Dark Snow

you know there's this electricity at this this event I'd love to bring that to the climate science uh meetings that I go to and I I will I'm going to do that because it makes uh the events more you know fun and you know to the extent that climate change is fun um um so I've dedicated my professional career to understanding ice climate interactions in in Greenland and so I want to share with you some of what I've learned to um to transfer that knowledge to you and it's a strange privilege to Bear the the climate change message because it's often kind of a bummer and it's a it's a you know something that you know don't want to worry really about we want to find ways to move forward and I loved hearing that at the introductory remarks of this event that we need to look forward we need to move forward and we can and we need to we must because of the challenge that that climate change uh presents us with and I learned something from Bill McKibbon about the power that exists if we get outside of our comfort zone and it's not easy to stand out and everything that we're kind of message from society is is not to go out far but I know that this community is doing that and you're pushing the boundaries and and we need to do that in terms of engaging the climate change which arguably is the defining issue of this Century dark snow is a project it was the first internet crowdfunded uh Arctic Expedition and it was we engaged with uh with media and social media and we were able to really amplify our message and I've learned a lot and we'll we'll take that forward in climate Communications um this dark material you see accumulating on the surface of the greeland ice sheet um part of it not a small part is bacteria so the ice sheet surface is fermenting also and it's very important for climate change because it's a multiplier and I'll talk about that um in a bit the world's largest island I like to call it the world's smallest continent three times the area of France 81% ice covered it's a dome of ice more than three kilometers thick and as it melts it contains enough ice to ra raise sea level 7 m the story for me and Greenland began with 11 years of installing and maintaining a network of automatic weather stations climate stations designed to measure the balance of energy coming down and upward and that gave me the the exciting job of touring around Greenland each year and I don't know if I would do this today but it was very important to level those radiometers so that we could calibrate satellite measurements and to understand if if the satellite data were accurate and indeed they were and the these data are of the surface reflectivity of of ice you know snow and ice to be very reflective and it's the impurities that that darken the ice that's part of the dark snow message so here's the year 2000 I'm going to fast forward to year 2012 and look at the color change of the ice sheet I'll go back to 2004 to 2012 and what we've observed with this high quality record of satellite data is the darkening of the ice sheet 7% darker in just 12 years this is equivalent with about twice the United States energy consumption and that's going into additional heating of the ice sheet surface it's about 400 times the Danish um annual energy consumption going into heating Ice uh and some of that into melting there's this word albo or whiteness and the this leaf on the frozen lake surface illustrates you know that darker objects absorb more sunlight and that produces some local melting and that locally melted area darker than the surroundings and this has a multiplying effect this is the albo feedback just a time lapse of melting snow and just in one day we we measure the the the reflectivity of the surface declining That's The Power of melt and you can see it here on the microscopic scale that fresh ice crystals have these Jagged edges that scatter light and that's what makes fresh snow so reflective and it's heat that that rounds those crystals and they simply scatter less light that's half of the the story meanwhile a reconstruction I published shows uh the last decade of of temperatures being the warmest in at least 170 years 10 years ago we couldn't really say that it was maybe the 1920s were warmer but just in the last 10 years we can now conclude that not only is it the warmest decade in the last 100 the warmest summer in the last 170 years in Greenland but zooming out to the pre-instrumental record from an ice core it's now reasonable to conclude that this decade is the warmest since 860 years ago when the Norse settled Greenland that intervening cold period we call the little ice age and I think it's very reasonable to um that we understand that that it's um industrial pollution that that is a main source a main driver of this um according to the position statements of all scientific acmis around the world there's no longer any doubt that human activity has become a force of of Nature and that in fact according to to a mountain of of data um human activity is by far the largest single um agent for change in in our environment and we can put the climate change story aside and just consider the impact that we have on rearranging our um our environments um how we've resculpted um the surface of of the earth when you fly over it you can see that and these curves are kind of what set my career in motion I I saw these spikes in um heat traing gases and I and I thought okay I want to work on this problem that was about 20 years ago these are the greenhouse gases and it was the Industrial Revolution that that set these these data spiking upward and we see that in the the red line is the uh instrumental record and it shows this warming Trend and the the lines to the left are the pre-instrumental reconstructions from tree rings corals Lake sediments Etc that you can see the medieval warm period the little ice age and then this Rocket Ride that we're on now we're on this rocket and it's it's started to blast off and that happened in the industrial revolution and you can see how steep that is this is called the hockey stick because it it resembles that and we bear witness now to abrupt climate change within our lifetimes we are in Uncharted Territory this isn't something in the future we we've just gotten off the Launchpad I think it's going to get unfortunately a lot more interesting to put it mildly we are going to go past the so-called two degree guard rail that's about four Fahrenheit there um where all countries in in Copenhagen in 2009 signed that um that that anything above 4 Fahrenheit or 2 Celsius was put us into dangerous climate change territory the the red curve there that's the trajectory and that's what we have a chance to influence now small changes we can we can change that and that's the challenge that we have today is to aim for uh a an to restabilize climate and in terms of the food system this is of course destabilized ing agricultural system and we've known this for quite some time um remember this name James Hansen who published this in 1987 and this was a temperature change that showed that most of the warming was in the Arctic far away from where where people are and here's a modern version of that graphic that shows that most of the warming is concentrated in the Arctic climate models for about four decades now have been reproducing this Amplified warming in the high latitudes in the Arctic and you can see in these two different scenarios um the the top one is um the world gets serious about stabilizing carbon dioxide emissions the bottom one the fossil fuel intensive scenario that's business as usual um the short-term economic problems always Trump the long-term planning and and th th that's the choice that we have really is between these two Futures and you can see most of the warming is in the Arctic why is that it's because of that reflectivity feedback that a darker surface absorbs more sunlight and and if the snow cover and the sea ice goes away you have a much darker surface that's absorbing more that's why most of the the temperature changes in the Arctic okay and and these are measurements of Greenland how is Greenland ice reacting to that and we see a doubling in the loss rate of of Greenland ice from about a half a millimeter per year sea level rise um in the first in just 10 years ago and and doubling so today Greenland's contributing more than a millimeter per year to Global sea level rise Antarctica the Antarctica I sheet much bigger nine times the volume it's more of a sleeping giant starting to wake up there's evidence of that it's a similar curve Greenland is contributing twice Antarctica these days more than that for the last 20 years so it's like Greenland's the the sleeping giant that's Awakening with a hangover and um it's uh you know it's not too pretty um these are sea level reconstructions and the the hump you see in the middle that's the medieval warm period then you go down into the little ice age where we saw ice advancing around the world the the dark black line then is the instrumental record and it shows um the the beginning of of what is projected to be a kind of a hockey stick in in uh sea level by the end of this Century we should see something like a meter and a half or more and we cannot rule out much larger uh sea level rise because um really small changes in that nonlinear curve can produce big differences going into the future and I think that underscores the the message that we we need to influence the initial conditions now Now's the Time when when we can and some of that is underway and and we really need to get behind that and it's it's not just in science and policy but I I think in every segment of the economy every activity and I I I can see that the the food movement is starting to lead in in this and to do local um local food and and local production that we're not eating the Thousand Mile salad and that's very important of course that also you get that message out why it's important because even with today's CO2 concentrations if the ice and climate could equilibrate to that we already have cooked in about 20 meters of sea level rise that's with today's CO2 concentration and that's what these data show that there's somehow a functional relationship and it's it's uncertain and and we don't know how fast we get 20 M of sea level rise it will probably take centuries um and we to forge policy we have to do that with deep uncertainty so it's it's very challenging of course to do this in a way that's not disruptive let me take you to the world's fastest Glacier um they on the the Western ice sheet a place called a lulet that means icebergs this 1946 photo showed that it took about 100 years for this world's fastest glacier to retreat um about 10 15 km and then just 10 more years um this the ice shelf in front of this Glacier broke up that's been since 1997 that that began and that's what this looks like the blue bar is the historical observed front of this Glacier and then in 2002 2003 it loses area um the the dash line across that's the area of Copenhagen and and this fastest Glacier is retreating as we were we're observing this we set up some time-lapse cameras and and I have this privilege to share with you the largest iceberg cing event ever captured um on on film and there's there's not an audio track here so you'll have to use your imagination the sound that this kind of event could could take but in just 90 minutes an area of 8 square kilm um goes away and we were shooting a camera every 30 seconds so you'll see eight square kilometers go away and in about 20 seconds it it goes in in a few stages and the cliff that's left behind is taller than any of the buildings in Copenhagen I try to give you a sense of the scale which is is difficult but uh let's just watch this um short animation that that illustrates how quickly ice goes away and it takes a long time to build up it's kind of a Sawtooth pattern it takes a long time to build up the ice it goes quickly here we go when that ice moves away from the front of this Glacier there's less flow resistance and it's it's tripled in speed um in the last 10 years this this Glacier that illustrates the the profound acceleration that that we can observe let me talk about dark snow we observe an increase in the fire season in Colorado where I'm from there's two months longer Fire season seon in the last 60 years this is also happening in the Arctic tundra fire which is a natural process but that's that's increasing in in time so that's the the Wildfire component probably the most important for dark snow but we're also concerned about um ship traffic in the Arctic that's increasing dark light absorbing material from industrial pollution and if drilling occurs in in uh Greenland we uh in the Arctic we we're trying to understand this so we we actually made an expedition to Greenland this year we gathered samples and the samples are at Nasa now and we're we're actually dis distinguishing Wildfire from Industrial Source in terms of of its its um impact and trying to unravel this this um multiplying feedback loop so you can go to dark snow project.org to learn more about that um we we're very fortunate to have um satellite observations which give us for example daily views of where the fires are and this is just a typical June um where we've got active fires uh Upstream of Greenland and this fire in Labrador was the most obvious case it's going on for a number of days and we were able to by looking at these data to find um a few cases is when we we could see smoke drifting in contact with the Greenland ice sheet surface and then we confirmed this with atmospheric trajectories that this material was arriving with my remaining two minutes I want to upscale try to put this in into significance and and perhaps the most important thing is as our changing weather because as the Arctic warms at about twice the rate of the lower latitudes we actually have a slowing down of this River of air in high above the surface this jet stream is moving more slowly and it's Meandering more and that gives us more persistent weather and that could be more persistent warm weather more persistent cold weather and I we've already felt some of that we've had some cold Winters we've had some hot Winters we've we've we start to see this less stable uh climate and this is where climate and weather overlap and that can produce drought or too much water too little water um and that is I think is really what's most challenging about our agricultural system so here's here's James Hansen that I mentioned earlier he's been called this this historic figure the Paul Riv who who warned Americans that um the British were invading and he's been called the Paul R of climatology and he's outside of his comfort zone for the sake of his grandchildren getting arrested at the White House protesting a pipeline that if it's connected virtually guarantees this climate chaos that that we need to work together to stop there were more than a thousand people arrested in in front of the White House um it was a a transgenerational um movement this was the largest um active civil disobedience in more than a a generation in the United States and and I drew a lot of fire to from participating this as a scientist because we we should not Advocate we should just deliver facts but you know when when you have kids it's a lot easier to make that decision um I'll wrap up by pointing out I think what we know we need to do is to stop treating nature just as a commodity but to to give nature value just to exist and to confront the consumer culture that is really the source of of a lot of our problems in sustainability we know that we're we're harvesting too much and that's why this needs to happen sustainably and that's the challenge The Balancing Act this phrase um development that meets the needs of the present without compromising the needs of future Generations who knows what what year what decade this this uh statement was was developed a few hands this was 1987 that's when we first come to terms with this this concept that we need to develop without compromising in the future that is not long ago so we've got um we're we're reacting quickly and um and I think thanks to the food movement in a in no small part we can make um this Balancing Act thank you [Applause]