Hi, I'm Jonathan Tomkin from the University of Illinois. We've spoken quite a lot in this class about the effects that people have on the environment. I'd like to turn that around a bit in two ways. Firstly, We, I'd like to consider the question, how do people depend on the environment? What are the services that the environment provides that we need to survive? And secondly, I'd like to think about the ethical nature of the environment and nature generally. Does nature and the things in nature have values beyond those that help humans and, and our goals? So we'll look at both of those issues in this lecture. One of the threats to sustainable life on this planet is the loss of species individually and ecosystems generally. The organisms themselves and the habitats they live in are very important in the quality life for everybody on this planet. Why is this a threat to sustainability? Is there a way that we can measure or quantify the impacts of losses of species or ecosystems in the context of the sustainability of social systems? To begin to answer that question, we need a measure of how successful biological systems are at functioning. One way to do this is to use the idea of biodiversity. This measures the variability in not just individual species but genes and genomes all the way up to the whole level of ecosystems. Here's a definition. The variability among living organisms from all sources including terrestrial, marine and other aquatic ecosystems, And the ecological complexes in which they are part. This includes diversity within species, between species and of ecosystems. Single ecosystems can support a very wide variety of species. For example, if we take the case of the Cerrado, a dry forest in Brazil, there are over 10,000 species of plants almost 200 species of mammals, 600 species of birds and about 800 species of fish. Generally. biodiversity is greatest in rainforest regions. But, in fact, biodiversity hot spots are found all over the world. If we look at this map we can see places from almost every continent except Antarctica. The green areas are the original biodiversity hot spots and the blue areas were more recently added. One way that scientists can measure biodiversity is by examining the fate of individual species within ecosystems. Scientists who do this say that, that the world is losing species and the rate of loss appears to be accelerating in many taxonomic groups. This is according to the International Union for Conservation of Nature. These estimates are largely based on loss of habitat. Around one in five mammal species and about one in seven bird species are considered endangered because of this loss of habitat. As humans have converted natural areas to our own use, to farming places to live, pasture land. There's less room for non-human species to exist. This is resulted in habitat destruction and fragmentation. And, other effects that have caused damage to ecosystems include invasive species, sometimes on purpose and sometimes by accident. over-exploitation of natural resources, for example, logging of forests, and sometimes it's a question of habitat or ecosystem degradation. Classically, this has been seen through pollution, and the big fear for the twenty-first century is that climate change will cause large scale ecosystem disruption. Another reason why we might focus on ecosystem level functions instead of individual species level is that, individual species can become locally extinct. If they're locally extinct, then this means that they're no longer contribute to that local ecosystem. A good example of this in North America is local wolf populations. Wolfs have never really been in danger of becoming extinct, but in many local places, they are entirely removed, For example, Yellowstone Park. This changed the features of the ecosystem. When wolves were reintroduced to Yellowstone in the 1990's, this reduced the local Karaboo pop, population, which in turn reduced pressure on native plants which were then able to grow back. So, by introducing species that had been lost from that natural eco, ecosystem, it was able to more closely return to it's original state. So, in this sense, it doesn't matter if there are wolves elsewhere, what matters is that there are wolves in that local ecosystem. So we might not just be concerned with the fate of individual species globally, but also individual species locally. So, what's the current situation with biodiversity? Well, in many places around the world, it's been severely reduced due to human action. For example, in this part of the American Midwest, there's been an almost complete removal of tallgrass prairie. And if we look more broadly across the Midwest, about 90% of the original tallgrass prairie habitat has been completely destroyed. One very telling statistic is that about 25% of the earth's surface is now used for agriculture. Tropical rainforests which are very important habitat nearly half of the world's plants and animals species are found rainforest covered about 4,000,000,000 acres of the earth originally and now that's down to about 2.5 billion acres. And, furthermore, about one percent of the world's rainforests are lost every year. Another very important ecosystem provide diversity is wetlands. About half of the world's wetlands have also been destroyed. So, what's the cost of losing these natural ecosystems? Well, one way that is being used to measure these costs is a term known as Ecosystem Services. An example of an ecosystem service is a wetland that purifies water. Another might be a forest that provides oxygen for the air or an ocean that provides habitat for fish. This list of ecosystems is, of course, enormous, and if we were to try and value this we'd get very large numbers. One study suggested that the value of natural capital was between sixteen and 54 trillion US Dollars per year with an average of around 33 trillion US Dollars per year. But, of course, the total value of ecosystem services is beyond measure because nothing can live outside of nature. It's still worthwhile at the margin to consider the cost of transforming a parcel of land, however. By using the concept of ecosystem services, we can see the cost of transforming one type of land to another. This is something that is not historically being done by human societies, But now we might consider if we want to drain a wetland and turn that into a productive farmland, for example, That we are giving something up as well as gaining something. In the past, humankind has most often thought, this is what we get and the natural system was not valued at all. So, all of the things I have spoken so far is, again, values in the human context. What of non-human values? This is an image of a Sumatran tiger. The systems I've spoken about failed to account for the intrinsic right of, say, this tiger to exist. Just as we value the intrinsic right of other people for their own autonomy, Their own right to exist, Their own right to make their own decisions. Wouldn't it make sense that we could extent some of that ethic to non-human animals, plants, objects? So, we ask in this case, do tigers have an intrinsic right to exist beyond the needs and desires of people? Now, like many philosophical questions, this can quickly become very complicated. If all tigers have an intrinsic right, what about other organisms such as musquitos or bacteria? The bacteria that caused the black death is now considered extinct. Is that a problem? Should we be trying to bring the black death bacterium back? And, of course, this concept can go beyond individual organisms or species. We can also consider other parts of the natural world. Humans often value things for aesthetic reasons. And here, we have a beautiful arch from Arches National Park in the United States. So, here we might be able to quantify its beauty value and we might say, well, that's worth something to people. But does the natural landscape have its own value even if it's not found aesthetically pleasing by people? This week, we're going to use metrics to try and measure progress, or otherwise, towards sustainability. But I want you to be aware that if we think about these ethical issues, we know that these metric approaches don't completely encompass what's important about sustainability. In the next lecture, we'll look at some of those sustainability metrics and see what kind of progress we're making. Produced by OCE Atlas Digital Media at the University of Illinois Urbana-Champaign.
