 I'm just going to, this is a science, here's my toolkit, sorry about that, and I'm just going to explain this thing called the Ominous Southern Oscillation. So, what climate change is going on, the expression of climate change will still be delivered through natural variability. This is the dominant mode of natural variability in Australia, and it's the one that we should still be looking out for. So we can predict this thing about six to nine months in advance. It's what our operations in terms of climate are centered around. It gives you a heads up for that disaster season, which is which fire and cyclone season in Australia. So it's El Niño and La Niño, which most people have heard of. What does that actually mean? I'm going to ditch this thing, use the spacebar if that's okay. So normally what is El Niño and La Niño, what does it mean for Australia? It's variability that's driven off the tropical Pacific. So normally you can imagine the earth sits there, the sun is shining on the tropical Pacific, it's making it very warm, the surface of the water over the tropical Pacific, and the trade winds blow from east to west. So what they tend to do is they pile that warm water up in what's called the western Pacific warm pool over the Australian region. And that's where the rainfall is, so the rainfall follows that warm water. So normally you're getting a situation where it's drier over the other side of the Pacific and it's very wet over the Indonesian and New Guinea region. So that's like a neutral phase, that's what it normally looks like. During the La Niño what happens is those trade winds blow even stronger and they pile more of the warm water up in the Australian region. So that pool of warm water now sits well over the northern coast of the Australian continent. And it means an increased chance of rainfall over the eastern half of the continent and that includes down to Victoria. So this is still the dominant mode of bringing floods to Victoria essentially. What's an El Niño? An El Niño is a reversal of the trade winds, so I won't go into why these things happen. They're just part of the dynamics of the climate system. But what happens is the trade winds reverse and you actually pushing that warm water over the eastern Pacific and the rainfall follows it. So it's now raining in the eastern Pacific, over Chile and South America and you tend to have droughts or reduced chance of rainfall over eastern Australia. So often those large stretches of heat waves and dry conditions come during El Niño events themselves. So this is that really big roundabout of swimming in the climate system that affects Australia. There is a cohort to this in the Indian Ocean and the phase of these two things is really important for Victoria. So normally in the Indian Ocean the trade winds blow the other way. They're piling that warm water up into the Indonesian region again right throughout that southeast Asian area. A negative phase of the IPO is the intensification of that pattern. So you're having more warm water to the north of Australia. It brings this rainfall down in this northwest cloud band kind of pattern and you can see that green zone there is the chance of increased rainfall. This is something that you quite commonly see just as a natural expression of the weather. So it's an intensification of that cycle. And the positive phase is the reversal of that. So reduced chances of rainfall. So why I'm showing this is because for Victoria what happens is really when you get these two things reinforcing each other is when you're almost guaranteed of extreme climate conditions in Australia. So when you have a negative phase, the Indonesian dipole and the La Niña you're almost guaranteed of heavy rainfall to that eastern-southeastern part of the continent. So just before I move on this is what I'm talking about. So the blue here is where you get highest on record rainfall. So you're drawing your eye down to the southeast. These are the really big La Niña events. So you can see almost the whole continent is blue here. So very much above average to record rainfall. This stuns climatologists from overseas. Mostly continents have a mix of dry and wet conditions. But these are the sorts of events we're talking about. Going into the most recent period where we had a twin La Niña event and really extensive flooding through Victoria. And flooding in Victoria once it gets there lasts for weeks, if not months. So that's natural variability. That's one element of climate risk. I'm here today to talk about a new climate risk introduced by changing atmospheric chemistry itself. So you can hear about globulinmy temperature and a range of other things when they talk about the climate system. This is the one graph that really is salient to climate scientists and to the downstream impacts of climate change. It's carbon dioxide in the atmosphere over the last billion years or so. This natural variability in carbon dioxide is driven by the ice age cycles. So the peaks here are the interglacial warm period, which is where we were when human civilization came along and the troughs there are what the collice age is basically. So what's happened in the last 100 years is you can see the maximum CO2 content in the climate system during this era known as the Pleistocene where we were known for the ice ages and interglacial warm periods was about 280 parts per million. That's now shot up to around 400 parts per million. Why is that important? If you go back before the Pleistocene there's an error called the Pliocene. That's the last time CO2 levels were about 400 parts per million due to naturally occurring changes in the climate system. It was about two or three degrees warmer. Sea levels were about 20 metres higher at equilibrium. So what happens if we stop emissions tomorrow? Over the next thousand or 2,000 years we'll slowly warm up to that mid-Pliocene level so you have a warmer planet and a higher sea level. So when you talk about mitigation we're basically talking about putting a break on further emissions because we want to actually slow the pace of climate change. These sorts of spikes in atmospheric chemistry have only occurred in the geological record in association with massive planetary outgassing when you have really large volcanic activity or asteroid strikes. They're almost all of them are associated with mass extinction. So that's why most climate scientists are actually faced when they talk about this plot. It's not a good mind at least. So what does that mean? What we've had is a 40% increase in greenhouse gases. This is a plot of global mean temperature. That's land and ocean temperature. You can see this large trend so all of the warm years have occurred in the last decade or two. Significant warming from the middle of last century. In terms of that important part of the climate system, the oceans and how important it is for Australia here's a plot of ocean temperatures as we estimated them about the middle of the 19th century compared to today. So it's a massively different climate system and this means a very different region for weather already over Australian globe. So I'm just going to focus now on Australia and Victoria itself. Australian mean temperatures increased as well so broadly in line with the globe. You can see there's more variability here and that's basically because we're looking at a smaller part of the globe. So that's mean temperatures. They've warmed up by about 0.9 if a degree. So almost a degree since good measurements are available which is about from 1900 to 1910 onwards. So it doesn't sound like much about degree of warming. It changes by more than that from night to day and from one season to another. Why we're concerned about that degree of warming. It basically pushes the extremes even further and it means that the frequency of weather is quite different. So if we look over the last two years these are our warmest periods on record for Australia. We had the warmest year on record in 2013 and the 24 months were easily the warmest on record as well. If we go further north into Queensland for example where they've been experiencing quite bad drought. The rainfall deficiencies they've experienced haven't been historically the worst on record. They're probably not as bad as they were in 2002-2003 but they've had more drought declarations than any other time since about 1960 when they start collecting those statistics. What are one of the reasons there's probably socio-economic reasons for that. The other one is that that drying and that drought occurred during record temperatures over a 24 month period. So that just means that you're basically sucking the moisture out of the soil and out of the vegetation as well. So that's one impact of a change in mean temperature. The other and this is as science is the talk gets. These are bell curves of temperature so temperature is normally distributed near anything else. And this is a plot of what happens to the extremes. So what we've got there is bell curves from 1951-1980 in blue 1981-2000 in grey and 2001-2010 orange. So these bell curves are moving to the right. That means it's warming up. So the average climate is warmed by about a degree. It's out at the toes that we're interested so these are two standard deviations which means extreme monthly temperatures. And so the main thing I want from this plot is really these 2, 7 and 10%. So extreme weather that occurred about 2% of the time in the 50s to the 80s. It's now occurring about 10% of the time so it's about a 5-fold increase in extreme heat. And that's the same for daily temperatures, monthly temperatures. What we're finding is the extreme heat is occurring about 3-5 times more than it was in the past. So here's another way of looking at that. This is in Australia where we can actually calculate daily temperature for the whole continent back to about 1910. We've got really good records. So that means we can sort that into a percentile. So a bit like exam marks, this is the 99th percentile and the frequency of how many times we hit that 99th percentile. So the very warmest 1% of days over the last century. And you can see there's a trend there. So something's happened to my years at the bottom there, I'm not sure what. So this starts in 1910 takes about till 1940 to accumulate 28 days where the national temperature hit that 99th percentile so that top 1% of warmth. Why do I choose 28 days? We've got 28 days in 2013 alone. So that means the frequency is rapidly increasing. You can slowly change that mean temperature. You can see there's no change for the first 5 or 6, 7 decades. And then suddenly you're pushing that tail out to the other end and you're starting to see large changes in the extremes and that's salient for everyone who's in the adaptations base basically so they still have to cope with those extremes. And I've chosen temperatures here I could have talked about sea level so if we're up north and we're more exposed to storm cessation, tropical cyclones I could talk about that. But you can take this I guess as a general overview of extremes of the climate system. This one's just expressed on temperature itself. So I'm going to talk about a couple of days that would have been included in that plot so the sorts of days we're talking about is where we have heat spread over more than one state it's over a large fraction of the continent. So basically that plot summarizing that we're getting more heat waves they're more frequent they're longer when they are occurring and the central intensity of those heat waves is hotter. Especially in the last 10 to 15 years. So one a day that would have made it in there or one week really is the Black Saturday 2009 heat wave. So we're talking about events that look like that. More silently again I guess is the January heat wave in 2013. So 2013 for that January we started off that record year with really really hot temperatures a heat wave that was we only came close to once before in the record in 1971-72 and even then not really. So basically we broke every sequential record from one day through to one month in January 2013. This is important for people in charge of operations so from the Bureau's perspective during that week we were flying in or that month we were flying in forecasters from the US to give people relief off the bench so they could get some sleep. Of course these days you just go out and fight a fire and our models and our grids as much as possible during that period. So you know when you're getting these events and we're very lucky during this period in terms of the fires that did occur there was a lot of fires but luckily not a huge loss of life. The most high profile one I guess was down in Tasmania and the Denali fire but across New South Wales and Victoria and South Australia. So as you can see from the combination of these plots we're talking about these sorts of conditions not occurring for the next 10 years. We're talking about them occurring multiple times per season as we go into the future so that's a massive change when I go and talk to others around the Country Attorney General's departments and others it's really that change and that frequency that starts to increase itself in terms of what we're talking about here. And that really leads to an increase in fire weather as well I'll quickly talk about rainfall after this but this is the forest fire danger index and these red dots are where the danger index has increased both in terms of the amount of fire weather during the year a longer fire season and the extreme days, the extreme fire weather days becoming more extreme essentially and you can see the clustering around the south southeast there fire prone region anyway here's our graph from Melbourne Airport a lot of that variability is due with droughts and rainfall cycles but you can see a clear trend in terms of this FDI going up I'll quickly look inside so that's our sort of case study Black Saturday you couldn't say it was caused by climate change but it's really consistent with the sorts of events that will become more frequent and my won't go into the impacts I don't need to here but the sort of things that line up is a record heatwave record daytime temperatures record nine time temperatures a prolonged drought that was record breaking in some of its aspects and consistent with some of the projections going forward so I'll quickly talk about some long-term over Australia rainfall has gone up which is consistent with the greenhouse world you actually hold more water vapor in the atmosphere and in the tropics it tends to rain more in the higher latitudes it tends to rain more as well so you see that so when we're talking about rainfall increasing in Australia it's mostly from tropical systems that have originated north of that red line that I've drawn there it's just a marginal increase it's not a statistically significant increase and you can see it's concentrated on being fed by a much, much warmer Indian Ocean for us here in Victoria and our friends in southwest WA it's really the dry and this is again related to climate change those sub-tropical regions as you increase you don't just increase the water holding capacity you actually increase the ability of the atmosphere to evaporate so already dry regions tend to get drier and wet regions tend to get wetter so I've chosen southwest WA here just because the signal is so clean so again blue here is wetter than average red here is drier than average and I'm looking to walk away from this microphone but hopefully you can see the step change in the rainfall that occurred in the late 60s, early 70s so you have to go back to the mid 60s to get a really wet period in southwest WA and since then the wet years have gone and we've had this 10-15% drying in their winter climate so still getting rainfall in summer but the main rainfall coming from coal fronts and cut-off loads so the things that I've circled there that's where the rainfall is coming from and we're getting less rainfall from those it's still raining when we look at the rainfall over the southern ocean to the south it's actually raining more so what's happened is these fronts have pushed south it's a little bit like moving into a more permanent spring or summertime situation you're pushing those fronts further towards the pole and it can switch off quite suddenly just because it's quite marginally it was only getting the tip of those fronts coming through and then as you move the south it can actually change and the step change. We've seen a similar change in Victoria and the southeast since about 1995 even given those two wet years there is a 10-15% reduction in autumn and winter rainfall which is related to that fire increase that I've just shown and it's related to the impact of the next long drought I guess in Australia itself I've been over the southwest WA I've gone down into limestone casts underneath the carry forest that forest is similar ecological niche to the mountain ash so it's obviously rained in that part of the country for millennia it was the most reliable which time rainfall in the country actually it's still that most important grain-grain district and the limestone casts are dry you can see the high water mark from the mid-70s you know a couple of minutes above your head you can snap off some of the carry roots in your hand it's quite stark actually going down so that's what we're talking about in the introduction we talked about southern California they're experiencing similar things basically any part of the globe which was in the subtropics getting these westerly winds delivering the rainfall has experienced this drying and that is very symptomatic of global climate change itself so change is an extreme rainfall even in those regions where it's projected to dry when it does rain the rainfall is going to be heavier and that's just this densification of the hydrological cycle itself so that little sort of schematic that you would have been shown at school water evaporating off lakes going into the clouds and rainy you're basically souping that cycle up as you add the heat to the climate system and so just going through that I showed this plot earlier on of those twin line linear events that occurred in 2010 and 11 that's natural variability what was the influence of climate change well these are sea surface temperatures around Australia during that period and the orange there is when we've got the warmest on record so we've never seen those temperatures before you can see they're sitting off that northwest part of Australia so very important for rainfall in Victoria and you can see the impact on the record rainfall so we think the studies are showing there's probably about an extra 10% push from climate change on top of natural variability so that's what we're talking about and this is just a plot of the proportion of rainfall that's coming from really heavy heavy rainfall events there's sub-24 hour rainfall events across Australia and that's going up so what we're saying is the proportion of rainfall that's coming from extreme rainfall events is actually increasing and that's consistent across the globe and it's consistent with the climate model projections so just quickly touching on future projections this is just looking at sea level you can have this for temperature and really what I want to talk about here is the difference in the emission scenarios so RCP 2.6 is an theoretical emission scenario where we start removing carbon dioxide from the client system RCP 8.5 is an extreme or a high-end emission scenario it's also a business as usual business scenario unfortunately so when we talk about uncertainty and future climate change some of that's due to the emission scenario itself it has a natural component as well so if a volcano goes off a number of volcanoes go off that affects that emission scenario as well and then the rest here is just due to what we call the transient response or physics in the climate system so this is uncertainty in terms of what happens with the oceans what happens with polar ice caps things that aren't in the model so methane clathrate is permafrost in the northern hemisphere once that starts melting it releases carbon methane to the atmosphere very powerful greenhouse gas so when you're looking at that range these are the uncertainties the problem is the bottom of that range is really quite extreme in terms of climate change so when we present these to people it's like well that's a lot of uncertainty there's no comfort in that unfortunately really what we're saying is the bottom end is going to be hard to adapt to and that top end is one that you want to avoid I like to show you this at these kinds of talks so this is an uncertainty cascade and what it means is up this end is our uncertainty around CO2, global climate it's a lot smaller than it is for specific localised impacts this is kind of diabolical because specific localised impacts it's at that end of scale that a lot of the policy agility is it's where people need to act it's where people in this room actually have to start enacting their plans the less you mitigate into the future the bigger that uncertainty is at our end of the scale so I like to connect these two things together we're not just talking about adaptation here the two things go hand in hand so here's another way of looking at that here's that RCP 2.6 limiting warming to about 2 degrees over Australia and I'll come back to that RCP 8.5 you're talking about maybe 6 degrees of warming over Australia the rainfall on the right there the stippling there is where you have no significant change from natural variability so under a low emission scenario not much change in the rainfall under a high emission scenario you're actually starting to see a significant drying out of the southern half of Australia and interestingly how it's picked out south west WA these models know nothing about the real world observations they don't know anything about what's happened to rainfall in south west WA all they know is that the greenhouse gases have increased so it's really quite stark to see how they line up with the real world itself so this is the way I communicate that these days so instead of showing the projections we've actually got landscape analogs out there that we can look at and that people can understand so if we start in the Yarra Valley there in Melbourne and we just theoretically get 2 degrees warmer and 20% drier you actually move to somewhere out in the Wimmeram Alley or out in the clear south Australia so similar but different but a lot less rainfall you're losing your high-end rainfall ecosystems you're going to slightly drier cropping cycles and the like that's 2 degrees so that's like that guardrail that we're basically saying we want to limit warming to you can go 2 degrees warmer from clear or 4 degrees warmer from Melbourne and now you're in the Central Darling so a very very different climate system altogether there's no agriculture there's a very different environment and that's what we're trying to avoid that 4 degree scenario so this is another way to look at the projections I guess from that perspective so this is RCP 4.5 we're currently overshooting that it's a mid-level emission scenario these are about 30 different simulations for Australian annual temperature and the white there is what's actually happened over Australia and again these models don't know what's actually happened over Australia it's amazing how well that lines up really showing the influence of greenhouse gases dominant in Australia and there's that record warm year 2013 sitting there in the record with you know why heat waves and everything that ensues so that becomes about an average year by 2030 in terms of its impacts on Australia and then going out to about 2070 it actually becomes a cool this year so again adaptation has its limits in terms of what we're talking about I don't want to be too going home about adaptation when you're looking out to the end of the century what that upper graph there means those extreme years up the top there whether you can adapt to that or not and again this is why climate scientists you want to limit that warming to something that's manageable so I haven't talked about adaptation I think that's in the talks that follow here but I'm just again setting the scene and that's the end, thank you our reflection there everyone is that we are just so lucky to have the Bureau of meteorology doing this work for us and there's so much expertise that we can learn from and draw from that well if you're anything like me your minds have just been blown a little by some scary projections and some things, some motivation for us if we take them on the day does anyone have any questions for Carl anything you'd like to understand a little more about Craig does I think there certainly seems to be a step change in the rainfall from the early 70s going onwards now it's probably it's hard to say whether that's definitively a result of climate change it's definitely consistent with a warming planet at that time there's natural variability in there as well so there's this sort of decadal variability through the ENSO or the El Mino cycle as well but yeah certainly it seems like we've moved into a different rainfall regime following a really large cluster of Latina events and when you're looking at the way climate change is unfolding as I say it's sort of, it's managed in a way by natural climate variability so you'll notice the big spikes up in global mean temperature the last one was in 98 and that was coinciding with a really large El Mino event so we're sort of adding heat to the oceans at 90% if the additional energy from greenhouse gases going into the oceans that's changing the way the oceans vary so the planet's kind of warming up like a staircase and you can see these kind of step changes in the rainfall and the temperature so we don't quite know why there's a sudden change in the early 70s but we suspect it's due to the background change in the climate system I have a question if I can I've been hearing through rooms such as this or people in the rooms such as this about this summer and an El Mino after way now that I've learnt a little bit more is it on both sides? No, we've got neutral conditions in the Indian Ocean but we've got an El Mino event now at the moment so we can close last year to getting an El Mino event sort of surprised a lot of climatologists that we didn't get one and in this year we've got one quite early they kind of spurred on by tropical cyclones in the western Pacific so we had twin tropical cyclones around the time that I think Pam hit Vanuatu that kind of spurs El Mino along and we just had a couple more really late in the season that's pushed it on again so almost certainly we'll be in El Mino conditions by spring in summer in Australia which means dry conditions most likely when you get really extreme El Minos you almost always get flooding in Australia extreme El Minos don't always mean drought it's not quite symmetrical with the tropical and the late impacts but certainly the last we've missed out on the monsoon up north the last three seasons in a row so the very way we use that weather and Queensland but western Victoria is actually really dry and that's again it's a long-term run and there's sort of starting off or looking into the remainder of the year with a bit of trepidation that plot I showed about the changing frequency so we're getting more heatwaves in spring to give you an impact of what that means so that can knock about 10% for wheat yield in western Victoria just by coming at the wrong time of year and the fine parts of WA they're actually sowing earlier so they're taking advantage of the summer rainfall and they're trying to actually harvest before so they've changed their cocking cycle there and most of the viticulturalists because they keep such fine data so you find viticulture I think like really fine wool merino breeders they're under no illusions as to what's happening with the climate system because they're seeing it across the landscape for their own peace so yeah would you all join so I'm going to have questions SES I'll do that sometime can we hear the spaces Jack Marcus said that I was interested in your comment about the weather systems that come across from the west and how some of them are tending down towards the Antarctic what is the relationship between that and La Nina and El Nino and is there also an impact from the monsoon that's coming down from the north they're all interconnected basically so there's a pole of vortex around the continent and that contracts towards the continent or pushes north part of it is in concert with El Nino and in concert with say in the Indian Ocean so generally what we're seeing is that vortex is more contracted around the continent more of the time which means that storm tracks are getting pulled further south they're all they all share variability and yet negative IODs or dry conditions in the west in association with El Nino is on average but yeah I'm not sure I've answered your question but you can maybe chat to me afterwards and I can answer a bit more but yeah all those expressions of natural variability as you're adding heat to the system they're actually changing and that's the major challenge for us is to understand how those modes are changing the background climate system Tim, did you still want to ask a question? Carl, the current modelling that the Bureau has quite often struggles or is challenged by the extreme so extreme heat or extreme rainfall sometimes underestimated by 2 or 3 times a year in light of what all the statistics are showing what's the Bureau doing I guess to work at those models to try to give us a better chance of knowing what we could replace it So you're talking about a weather forecast now? Yeah, absolutely The extremes is really interesting for us so I'm not being recorded so I can sort of say some of this stuff I know it's live, I am live thanks so as you go further back in so if you go back to 30 years or so the rule of thumb was don't forecast a record particularly not on a weekend because there's no one on duty so the forecasters for years were trained to be skeptical of something where you were seeing a temperature that you've just never seen before that's now changed so we've sort of moved into a space where we're starting to get forecasts that basically forecasting records so we're implementing a system that actually tracks that in itself rather than just a forecast now it's going to be 45 we actually want to know where that sits in terms of the historical record so that means we've got to do a whole lot more verification to actually understand whether we can just trust the model without any input from a forecaster because a forecaster's biggest job is to use their personal experience of what six different models have done in a particular instance so you get an east coast low you might survey the Australian model the US model and you know which ones the system is better when you move into a climate system that's doing stuff you've never seen before then you have to really place your trust in the models itself and actually I think the models have been coming out pretty good we're about to move to a new supercomputer which is the biggest increase in terms of model skill that you get and the new satellites just come online which is Himalari 8 so previously we used to get about a 10 minute imagery that means we can basically watch a tropical cyclone or a weather system in real time and we're starting to draw with a bigger supercomputer you're actually pulling more observations in at the start so really in about two years time I think you'll have another step change in the forecast capability it's already increased basically the skill of a one day forecast at the time of Ash Wednesday is now about the skill of a four day forecast in terms of a Black Saturday event and things like the wind changes and others are what we're focusing on predicting so I think in terms of meteorology as a form of adaptation that's something that certainly we're thinking about and moving towards do you all thank you so much Carl would you all join me in thanking Carl thank you again Carl that was really great