Glen Paul: G'day, and welcome to CSIROpod, I'm Glen Paul. The affects of climate change on marine life through warmer waters, changes in currents, disruption of reproductive cycles, and mass migration of species, is well documented. But what’s less certain is the speed at which this might occur.
New research from an international team of marine scientists is challenging previous thinking that sea life would respond more gradually than species on land to climate change, warning that marine life will actually have to adapt or relocate faster to escape extinction.
The findings were recently published in Science, and joining me to discuss it is co-author Dr Elvira Poloczanska, from CSIRO's Climate Adaptation Flagship. Elvira, I was under the impression that the ocean was warming more slowly than the land, so why is it that marine creatures have to adapt faster?
Dr Poloczanska: The oceans are warming more slowly than land – they’re warming about three times more slowly – but what we’ve done is think about warming from a different perspective. So for example, if you section(?) a particular area and you wanted to track your thermal environment, so that’s the temperature conditions in which you’re most comfortable, what we thought about was in what direction would you need to go, and how fast would you need to go, and when we started calculating the rates of speeds that organisms would need to shift, that we actually found that surprisingly the rates are very similar between land and ocean.
Glen Paul: So will it require much of an ocean temperature change for marine life to feel the impact?
Dr Poloczanska: So one thing that really surprised us was that for very little ocean warming in some areas species are going to have to move pretty fast, so if you think about a very, very flat landscape, if there’s very little change in temperature over that landscape you’re going to have to move a long way to find yourself in a new climate, and it’s similar with warming. So if that flat landscape warms by say half a degree, you might actually have to move hundreds of kilometres to find yourself in a slightly cooler environment.
Glen Paul: Hmm, so travelling these long distances, will all the affected marine species be up to that?
Dr Poloczanska: No, no. So organisms are going to respond two ways to climate change – they’re either going to stay where they are and adapt, or we’re going to see a number of species are actually going to try and track the thermal environment, but some of these rates are particularly fast. So for example, in the oceans we’re finding that the average rates of movement are going to be around 2.7 kilometres a year, and this is based on observations of global temperature over the past 50 years. And that’s going to be a challenge for many of our marine species, particularly some of our more (indistinct word – 2:45) species. So if we think about coral reefs, for example, these rates of shift are definitely going to be a challenge.
Glen Paul: And with some of these species moving out, and some adapting, and then I guess some becoming extinct, what if any species will come in to replace those moving out?
Dr Poloczanska: So we’re going to see changes in our biodiversity, so you know as much as we’re talking about for human population, we’re going to see climate change refugees in the ocean as well. So these are species that are trying to outrun global warming. We’re going to see changes to biodiversity of species who stay there adapt, so they might start changing their timing of their reproductive events, or changing their growth patterns and all of these are going to have knock-on effects for our biodiversity.
Glen Paul: And of course other sea life will then move towards the poles in search of cooler water. What happens to the species who are already there living in that part of the world when these refugees arrive?
Dr Poloczanska: Well we had a few more surprises came out this study, so one of the things that became very obvious for the oceans is that these general expectations we have that species will move polewards to cooler waters doesn’t actually hold in all places of the ocean. So if we look at the warming pattern over the past 50 years in the oceans you can see we do have quite large areas which are actually cooling at the moment. So our sort of expectations for how species are going to move in those areas might be very different to polewards, and when we start looking at what’s happening in the polar region certainly we’re seeing some very complex patterns up there as well.
Glen Paul: Right. So what about the creatures that live in the deep ocean, where there’s obviously a lack of sunlight, it’s going to be dark, it’s going to be cooler, will they feel the impacts, or is it more just those that live closer to the surface?
Dr Poloczanska: Yeah, we expect so because most of the primary production in the ocean happens in the sunlit layers. So phytoplankton living up in the sunlit layers of the ocean’s surface are primary producers, so they’re the equivalent of trees and plants on land. So they’re at the base of the food chain and this production filters down to the organisms, to the fish, and other organisms living in the deep waters, so we would expect to see knock-on effects down in the deep oceans.
Glen Paul: Hmm. And what about the data itself that’s led to these findings, how far back did you have to go looking at global temperature changes?
Dr Poloczanska: So for this particular study we just went back over 50 years of global temperature data, and why we particularly chose 50 years is because we wanted to make some expectations of how we would expect organisms to respond to the changes we’ve seen in temperature. So the driver behind doing this analysis is to produce some expectations for us for how we think species are going to change to climate change, and from those expectations we can start investigating how our natural biodiversity is actually responding.
Glen Paul: So when are we likely to really start to see these changes take hold?
Dr Poloczanska: We’re already seeing these changes, so just having a look across the scientific literature at the moment we’re already seeing reports of shifts in phenology, so the timing of biological events, for example egg laying in sea birds, or egg laying in marine turtles. We’re seeing shifts in timing of migration patterns of fish and other organisms, and we’re also recording distribution shifts, so mainly expansions at the moment in a whole suite of marine species. So as we’re starting to look for these signals we’re starting to find them.
Glen Paul: Hmm, some serious and worrying findings there, and I do hope it is taken note of. Just on that, is the report likely to be handed to any sort of international body?
Dr Poloczanska: We hope that this report will underpin some of the scientific research that’s been done on climate change responsive, but certainly this report highlights to us that we shouldn’t be complacent about the impacts of climate change in the oceans. A lot of our focus has been on land systems for a number of reasons – we live on land, it’s easy to measure and count animals and plants on land – but certainly we shouldn’t be complacent about what’s going to happen in our oceans.
Glen Paul: Indeed. Thank you very much for talking to me today, Elvira.
Dr Poloczanska: Thanks, Glen.
Glen Paul: Dr Elvira Poloczanska. For more information find us online at www.csiro.au. You can like us on Facebook, or follow us on Twitter at CSIROnews.