Why the Arctic Warms Faster: new science—Interview w/Dr. Malte Stuecker—Radio Ecoshock 2019-01-31

[00:00:00]this is radio equal shop with your host Alex Smith in the Arctic darkness of February 2018 there was an extreme heat event at the North Pole the temperature was over 30 degrees Fahrenheit over 17 degrees C above normal that is part of the amplified Arctic warming that crashed the summer sea ice and started the great melt of polar glaciers it changes everything new science is struggling to explain why it is happening in the Arctic researchers from China the US and Australia worked on a breakthrough paper published last November in the journal Nature climate change here to explain the surprising findings is the lead author dr. multicooker in a way Malta is representative of the global nature of climate science these days after an education in Germany he got his PhD at the University of Hawaii following a physician as a NOAA climate and global change postdoc fellow he's now a research professor at the IBS Center for climate physics at Pusan National University Republic of Korea from Busan Korea multicooker welcome to Radio ECOSOC thank you well you have published papers on the Pacific Ocean and rice in the Philippines but how did you get drawn into the problem of why the Arctic has become so wildly warm most my PhD work was actually focused more on the tropics but when I moved to the University of Washington for my postdoctoral research I worked together with a lot of polar scientists and I got really excited about learning more about what's happening in the high latitudes and that was when this project that we published last November started it was shocking when the summer sea ice crashed in 2007 and now Siberian ports are gearing up for commercial traffic how strange is it when the whole Arctic changes within a couple of decades it is certainly one of the big issues we face and a changing climate and we've known for long that the Arctic will be one of the regions of the home fastest response to increasing greenhouse gases in a way there is a situation that's been long in the coming but the detailed process is what are most important for for these changes in the Arctic they've been debated for a long time and our recent data is a helped us to understand a little better driving forces behind the exchange well yes before we get to the conclusions of your study there were several competing theories of why warming in the Arctic is so much greater than in the rest of the world what was the strongest contender would you say before your team's paper came out yes many different processes have been proposed for this amplified warming and it depends a little bit about what we are talking about there certainly changes in the Arctic - that - due to internal variability and due to internal variability in the tropics that might influence how heat is transported into the Arctic but then they also local processes that have to do with changes in the sea ice so once we have melt and sea ice we can absorb more incoming variation so that would because less is reflected back to the through space which was hypothesized as a driving force so there's been all these ideas around and they certainly all play a role but we wanted to really quantify what is most important I thought it was mainly ocean waters coming up from the tropics we've seen heat maps that show hotter waters going from the Gulf Stream into the Arctic and also through the Bering Strait via Alaska are you fairly confident that you've ruled out oceans as the agent transferring tropical heat to the Arctic as this primary cause of amplification changes and ocean currents can certainly influence local changes and temperature and sea ice but it's not really when we talk about the influences from the tropics that's been discussed previously it's not so much the ocean current that they would discuss but it the fact that if the tropics warm we change really the global circulation of the atmosphere and you have transport of heat via the atmosphere into the Arctic region which is a much more efficient process than changes in the ocean currents which are much usually occurring are much slower timescales well that makes sense so as I understand it for the purpose of this study your team produced a model that quadruples pre-industrial carbon dioxide and when you run this experiment with much higher co2 which may very well happen all too soon what did you conclude is the main driver of Arctic amplification so as you mentioned we approach this problem by trying to really isolate the role of local radiative forcing that coming from changes in the co2 concentrations and we noticed when we put increase due to consultations just in the tropics which is it's an idealized experiment we didn't see much of a response in the Arctic region so when we increase the co2 concentrations in the subtropics and middle mid latitudes we see some pronounced warming in the Arctic that's coming from heat transport from the mid latitudes into the Arctic however this warming is pretty uniform globally and there's not this pronounced amplified warming in the Arctic that means that the Arctic is warming much more than the rest of the globe so we only get this amplified signal when we prescribed these co2 concentrations locally in the Arctic which means which really points at local processes in the Arctic and the main driving force and there are several candidates then that we looked at and we isolated which of these are most important so we found that this is process called the lapse rate feedback which has to do with the vertical structure of the atmosphere that's most important but then there's other factors for example like the sea ice feedback albedo feedback and changes in clouds it also play a role but these are of secondary importance so is the atmosphere in some way creating a kind of lid that's keeping the heat in the Arctic and that's something that doesn't happen further so so yeah that's exactly the case but very interesting if you compare the tropics the tropical atmosphere with the Arctic atmosphere they are very different there with very different systems so in the tropics we really have these deep clouds the storm clouds that go all the way from the surface into the upper troposphere and they're very effective for bringing heat and moisture on the lower lower atmosphere all the way up so what happens is that when you have increasing co2 concentrations in the tropics a lot of the warming is actually happening in the upper atmosphere not in the lower atmosphere and because it's happening in the upper atmosphere can actually well that energy can radiate back out into space but if you compare that with the Arctic region the Arctic region we have something what we call a very strong inversion what that means is that we have this strong lid on the atmosphere and air that the surface hardly can move up because it's very stable so what then happens if you warm the Arctic is that that heat is really trapped near the surface and it still tries to radiate out some of this energy into space but because it's radiating out from the surface and not the upper atmosphere much less efficient in doing so and that process is something what we call this lapse rate feedback well I have to admit at first I was a bit confused by the paper I kind of wandered away from the real point of it but I was wondering where does this local carbon dioxide come from and I know that wasn't really what you're talking about but there are not many sources in the Arctic other than a few Russian cities and maybe aircraft flyovers does it matter where the carbon dioxide comes from or do we know where it comes from yes it can be a bit confusing if I should motivate this paper a little bit better so of course you took concentrations and reality are well mixed throughout the atmosphere due to the storms that circle around the earth usually they mix up all the gases in the atmosphere so we have very similar concentrations across the globe so even though you have some sources maybe an industrialized regions where you emit more co2 it's going to be well mixed within the atmosphere within a couple of months to a year in our case we were just wanted to understand actually the dynamics of the of the coupled system and to the two that we usually have to do more idealized situations because in the real world if you increase in all and the climate model co2 everywhere we see that the Arctic is warming more but we don't know what is the driving process so by kind of separating it out from regional changes we can get understand the actual dynamics of the capital system a bit better but that's not to say that this is a realistic case but we have confident that the mechanisms that we find actually apply to nature because if we look at the response in these climate models to a global increase in co2 concentrations first of all it looks very similar what we see happening in nature though nature actually showing this Arctic amplification what the models predict so that's given sources confident that the models are have skill and we can trust them and then next is if we separate out these experiments with increasing the greenhouse gases just in certain regions and we look at the individual responses to these experiments and add them all up actually the results look the same as the response to the global forcing so this allows us to decompose these local changes into local processes which is a very powerful way of understanding the climate system by some Russian scientists and others in the Arctic methane emergency groups say methane from the seabed and from thawing permafrost under millions of Arctic ponds are contributing to Arctic heating did your study consider the influence of methane no in our study we only looked at one greenhouse gas that is co2 in reality we have additional players like methane as you mentioned that are very important but the net effect is similar so both co2 and methane will trap more heat in the atmosphere and contribute to a warming of the planet through the simulation if we would do the simulation instead was increasing methane it would give quality of Lee the same results but only the difference would be that methane is an even stronger greenhouse gas so would expect an even stronger response that's why we should be worried about methane emissions because the greenhouse gas potential of this gas is even stronger than of co2 based on the processes that you've looked at in this study do you think the Arctic will continue to warm more than the rest of the world or is there some kind of limit that it might reach and stabilize we're pretty confident every single visual model shows that the Arctic will continue warming stronger than the rest of the planet all the models will show that Arctic sea ice is increasing at rapid rate so that's relatively a future that we are facing unless we reduce emissions however on top of this of this there's certainly also internal variability of the climate system that can give you certain years where ice put maybe increase again before it drops so we don't expect these changes that every year is going to be another record hot year but if you look at changes over five years or ten years we will certainly see an S eration of the warming and that's something the models are very consistent and we have very confident it will happen unless that big changes and in our mission if you have a story idea or thoughts on something you've heard contact us radio at eco shop org that's radio at eco Sean dot o-r-g you are tuned to Radio eco shark I'm Alex Smith from south-korea our guest is the research scientist dr. multicooker he is the lead author of a new study explaining why the Arctic is warming much faster than the rest of the world will these study results help us understand how fast Greenland ice could melt certainly for things like the ice sheets what's really important is how many days in the summer we stay over the melting temperature and this accumulated effect of this warm summer days will be one of the major driving forces of melt so we can certainly use experiments like the one we did to quantify this processes however we haven't looked at the specific problem in our experiment yet there is a secondary result from your paper which could be controversial the paper says quote thus reducing radiative forcing at the pole may be a more effective policy to minimize Arctic amplification than previously thought now I could read that as saying that solar radiation management like spring sulfate aerosols in the Arctic might be effective because of the local nature of the problem is that fair that is certainly correct so if humans decide that they want to go ahead with radiation management which in my personal opinion zinc should only be a last resort because it's an it's not an easy easy fix the easier fix is changing our technology into a more a carbon efficient Society but in case human ship decides that they want to employ radiation management and the question is where would you put those aerosols to have the biggest biggest net effect and also it depends on what you want to achieve so are you concerned about the monsoon regions are you concerned about maybe weather in Europe or in Asia so these are very complex questions that humans have to grapple with but we just ask this very very simple question without giving a political judgment that in case you wanted to decrease the temperatures in the Arctic then having radiation management by spraying aerosols in the Arctic region would be an effective way of decreasing the effect of global warming there of local warming there but yeah that's not said that it's a good idea to do so with this new study Malta are we now at the point of a confident solution to the problem of Arctic amplification or is this still a matter for scientists and competing climate models so one thing I need to acknowledge is that we tested this mechanism just with one climate model it's a very good model but we certainly would like to get more confidence by having other groups using different models to it do similar experiments to see if they can confirm our results in general though we are pretty confident because all other climate models give this general pattern of of electrification so I think our confidence is pretty strong however there are certainly more things to figure out and one of those things are the importance of chain ocean currents that you alluded to earlier so as the globe warms we have likely changes in ocean currents and how much heat is transported into the Arctic or out of the Arctic will further determine how sea ice and temperatures will change and that's something that might be more model dependent and something that we need to look into in more detail especially we might need to use higher resolution models that really can resolve those narrow currents into the Arctic that are important while we have you here let's touch on a couple of previous papers you co-authored for example many of us are worried about the planet will not be able to feed billions of humans if earth warms beyond the tolerance of some major food crops and your August 2018 papers suggested rice may hit that ceiling during this century in the Philippines can you talk to us about that sure this was a project I worked together with biologists from the University of Hawaii and the fellow climate scientist also at the University of Washington and we got really interested in this next source of water climate energy and food and there's been a lot of interest in the climate community to see how these changes that we are projecting to occur how will it affect humans on these really fundamental levels and one of the most fundamental levels is of course food security and one of the crops that is most important worldwide is rice because it feeds most of Asia where most of the global population lives so just to tackle this a bit to understand how climate variability actually can impact rice production we decided to use the Philippines as a case study because it's not that we have for the Philippines we have very good rice production data for a couple of decades now and the Philippines has a lot of different provinces and we have this data actually on a province level and we have it on a quarterly it's reported quarterly we could really go on to the very small province level and under the small temporal level and see how it relates climate variability that's occurring in the Pacific and there we found that your answer really depends a lot in which province you are located so that really pointed out to highlight that the local policymakers they need much more much better information on how larger climate signals like alanine you'll really affect their local County or the local province to make make informed decisions on how they plan for for their rice production in the coming growing season and again most climate science worries about positive feedbacks the interactions that heat the planet even more but you participated in a paper in Nature climate change that found a negative feedback why would a warming Atlantic Ocean lead to a cooling force in the Pacific oh it's maybe not really correct to say it's a negative feedback per se because and the mechanisms we looked at it's more a cyclic phenomena that occurs on timescales of 20 years but it can easily reverse so it's not something that will have much impact in the long term future in response to global warming however it can really be important on timescales that are also important for humans for the next ten years if you want to make policy decisions and what we found is that one of the reasons that the earth over the last 20 years has one slightly less than all models projected was that the tropical Pacific was in an anomalous cold stage so something it's been referred to as a negative phase of the inter decade of Pacific oscillation which just means that enhanced upwelling of cold ocean water in that region and in this study we actually found that one of the main reasons of the Pacific was enormously cold was at the Atlantic the tropical Atlantic Ocean has warmed over this period enormous Lee so as I mentioned earlier the Trop in the tropics we can really propagate these signals throughout the atmosphere so when you have a warming signal in the Atlantic we heat the atmosphere we have air moving up and this changes the wind pattern throughout the globe especially around the tropics so what this warming in the Atlantic did it was it created very different winds in the Pacific Ocean which changed the structure of the upwelling of cold waters and increased the upwelling at the same time it actually enhance sea level rise in the western Pacific so inspecting a lot of people locally however this eventually this pattern will reverse as the Pacific will warm more and also of course the ocean waters that effect will see more influence of the increased radiative forcing due to the increasing co2 concentrations so eventually everything will warm up but there can be periods over 10 20 years that have very distinct patterns that look different from a uniform warming around the globe well I think this is very important because yes things may even out later in the century but we have to live through the next couple of decades and I just spoke with dr. David Victor about their paper saying global warming will happen faster than we think and one of the factors that they mentioned was a natural warming that might occur in the next 10 to 20 years as part of a cycle but that will reinforce other warming factors and and could really affect everything from food to the rate of sea-level rise to ice melting so yeah we got to get through the short term before we get to the long term - I completely agree and that's a lot of effort actually within the climate community to try to make this initialise be Cadle predictions by putting the information we have of that what's happening and the below the surface in the ocean into climate models to make predictions how it will change the surface warming patterns over the next ten years or this fear that's still very in it early steps and there's a lot of challenges to predict the climate system on on these the the regional patterns of the kind of system on these ten-year timescales but it's something we should really pay a lot of attention to because you're right people live locally and if you never accelerate locally in one region it has enormous impact on the local populations the same as if we have a enhanced warming in in the Philippines for example this will affect rice production in this region enormous Lee and these things can have ripple effects due to the interconnected society that we live in so it's not that just price production effects only the people in that in that province but it will affect global markets and it will have ripple effects were the world and that's something we know for a long time actually in the climate community we've been studying and in your this cyclic warming events in the Pacific for a long time and we see even though it's a local phenomena that's happening in the near the equator in the Pacific we see global impacts in weather and climate and we see global impacts in markets we see global impacts in food production so we have this case studies we can work on to try to understand this these impacts of local patterns but yeah much more work has to be done to really inform regional policymakers unfortunately we are out of time we have been talking with dr. multicooker a research professor at the IBS Center for climate physics Pusan National University in the Republic of Korea you can find links to the science we discussed in my show blog at eco shock org multi thank you so much for sharing your valuable time with us thank you very much for having me it was a pleasure we're out of time but we won't quit the climate fight join me again next week for more radio eco shock [Music]