 ...duriosity driven, but over time the evidence has become more and more overwhelming that we're having a very damaging effect on the climate system. And we know that organisms face environmental changes all the time, we know that they're dealing with the environment changing on a daily basis, on a weekly basis. The issue is how much climate change is going to take that beyond the bounds that they're used to experiencing. The thing that I'm especially concerned about is actually increasing incidents of weather extremes. Heat waves kill things and weird heat waves in the middle of winter time kill things really fast. And what climate change is doing is it's increasing the probability of extreme events. So not only is the mean changing, the mean is changing actually doesn't seem that much a few degrees, but the probability of extreme 15 degree differences is becoming much more frequent. The early evidence is alarming to me because it suggests that we're losing populations from places that are experiencing increasing frequencies and intensities of hot summer weather. They've worked out that there is a threshold temperature above which they get mass extinction events and fruit bats. So it's something like 42 degrees. One of the things that's interesting for me as an ecologist of course is that you don't need a thermometer to tell that climate is changing. We see this in hundreds of species across Canada. They are shifting north at a pace which is incredible and the only explanation that we have yet been able to come up with any biological meaning for is that this coincides with rapidly warming temperatures. So if you get really hot dry conditions in places near the southern edges of species ranges, this wipes them out. So it actually looks like it is possibly the mechanism for range loss at the southern boundaries for species ranges might actually be these increasing intensities of those kinds of events. Climate change is very much pushing koalas eastwards towards urbanising centres. So what we're getting almost is a real impact from increased weather extremes to the west of their range. Long, long periods of drought and heat wave and the koala just can't thermoregulate. The question about whether the issue of whether or not the organism is going to be able to track the environment sufficiently fast, I think in many cases they won't be able to. We have shown that the even butterflies, this is like the ultimate in mobile species, short generation times, highly mobile on an individual level, even butterfly species are not able to keep up with the rapidity of northern climate change. The adaptation measures for koalas are not great, they're not very mobile species. So for instance if their climate envelope has shifted 300 kilometres eastwards, a koala can't just think, I'll just hop over 300 kilometres, they're not that mobile, a male may travel up to 20 kilometres maximum if he's leaving his home range and leaving his mother and wants to create his own territory. But a female koala, if she has adequate habitat, will often only move 4 or 5 kilometres, even smaller home range if the conditions are favourable for her. So to expect a koala to move hundreds of kilometres under such rapid climate changes we're experiencing now is impossible. So this is why we're getting real population crashes in those areas. One of the things we really value about biodiversity is these interactions between the species. It's not just this species that looks like this and lives here, it's actually the interactions it has with all the other things it interacts with in its lifetime. And those things, particularly in seasoned environments, they depend on all this and synchronising their emergencies or their emergence times or their behaviours with each other. The timing, the emergence periods for species around the world have shifted. So they are coming out by and large earlier. For species which are locked to things like the seasonal differences in light availability, so the timing of day length. For flowering plants, that's particularly important. Most of the time, that is not how it works for animal species. So in the case of pollinators, for instance, and the flowers that they may be associated with, what we are beginning to see is that where their timing used to be more or less matched up, because of the rapidity of climate change, that timing is kind of being ripped apart. It's a bit of an overlap problem in terms of when some pollinators emerge and the flowering plants that they are associated with will emerge perhaps a little bit later. And that, it always uses kind of these environmental cues, which is incredibly fantastic and amazing things that organisms do to match. So they can survive winters, they know when to go and they use environmental cues to decide when to go into diopause, when to hibernate and then when to emerge. Now the difficulty is with climate change, those cues are no longer as coordinated as they were, they're no longer as useful. So for example, the temperature and the photo period, so the day length, is no longer has the same correlation that it used to have, it has a different correlation. And this means organisms may start to make mistakes. And so not only for their own survival, they have to actually come out at the right time to actually exploit their resources, so they have to emerge, say pollinators have to emerge at the same time as the flowers. Otherwise the flowers don't get pollinated and the insects don't get fed. The other thing that happens is that they run out of host plants. So butterflies can move really fast, but their plants are not fabulously mobile, as you might well expect. And so if they run up against the boundaries of their obligate host plants, they're out of luck. I mean they can't go any further than this. But the trees are also being affected by those droughts and heat waves. So the trees are drying out, so the koala's not getting the nutrition and the moisture through the leaf content. Because of course that's what they're completely dependent on. They have a very limited diet. And then of course, so their food resources getting affected as well. But their climate envelope that I've modelled suggests that anything over about 37 degrees stresses them. And of course now in Australia, we're experiencing a week of days in the 40s. So those prolonged extremes in climate are really affecting the koala. As I say, in butterflies, 75% of the species we define as specialists, they have particular species they depend on, their ranges haven't tracked, they haven't responded to climate change effectively. They are effectively condemned to extinction in increasingly fragmented patches. When you're a global change biologist, a lot of the time it feels like what you're studying is like global catastrophe that's unfolding in slow motion and it's important stuff. It's really important that globally the oceans are acidifying or that we are losing species at the rate at which we lost them at the end of the age of the dinosaurs. I mean, this is disaster movies, it's just unfolding at 100 year timescale. We have to tell people that that's what's happening. Failing to do this, adding unnecessary layers of caution that is inaccurately conveying that these processes may or may not be happening is doing the public a disservice.