world our guest is professor andrew camp at tufts university dr kemp is an expert on the patterns of sea level change over two thousand years he'll be telling us about the patterns and their causes and how the current sea level rise compares to the ancient ones his studies are used by the intergovernmental panel on climate change and will be important in the international effort to address the problem of rising sea levels we're very pleased to welcome dr andrew can welcome sir thank you but you have studied your concentrate on on the last two thousand years can you tell us the special reason for concentrating on this period of sea level rise and what's involved suddenly my research focuses on trying to understand how and why and where syllables changed over the past two thousand years or so and the reason we're interested in the last two thousand years principly is because it's a period in earth's history from which we can extract a lot of very detailed information from a geological archive so it gives us the ability to look for relatively small changes in sea level that confidence that we are looking at changes that took place over the same period of time that the two thousand years we look at isn't a necessarily a good analogue for what may or may not happen in the future we can certainly learn a lot about how different processes were by examine this time period so it's the accuracy of the geological the what something on the ball for the evidence is is particularly good in this period compared to really ancient times and yes we can see things with a level periods in that time so we know from evidence for example from tree rings that the climate changed in a systematic fashion joy in the past two thousand years so we know for example we have a very recent warming of the climate system from instrumental records weather stations but also from tree rings and similar proxy records it was preceded by a period of relatively cool temperatures called the little ice age and before that we have a period is sometimes called the medieval climate anomaly where there's evidence that at least in the northern hemisphere was a period of relative warmth so we're interested in seeing how sea level responded to those changes joy in the past two thousand years  period when we touched upon the medieval climate on the little ice age all relatively very short by geological standards that intervals that less than a couple of hundred years a few hundred years is very long on a human time scale very short on a  cycles what what made those occur recently cycles in earth's climate history for example we have very pronounced large scale changes on periods of tens to hundreds of thousands of years that take place had argued if presumably are still arguing that this is part of a natural cycle that earth has gone through this over and over again or there's an orbital change in that and so on but scientist animists as far as i know that this present cycle is human produced tell us about that if you would in the context of sea level change specifically what we see from the geological record and instrumental measurements is that around eight hundred fifty sea level globally began to rise again sharply and we know from some of the work that i've been involved in that the modern right of silver was the right of the twentieth century was faster than at any time during the preceding twenty six centuries at least so the the rate and the amounts of sea level rise we've seen since industrialization is unprecedented in the context of the last two thousand and apparently this is accelerating is that true so acceleration another good reason to study the last two thousand years is instrumental measurements of sea level are relatively we have data probably on the east coast going back maybe a hundred years an honest handful of places a little bit longer if you go to northwest europe but pretty short periods of time for us to look at last two thousand years gives  see the shop uptick in the rights of rise and certainly acceleration is is predicted under many models for the future ok that's why i wanted to try to get very clear that this acceleration is demonstrated there is very strong evidence for that and that that is different from the patterns of the past is that correct substantially yes the global scale sea level over the past four thousand years or so was relatively stable probably been falling a little bit since the one eight hundred early nineteen hundreds we see a rapid here right and so there are some unknown presumably is is this because it's a different kind of a pattern an anomaly or something like that is that the way to see it they can't quite predict h not uniform all over the world can you explain how that's governed or what pushes that so it's certainly the pattern of sea level rise has a very very strong suggests the difference in elevation between the lancet face and the the adjacent sea surface and when you think about relative sea level that's what you're interested in if you live in boston or miami or london for example you want to know her relative sealevel at you location is going to change and there are all many factors that contribute to that at a given location for example there is the amount of water in the ocean ocean mass which we can address by melting land based ice we can change small spatial scales for example compaction of the land which results in lowering an exaggerated sea level rise oh i see ok so the big picture is that it's an event the other thing from the melting ice sheet such that you can get this very strong fingerprint especially expert this special expression of melt that varies from place to place where you might actually see a sea level for very close to the melting i relative sea level to fall at locations from nova scotia northward for example and the amount of rise we would experience would become increasingly large as we move away from the greenland ice sheet such that there would be more rise in new jersey than in boston and it would be more rise in florida than it would be in new jersey so we have more to worry about on the east coast if the  want to factor in if you think you have future changes and how they may vary from place to place it depends which i she is going to contribute the water in the first place which goes back to your relative point just opposed to the average point  we in terms of where the so there's this distribution of the rise is an equal come back to that in just a second because does the geology of the land itself have any effect on the vulnerability of that particular area for example on the east coast apparently we're quite vulnerable and does the do the difference in the geological differences along the east coast have an effect on the sea level rise there are several ways in which we can think about risk in vulnerability very along the coast if we think  was thinking of florida and its limestone problem as opposed to other areas on the coast the same coast that might have a much different rock based i don't know if that matters in dear and near the sea it seems so all of a these coastal areas the largest cities i believe in the world are all in coastal areas how does that business of continue development along  sea how does that affect this sea level rise should we all be running away from this or should we be continuing to develop as they are in florida on the coast so certainly people for generations have lived disproportionately everything on the cloud that most of the coast for for a multitude of very good reasons put certainly that development is something that leaves us with potential vulnerabilities yes so which is of the world scene the most vulnerable at this time you mention are eastern seacoast so we should be moving new york and boston and stuff back a wee bit apparently what else in the world is certainly been the path locally to was the east coast is an area that is potentially at risk for the reasons that it has ongoing s from ocean dynamics that push water towards the east coast he said well the vulnerable areas for example low lying islands in the pacific in part because of the amount of rise they're expected to see but also in part tonight although vulnerable areas include cities built on large delta systems yes life in india where they have ongoing subsidence as well so southeast asia bangkok for example miss pronounced right what's your prediction in terms of what these this is a lot of people in these areas what what's going to happen and how much time do they have to think i mean they're not going to be able to just build right i think we have to decide as a society what our response should be and i think the role of scientists is to provide the best most robust projections that we can and that information should be used in a transparent way for decision making and it's all about tolerance to risk and your tolerance to risk is very variable depending on what what kind of infrastructure we're talking about for example if you're building a beach home that you hope to own perhaps for twenty or thirty years you have a very different tolerance to that risk that if you're replacing logan airport for example with a structure that needs to last a hundred years it's been paid for with taxpayer money so we need  predictions to be at the heart of decision making i think the predictions are there the scientific community has certainly been forthcoming with the information but there is resistance at certain governmental levels what can the scientific community do is just put the information out there get the public revved up what's the best i think the so that the science is always evolving there's always a moment to predict has been made and i think one of the major areas of progress recently has been moving away from predictions of how global sea level will change in the year twenty one hundred a day which has been a big focus of of work in the past to try to zoom in and talk about how we'll see level change in specific l should we do about it and i think we are making progress and certainly some some areas like but they're talking twenty thirty twenty fifty now forget twenty one hundred right that it's the happening so fast let me ask you quickly about the west coast you said there is a difference there and you've done some work around that what's the deal with the west coast the west coast is a very interesting of waiting for an earthquake had been and we're talking major earthquake there can you tell us anything about that expectation so the cascadia subduction zone we know has the potential to produce a very large with a large variability in the returns from one hundred years props to as much as a thousand years certainly it is a there is a threat to the west coast from this kind of event and we actually coast the sea level rise but this would be rather dramatic if there was this significant earthquake in terms of in terms of the sea level history of the west coast it has all those factors at play that affect us here on the east coast we have up about this i've asked you specifically because you have been kind of interdisciplinary approach to your work this is a very important trend in a number of sciences right now and i wonder if you give us a little idea of how you work in this field but is trained as a as a scientist my work i frequently work with biologists and chemists statisticians computer scientists level research i think is a big part of it's good to now science in general yeah right there's very definitely it seems to be a shift and especially in terms of dealing with some of these huge issue things that you need many many speciality is you have done data that is used by the inner governmental panel on climate change is that the purpose now of this kind of work is to present this to these international forums i think this is in the broadest sense as to motivations but in this kind of work the first is very much on the science side and that's to learn something about process about how worth works from revising constraining predictions of future change do you have any speculation for the future will be ok can we do a deal with the science with the with the sea level rise  have a c o two build up in the air for example in the atmosphere there's very little that can be done about that now if we stop now we still have that problem but what if i understand you you're saying that if we could get things under control that the sea level rise would be diminished at least that it can as and if we don't get it under control then it will continue to accelerate i thank you so much for giving us this very valuable information i wish you well with all your most interesting research i hope you'll come back and tell us more about some of this other stuff that you do