what we expected. And, you know, so they're like a lot of good questions. I think that, you know, they understand, you know, how the ice sheets evolve and how the ice ocean interaction affect that and how try to understand what are the processes. We still have a lot to do in understanding, you know, how the different, the mass loss, you know, how to be able to model, fully model, you know, the time variability and how the ice sheets respond to climate variability. I actually, so I always like science. It's kind of a funny story to me, but I just, I wanted to do physics when I was in high school. I did physics and then I wanted to do research, so I started to do geophysics. And then I was, during my PhD, I was in the U.S. for, I was doing something very different. I was doing tectonics more and actually flexurized geodynamics. And I was looking for a postdoc and I went around and I ended up having an offer to work on grace, which was no lunch. It was like in 1999. It was three years before it was lunch. And I started working on this mission and then I started working more and more on the cryosphere. I think, you know, life's in time up in this way, but it's much better than what I was doing before. So I'm very lucky. Do you ever do any site research? Do you go out on site? Yeah, so with Leili, I started the last, Leili in the last, you know, a few years, a few years, maybe a decade. I was like to go in the field sometime. I went in Greenland on a boat to take measurement in the fjords of the temperature and salinity profile within the fjords and, you know, debatimetry. And, I mean, it's great. I think he, and I went also, I flew on top of Antarctica in some missions and survey. And I think it makes a big difference. I think if one study of the glacier is good to go see them, to see what happened, you know, you go after a couple of years and it's a different glacier if you are on the front, you know, some glacier in Greenland. I go and I love it. You have to pay attention, but it's a different work if you are on the computer and you have to code and you have to write a equation and you have a different experience and then you realize, you know, what is going on, you know, like how are the conditions, you know, the ice sheets. So I think it gets you a better understanding of what you're doing when you use the other data set. You do all your modeling, all the other things. But it was, you know, it's great to get together. I think there is a special thing about people that do field work in the cryosphere because you get together also with your colleague in a different way because, you know, you wake up sometime at 3 a.m. to do measurement, you know, you have, like, 24-hour measure so you have turn and, you know, you end up doing measurement, maybe you put up, you know, music and you're all dancing when you're doing the measurement. So there's like a part of all of this, you know, or maybe you're all soaking wet and you're just, you know, you're there and it's still fun. You're off, you know, there we didn't have email, we didn't have anything, so it's good. You just focus on seeing how things happen. I think it's very good also because you really see the changes. You see the things change a lot. A store is a glacier in Greenland and last time I was there it was more than, I think it was about five years ago and I saw it and I was like, oh, wow, it's like a different glacier because it retreated so much. It's like, you know, it's like you see someone with, I don't know, blond with blue with blue eyes and then you meet him again, it's like dark air and dark eyes and you say, oh, this is a little bit accessible, it was really, is this the same glacier? And I want to look at my picture that I took five years ago and it's really changed, you know, the ice retreated. It's very different. The flow on Antarctica, it was like I never was on land there. I think it gives you more perspective. I think, you know, you just try to, also when you think about the processes, you see, you know, the ice, you see the ice, you see the mountain range, you see, you know, the glacier, you see how, you know, the glacier, you know, the topography of the glacier, I think it makes you think, you know, the data more, you know, connected more without the process of what is out there. There is one graph. I think it's the one that really anybody that look at that, it cannot. It's like this, and it's this plot of the change in temperature and CO2 concentration. And, you know, we have, ice is a great thing, not because, you know, it's like, it's a fan media, but from ice core, we can get information, you know, about past climate. And the one thing that is really preserved in the bubble of ice and, you know, it's very thick. So we can go back many, many, you know, under 1,000 years. And if we can get information about what is the concentration of CO2 and the main greenhouse gases in the atmosphere, because those gases have this very nice property that they are very uniformly distributed, you know, mixed in the troposphere, which is the layer, you know, closer to the surface. And you can see that, you know, if you look at temperature, you know, and changing in CO2 concentration, they go together. When temperature is high, CO2 concentration is high. And when it's low, CO2 concentration is low. And, you know, they go up and down. And after the industrial era, you can see that, you know, the temperature, sure, goes up and down, but the concentration of CO2, especially just sky rocked and all this other, and the only thing that change is us. And we're not saying, oh, temperature has been higher, you know, in the last, you know, a little bit less than a million years, you know, like in 900,000 years on our planet. But CO2 concentration has never been as high. And also it's changing in the last, and I think that that, you know, that's data. And I think that that, you know, doesn't leave any doubt that, you know, there is an anthropogenic effect. But, you know, that's okay. You know, we do things. I think that, so I don't think that that's the question anymore. Anyone that shows their plot cannot have doubt.