In 1977, on the islands of French Polynesia, government authorities released a predatory snail. They hoped this introduction would effectively control another species of invasive snail, previously introduced to supply escargot.
Instead, by the early 1980s, scientists reported alarming declines of native snail populations. Within ten years, 48 native snail species (genus Partula) had been driven to extinction in the wild.
The extinction of the Partula is notorious partially because these snails were, before going extinct, the study subjects of the first test in nature of Darwin’s theory of evolution by natural selection.
In the decades since, attempts to control and eradicate invasive species have become common, generally with far better results.
However, our paper, published today in Nature Ecology and Evolution, highlights the importance of scientific evidence and independent assessments when deciding whether to control or eradicate invasive species.
From islands to continents
Increasingly, large-scale invasive species control initiatives are being proposed worldwide. As early as 2018, a herpes virus will be released in Australia’s largest river system, targeting invasive common carp. As part of its Threatened Species Strategy, Australia is also planning to kill two million feral cats.
Across the Tasman Sea, New Zealand has made a bold commitment to remove three groups of invasive predators entirely by 2050.
It’s not just Australians and Kiwis making ambitious invasive species control proposals: bounties are being paid to catch invasive fish in the United States. The European Union has blacklisted 37 species of plants and animals within 4 million square kilometres, many of which are well-established and will be targeted by control (not preventative) measures.
Meanwhile, new gene editing technology has made the continental-scale eradication of invasive species a real possibility, for example by implementing gene drives that reduce breeding success. If you haven’t heard of it, CRISPR is a startling new biotechnology that makes genetic modification of plants and animals much easier. It offers new potential solutions to some of the world’s worst environmental, agricultural and human health problems.
These schemes will be implemented across large and complex social-ecological systems, and some options – like releasing a virus or genetically engineered species – may be irreversible.
While these projects may yield great benefits, we must be aware of the potential risk of unexpected and undesirable outcomes.
A prime example is the project to remove invasive carp from a million square kilometres of Australia’s rivers. Some scientists have expressed concern about the potential for the virus to jump species, and the effects of having hundreds of tonnes of dead fish fouling waterways and sapping oxygen from the water. The CSIRO and those planning the release of the virus suggest it is safe and effective.
Despite extensive media reporting giving the impression that the plan is approved to go ahead, the National Carp Control Plan has yet to publish a risk assessment, and is planning to deliver a report in 2018.
Removing well-established invasive species can create unforeseen consequences. These species can play significant roles in food webs, provide shelter for native animals, support ecosystem services, and their sudden death can disrupt ecological processes that are important to native species.
For example, a large amount of time and effort was spent in removing the non-native tamarix (or “salt cedar”) in the southwestern United States, because of the belief it was harming the water table.
Yet, subsequent research has indicated that the negative effects of tamarix have been exaggerated. In some areas, the plant is actually used by large numbers of endangered flycatchers to nest and fledge their young.
A science-based solution
In our paper, we highlight a series of considerations that should be addressed before plunging into large-scale invasive species control.
Fundamentally, there must be a demonstrable ecological and social benefit from control or eradication, above and beyond the purely ideological. At first this might seem facile, but invasive species control initiatives are often highly politicised, with science taking a back seat. Given scarce funding for conservation, it is crucial that resources are not squandered on programmes that may not deliver – or could cause environmental damage.
We must avoid assuming that attempting to control invasive species will, by default, solve our environmental problems. This means addressing the full range of human pressures which negatively affect biodiversity. We must also consider how removing an influential invasive species could benefit other invasive species, harm native species through increased predation and competition, or alter ecological processes or habitat.
Comprehensive risk-benefit assessment of invasive species control programs allow decision-makers to proactively avoid, manage or accept these risks.
For example, tonnes of decomposing carp post-virus may cause short-term water quality issues, or the death of native species. Ultimately, however, these risks could be acceptable if the virus is effective, and allows native species a window of opportunity to recover.
Large-scale invasive species control demands careful investigation of the risks and rewards. We hope our paper can provide policy-makers with better guidelines for science-based decision-making.
Dingoes could be the key to controlling red foxes and other invasive predators, but only if we encourage them in large enough numbers over a wide enough area, our research shows.
Interest in re-introducing or restoring top predators, like dingoes and wolves, has been fuelled by recent studies demonstrating their important roles in their ecosystems. They can especially be vital in suppressing the abundance of lower-order competitors or “mesopredators”, like red foxes and possibly feral cats (which can have devastating effects on native species).
But researchers have found top predators aren’t always successful in reducing mesopredator numbers. Until now, such variation has been linked to human presence, land-use changes and environmental factors such as landscape productivity.
However, our research, published yesterday in Nature Communications, found that a key factor for success is high numbers of dingoes and wolves across their natural range.
The density effect
If you look at how species are typically distributed across a landscape – their range – ecological theory predicts there’ll be lower numbers at the outer edges of their range.
If you do need large numbers of top predators to effectively suppress mesopredators, the core of their range is potentially the best place to look.
We tested this idea, looking at the dingo in Australia and the grey wolf in North America and Europe. The mesopredators included the red fox in Australia, the coyote in North America and the golden jackal in Europe.
We used information from bounty hunting programs, as these provide data on predator numbers across a wide geographical area. In the case of Australia we used historic data from the 1950s, as this is the most recent reliable information about red fox and dingo distribution. The actual population numbers of red foxes and dingoes have changed substantially since then, but the nature of their interactions – which is what we were investigating – has not.
We determined that top predators exist in higher numbers at the core of their ranges in comparison to the edges. We then looked at mesopredator numbers across the range edges of their respective top predator.
The results, which were consistent across the three continents, suggest that top predators can suppress mesopredators effectively (even completely) but only in the core of their geographic range, where their numbers are highest.
In other words, abundant top predators can exert disproportionate mesopredator control once their numbers increase past a certain point.
The ‘enemy constraint hypothesis’
The relationship we uncovered is now formalised as the “Enemy Constraint Hypothesis”. It could apply to other predator dyads, where two animals compete for similar resources – even relationships involving parasites and pathogens.
Our findings are important for understanding species interactions and niches, as well as the ecological role of top predators. It could explain why other studies have found top predators have little influence on mesopredators: they were looking at the edge, not the core, of the top predators’ range.
How many top predators do we need?
Dingoes can be vital for reducing red fox and possibly feral cat numbers. In our case studies the ranges of each top predator were limited primarily by human use of the land and intensive shooting, trapping and poisoning.
Killing pack animals like dingoes can fracture social groups, potentially altering their natural behaviour and interactions with other species. Future studies on predator interactions therefore need to consider the extent to which the animals are acting in response to human intervention.
If we want to benefit from the presence of top predators, we need to rethink our approach to management – especially where they are subjected to broad-scale control, as the dingo is in some parts of Australia.
Changing our relationship with top predators would not come without its challenges, but high extinction rates around the world (and especially in Australia) clearly indicate that we urgently need to change something. If this includes restoring top predators, then we need to think big.
Hi all – just a quick note to let you know I’m taking a short break from the Blog. I’ll be away from the Blog for about a week. Thanks.
2016-17 has been a great year for Australian farmers, with record production, exports and profits. These records have been driven largely by good weather, in particular a wet winter in 2016, which led to exceptional yields for major crops.
Unfortunately, these good conditions go very much against the long-term trend. Recent CSIRO modelling suggests that changes in climate have reduced potential Australian wheat yields by around 27% since 1990.
While rising temperatures have caused global wheat yields to drop by around 5.5% between 1980 and 2008, the effects in Australia have been larger, as a result of major changes in rain patterns. Declines in winter rainfall in southern Australia have particularly hit major broadacre crops (like wheat, barley and canola) in the key southeastern and southwestern cropping zones. There is strong evidence that these changes are at least partly due to climate change.
Climate change is affecting farm productivity
A recent study by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) confirms that changes in climate have had a negative effect on the productivity of cropping farms, particularly in southwestern Australia and southeastern Australia.
In general, the drier inland parts of the cropping zone have been more heavily affected, partly because these areas are more sensitive to rainfall decline. Smaller effects have occurred in the wetter zones closer to the coast. Here less rain can have little effect on – and can even improve – crop productivity.
Farmers are reacting
However, it’s not all bad news. The study finds that Australian farmers are making great strides in adapting to climate change.
Much has been written about the fact that farm productivity in Australia has essentially flatlined since the 1990s, after several decades of consistent growth. The ABARES research suggests that changes in climate go some way towards explaining this slowdown.
After controlling for climate, there has been relatively strong productivity growth on cropping farms over the past decade. However, while farms have been improving, these gains have been offset by deteriorating conditions. The net result has been stagnant productivity.
Furthermore, there is evidence that this resurgence in productivity growth is a direct result of adaptation to the changing climate. Our study found that over the past decade cropping farms have improved productivity under dry conditions and minimised their exposure to climate variability.
This contrasts with the 1990s, when farms focused more on maximising performance in good conditions at the expense of increasing their exposure to drought.
Anecdotal evidence suggests that winter cropping farms have made a range of changes over the last decade, to better exploit soil moisture left from the summer period. The most obvious is the shift toward conservation tillage during the 2000s, where some or all of a previous crop’s residue (such as wheat stubble) is left in a field when planting the new crop.
It seems that farmers are adapting to new seasonal trends of rainfall, which for most cropping farms means less rain in winter and more in summer.
Is the Australian cropping belt moving south?
Previous research has suggested that the zone of Australia suitable for growing broadacre crops, known as the cropping belt, appears to be shifting south.
Our study found evidence to support this, with ABARES and ABS data showing increased cropping activity in the wetter southern fringe of the cropping belt in Western Australia and Victoria. At the same time, there have been declines in some more inland areas, which have been heavily affected by the climate downturn.
These shifts may be partly due to other factors – such as commodity prices and technology – but it’s likely that climate is playing a role. Similar changes have already been observed in other agricultural sectors, including the shift of wine grapes into Tasmania in response to rising temperatures.
What does this mean for the future?
At present there remains much uncertainty over future rainfall patterns. While climate models and recent experience suggest a clear direction of change, there is little agreement over the magnitude.
On the positive side, we know that farmers are successfully adapting to the changes in climate and have been for some time. However, so far at least, farmers have only been able to tread water: improving productivity just fast enough to offset the decline in climate. To remain competitive, we need to find ways to improve productivity faster, especially if current climate trends continue or worsen.
Neal Hughes is Director, Water and Climate, at the Australian Bureau of Agricultural and Resource Economics and Sciences, and a visiting fellow at the Australian National University’s Crawford School of Public Policy.
The conventional wisdom that the United States should remain under the Paris Agreement is wrong. A US withdrawal would be the best outcome for international climate action.
With Trump set to decide on the matter after this week’s G7 meeting, his aides are split on the issue. Chief strategist Steve Bannon heads the faction pushing for an exit. Secretary of State and former ExxonMobil chief executive Rex Tillerson has argued for the US to retain a “seat at the table”.
It is within the president’s power to withdraw from the Paris Agreement and perhaps even the United Nations Framework Convention on Climate Change (UNFCCC), which has overseen global climate diplomacy for some 25 years.
In a commentary published in Nature Climate Change today, I argue that a US withdrawal would minimise risks and maximise opportunities for the climate community. Simply put: the US and the Trump administration can do more damage inside the agreement than outside it.
There are four key, interconnected risks related to US participation in the Paris Agreement: that the US will miss its emissions target; that it will cut climate finance; that it will cause a “domino” effect among other nations; and that it will impede the UN negotiations.
Money and emissions are all that matter
The first two risks are unaffected by withdrawal. The Paris Agreement doesn’t require the US to meet its current emissions reduction pledge, or to provide further climate finance to developing countries. The agreement is procedural, rather than binding; it requires a new, tougher climate pledge every five years, but actually hitting these targets isn’t mandatory.
The US will probably miss its climate target regardless. It would need more than just Obama’s Clean Power Plan to hit its goal of reducing emissions by 26-28% on 2005 levels by 2025. And now that Trump has decided to roll back those policies too, US emissions are set to increase through to 2025, rather than decrease.
The same goes for international climate funding, which will be cut under the “America First” budget plan. That includes funds previously earmarked for the Green Climate Fund, which has so far raised US$10 billion in climate aid. The US was to provide US$3 billion but has donated just US$1 billion so far. The remaining money is almost certainly not coming.
The third risk is the domino effect: that US actions could inspire others to delay climate action, renege on their targets, or withdraw. But there is little evidence to suggest that the US dropping out will trigger other nations to follow suit.
The closest historical parallel is the Kyoto Protocol, which the US signed but never ratified. When President George W. Bush announced that the US would not ratify the treaty, others rallied to the protocol’s aid and pushed through the Marrakech Accords in 2001, to strengthen Kyoto’s rules.
What’s more likely to cause a domino effect is US domestic behaviour, rather than any potential withdrawal from the Paris deal. Other countries are more likely to delay or free-ride on their pledges if they see the US miss its target, revealing how weak the Paris Agreement really is.
Paris has little aside from inspiring public pressure and long-term low-carbon investment patterns. Neither pressure nor the “investment signal” is likely to work if a renegade US shows that Paris is an empty global show-and-tell regime. Investors and the public are likely to lose faith in an agreement that can visibly do nothing to constrain a climate laggard.
The fourth risk is that the US will act as a spoiler in international climate talks. This requires membership. If the US remains in the agreement it will retain a veto in the negotiations.
The negotiations are at a crucial juncture. The so-called “Paris Rulebook”, which details how exactly the agreement will be fulfilled, is being negotiated, with plans for it to be adopted in 2018.
The US could use its voice and veto to water down the rules. It might even stall and overload negotiations by demanding amendments to the Paris Agreement, as Energy Secretary Rick Perry has suggested. A US that has credibly threatened to withdraw may have even more diplomatic clout going forward.
Considered in this light, giving the former head of ExxonMobil a “seat at the table” is a terrible idea.
A US withdrawal, on the other hand, could create new opportunities, such as renewed European and Chinese leadership. In the wake of the 2016 US election, former French presidential nominee Nicholas Sarkozy raised the idea of applying a carbon tax of 1-3% on US imports. In a time of rising protectionist policies, particularly in the US, carbon border tariffs may become more politically palatable.
A US dropout would also be an ideal opportunity for a rising China to stamp its mark on an international issue. It would give both China and the European Union a chance to jump even further ahead of the US in the renewable energy markets of the future.
The EU previously showed leadership in the absence of the US to revive the Kyoto Protocol and forge ahead with renewable energy. This time Europe could do so with the support of another great power.
Such cooperation could take numerous forms. One simple way would be for the two to put forward a stronger joint climate pledge. This could be strengthened by uniting their respective carbon trading schemes and applying a common border carbon tariff.
Trade measures and an EU-China climate bloc will be far more effective than Paris ever could have been. Yet none of these possibilities is likely to become reality without the diplomatically drastic move of US withdrawal. On balance, it is clear that a US climate exit is preferable to remaining.
It is worth stressing here the difference between pulling out of the Paris Agreement and withdrawing from the UNFCCC. The latter is far more dramatic, and more likely to trigger a domino effect. It would also mean the US would no longer be legally bound to report on its emissions and actions to the international community. It would become a complete climate pariah.
A future president could easily rejoin Paris through an executive agreement. In contrast, re-ratifying the UNFCCC might require a vote in the US Senate, which has become more partisan and divided since the convention was first ratified in 1992. However, withdrawal from the UNFCCC would lessen the threat of US obstruction, as it would lose its veto in the wider negotiations and be even more politically ostracised.
Despite this, the same basic risk-opportunity calculus applies. The domino effect may be more likely, but overall a withdrawal is still preferable.
Participation is a red herring
Wanting the US to remain is a short-sighted, knee-jerk reaction. The international community should be much more worried about the real domestic actions of the US, rather than whether it is symbolically cooperating internationally.
The international community appears to be mortally afraid that the US will make the largely symbolic gesture of quitting Paris. Yet there was less concern when Trump rolled back domestic climate measures.
EU Climate Commissioner Miguel Arias Cañete recently stated that Paris allows for the continued use of fossil fuels and provides the flexibility for a “new US administration to chart its own path”.
Is this really a worthwhile message to send to the White House: that blatantly violating the purpose and spirit of the Paris Agreement is fine, as long as you are still cooperating on paper? It is disturbing that symbolism has apparently become more important than action.
Policy, not participation, needs to be the focus of criticism. Otherwise Paris will prove itself to be nothing more than a diplomatic fig leaf.
While Paris may be weak, international climate action can still be strong. The shock of Trump’s withdrawal could make international action stronger by allowing emboldened leadership to blossom elsewhere.
This article is part of the Democracy Futures series, a joint global initiative between The Conversation and the Sydney Democracy Network. The project aims to stimulate fresh thinking about the many challenges facing democracies in the 21st century.
Until recently, weather talk was an easy filler for any awkward silence. But tragically for polite conversationalists everywhere, the weather is no longer mundane.
Especially in summers like the one we just had in Sydney, weather talk has many of us breaking a surprising sweat — and not only from the heat. With climate change a hot-button issue globally (in spite and even because of its lack of mention in national budgets, or erasure from government websites), talk about the weather now has an unavoidably political tinge.
While it may not lead directly to impassioned critiques of climate governance, nor immediately sort the sceptics from the believers, talk of brewing storms or dried-up reservoirs now carries with it a whiff of trepidation about our collective forecasts.
Bridging the divide
Despite the growing politicisation of weather talk, weather and climate are usually understood as empirically distinct bodies of knowledge. Climate is, to quote British comedy duo Armstrong and Miller, “a long-term trend averaged over many years”, as opposed to weather, “which is what’s going on outside the window right now”.
The problem with this distinction is that climate change’s global reach and extended time scale can make it seem like it is happening somewhere else and to someone else (or, indeed, not at all). So perhaps the distinction is not useful for the cultural processes of adaptation. What might happen if we were to breach official definitions and disciplinary lines and think of the two things together?
Closing the distance between weather as event and climate as pattern can accomplish several things. Most obviously, it reminds us that there is a relationship between the two. Without weather, there would be nothing to amalgamate as climate.
While one heatwave does not equate to “climate change”, many and increasing ones give us pause to wonder. Leslie Hughes and Will Steffen are doing the data-driven work in this regard.
Ironically, though, while the complexity of climate data might put me off engaged concern for the global climate, the exhaustion I feel cycling behind a truck in 30℃-plus weather might do the opposite. Maybe this bodily discomfort is part of the point.
In other words, bringing climate and weather together can remind us that climate change is not only about abstract calculations on scales too big for our small and ultimately short-lived human forms to fathom.
Thinking about weather as part of climate underscores that we experience climate change with and on our bodies; climate change is lived by us at a very human scale, too.
The daily experience of weathering
So, what would it mean to harness the daily, mundane intrusions of weather as political? In contrast to terms like resilience (complicit with neoliberal incitements of bootstrapping) or sustainability (which suggests we get to keep something intact), weathering invites us to consider what we will lose along the way.
Weathered bodies, weathered houses, weathered cars, weathered clothes, weathered relationships, weathered dreams – these all bear scars of what has worn them down, and of what they have been asked to carry, to survive, and to hack.
Bringing this sense of lived climate change to our everyday perception is neither an easy nor comfortable thing. For one, discomfort is not a place we generally like to dwell for long. In a more political sense, though, paying attention to the weather as something in which we are intimately implicated, not just a disconnected backdrop to our human dramas, reminds us we are weather-makers too.
Environmental activist Bill McKibben observes:
On a stable planet, nature provided a background against which the human drama took place; on the unstable planet we’re creating, the background becomes the highest drama.
This could be the epigraph for the Anthropocene.
Even in wealthy, climate-controlled places, weather inserts a reminder of one’s privilege, or luck, or vulnerability, or hardship, into those once mundane spaces. We may bemoan the slipping away of vacuous weather chats — “does everything have to be political?” — but perhaps noticing the weather can become an opening for everyday engagement in the politics of climate change instead.
In gender and cultural studies and the environmental humanities, rather than trying to leave weather-talk pregnant with fear, anticipation or political outrage, we are explicitly thinking with and through the weather to develop strategies for a rigorous and political response to climate change.
One way we are doing this is through a tactic or practice we call “weathering” – that is, cultivating attunement to how our own bodies, and bodies of others, experience weather. This includes how we and they manage it architecturally, technologically, professionally and socially.
We don’t all weather equally
Through the concept of “weathering”, our work forces a confrontation between large-scale climate data and embodied sociopolitical experiences that are too often treated as separate. It also underscores the politics and activism we hope this tactic can engender.
Such attentive acclimatisation reveals that, even though we’re all in the same planetary boat when it comes to global warming, we’re not all in it in the same way. This is something ecofeminists and environmental justice scholars have long known. Our work helps articulate how difference also marks our apparently banal encounters with the weather.
At a “Hacking the Anthropocence” symposium in Sydney this month, scholars, artists and activists are responding to the idea of “weathering”. The variety of experience that such a provocation reveals is astounding.
For Anne Werner’s and Genevieve Derwent’s work growing chickens on Autumn Farm and Cameron Muir’s reflections on life jackets for refugees, the weather holds a very different significance and function. Climate change is undoubtedly political – but all the more so because of these uneven individual and collective experiences of the weather.
Other kinds of bodily, socioeconomic, historical and geopolitical differences further complicate how we weather the world. When it comes to rising sea levels, or dried-up water holes, for example, racism, colonialism and gendered labour are all significant. Weathering as a concept thus asks us to think about what else, besides meteorological phenomena, one might be asked to weather.
Note that a more common meaning of “weathering” is as synonym for withstanding or enduring. Not only will different regions weather differently in a changing climate (drier, hotter in central Australia; more flooding on the US Atlantic coast; disappearing land in Pacific Islands), but people within those regions weather differently too.
A world weathering together
Our human experiences of weather are linked to how the non-human world is weathering what we have forced it to carry. Artist Victoria Hunt will ask us to imagine with her “The Cry of Water”, while archaeologist Denis Byrne will explore the significance of seawalls, which are weathered by erosion. Human and non-human worlds weather together in a fraught and desirous intimacy.
The animal world is also constantly weathering. We know about catastrophic events such as the endangered bats that cannot cope with heat above 42℃. We’ve learned that the Great Barrier Reef is bleaching as water temperatures rise.
But what about the less-well-known water-holding frog or, indeed, ants and brine shrimp? How do they weather? At our symposium, Rebecca Giggs, Kate Wright and Emily O’Gorman (respectively) will let us know how, and suggest what we humans might learn about weathering the world differently.
These contributions invite us to explore how our experiences of the weather are highly mediated by a range of social, political and cultural forces. Anthropologist of institutions Tess Lea will investigate how bureaucracy (materialised as mountains of paperwork) orients different populations’ capacity to weather. Cli-fi expert and petrocultures scholar Stephanie LeMenager invites us to speculate on what a new kind of civic engagement might look like in this context.
Weathering directly connects human social, cultural and economic structures such as racism, colonialism and gender oppression to climate change. It insists that we think about global warming on a massive scale as always textured by acute experiences of social phenomena.
We recognise that the weight of a changing climate will not be borne equally by bodies – across geographies, economic status, or species.
So next time you curse a forgotten umbrella as the skies open up, or welcome the sun shining on your kid’s birthday party in the park, remember that when it comes to the weather, the personal is getting more and more political.
Hacking the Anthropocene II: Weathering (May 25-31) is supported by the Sydney Social Sciences and Humanities Advanced Research Centre (SSSHARC); the Australian Research Council Centre of Excellence for the History of Emotions; the Sydney Environment Institute at the University of Sydney; the Planetary Health Initiative at the University of Sydney; and the Seed Box: a MISTRA-FORMAS Environmental Humanities Collaboratory (hosted at Linkoping University, Sweden).