Looking Forward

Writing this blog week after week has been an enriching experience to say the least. I’ve learnt so much about an issue that I truly care about, and have relished the opportunity to share it with not only my friends and fellow students, but also the community at large.

Before I reflect on the process of creating this blog, however, I would like to take this opportunity to look forward, just for a moment, at what needs to be done if we are to have any hope of salvaging the species and biodiversity of our planet. 

As we have discussed time and time again, climate change is projected to have a huge impact on biodiversity at all levels. Such a phenomenon creates a significant challenge for conservation measures, and often can be overwhelming when considering where even to begin with tackling this problem. However, recommendations and directions for conservation do exist, and it is these I would like to discuss briefly.

One of the most important responses to this climate change, as I have argued previously, is continuing to develop scientific literature that sheds light on the nature of biodiversity change and provides guidance for effective conservation strategies. We need to continue to develop understanding if we hope to protect our flora and fauna, and that is why projects such as Nature’s Calendar are so important for supporting research. This science will become the backbone of any real-world response, and it is essential that it continues unhindered (Bellard et al.2012).

Also of critical importance, according to both Bellard et al. (2012) and Heller and Zavaleta(2009) is continued development of modelling techniques, as to reveal the nature of future risks, where they are greatest and how they will affect species and biodiversity. Modelling and projections will also be key in informing further conservation measures, such as the creation of new reserves and how best to develop landscape connectivity.

On the topic of reserves, both Bellard et al. (2012) and Heller and Zavaleta (2009) raise some interesting suggestions on how these also should be developed in the future. As Heller andZavaleta (2009) deftly point out, as climate forcings begin to affect species dynamics, reserves will lose their ability to protect the species they were designed for, as these species lose representation in these areas. This requires a change in the way that reserves are managed and created. Rather, the two papers suggest that the creation of new reserves should be based on both projected future hotspots of biodiversity (according to models) and also to create and sustain habitats for species that have a high conservation value, that is, species that provide strong ecological resilience and can influence local abiotic conditions, such as forests which help maintain cooler temperatures and precipitation.

Also key according to the two papers is the improvement and proliferation of habitat connectivity through the creation of corridors and stepping-stones that link ecosystems together. According to Bellard et al. (2012) and Heller and Zavaleta(2009), by rebuilding this connectivity, we can create pathways which allow species to migrate and escape to more suitable climate conditions. Where this is impossible, however, such as if there is no overlap between a species current and future range, or no possible pathways exist, more direct measures will need to be taken. Bellard et al.(2012) suggest that the answer may lie in human-assisted colonisation, or artificial species migration. Although typically there is a degree of controversy involved in direct human transportation of species, due to the risks they may pose as invasives, in these scenarios, it often appears that direct human assistance is the only solution to a human-created problem.

What is arguably most important, however, according to both papers, is the need for a shift from species-centred conservation strategies to a more holistic outlook that takes into account interactions within ecosystems, as well as the importance of functional and genetic diversity. This in turn needs to be integrated into a multi-disciplinary framework that fits conservation more neatly into the bigger picture of development and politics. If we can bring discussion of conservation into everyday decisions, rather than having it as a standalone venture, then maybe a more significant difference can be made.

Regardless of how much we adapt conservation to climate change however, it will always remain a process of treating the symptoms, and not the disease. In my mind the real “best solution” would be to stop climate warming in the first place. Although this is somewhat impossible now, due to the huge amounts of carbon already emitted into our atmosphere that will take generations to diffuse, reducing global warming as much as possible will be the greatest favour we can do to our non-human friends. As Urban (2015) points out, the level of warming is directly linked to the amount of species at risk of extinction. The prevention of further warming, then, should be the absolute priority in any conservation ventures.

That pretty much brings the blog to a close. We have taken this discussion from exploring the numerous and somewhat surprising ways in which climate influences the lives of species, to how this affects them as communities, all the way to how climate change will potentially erode ecosystems resilience and cause widespread extinction.

What you may have noticed throughout this blog is the absolute absence of anything that concerns human activity or involvement. I found in the literature that all too often the rationale for investigating the effects of climate and how to protect species came back to what value they offer humans through what are termed “ecosystems services”. This is a trap I did not want to fall into in my blog. Although some may criticise me for not addressing what is considered a huge part of the ecological paradigm, I wanted to investigate climate change from a flora and fauna point of view, where I could focus on all species at risk, rather than just those humans find most cute or convenient.

In any case, I have found writing this blog to be a hugely sobering experience. I came into this project, and this module, feeling relatively optimistic about the outlook for our planet and the flora and fauna that inhabit it. Throughout my research however, I have seen time and time again the enormity of the challenge that is now facing life on our planet. Flora and fauna are seemingly assaulted from all sides by climate change and other human factors, with little hope of relief. The magnitude and speed of change is relentless, and in most cases absolutely dwarfs the ability of those affected to respond. I am no longer shocked when I read projections for species extinctions, as it is simply a fact that humans, through their own selfish misuse of resources and the environment, have already crossed a threshold of expected warming that dooms numerous species to extinction and will result in the loss of the lives of countless organisms. Even if we curb the planet’s warming now, there are numerous species, such as those that are endemic or birds and amphibians that are particularly sensitive to climate forcing, that simply will not be able to cope with the new world we have created.

I wish I could end this blog on a happy note or on an upbeat piece of news, however I feel to do so would be to betray the tone and message that this blog has portrayed over the past few months. Climate change and its effects on our biosphere are anything but a happy affair. I am no idealist, and personally can only see things becoming a lot worse for our flora and fauna before they become better. A lot of lives and a lot of species will have to be lost before humankind learns its lesson. The truth of the matter is that we are living in mankind’s world now, and it is no longer very clear whether animals and plants have that much of a place in it.

The Big Picture - Climate Change and Extinctions

One of the most important messages of this blog has been to get across the sheer variety of ways that climate change influences the lives of species and their associations within and beyond the ecosystem. This influence has taken the form of many different ecosystem responses, such as rapid range shifts, changing phenologies, increased invasions, genetic polarisation and much more. Last week we saw how all of these effects come together to erode ecosystem resilience, and this week, as we come towards the end of our blogging journey, I would like to discuss how they are pushing species on a global scale towards extinction.

As Bellard et al.(2012) state (and we have seen), climate change is expected to affect all levels of our planet’s biodiversity. This ranges from biota at an organism level, all the way up to the biome, and will affect not just individuals, but species, their populations, ecological networks and ecosystems as a whole. At the small-scale level, as we have seen over the past couple of months, climate change causes phenological desynchronization (such as with the Pied Flycatcher, as discussed in an early blog), can damage genetic diversity (as shown by Cobben et al. 2012 in a previous blog on the unforeseen consequences of range shifts) and can make ecosystems more susceptible to invasions by non-native species. At the community scale, we have seen that the complex “web of interactions” can become desynchronised or entirely broken, through examples such as that of benthic plankton communities. At yet a higher level, climate change also threatens to cause ecosystem and even biome collapse (as discussed last week). In fact, the Millennium Ecosystem Assessment predicts biome shifts for 5 to 20% of Earth’s terrestrial systems (Sala et al. 2005; chapter 10).

We have also seen that species, populations and ecosystems have a variety of mechanisms with which to deal with these changes. When looked at together, and as Bellard et al.(2012) state, these responses can be largely grouped into three categories. These include spatial responses, such as range shifts in both latitude and elevation, temporal shifts, such as phenological plasticity, and finally “self” shifts, which Bellard et al. (2012) describe as species or communities adapting themselves to new conditions through a process of microevolution, whereby species genetically adapt by way of new mutations or selection of already existing, and better adapted, genotypes.  Whilst this provides affected species and ecosystems a variety of methods by which to “get out of dodge”, ecologists across the board are finding that many of these responses are entirely inadequate to counter the rapidity and scale of modern climate change. Not only this, but unlike in previous episodes of climate change, that were arguably well weathered by Earth’s biological community, species are now finding themselves having to cope with additional threats such as land-use change and pollution, which act somewhat in tandem with climate change to really drive species towards the brink (Bellard et al 2012).

When species do find themselves unable to cope with the challenges of climate change, the harsh reality is that they go extinct. This can happen both at local and global levels, with local extinctions understandably being significantly more common. Understanding the possible trends of these extinctions, alongside biodiversity change is incredibly important both for understanding of the issues and the construction of efficient, focused and relevant responses (Bellard et al.2012). Many ecologists, then, have strived to understand the potential future patterns of these extinctions, and numerous studies exist that project these future changes.

One of the most referenced comes from Thomas et al. (2004), mentioned in our first blog, who famously estimated that 15-37% of all of Planet Earth's species could be committed to extinction by 2050 under more intermediate models of climate warming. A similar meta-study, published in 2011 by Maclean and Wilson, estimated relatively similar rates of 12.6% of plants committed to extinction, 9.4% of invertebrates and 17.7% of vertebrates. A range of studies that investigate more specific extinction projections also exist. Koh et al. (2004) for instance conducted a study of 9,650 interspecific relations and found that an estimated 6,300 species could become extinct following the extinction of their associated species. Sekercioglu et al. (2008) on the other hand investigated extinction risks for terrestrial avian species (as birds are deemed to be especially sensitive to changing climates), finding that up to 30% could become extinct by 2100. Moreover, Malcolm et al. (2006) found that endemic species were also at significant risk from climate change and that losses of 39-43% might be realised in worst-case scenarios, translating to an absolute loss of 56,000 endemic plants and 3,700 vertebrates.

Similar predictions also exist in relation to biodiversity loss. Alkemade et al. (2009) for instance found that we could face decreases of between 11 and 17% of mean species abundance, and the International Union for the Conservation of Nature forecasted that globally, 35% of birds, 71% of warm-water corals and 52% of amphibians would be especially at risk of degradation (Foden  et al. 2008).

There are an incredible range of studies then that attempt to project and quantify the future for species across the globe. However, as Urban(2015) states in his very recent study from May, these current predictions vary hugely depending on the assumptions, method, focus and thresholds of each study. Whilst other meta-studies circumvent this problem, such as those aforementioned, it makes it hard to build up a large and reliable global picture. Urban (2015) hence conducted a meta-analysis of 131 multi-species predictions, finding that 7.9% of species globally can be expected to become extinct due to climate change. Specifically, this projection is 5.2% for 2^oC warming (that many experts (and myself included) no longer see as a feasible target), 8.5% for 3^oC warming and a staggering 16%, or as Urban (2015) puts it, 1 in 6 species, if we continue business-as-usual.

A graph from Urban (2015) that details the predicted extinction risks associated with varying global temperature rise

If the past three months’ worth of blogs hasn’t made it clear, then hopefully after reading today’s blog the sheer scale of destruction caused by climate change will finally have hit home. These projections show that the natural world is currently on the path to becoming completely devastated. Even the lowest, most conservative estimates such as Urban’s (2015) 5.2% or Thomas et al.’s (2004) 9% would be absolutely devastating for our planet’s ecology, causing widespread ecosystem and biome collapse and resulting in the permanent loss of many wonderful and unique species.

Throughout this blog we have examined closely the direct effects of climate change on our flora and fauna. Now, to round it off, we start looking at the future. It's not a bright one. After conducting so much research and learning so much about the whole sorry state of affairs, it looks like climate change is one of the biggest threats to our fauna and flora for millennia. 

In the last blog of the series, which should be coming out tomorrow, I would like to look to the future, and briefly discuss what needs to be done before bringing this project to a close. As much as I’d like this blog to have a happy ending however, already it is becoming too late for numerous species, and however hard we do try to change our ways and save species, the time is well past that damage can be entirely prevented.

Biodiversity and Resilience - Thoughts

In the blog I posted yesterday, we discussed the “big picture” of climate change, and how climate induced biodiversity change would destroy resilience and push ecosystems towards collapse. I would like now just to talk briefly about some of the values and perceptions I observed in the papers I read, and offer my own opinion about how some of the academics have framed their argument.

All of the papers I read on the subject during my blog research framed this issue in a very human light. Jones (2014), Folke et al. (2004) and the briefly mentioned Côtéand Darling (2010) all brought the argument back around to the idea of ecosystem services (the services and functions provided by ecosystems that benefit humans) and how they were at threat. Whilst I understand the importance of framing the issue of ecosystem collapse in a human light, thereby making it relevant, it still seems rather sad that this problem is viewed on an ecosystem scale and not on the scale of individual species.

Whilst yes, the services provided to us by the natural world are massively important, I saw no academics arguing that biodiversity should be preserved for biodiversity’s sake. None of the academics I read in fact suggested that ecosystems and biodiversity should be managed because animals have their own intrinsic value. If environmental management is conducted with the perspective that value comes from contribution to the human lifestyle, then huge numbers of species that are part of functional groups deemed to have sufficient “functional redundancy” will be lost. If we truly wish to save our flora and fauna for the sake of our flora and fauna, we need to take a more individual approach to issues, and make sure that no species is left behind.

The Big Picture - Biodiversity and Resilience

We have talked a lot over the past couple of months about the drastic effects of climate change on individual species and their ability to survive and flourish in their habitats. From range shifts, phenological fitness changes, invasive species, extreme events all the way to ecosystem desynchronization, we have seen just how big the threat of global warming is to species across the globe.

But now we need to look at the big picture. What is the significance of these challenges to species? What affect will it have on ecosystems worldwide? Will it just be a case of losing some cherished species, or is the problem more significant for ecosystems around the globe?

What I have learnt throughout this blog is that the effects of climate change on biota are never isolated. Rather, they feed into global, local and regional systems, changing interactions within and between ecosystems. Specifically, climate, through its penetrative direct and indirect effects on the biodiversity of communities, is having significant effects on the overall resilience of ecosystems.

What is Resilience?

But what does ecosystem resilience mean? Côté and Darling(2010) provide a nice summary, describing it the ecosystem’s capacity to ‘absorb disturbance without shifting to an alternative state and losing function and services’. Similarly, Jones (2014) describes it as a measure of an ecosystem’s persistence in the face of change, whilst still maintaining the same relationships both with biotic and abiotic variables. Folke et al. (2004) support these views, summarising that resilience is the ability of ecosystems to retain their identity, alongside structure, function and feedbacks.

Ecosystem resilience plays an incredibly important role in preserving the integrity of the biosphere by preventing ecosystems from incurring irreversible damage in the face of changing environmental, biological or nutritional conditions. Resilience acts almost as an “insurance policy” or “buffer” and prevents what is commonly referred to as “regime change”, whereby the make-up of an ecosystem changes dramatically from one form to another. These regime shifts by nature are sudden and irreversible; it is very rare for ecosystem change to be a gradual or smooth progress. These usually occur after a threshold has been passed causing drastic change to feedbacks within ecosystems and changing its entire form and function (Folke et al. 2004). Resilience, then, plays a critical role in preventing this from occurring.

Resilience and Climate Change

Ecosystem resilience is driven largely by biodiversity at a variety of scales. It is this biodiversity that allows ecosystems to weather disturbances without drastic change, and to recover to optimum conditions after such disturbances have occurred. “Resilience”, according both to Folke et al. (2004) and Jones (2014), can be theorised as made up of three general components. These are; functional-group diversity, functional-response diversity and renewal and reorganisation.

Unfortunately, all three are highly susceptible to climate change. Biodiversity, as we have seen, suffers greatly as temperatures warm at unprecedented speeds and precipitation regimes become highly variable and uncertain. And, as biodiversity is central to resilience, it is unavoidable that ecosystems find themselves more vulnerable and pushed further and further towards breaking point. 

Functional-Group Diversity

Functional group diversity in essence refers to a group of organisms that complete a certain service or function within an ecosystem. These “functional groups” can range from pollinators and grazers to those that generate soils or moderate water flows, and their presence and persistence within ecosystems are essential for performance and sustainability (Folke et al. 2004). The loss of a functional group then means that ecosystems can become unbalanced and critical processes are lost, reducing resilience and pushing the system closer to its threshold. As we have explored over the past few months, climate change causes mass declines in species and could potentially lead to significant loss, meaning it seems inevitable that functional groups will disappear and resilience damaged beyond repair.

To expand on this point, we will look at Jones' (2014), exploration of the consequences of the loss of the top predator, a key functional group. He suggests that such an occurrence can trigger what is referred to as a “trophic cascade” whereby the removal of the apex predator removes suppressive effects on those lower in the food chain, which can in turn increase predation on producers and have unpredictable and uncertain effects on the food web of ecosystems. Jones (2014) offers the example whereby removal of sea otters in a marine community led to a dramatic rise in numbers of sea urchins which predate on kelp. This, in turn, reduced the numbers of those species who relied on kelp for cover and protection. Removal of any functional group then can have unforeseen consequences for all members of the ecosystem and can subsequently affect balance and stability.

Climate change, as we have seen, also encourages invasive species by increasing their potential distributions. This can affect resilience whereby an ecosystem that originally lacked a functional group finds it filled by an invasive species. This can be devastating for an ecosystem, affecting both relationships and environmental conditions and causing further disturbance. Take for instance the spread of Myrica faya (also known as the firetree) into Hawaii; this plant, being a nitrogen fixer (an organism that converts nitrogen from the atmosphere into ammonia), introduced a new function to the ecosystem, resulting in nitrogen inputs increasing threefold and consequently facilitating the spread of further invasives to the area which were better adapted to nitrogen rich conditions, whilst making conditions considerably more hospitable for native species adapted to low nitrogen conditions (Folke et al. 2004).

Climate change hence can have significant effects on the functional-group diversity of ecosystems. Climate change not only can result in the removal of functional groups, reducing resilience and destabilising ecosystems, but can also create new functional groups that push ecosystems towards a new state.

Functional-Response Diversity

Also essential for resilience is what is referred to as “functional response diversity”. This refers to species within a particular functional group having a diversity of responses to environmental changes or disturbances that may undermine dominant actors in said group. This creates resilience as if one species were to suffer, there would be others that contribute to the same ecosystem function who could take their place. It is in this way that higher biodiversity (specifically species abundance) buffers an ecosystem against change, and the greater number of species that can perform an ecosystem function and have diversity in responses, the greater the functional redundancy (that is, the amount of species that can replace a dominant functioning species) (Jones2014).

Climate change has a negative impact on resiliance then if it reduces the biodiversity of an ecosystem. By making species less fit or removing them from an ecosystem entirely, functional redundancy is reduced and hence functional-response diversity contributes less to resilience.

Renewal and Reorganisation

According to Folke etal. (2004), the ability of an ecosystem to recover to an equilibrium state after disturbance is also a key determinant of ecosystem resilience. Although referred to by Folke et al. (2004) as “renewal and reorganisation”, this is sometimes referred to as the “back loop of ecosystem development”. 

This re-building, if you will, is conducted mainly through the functional groups of both biological legacies and what Folke et al. (2004) refer to as mobile link species. Biological legacies, for instance, are those species that are sufficient at weathering disturbances and re-establishing populations afterwards. Large trees, for instance, can serve as biological legacies in forest ecosystems after storms or fire have ravished the ecosystem. In the tundra, this job is taken by those species that create seed banks or make use of vegetative propagules. Mobile link species, on the other hand, are those that bring in seeds and other organic material from surrounding ecosystems, such as birds and other animals that eat matter that, after passed, can be used to reintroduce species. In this way, it is not only local biodiversity that is important for resilience, but also biodiversity at larger scales such as those of landscape and region, as this can ensure key species are reintroduced to local systems.

Flying foxes (of the genus Pteropus) are a fine example of a species that exists in the mobile link functional group. As fruit eaters, they readily transport seeds between ecosystems and habitats, making them excellent recolonisers of vegetation. (Folke et al. 2004)

Once again, climate change can damage resilience by making it harder for ecosystems to redevelop after disturbances. If key species suffer at the hands of the climate (through methods we have discussed), this can limit the ability of an ecosystem to rebuild, reducing its resilience and pushing it closer towards total regime change. 

Conclusion

Over the past few months we have explored in detail the range of consequences that climate change can have for species and ecosystems alike. Today we see the ramifications of these changes. If climate change continues as is, and biodiversity continues to decline, then the resilience of ecosystems could become completely subverted. This would make these communities vulnerable to disturbances that previously could have been absorbed and mitigated with ease by these systems, and could eventually lead to thresholds being crossed and irreversible changes to our planets biosphere.

Widespread collapse of ecosystems seems inevitable if climate change continues on this path. Next week I would like to look at the potential ramifications of this, and what the future really does hold for biodiversity. Are we moving towards a 6^th mass extinction?

The evidence really doesn't seem very optimistic.