This week many people across the world stopped and stared as extreme headlines announced that one eighth of the world’s species – more than a million – are threatened with extinction.
According to the UN report from the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) which brought this situation to public attention, this startling number is a consequence of five direct causes: changes in land and sea use; direct exploitation of organisms; climate change; pollution; and invasion of alien species.
It’s the last, invasive species, that threatens Australian animals and plants more than any other single factor.
Australia’s number one threat
Australia has an estimated 600,000 species of flora and fauna. Of these, about 100 are known to have gone extinct in the last 200 years. Currently, more than 1,770 are listed as threatened or endangered.
While the IPBES report ranks invasive alien species as the fifth most significant cause of global decline, in Australia it is a very different story.
Australia has the highest rate of vertebrate mammal extinction in the world, and invasive species are our number one threat.
Cats and foxes have driven 22 native mammals to extinction across central Australia and a new wave of decline – largely from cats – is taking place across northern Australia. Research has estimated 270 more threatened and endangered vertebrates are being affected by invasive species.
Introduced vertebrates have also driven several bird species on Norfolk Island extinct.
The effects of invasive species are getting worse
Although Australia’s stringent biosecurity measures have dramatically slowed the number of new invasive species arriving, those already here have continued to spread and their cumulative effect is growing.
Recent research highlights that 1,257 of Australia’s threatened and endangered species are directly affected by 207 invasive plants, 57 animals and three pathogens.
These affect our unique biodiversity, as well as the clean water and oxygen we breath – not to mention our cultural values.
When it comes to biodiversity, Australia is globally quite distinct. More than 70% of our species (69% of mammals, 46% of birds and 93% of reptiles) are found nowhere else on earth. A loss to Australia is therefore a loss to the world.
Some of these are ancient species like the Wollemi Pine, may have inhabited Australia for up to 200 million years, well before the dinosaurs.
Wollemi pines are dinosaur trees
But invasive species are found in almost every part of Australia, from our rainforests, to our deserts, our farms, to our cities, our national parks and our rivers.
The cost to Australia
The cost of invasive species in Australia continue to grow with every new assessment.
The most recent estimates found the cost of controlling invasive species and economic losses to farmers in 2011-12 was A$13.6 billion. However this doesn’t include harm to biodiversity and the essential role native species play in our ecosystems, which – based on the conclusions of the IPBES report – is likely to cost at least as much, and probably far more.
Rabbits, goats and camels prevent native desert plant community regeneration; rabbits alone impacting over 100 threatened species. Rye grass on its own costs cereal farmers A$93M a year.
Aquaculture diseases have affected oysters and cost the prawn industry $43M.
From island to savannah
Globally, invasive species have a disproportionately higher effect on offshore islands – and in Australia we have more than 8,000 of these. One of the most notable cases is the case of the yellow crazy ants, which killed 15,000,000 red land crabs on Christmas Island.
Nor are our deserts immune. Most native vertebrate extinctions caused by cats have occurred in our dry inland deserts and savannas, while exotic buffel and gamba grass are creating permanent transformation through changing fire regimes.
Australia’s forests, particularly rainforests, are also under siege on a number of fronts. The battle continues to contain Miconia weed in Australia – the same weed responsible for taking over 70% of Tahiti’s native forests. Chytrid fungus, thought to be present in Australia since 1970, has caused the extinction of at least four frog species and dramatic decline of at least ten others in our sensitive rainforest ecosystems.
Myrtle rust is pushing already threatened native Australian Myrtaceae closer to extinction, notably Gossia gonoclada, and Rhodamnia angustifolia and changing species composition of rainforest understories, and Richmond birdwing butterfly numbers are under threat from an invasive flower known as the Dutchman’s pipe.
Australia’s rivers and lakes are also under increasing domination from invasive species. Some 90% of fish biomass in the Murray Darling Basin are European carp, and tilapia are invading many far north Queensland river systems pushing out native species .
Invasive alien species are not only a serious threat to biodiversity and the economy, but also to human health. The Aedes aegypti mosquito found in parts of Queensland is capable of spreading infectious disease such as dengue, zika, chikungunya and yellow fever.
And it’s not just Queensland that is under threat from diseases spread by invasive mosquitoes, with many researchers and authorities planning for when, not if, the disease carrying Aedes albopictus establishes itself in cooler and southern parts of Australia.
What solutions do we have?
Despite this grim inventory, it’s not all bad news. Australia actually has a long history of effectively managing invasive species.
Targeting viruses as options for controlling rabbits, carp and tilapia; we have successfully suppressed rabbit populations by 70% in this way for 50 years.
Weeds too are successful targets for weed biological control, with over a 65% success rate controlling more than 25 targets.
The IPBES report calls for “transformative action”. Here too Australia is at the forefront, looking into the potential of gene-technologies to suppress pet hates such as cane toads.
Past and current invasive species programs have been supported by governments and industry. This has provided the type of investment we need for long-term solutions and effective policies.
Australia is better placed now, with effective biosecurity policies and strong biosecurity investment, than many countries. We will continue the battle against invasive species to stem biodiversity and ecosystem loss.
Today the Australian Koala Foundation announced they believe “there are no more than 80,000 koalas in Australia”, making the species “functionally extinct”.
While this number is dramatically lower than the most recent academic estimates, there’s no doubt koala numbers in many places are in steep decline.
It’s hard to say exactly how many koalas are still remaining in Queensland, New South Wales, Victoria, South Australia and the Australian Capital Territory, but they are highly vulnerable to threats including deforestation, disease and the effects of climate change.
Once a koala population falls below a critical point it can no longer produce the next generation, leading to extinction.
What does ‘functionally extinct’ mean?
The term “functionally extinct” can describe a few perilous situations. In one case, it can refer to a species whose population has declined to the point where it can no longer play a significant role in their ecosystem. For example, it has been used to describe dingoes in places where they have become so reduced they have a negligible influence on the species they prey on.
Dingoes are top predators, and therefore can play a significant role in some ecosystems. Our innocuous, leaf-eating koala cannot be considered a top predator.
For millions of years koalas have been a key part of the health of our eucalyptus forests by eating upper leaves, and on the forest floor, their droppings contribute to important nutrient recycling. Their known fossil records date back approximately 30 million years so they may have once been a food source for megafauna carnivores.
Functionally extinct can also describe a population that is no longer viable. For example in Southport, Queensland, native oyster reef beds are functionally extinct because more than 99% of the habitat has been lost and there are no individuals left to reproduce.
Finally, functionally extinct can refer to a small population that, although still breeding, is suffering from inbreeding that can threaten its future viability. We know that at least some koala populations in urban areas are suffering in this way, and genetic studies on the Koala Coast, located 20kms south-east of Brisbane, show that the population is suffering from reduced genetic variation. In South East Queensland, koalas in some areas have experienced catastrophic declines
We also know that koala populations in some inland regions of Queensland and New South Wales are affected by climate extremes such as severe droughts and heatwaves and have declined by as much as 80%.
Exhaustive multi-disciplinary koala research continues apace in an effort to find ways of protecting wild koala populations and ensuring that they remain viable now and into the future. Habitat loss, population dynamics, genetics, disease, diet and climate change are some key areas being studied.
How many koalas are there?
Koala researchers are often asked “how many koalas are in the wild?” It’s a hard question to answer. Koalas are not stationary, are patchily distributed throughout an extremely wide range encompassing urban and rural areas in four states and one territory, and are usually difficult to see.
To determine whether each population of koalas scattered across eastern Australia is functionally extinct would require a gargantuan effort.
In 2016, in an attempt to determine population trends for the koala within the four states, a panel of 15 koala experts used a structured, four-step question format to estimate bioregional population sizes of koalas, and changes in those sizes.
The estimated percentage of koala population loss in Queensland, New South Wales, Victoria and South Australia was 53%, 26%, 14% and 3%, respectively. The estimated total number of koalas for Australia was 329,000 (within a range of 144,000–605,000), with an estimated average decline of 24% over the past three generations and the next three generations.
Since May 2012, koalas have been listed as vulnerable in Queensland, New South Wales and the Australian Capital Territory because populations in these regions have declined significantly or are at risk of doing so.
In the southern states of Victoria and South Australia, koala populations vary widely from abundant to low or locally extinct. Although not currently listed as vulnerable, these koalas are also experiencing a range of serious threats, including low genetic diversity.
To date, the present “vulnerable” listing has not achieved any known positive results for koala populations in Queensland and New South Wales. In fact, recent research invariably shows the opposite.
This is because the key threats to koalas remain, and are mostly increasing. The primary threat is habitat loss. Koala habitat (primarily eucalyptus woodlands and forests) continues to rapidly diminish, and unless it is protected, restored, and expanded, we will indeed see wild koala populations become “functionally extinct”. We know what comes after that.
New Zealand’s long-awaited zero carbon bill will create sweeping changes to the management of emissions, setting a global benchmark with ambitious reduction targets for all major greenhouse gases.
The bill includes two separate targets – one for the long-lived greenhouse gases carbon dioxide and nitrous oxide, and another target specifically for biogenic methane, produced by livestock and landfill waste.
Launching the bill, Prime Minister Jacinda Ardern said:
Carbon dioxide is the most important thing we need to tackle – that’s why we’ve taken a net zero carbon approach. Agriculture is incredibly important to New Zealand, but it also needs to be part of the solution. That is why we have listened to the science and also heard the industry and created a specific target for biogenic methane.
- Create a target of reducing all greenhouse gases, except biogenic methane, to net zero by 2050
- Create a separate target to reduce emissions of biogenic methane by 10% by 2030, and 24-47% by 2050 (relative to 2017 levels)
- Establish a new, independent climate commission to provide emissions budgets, expert advice, and monitoring to help keep successive governments on track
- Require government to implement policies for climate change risk assessment, a national adaptation plan, and progress reporting on implementation of the plan.
Bringing in agriculture
Preparing the bill has been a lengthy process. The government was committed to working with its coalition partners and also with the opposition National Party, to ensure the bill’s long-term viability. A consultation process in 2018 yielded 15,000 submissions, more than 90% of which asked for an advisory, independent climate commission, provision for adapting to the effects of climate change and a target of net zero by 2050 for all gasses.
Throughout this period there has been discussion of the role and responsibility of agriculture, which contributes 48% of New Zealand’s total greenhouse gas emissions. This is an important issue not just for New Zealand and all agricultural nations, but for world food supply.
Another critical question involved forestry. Pathways to net zero involve planting a lot of trees, but this is a short-term solution with only partly understood consequences. Recently, the Parliamentary Commissioner for the Environment suggested an approach in which forestry could offset only agricultural, non-fossil emissions.
Now we know how the government has threaded its way between these difficult choices.
Separate targets for different gases
In signing the Paris Agreement, New Zealand agreed to hold the increase in the global average temperature to well below 2°C and to make efforts to limit it to 1.5°C. The bill is guided by the latest Intergovernmental Panel on Climate Change (IPCC) report, which details three pathways to limit warming to 1.5°C. All of them involve significant reductions in agricultural methane (by 23%-69% by 2050).
Farmers will be pleased with the “two baskets” approach, in which biogenic methane is treated differently from other gasses. But the bill does require total biogenic emissions to fall. They cannot be offset by planting trees. The climate commission, once established, and the minister will have to come up with policies that actually reduce emissions.
In the short term, that will likely involve decisions about livestock stocking rates: retiring the least profitable sheep and beef farms, and improving efficiency in the dairy industry with fewer animals but increased productivity on the remaining land. Longer term options include methane inhibitors, selective breeding, and a possible methane vaccine.
Ambitious net zero target
Net zero by 2050 on all other gasses, including offsetting by forestry, is still an ambitious target. New Zealand’s emissions rose sharply in 2017 and effective mechanisms to phase out fossil fuels are not yet in place. It is likely that with protests in Auckland over a local 10 cents a litre fuel tax – albeit brought in to fund public transport and not as a carbon tax per se – the government may be feeling they have to tread delicately here.
But the bill requires real action. The first carbon budget will cover 2022-2025. Work to strengthen New Zealand’s Emissions Trading Scheme is already underway and will likely involve a falling cap on emissions that will raise the carbon price, currently capped at NZ$25.
In initial reaction to the bill, the National Party welcomed all aspects of it except the 24-47% reduction target for methane, which they believe should have been left to the climate commission. Coalition partner New Zealand First is talking up their contribution and how they had the agriculture sector’s interests at heart.
While climate activist groups welcomed the bill, Greenpeace criticised the bill for not being legally enforceable and described the 10% cut in methane as “miserly”. The youth action group Generation Zero, one of the first to call for zero carbon legislation, is understandably delighted. Even so, they say the law does not match the urgency of the crisis. And it’s true that since the bill was first mooted, we have seen a stronger sense of urgency, from the Extinction Rebellion to Greta Thunberg to the UK parliament’s declaration of a climate emergency.
New Zealand’s bill is a pioneering effort to respond in detail to the 1.5ºC target and to base a national plan around the science reported by the IPCC.
Many other countries are in the process of setting and strengthening targets. Ireland’s Parliamentary Joint Committee on Climate recently recommended adopting a target of net zero for all gasses by 2050. Scotland will strengthen its target to net zero carbon dioxide and methane by 2040 and net zero all gasses by 2045. Less than a week after this announcement, the Scottish government dropped plans to cut air departure fees (currently £13 for short and £78 for long flights, and double for business class).
One country that has set a specific goals for agricultural methane is Uruguay, with a target of reducing emissions per kilogram of beef by 33%-46% by 2030. In the countries mentioned above, not so different from New Zealand, agriculture produces 35%, 23%, and 55% of emissions, respectively.
New Zealand has learned from processes that have worked elsewhere, notably the UK’s Climate Change Commission, which attempts to balance science, public involvement and the sovereignty of parliament. Perhaps our present experience in balancing the demands of different interest groups and economic sectors, with diverse mitigation opportunities and costs, can now help others.
The world’s largest assessment of biodiversity recently shared the alarming news that 1 million species are under threat of extinction.
Australia’s extinction record is poor compared to the rest of the world, and our investment into conservation doesn’t do enough to restrain the growing crisis.
Currently, 511 animal species, 1,356 plant species and 82 distinct “ecological communities” – naturally occurring groups of native plants, animals and other organisms – are listed as nationally threatened in Australia. And these numbers are increasing.
While much conservation effort focuses on protecting individual species, we are failing to protect and restore their habitats.
Our ongoing research into environmental investment programs shows that current levels of investment do not even come close to matching what’s actually needed to downgrade threatened ecosystems.
One of the programs we evaluated was the 20 Million Trees Program, a part of the Australian government’s National Landcare Program. For example, we analysed investment targeted at the critically endangered Peppermint Box Grassy Woodlands of South Australia.
Fewer than three square kilometres of woodland were planted. That’s less than 1% of what was needed to move the conservation status of these woodlands by one category, from critically endangered to endangered.
Conservation efforts are often focused on species – easily understood parts of our complex and interrelated ecosystems.
In recent years, some effective measures have been put in place to conserve species that are teetering on the edge of extinction. We have, for instance, seen the appointment of a Threatened Species Commissioner and the release of a Threatened Species Strategy and Prospectus.
But we don’t often hear about the 82 threatened ecological communities in which many of these species live.
Temperate eucalypt woodlands once covered vast areas of southern Australia before being cleared to make way for agriculture. The Peppermint Box Grassy Woodlands of South Australia, for instance, have been reduced to 2% of their former glory through land clearing and other forms of degradation.
These woodlands provide critical habitat for many plant and animal species, among them declining woodland birds such as the Diamond Firetail and Jacky Winter.
Focusing on the conservation and restoration of our threatened communities (rather than individual species) would create a better understanding of how much effort and investment is required to curb the extinction crisis and improve the outcomes of biodiversity restoration.
A problem of scale
Large-scale restoration investment programs are often touted in politics, particularly when these have a national focus. And many recent restoration programs, such as the Environment Restoration Fund, National Landcare Program, Green Army and 20 Million Trees, are important and worthwhile.
But in the majority of cases the effort is inadequate to achieve the stated conservation objectives.
Underlying threats to the environment often remain – such as vegetation clearing, genetic isolation and competition from introduced pests and weeds – and biodiversity continues to decline.
The 20 Million Trees program, for example, is the most recent national initiative aimed at restoring native vegetation systems, attracting A$70 million in investment between 2014 and 2020.
To place the scale of this investment into context, we analysed the impact of the 20 Million Trees program on the critically endangered Peppermint Box Grassy Woodlands of South Australia.
The restoration priority for this community should be to enhance the condition of existing remnant areas. But improving its conservation status would also require more effort to increase the area of land the woodland covers.
Even if the full six-year budget for 20 Million Trees (A$70 million) was used to replant only this type of woodland, it would still fall short of upgrading its conservation status to endangered. We estimate that moving the community up a category would require a minimum investment of A$150 million, excluding land value.
And Peppermint Box Grassy Woodland is just one of the threatened ecological communities listed for conservation. There are 81 others.
Although any effort to improve the status of threatened ecosystems (and species) is important, this example shows how current levels of effort and investment are grossly inadequate to have any substantial impact on threatened communities and the species that live there.
Our estimates relate to how restoration activities affect land cover. But ensuring they are also of adequate quality would need more long-term investment.
Investment in biodiversity conservation in Australia is falling while the extinction crisis is worsening.
Protecting and restoring ecological communities will preserve our unique native biodiversity and develop an environment that sustains food production and remains resilient to climate change. But failure to invest now will lead to extinctions and the collapse of ecosystems.
To make genuine inroads and have an enduring impact on Australian threatened species and ecosystems, restoration programs must be clear on the amount they expect to contribute to conservation and restoration objectives, along with co-benefits like carbon sequestration.
The programs must be at least an order of magnitude larger and be structured to produce measurable outcomes.
Stuart Collard, Research Fellow, The Centre for Global Food and Resources, University of Adelaide; Patrick O’Connor, Associate Professor, and Thomas Prowse, Postdoctoral research fellow, School of Mathematical Sciences, University of Adelaide