tv [untitled] December 22, 2010 3:30am-4:00am PST
impact but what the impact to put it back in the ocean. what are the electrical costs. pipeline insulation costs if there's a leadership or new opportunity out there who will be responsible at least from how things done get the committee to put pipelines in. what is actual cost of water today and then we with this can form a solution. >> are you part of the de salinization group where it uses part of the depth of the ocean to reverse. it's pretty fascinating technology and one that raises the question that i'd like to throw in the mix. what happens when the energy line for this crosses our on
vengsle sources today? >> i'm not sure the question the question asked who owns the pipelines. to me that depends where they are and who is served by them. lot of these kinds of investments, there maybe a call. the state obviously has along track record to investing in invasion. less though. whoever benefits from the pipeline needs to day for it. the energy issue is an interesting one and that's why we have to pay attention not just from total energy but what's the actual energy profile. when are you using it and what's the source of it some it's a very different more complicated issue when you look at the trade-offs and
in,maurine, what's the case with de salinization and the pattern, where you can avoid peak it's a lot more complicated. >> i think another issue is the technology. the cost using membranes has dropped while energies gone up. there's very advanced in singapore they have to recycle every thin with their membrane technology so our subscribers are all looking for this. de sal is not the answer to all of it. where it's wherever. conjunctive use is one of our prime uses is a way we're meeting it, soy have to believe on the membrane which is what
you represent in de sal that technology is moving so quick in respect to smart and a insuranced membranes that we're not asking the question that we're asking now with respect to membrane. >> one final piece you talked about the cost of water and that's one element to be considered but not the sole element in incremental water supply element. it goes back to the no silver bullet approach where there's not one single strategy that will work but a come polation of all the tools to help us be flexible and responsive to this changing environment. >> well on that note our time is up and please join me in thanking this excellent panel. and thank s to all of you.
at,uc san diego and researcher at is tusds and serve at the climate research division director. his work is understanding climate variability and changes particularly as they apply to the pacific ocean and north america. his specific work concerns impacts of climate changes on water resources and other sectors in west europe north america and he also worked on large scale exchange of heat and water between the ocean and the atmosphere. dan is also a director of the california climate change center a center that works to improve and forecast for decision makers in the california region and i'm sure
it's information we can take throughout the united states. dan recieved a bachelor of science in meterologist and oceanographer and received in 1971 from university that makes us about the same age dan, but i'm just a broken down lawyer and economists. he received a, ph.d., in ee in san diego. his speech today will focus on climate change and it's challenge to our water supply. please welcome doctor dan cohan. >> thank you susan, well, it's
a privilege to be here. i'm really impressed with the gathering that you've all assembled here in and the quality of the discussion. so i know that i don't want to wear out my welcome so i'll try to get through this sort of on time. you know at one time there was a pointer up here, and seems to have disappeared. so, maybe we can go on to the next slide and in the meantime we'll find a pointer. it wasn't very many years ago or not that many audiencesing a that i sort of felt like i was
in a slightly different environment than the one i heard this morning. the way i'm going to structure this talk is to - thank you - okay. is to talk about mainly observations first and then models and observations second, and then kind of sum up. so next one. if you look at the traces on this plot, which is a global average version of surface temperature of the earth, the thick dark line in this trace is actually the observe or what we estimate to be the observed temperature of the earths surface, and the other part -
the colored parts - are actually modelled these,gcms, global climate models, versions of the surface temperatures the first thing i point out, is if you look up to the middle part of the 1900's, what you see is the models replicate observations pretty well. now what i should say is there's two versions of the models run here and this is the beauty of models. we can run them, within this case greenhouse gas enforces included or excluded. the blue envelope is the set of model runs done without greenhouse gasses and the red envelope is the one with. so the message here is that up
until about 1970, the two families follow each other pretty closely then they start to diverge. the reason they diverge of course, is greenhouse warming is becomeing a stronger influence and the actual earth climate is starting to feel that and depart from what it would look like if - i can't get the pointer to work - but if we only had natural variability, which you can see by the end of the 20th century the difference between modelled with natural variability and the actual observations or model with greenhouse gas forcing is half a degree
celsius or fahrenheit difference. so we think what we think we can attribute to, anthro pe ingenic, forces. now i would assert that whether it's human or not. it does matter because if it is, then we can anticipate this is going to continue. in other words having a reason of the cause of climate is imperative for your business because it let's you plan, and if you believe us guys, the climate guys, then what we're going to see is going to
amplify this diverge. in the west you heard an interesting session just an hour or so back on the mountain watershed issue and of course, one of the principal differences there is snow lines become compared to present day or the climate that are tradition based on snow climbs are going to be higher and they raise about half a kilo meter or so degrees celsius. 6 degrees,c, perky lom tear. i don't want to try to do this
on the podium. that has the effect of reducing the natural reservoir snow we could usually use in spring and summer and liberates more water immediately which is the flood water that you heard the director of the california water resource s talk about. we saw the global average picture but this is what's happened in the west part of america since world war ii, we've seen this large area - this happens to be a time averaged march, april and may. that's our classical springtime in climate terms. this red shading means we've warmed welltive to a longer term average by something like
a degree celsius to as much as two or three degrees celsius and that's in central or west canada. so, we have seen quite a warming over the period of our professional lifetimes. let's go to the next one. further more, if you simply play a sort of a thought experiment which my coleague mike has done here for the landscape of the united states, and what he's done is taken a census of precipitation, day by day every event that's occurred over along period, and he's cataloged how many of those events occurred where temperatures were in the range of minus 3 degrees celsius,
just below freezing and freezing and what's shaded on here is the fraction of time for a given location in which the precipitation has occurred in that temperature range. that's a range of what we might call vulnerability because if temperature rises by three degrees celsius, all of the sudden we're not snowing anymore we're raining. you can think of this as a flood vulnerability map or a potential loss of snowstorm or the western problem as you can see and particularly areas like the west slope of the sierras and the cascades and part of the rockies are especially vulnerable to this. we in california have a huge
stake in this sort of - this kind of vulnerability to warming. you can see there's some in the northeast but not to the degree we have here. we've already seen over the west,mory, is sitting in the audience, the hydraulicist and he looked that fraction of run off that happens between april and july. our tradition snow melt period in california, you can pretty much attribute the volume of run off from the sacramento system, which is - that's what
is mapped here occurring between april and july attributed to run off, and that has declined from what used to be, i'm having trouble reading my own slide here but i'm thinking that's 40 to 30 percent, but we've lost a significant fraction of that spring and summer snow melt run off, and when viewed across the western landscape, that's lower map picture here on the left where the red dots represent earlier timing of snow melt, basin flows and the blue one's mean later. earlier ones mean spring is coming earlier and things are warming up. we see an earlier footprint of
the flows and something of the timing of a week to three weeks averaged across the whole network probably about a week earlier in this period since 1948. next one please. coleagues that university of washington and coleagues have looked at snow courses across the west, and looked that april one measurement from snow courses and reconciled that there has been a trend in the april one water content which red here is a trend towards lower amounts, the blue is higher. you can see most all of the elevations except the really high ones in california and some of the southern rockies
have lost snow on april first - about 75 percent of the snow courses are showing this decline. when you map out these declines, this is this plotted - the trend is plotted from negative to the left and positive to the right that bottom there and elevation is traced on the vertical scale here, so lower is down and higher is up and lower is warming and higher is cooler - you can see the larger losses, of course are occurring to lower to middle elevations in our western areas and that makes sense. those are the areas closer to the freezing level.
mr.noels, conducted a study of precipitation gauges across the west where first of all, climate wise these have been ones that have received snow and they have a fairly substantial record and also they've recorded snow - snow fall, that is they have a snow board or some other ability to record daily snow accumulation and over about the same period as we looked at in the stream gauge network. he shows the ones that have lost and gained in the precipitation as snow. as you can see, the large majority - again about 75
percent of these weather stations are receiving more rain and less snow over this period. so, we are see inging rivers flowing earlier. the melting season is coming earlier and we're seeing storms delivering more rain and less snow. the storms themselves are warmer not just the interstorm periods that are warmer. so the climate of our generations is warmer than our moms and dads and our grandparents. next one. so, let's consider what the climate models have to say about all of this. next one. first of all, just to remind you about the greenhouse effect.
here we have two mra net bodies. the moon and the earth. the moon does not have an atmosphere so it has no trappings of gases like methane and co2, and so forth which are the reason global warming is happening. the moon has an average temperature that's about 33 celsius less than earths on average. so the greenhouse effect is a natural phenomena. the greenhouse effect your used to hearing about on the news by president bush and all those other experts is the
incremented effect well we've added about a third to the sea level and as well as others but if you want to question the viability of the physics, here's a great example. now, this is looking forward. these are these so called, emissions scenarios. you heard of the intricate climate on government changes which will announce it's first reports for the global assessment coming out this summer and spring and in order to conduct those experiments they have to make assumptions about the future. what sort of loading of the atmosphere we'll see in terms of greenhouse gases and here's a swarm of different scenarios
which of course depend on economics, sort ofgeo political relationships, regulations and technology and so forth. the environmentally friendly scenario that you might look at is this green one down here, and the more carbon intensive fossil fuel economies are these. this is not the, co2 content this is the flux of, co2 into the atmosphere, so this scenario has emissions increasing to the middle part of the century and for a variety of reasons. probably the variety resembles the variety of reasons people are talking about in imagining
their water supply portfolio. we also have a care upon supply portfolio to the atmosphere. so, there's been a number of climate experiments and to a large extent hinge on these scenarios of what's being loaded into the atmosphere. so that's lying behind what you see. in the recent california assessment, we used three of these scenarios. or at least models that were based on those to guide us in assessing what might happen in the state of california in sort of a broad base of different impacts ranging from water resources to forest, human
health, beeches, coasts, agriculture and so on. let's go on to the next one. okay this is kind of one of those tricky power point graphs and this is where i pretend i'm al gore. now we're taking longer point of view and these three traces here at the bottom is global temperature, surface temperature of the earth. this is made out from proxy records and we did not have thermometers a hundred and fifty years ago so this is reconstructed from sediments and ice ansisotopes and so forth and the top is co2, so
this is in hundreds of thousands of years and it's interesting that you see this pretty remarkable sigh lick or cycles and this is the climate and other periods of earth history we would be huddled in a cave right now or something. the - one of the primary factors in causing this period or rough period is the fact that there are orbital properties of the solar system and planets resolve around them and in this case the
exintrinsicty of the earths budget that changes and that goes, it has about a hundred thousand year period and low and behold there was a guy that was kind of able to reproduce temperature records going back and that's an old story that's well-known. let's go to the next one slowly. you see the temperatures tend to rise fast and then decline on this you see more co2, more plants and more liberation of co2 that's stored. but notice the vertical axis here. this to this point does not include the industrialization
period and the co2, never gets above 300 parts per million. oops, well go back. unfortunately we missed the climax here and that's why i'm not al gore because i don't have a production staff. but, what's happened now is that co2 has increased to about 280 parts per million and in those scenarios i showed you of the co2 flux, if we're lucky the co2 at the end of the century becomes about 550 parts per million and doubled and if we're unlucky or at least our kids or their kids it becomes over 900 and more than triples.