tv [untitled] August 18, 2010 3:00am-3:30am PST
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. that's what we're talking about in terms of concentrations of greenhouse gas. let's go to the next one. here is a whole bunch of model runs from thcipc, imagine there's international groups running different scenarios with different climate models and so forth and we line them all up so that the top we're just looking at one spot or grid or one pixel over north
california and the models are run not only forward in time but also retrospectively. run back. they can replicate what we've seen and that's one of the tests of climate models and what we see is, without a doubt, every climate model is warming. this is the 0 line today is todays so we took the actual temperature out of it. we'll call that 0 the departure from todays level. and this is 2100, so we can see here are those numbers that you heard earlier in the day rises the temperatures from 2 degrees celsius to more than 7 for california. this is the annual average temperature. precipitation is done in the
same fashion down here. my coleague mike calls these spaghetti diagrams for obvious reasons. this is sort of the sly mate studies and you see this but you don't see the consensus too much in this or these solutions but what is deceiving is your e ye, is drawn to the out liars going up and there's this number of a simulations that have gone down a little bit by ten percent or so. if you twisted my arm and said what's more likely for california, wetter or dryer in the future. first of all i would say our
precipitation is characterized to a large extent by variability like we've always seen. we've become accustomed to really wet periods. 1978 through 1986. and try periods. 1994 and sometimes we actually get a normal year but seems like that does not happen too often. but in these model runs there's again this subtle tendency for a little dryer so i would not be to likely to call for more wet because not too many models call for that. this is why i think there's some credibility about this. this is a little hard to see but this is a funny global
projection where the map is kind of just roll it out and it becomes a rectangle - any way the higher latitude has the advantage in this one because they got stretched out. but here's the equator, 30 degrees north and 60 degrees north and north america is here and here. let's just talk about the bottom part of this. this is the median of the projected change in precipitation where change is coated by color. red is less. what did you give me there david? 0? well, let's rearrange and i want to talk a little longer everybody is
giving me attention here. i'll promise to hasten up a little bit. red is dryer and blue is wetter. and what you can see here is that along the sub tropics the latitudes between 20 degrees north and south and 30 degrees or so there tends to be a trying so the way the atmosphere works if you look at it sideways from along the equator the air is rising along the equator and sinking polar to that in the sub tropics and in our area that's calledd the north pacific high. that's why we don't get much rain. we're under the influence of the north pacific high. what's happening in these
climate simulations is those subtropical highs, more or less, are strengthening, on the other hand if you live in seattle you might be more encouraged because it looks like there's a tendency for latitudes to get wetter and that wet goes further north. next one. well, here we have in this case just one scenario and he's imposed the warming on a hydraulic model and this is the remain of the watershed, this is the sierra nevada and this
is the infraction of april first and period surrounding 2060 and that around 2090, and you can see we're eroding the lower elevations of snow and by the time we reach 2090 in this case warmed by 2 degrees celsius, we lose 50 percent of the california snow pact. it's not in the snow. next one. that changes the hydro graph as you heard this morning. so this is october through september the aggravateded sierra run off. more in the winter period, and less in the spring and summer by a bit.
this is a recent flood. not a big one. but in may of 05, maybe some of you remember this event. it was raining up to about 9 thousand feet in,yosim ite park this is the valley and this is the storm that did it. a very warm and moist system. we had the valley flooded that the rain fall on average was just one inch but it was raining up to 9 thousand feet and above. frank back there has a bunch of snow collectors up there and his snow sensors were - rain was going through and to some extent it was melting but largely the story was we were getting more run off immediately and we got this sort of minor flood.
you can imagine if this was a may system what if it was a february system where instead of two days of precipitation we had something like 1986 or 1987 flood where we had very high snow levels. that's what we're very concerned about and that leads us to the levy problem in california. next. the bay delta here. and next one, please. and this was - we always talk about sea level rise and i heard a couple of orders of magnitude of estimates this morning and one of them was more like this where this is the more conservative,ip sfpuc, estimate where the change in
sea level you were told sea levels are rising by about half a foot. we can expect that at least probably. but we could see an accelerated rise of maybe three or four times that according to,ip sfpuc. instead of half a foot we could see three feet. you know out here at fort point here in san francisco. first of all we don't know what the climate is doing to do, but secondly, the way ice gets dumped into the ocean from the land based - well sea level rises from one, the water gets warmer and inflates because it's density is less and that's well understood and handled by
climate models. what's not well handled is the fact that when ice gets shed from green land and antarctica, there's 70 levels that if it all melted would raise sea levels but the problem is it's not like an ice cube where we're shining a lamp on it to watch it drip. it might slip. we're seeing more and more of these failures and we saw part of antarctica, shed off in a few days.
somebody was looking at satellite map's and away it went. that caused sea levels to rise. that mechanism is not well represented in models or understood very well. sea level rise by itself is gentle three feet of rise may not do too much but when it's couple with high tides and storms and el nino, by maybe close to a foot do things like this. this is 1983 in san diego area. and well, let's go on to the next one. that shows the actual sea level record. in the pay delta, it's not just sea level rises but the fact
that we have fresh water floods. this is the level that ice street water gauge in sacramento. darn this thing. okay. those are tides. mostly a summer period, but these are floods so you can see, you know the water levels get up to nine meters there. there's a book called, conquering the inner sea which is a history of levies in sacramento valley and trying to contain the water. the fact is, this sort of thing could potentially get more frequent and potentially higher. i don't want to sound like the national inquirer here and when you count, you take one of these climate models and look
at exceedings and this is open coast and now we took an hourly record and counted the number of times in our simulation where we included tides and elnonos, in a moderate this is 30 centimeters over the hundred year period. not three feet about. little more than one foot. these are exceeding above a level that happens less than once a year and you can see, over time how often those get exceeded. i won't go into the filigree here. let's go to the next one. you missed my cartoon but - summing up, in this report did you know the program manager
from the climate program from the energy commission and i have to say the state of california is - it's a wonderful place to work because you know, we have this rich area and we actually have a rich scientific community and state agencies that are pretty enlightening. this here meeting ain't happening in nebraska, guys. any way, california has the opportunity to really be a leader in a lot of different ways. do we have anybody from nebraska here? the magnitude of the impacts of climate change going back to the
different emission change, get much worst if the global greenhouse loading takes this higher rather than lower route. and the greenhouse loading in the atmosphere, which i should have said earlier is a big problem not only because of it's physics, but because of it's longevity. co 2 has a lifetime of more than a hundred years some what we do is compound in the atmosphere and that's why the analogy was this big barge. we can't change it rapidly. it does not rain out. this thing is there for generations. next one. it's already happening.
there's no doubt in the climate communities mind. the precipitation of course, is an enormous issue for you guys but i don't think your ever going to see with a big degree of confidence a projection you can believe. you're going to have to live as you always have. the water community is adept, but you can count on the fact that it's going to get warmer and sea levels are going to get higher. you can count on the fact that a lot of these things are going to be exacerbated when there's weather events that pile up
synergisticly. so that's where i think i'll stop. thanks. [applause] >> dan, will you take a couple of questions? anybody have any questions for dan? >> we heard from seattle that they went down to sort of a regional type model. what's the status of that, some of us have regional or coastal, not snow back. when can we expect possible help for modeling of that? >> right now. it exists. that's what we used in this
california assessment. for the scenarios they were all down scaled to twelve kilometers covering california and nevada. it's not totally adequate and i'm not saying this is a solved problem. the premium grape growers want to know what's going on in napa, valley but for a lot of water related problems i think we're okay. [inaudible]
>> what's the long-term climate - >> hopefully, we get on to that green emissions trajectory which would have co2 levels leveling off and declining. there's a lot of inertia in the system. we all have cars and you can't change power plants overnight and et cetera, et cetera. but in fact the earth response to climate is not going to make too much difference until about the middle part of the century between all those scenarios. through 2050 a climate model is sort of a climate model no whatter what you do with it. in fact if you stop all , co2 emissions today. fossil fuel is the reason it's
increasing because fossil means it's stored in the ground and now we're putting it in the air and burning it. it's recycled by the ecosystem and so forth. if we stopped everything today, it's estimated there's another half degree and full degree of warming in the system because the earth is not in a balance. that's why we're warming up. we are gaining more heat from solar radiation than infrared, the reason is it's being intercepted by the ozone and others and it's a little more
than a watt per square meter right now. but in the sort of mid range scenario we are out of balance by about two to three watts per square meter which is doing to cause all this problem. so if you had a 60 watt bulb and shined it offer the meter of the earth you'd have a big big problem. we're talking a 360th of a 60 watt bulb. that's the magnitude of our problem. the other thing to say here is on sea level rise, just because we sort of some of you watch this program called monk about this detective that's a sort of obsessive guy hung up on
numbers but we're hung up on 2100. it doesn't mean the sea level will stop rising at 2100. there was a debate on how much we should invest and so forth. as long as the earth is at a radiated balance it's going to rise and we have 70 meters of it. so it is a long-term problem. maybe i should stop i have the feeling i've worn out my welcome. so thank you. [applause]utes
IN COLLECTIONSSFGTV2: San Francisco Government Television Television Archive Television Archive News Search Service
Uploaded by TV Archive on