The Cost of Climate Change on Coral Reefs

We speak with Dr Katharina Fabricius about climate change's impacts on the oceans and coral reef ecosystems. We also talk about how little the ocean has been explored, that it is the worlds largest carbon sink, the effects of coral bleaching, ocean acidification, if there is any potential for corals to adapt to warmer ocean surface waters, and other topics.

Katharina is a coral reef ecologist and a Senior Principle Research Scientist at The Australia Institute of Marine Science. She's been researching corals for over 30 years from Australia to the Caribbean. Currently, she leads a research project looking into the long-term effects of ocean acidification in collaboration with scientists from 20 organisations. Katharina has also published over 150 scientific journal articles and advises government and non-government bodies on all things related to corals, acidification, climate and water quality.

AIMS profile: Dr Katharina Fabricius
Twitter: @fab_coral

Transcript

Host (01:15): We are here with Katharina Fabricius. Katharina, thank you so much for coming on the show. 

Katharina Fabricius (01:20): Thank you. 

Host (01:22): So Katharina, we'll be talking about all things related to the ocean today. For example, like how climate change is affecting corals and about the impact of ocean acidification. But first if I could get you to give us a summary of who you are and what you do and what your current research interests are right now, for example.

Katharina Fabricius (1:44): Sure. So my name is Katharina Fabricius. I'm a coral reef ecologist and have been working on coral reefs for over 35 years. I grew up in Germany and came to Australia in 1988 to study coral reefs in particular because I was fascinated by the Great Barrier Reef. I'm presently working as a senior principal research scientist at the Australian Institute of Marine Science in Townsville. [I] have been really working with many talented people and students, and postdocs on the complex questions of how do coral reefs respond to disturbances? How does water quality, ocean acidification, and global climate change are affecting coral reefs and what can we do about it? 

Host (02:35): Awesome. I wanted to get started on the ocean itself and I think it's safe to say that a lot of people find incredible joy or rely directly on what the oceans provide. I also think that in a sense people are drawn to water. I know I am, for example, and I assume you were as well, you just mentioned, you came from Germany because of that fascination with the reef. Keeping that in mind, I wanted to see how you described the ocean and what drew you to that, to your research? What's your personal history with the ocean itself? 

Katharina Fabricius (03:13): Yeah. Opposite, growing up in Munich means here miles away from the nearest ocean. So whenever I could spend time in the Mediterranean and along the coast, they're possible. But literally, I mean, 85% of Australians are living near the ocean. It is part of our existence and it is just scientifically, in the last frontier, almost on earth. Like, the oceans are covering 70% of the Earth and we know so little about it. It's fascinating. I'm totally fascinated by oceans. I love to be at sea. I love to be underwater and observe the marine critters that are colonizing the coastal areas. It's just a different world and yet so close to us. It's still one of the most fascinating things.

Host (04:13): Now you mentioned that the ocean really is the last frontier. I mean, how little do we know about it? Or maybe a better question would be how much do we know about it and how much more is there to explore?

Katharina Fabricius (04:27): It's amazing. I mean, the oceans are covering literally 70% of the earth, but we know more about looking at the surface of Mars than what we know [about] what is happening in the deeper waters. Humans are fairly visually oriented and we can get a lot of information by looking at things, and the deeper oceans are dark and we can't just look at things. In many places we've just got pinpoint ideas of what is down there, and we have to develop and use new technologies, which are typically quite expensive and very spatially limited to have a glimpse at what's in the ocean and on the bottom of the ocean here and there. 

The coastal oceans are a little bit better understood because we can look down there, but even then so little is known and so little is understood. In coral reefs on their own, we've got literally over a million species of plants and animals, and hardly any one of those are described, let alone, do we know what they are doing and what their role and importance is. 

The oceans are also economically quite important. The blue economy is estimated to be about 80 billion dollars for Australia per year. So it's an enormous resource that's for tourism and transport and fisheries and biotechnology and so on. It's not just a fascination issue, it's also a very important part of the economies of countries that have coastal areas.

Host (06:13): I guess that kind of ties into the question about what exactly does the planet and, of course, humanity get from healthy oceans? I think you've mentioned a lot of these. We rely on tourism, we rely on fisheries, and a whole bunch of different range[s] of other natural services we get from it. I think, for one example, carbon absorption rates. There's a lot of talk about rainforests absorbing carbon dioxide and exchanging it for oxygen and many people say forests are like the lungs of the earth, for example. But I think the ocean in this context doesn't get as much limelight in regards to the fact that the oceans absorb just as much, if not, more carbon than forests. So I just wanted to get your thoughts on that, about how this happens and what do people mean when they say the oceans store and absorb carbon? Like what would be a good example of that?

Katharina Fabricius (07:17): Yeah, so that's right. The oceans are in equilibrium with the air. So all the carbon dioxide that's being emitted into the air is also entering into the ocean. Initially,  about 30% of the CO2 that has been emitted has been absorbed by the oceans already. It's slightly behind what's happening in the air. So air [and] sea want to be in equilibrium and therefore the oceans have been absorbing a huge amount of the carbon dioxide that we've been emitting. Therefore, really providing a central service in reducing the impacts of the higher carbon dioxide onto our climate to date. 

Oceans are also really important in terms of feeding people. More than 3 billion people are getting a substantial proportion of their protein from marine seafood. And again, we need to make sure that the oceans are able to continue to provide those services. In terms of feeding people, in terms of transport, it's so much cheaper to get goods from one continent to the next, going over the water than going through the air or in other means. And recreational opportunities are obviously endless in terms of coastal tourism and just the benefits of having a healthier person from being able to chill out on the ocean and going for a swim and being on the beach and so on. So, they're endless economic opportunities from the oceans, but they're also very profound, what we call ecological services, to humanity in particularly for climate change, but also in terms of feeding people, in terms of providing shoreline protection, like coral reefs and mangroves can be very important in preventing coastal erosion and so on. So in many cases we have understanding very little of what the oceans are doing to us and yet they're using it at a fairly intense rate. There's a little bit of a discrepancy between the need to make sure we can continue using the oceans in a sustainable fashion in the longer term. 

Host (09:37): Lingering on the point of those natural services that you mentioned, for example, you said, coral reefs and mangroves can protect against coastal erosion. Now, there's been a lot of talk about putting a value on these services. Is that becoming more of a mainstream concept or is that still in its infancy? 

Katharina Fabricius (10:00): Environmental economy is a growing field of research and like all economic models, they're strongly dependent on assumptions and how much value you’re giving to certain non-monetary services. It's not a field I am totally familiar with, but it is obviously a field that speaks to politicians and decision makers very clearly. 

For example, there is a substantial amount of money now invested in protecting the Great Barrier Reef from the runoff of nutrients and sediments. And that is based on the knowledge that the Great Barrier Reef is earning the Australian economy 6 billion dollars per year. So investing a few hundred million dollars over 10 years sounds to all economists like, good investment for a fairly substantial return. Unfortunately, for climate change, for a while, those economic arguments did not quite stack up because the clear need to protect coral reefs against climate change was overwhelmed by just ideology and other motivations to continue, in the business as usual, the unsustainable consumption of fossil fuels. 

Host (11:26): Speaking of fossil fuels, I think we've just spoken about how important healthy oceans and coral reefs are across the world. I guess the news these days can become fairly, a bit depressing in regards to corals. So while I do want to dig into the details, and I know this is a big question, but perhaps first you could tell us about what kind of changes has the ocean undergone since the beginning of, say, the industrial era? What have we seen happen so far? 

Katharina Fabricius (12:01): Yeah, so climate models are now fairly reliable. There are many climate models that have been developed all around the world, and they're very consistent in the estimates of past change and also in their predictions of future change. So there's a very high confidence that the seawater temperatures have increased by approximately one degree Celsius, and that's a global average. There are regional differences with the poles and certain enclosed bodies warming faster than others. But around Australia, the estimated increase in temperature is about 1.0 degrees since about 1990, and that doesn't sound like very much, but we gotta remember this is a mean temperature difference. And the difference between an ice age and present times is only five degrees mean temperature. So despite experiencing substantial fluctuations in temperatures from winter to summer and from the north to south and so on, a one degree warming is a very substantial warming that is of real concern for marine ecosystems as well as terrestrial ecosystems, especially because it's happening so rapidly.

Host (13:17): In terms of impacts, that one degree increase in sea temperatures, what has that led to, for example? And maybe your research would illustrate this quite well. What kind of impacts are we seeing maybe in where you're working in Australia on the Great Barrier Reef and other impacts across the world? 

Katharina Fabricius (13:37): Yes. Speaking about coral reefs, coral reefs are highly sensitive to heat stress. Typically when corals are experiencing one degree, greater temperature than they normally experience in summer, the maximum temperatures, if that heat just lasts for eight weeks, then corals are getting severely stressed, they're losing their pigment, and that's what we're calling coral bleaching. If that heat stress is a little bit more prolonged, then many of the more sensitive species are literally dying from heat stress. So coral reefs have become a little bit of the poster child for the effects of climate change. Many other critters in the oceans are similarly suffering from heat stress, but they don't show it quite as spectacularly with changes in color.

What we are talking about is degree heating weeks, and it's a fairly universal valid number. Also the Indo-Pacific Ocean in Asia that either eight weeks of one degree warming or four weeks of two degree warming would accumulate to an amount of heat stress that makes a coral very sick and makes it unclear, depending on the conditions, whether they can recover or die.

Host (15:02): In terms of coral bleaching, you mentioned that the rising of temperatures makes the pigments disappear so we've seen pictures of the corals turning white. Now, is there a, for example, is there a chance that these corals can recover after such an event? Or does the bleaching just mean that the corals are finished?

Katharina Fabricius (15:26): The reason why they're turning white is because corals are, they're very simple animals, but they're incredibly complex. At the same time, they've got tiny little algae living in their tissue, and these algae are feeding the coral, so they use light to do photosynthesis, and the sugars from the photosynthesis, because they’re plants, are translocated to the coral and therefore contribute to the health of the coral. When the corals are bleaching, the algae that die in the tissue are pushed out from the corals, they're spit out basically because they,  the algae, are starting producing toxic oxygen radicals. 

The coral can still continue to live without the algae for a little while, but it's basically starving because the little algae in their tissue are not providing them with food any longer. It’s a fascinating story. It shows how complex tropical ecosystems are, where different animals are depending on each other and each of them have their own different sensitivities and tolerances.

If you're changing the environment for these highly evolved symbiosis or sort of complex living arrangements between several organisms, then ecosystems are suffering very quickly. So whether a coral survives and recovers eventually or dies depends a little bit on the different species, different environmental conditions, and how intense the heat stress is.

During very intense heat stress, most coral species tend to die, in particular in the shallow water when the light is pretty intense and photosynthesis is really strong, but also in airs that are more sort of ponding and therefore get hotter more quickly. Well flushed coral reefs in deeper areas and some particular species are faring a little bit better for a little bit longer.

But overall, the first mass bleaching we've seen all through the Asian region was in 1998, and the world really lost a large proportion of corals, an estimated 15% of all corals died in this one heat stress event. Then again, we are seeing more and more heat stress events and coral bleeding events since then. In 2002, 2016/17, 2020, 2022, they're all very, a little bit depending on what the wind conditions are, whether a cyclone or typhoon is mixing up the water again and so on. But overall, the heath stress is accumulating. The whole crisis in terms of climate change and coronaries is accelerating.

Host (18:18): Now you've been working particularly on the Barrier Reef. Have you been out in the water during a particular warm year where bleaching has happened? What's the experience going under the water and seeing these things happen, and researching these events?

Katharina Fabricius (18:36): Yeah, I mean, seeing bleaching events is really, it's very depressing. I mean, you can basically almost taste the corals that are dying. You're seeing rotting tissue all around you. It's an eerie experience because in the beginning coral always look actually quite pretty when they're bleached because it's what is typically so a little bit more duller, gold and brownish tinge throughout the reefs, turns fluorescent pink and yellow and light blue and white, and it can actually, initially, look quite interesting and fascinating. But we are really looking at severely sick corals and most of them will be dead a week later, start getting overgrown by algae and the reef dies.

The first time people see this, [they] tend to be quite fascinated, and I've had a few students coming back from dives being really overwhelmed by mixed feelings of immense short-term beauty and the knowledge that the reefs are in their deaths throes. Often the water starts stinking, the water is really soupy and full of slime, and hot. It's very, very distressing.

Host (20:04): Now I think you mentioned there's this relationship between algae and corals and how the bleaching events happen, but, what kind of impacts are we seeing with bleaching events? And then, for example, the fish species or the crustaceans in the oceans in response to bleaching events, are they getting affected by them as well?

Katharina Fabricius (20:26): So coral reefs are incredibly complicated ecosystems. The ecosystem itself is built by corals and the structure of the skeletons is providing habitat for all sorts of critters, like fish and crabs and shrimps and sea stars and so on. They all depend on the healthy coral reef to survive. The coral are forming their habitat for this, about 1 million species that are associated with these coral reefs. So if the corals are dying, all these quitters are losing their habitat. Some of them can wander off into deeper waters. Others are getting sick as well from heat stress, but we don't know much about that.

Once the corals die, the skeletons tend to crumble and in over a few years break down. And so organisms that can continue to live for a little while and don't get immediately affected by the heat stress are losing the habitat over the coming years. So what we are really hoping is that the reef is otherwise quite healthy in that there are sufficient numbers of coral surviving, that the reefs can be reseeded by little coral larvae and bounce back from those disturbances. Coral reefs are able to recover from disturbances. The problem is only if disturbances are too frequent that, they just simply don't have enough time to recover between those impacts by storms and by bleaching, and by all the other disturbances we are throwing at them from these rapidly changing climates and human use.

Host (22:11): So now I think another really important issue that's affecting the oceans is not just bleaching it but also, I think ocean acidification, and I mean this has been called climate change’s evil cousin, so to speak. I think this is to do with the carbon that's emitted and we mentioned before that the ocean does absorb a lot of carbon dioxide and it's literally changed the ocean's chemistry and is causing the oceans to acidify. This is one of your focus areas and I'd just like to get your take on how acidification really happens, and is this a recent phenomenon or has this been gradually building up over many years?

Katharina Fabricius (22:57): Yeah. Ocean acidification is a topic that is far less understood than the global warming that everyone is talking about. And literally, I mean, scientists started talking about it and predicting it in the middle of the last century, but it really only became known as a severe issue in the last 20 years or so. The story is that the carbon dioxide that's in the air that enters into the seawater in order to provide an equilibrium. And when CO2 enters into the ocean, it combines this water to form something that we call carbonic acid. So that's a very mild acid and it's also not stable, but it changes the seawater chemistry and makes the ocean, which is typically alkaline, just ever so slightly less alkaline. The problem with that is that many of the marine organisms are highly dependent on high levels of carbonate, calcium carbonate, which is basically limestone forming to form the skeletons and to be protected against predation. When this carbonic acid forms, it causes a whole cascade of changes in the seawater chemistry, including a slight acidification, so a drop in pH as well as a reduction in the concentration of carbon and irons and a few other things. 

CO2 is almost like a fertilizer for plants. The additional CO2 in the ocean can increase photosynthesis, but it also makes it more difficult for many marine organisms to deposit limestone, which they're using as a skeleton or shell. So like bivalves of carbonate shells and corals, skeletons are built out of limestone. I mean, we all know that Coca-Cola and teas don't go together, so acid and lime really don't go together, and the same is applicable in the ocean as well. 

If the pH, the acidity in the ocean changes, corals can't grow quite as fast. And that's particularly true for some very small marine organisms. For example, the larvae of oysters are highly sensitive to ocean acidification. Coral reproduction and recruitment is highly sensitive to this and the whole number of, again, marine plants that are benefiting in terms of photosynthesis, but also suffering if they've got carbonates in their tissue. 

So again, like with the warming, we are changing marine ecosystems fundamentally, we are causing shifts that are, at this stage, we are slowly getting a better understanding of how it all works. But it is very complicated and ocean acidification and warming are obviously both affecting our marine ecosystems at the same time, because both are increasing and changing at the same rate. 

Host (26:08): Is there any data to suggest that acidification is worsening over time the more that fossil fuels are burnt and the more carbon dioxide is emitted into the atmosphere? Is there any evidence to suggest that the acidification rates are going up?

Katharina Fabricius (26:25): Absolutely, yes. The acidification is directly proportional to the CO2 in the atmosphere that we are emitting. And that applies to the past so we know exactly what happened in the atmosphere will also happen in the surface oceans, and that is also the forecast for the future. Exactly depending on how much more CO2 we are going to emit, the more severe this whole concept and problem of ocean acidification will become. It's entirely in our hands to determine how much CO2 and how much ocean acidification the coral reefs are going to suffer. If you're waiting long enough, the CO2 from the surface of the oceans will eventually be conducted into [the] deepest seawater, but it is a very slow process.

So CO2 will eventually over the timescale of hundreds to thousands of years, be removed from the atmosphere and from the oceans, but that requires uptake by biota, uptakes per soil, the weathering of geological formations and the subduction of the CO2 into deeper waters. If we are stopping burning fossil fuels tomorrow, the CO2 levels would start dropping, but it would take some time to come back to pre-industrial limits. 

Host (27:50): So I guess what you're saying is that because there's that long process of the CO2 to get drawn down into the oceans, right now we are seeing a really quick impact on ocean ecosystems and basically if we don't stop emitting excessive amounts of CO2, then we're gonna have more and more of these, I guess, events where you have that skeletal erosion from the acidifications of the ocean. 

Katharina Fabricius (28:20): That's right. And the problem with ocean acidification is [that] it is a global issue because CO2 is everywhere and it is entering into the ocean everywhere. So with temperature, we've got some thermal refuge here and there are coral reefs that are not getting quite as hot as others. We've got the natural temperature gradient from the tropics to the subtropics. So we are hoping there will be some opportunities for corals from the further north to colonize areas that are cooler and in this case adapt. 

But the same problem is the opposite for ocean acidification. It's actually worse in the cooler waters, but yet it is affecting coral reefs, even in places that are protected from warming. Because it is such a global issue, it's affecting reefs all around the world, all throughout Asia and the Caribbean.

Host (28:29): Is there any kind of relationship, not really a relationship, but is there, I guess, kind of cascading impacts, for example, from a bleaching event and then acidification. Is acidification making, for example, bleaching events worse, or is bleaching events making acidification worse? 

Katharina Fabricius (29:40): So bleaching and acidification are acting together in impacting coral reefs. Bleaching tends to be causing mortality and therefore reef disturbance. Acidification is more [of] a chronic condition. It makes it more difficult for coral reefs to recover because corals don’t reproduce quite as well. They can't recolonize areas quite as well. And once the young corals have established they're not growing as fast to help the coral reefs recover. So, yes, the two, both ocean acidification and temperature are acting together in affecting coral reefs in this changing environment. 

Host (30:26): So, now those are some big issues. For example, bleaching and acidification are pretty macro in scale, but we've also got some lesser known issues or threats that are challenging the health of, for example, coral reefs and the ocean in general. But, I think these are more related to land management, for example, like fertilizers from farms that are being washed into the ocean and then affecting the water quality. I was just wondering if you'd go a bit more into that and just explain how maybe these land use changes are affecting corals and if that has a weakening effect on corals and their ability to rebound from, say, acidification and bleaching events.

Katharina Fabricius (31:13): That's right. Water quality is a huge issue for our coral reef all throughout the Asian area. Because we are colonizing the coastal areas fairly intensely, the loss of vegetation and coastal development means that more soils and sediments and nutrients are washed from the land into the ocean. That can be due to deforestation, that can be used [for] road construction along the coast, that can be due to application of fertilizers on farms and so on. And can be due to the more intense rainfall that we are seeing due to the warming temperatures. So more and more sediments and nutrients are washed into the ocean. They are, again, like CO2, fertilizing the algae, the seaweed that are competing with corals for space on the reef. 

Coastal areas are quite often very vulnerable to exposure to sediments and nutrients. If you've got high sediments, corals are suffering. If you have got high nutrients, then the corals are suffering and the algae are flourishing. So like with ocean acidification, poor water quality makes it more difficult for corals to recover after disturbance from bleaching. That's why it's so important to really make sure that soil and sediments are staying on the land where they're useful for our crops and for our terrestrial ecosystems and don't get washed into the oceans.

But there's climate change. It's, again, more difficult to do so because these intense rainfall events, the big floods we are seeing, in particular drought-breaking floods, are very hard to manage. After drought when there's very little vegetation on the ground, the amounts of sediments and nutrients washed into the oceans are often humongous. We've all seen these pictures of brown rivers running into the oceans and basically washing the topsoil of the land so that these are real severe issues in particular for coral reefs that are close to the land, which are those coral reefs that are typically most intensely used by humans for protein and for tourism and vacation. 

Host (33:30): Yeah, that's really interesting. I've never actually thought about the connection between droughts and then [the] drought breaking-floods and the impact on ocean water quality. I mean, I think Australia's a pretty good example of drought. It's pretty known for its lack of rainfall. Now, where the Barrier Reef is, it's up in a more tropical area in North Queensland. Are you seeing those drought-breaking floods in Queensland having the same effect on the water when the rains do come? I mean, the area is quite green so to speak, but is that sediment runoff still happening up there?

Katharina Fabricius (34:10): Yeah, so the Great Barrier Reef is 2,000 kilometers long. In the center we've got the wet tropics that tend to be green all year round. But then in the Burdekin region and Fitzroy region, so in the subtropical areas and in the far North, we've got what we call the dry tropics. There's good rainfalls but very episodic rainfalls in summer and pretty much no rainfall whatsoever throughout the autumn, winter, and spring time. So we've got ecosystems that have relatively good current cover in summer, but then very little in winter. If the monsoonal rains are failing and we've had lots of drought and conditions for prolonged periods of time, then in all these grazing areas that are adjacent to the Great Barrier Reef, then we are having these enormous discharges of nutrients and sediments. The Burdekin and Fitzroy River, typically on average, the Burdekin River on average discharges 12 million tons of sediments per year. But that is quite a few years where not much happens because there's no rainfall. Then other years where we've got these monumental floods and it's hard to visualize 12 million tons of sediments, but it's basically a train spanning from Brisbane to Townsville. So over 2,000 kilometers, almost. One carry on after the next full of sediments and chipping all of that into the ocean. It's amazing. 

Host (35:47): Yeah, that's a lot of sediment. Sediment erosion is a natural phenomenon, obviously, but in terms of the extreme events that you're mentioning, I guess the systems in the oceans are getting overloaded, would that be a safe assumption to make?

Katharina Fabricius (36:05): We know that sediment discharges along the Great Barrier Reef is between three and eight to ten times higher than during pre-industrial times. So those numbers vary between different catchments and again, whether it's a wet tropical area or in a dry area predominantly used for grazing, but we've lost a lot of ground cover. We have got heavily overgrazed ecosystems and the damage of topsoil to dry grasslands is a global problem that is really showing how little we understood the ecosystems, how they have been functioning in the past. So unsustainable grazing practices are contributing substantially to sediment discharges into the marine ecosystems.

Host (37:00): Right. Okay. Bearing all of this in mind of what we've talked about, I just wanted to shift gears a little bit about some solutions to these challenges we're facing. I think you've probably thought about this a lot, but are there any kind of short-term, quick fixes that we could really do now that would assist and or support oceans to become healthier or coral reefs to recover better?

Katharina Fabricius (37:29): Unfortunately, I mean, the number one and the only thing that really in the longer term will make a difference is managing our carbon pollution. So reducing our emissions of carbon dioxide into the atmosphere. But there are lots of work that can be done locally, and that's true all throughout Asia. I've spent a fair bit of time working in places like Palau. I've also worked in Hong Kong and many countries have local water quality challenges that can be addressed locally in the time scales of a few decades. So they're much more manageable than the global issues of climate change. Investing in water quality improvements is a key factor for coral reefs all around the world. And something this can be done. The solutions differ between different catchments and need to be supported by good science, but in most cases we know what to do and it can be done. 

In terms of adaptation to climate change, that is an area of intense research at present as well. I'm involved in a large program called [the] Reef Restoration and Adaptation Program, where the effort goes towards understanding how we can help coral reefs adapting and flourishing in a changing climate, either through helping in some form of fashion, developing methods to restore coral reefs. These methods have to be can be upscaled to whole reefs and hard reef ecosystems. Also to understand better what limits reef recovery locally, and in what areas would, what type of interventions be particularly useful? 

For example, in some coral reefs, you may have ample coral larvae still arriving, but the settlement and survival of these coral reefs may be compromised. Then, water quality may be the key solution. In other places, in more isolated areas, you may not get enough coral larvae to recolonize an area after bleaching disturbances, then it may make sense to, sort of catch a large quantity of larvae from healthy coral reefs and take them over to those disturbed areas and help pre-colonization in that way. We are also investigating what are the genetic backgrounds for the different abilities of corals to deal with temperature stress. Sometimes you go out in the ocean and during a temperature stress event, you see some corals sitting side by side, some look still quite healthy and others are severely stressed. So there are genetic differences between more resilient and less resilient corals, and all the more resilient, less resilient coral reef types. So we are trying to accelerate the research to understand where do you find the greatest resistance and resilience. And how can we help other coral reefs that have got less resilient, resistance properties to a quickly as possible transition into ecosystems that can withstand those rapidly changing conditions.

Two problems are the frequency of disturbance and how often these temperature stress events are happening. And that's obviously increasing into the future. The big problem for adaptation is the speed of change. Ecosystems can always adapt and we get many different types of ecosystems all around the world living in hotter and in cooler conditions, but they're typically developed under those conditions over hundreds and hundreds of years. The ecosystems are changing their exposure to temperature now within decades. Many corals are taking a decade before they start reproducing. So coral reefs are quite slow in naturally adapting to changing conditions. The real issue we've got is the rapid change that we are exposing our ecosystems to.

Host (41:45): Given that context, I mean, provided the globe gets its act together and reduces carbon emissions to a meaningful extent, would you say that there is room for some cautious optimism in that regard? 

Katharina Fabricius (42:01): Look, I am, what makes me optimistic is that all the technologies exist to transition into a cleaner future. We also have seen massive changes in societies, literally from one year to the next, having grown up in Germany and seeing the fall of the Berlin Wall makes me a little bit more optimistic that people's preferences and behaviors and society can change quite rapidly. Our main problem is that at present with our present societal structures, our focus is so much on economic growth and consumption rather than human happiness and living sustainably within the means of what our planet is giving us. But many societies have done that for a long time. Many societies today still do it. So, yeah, I'm still hopeful we can turn the ship in time, but it's a big ask and it does require a lot of real conscious living by everyone and questioning of our own private behaviors and how we are divulging, in order to have a happy and healthy future, and feel responsible for what we are passing on to our children. 

Host (43:22): Well, Katharina, I think that your research is definitely contributing to that cleaner future. I just want to thank you again for your time and for your expertise, and your thoughts on this really big but important issue that really does affect dozens and dozens of countries across the globe.

Katharina Fabricius (43:43): Thank you too, Ashley. Enjoy talking to you. 

Host (43:45): Thanks a lot. Until next time.