The world’s best fire management system is in northern Australia, and it’s led by Indigenous land managers

Rohan Fisher, Charles Darwin University and Jon Altman, Australian National University

The tropical savannas of northern Australia are among the most fire-prone regions in the world. On average, they account for 70% of the area affected by fire each year in Australia.

But effective fire management over the past 20 years has reduced the annual average area burned – an area larger than Tasmania. The extent of this achievement is staggering, almost incomprehensible in a southern Australia context after the summer’s devastating bushfires.

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Read more:
I made bushfire maps from satellite data, and found a glaring gap in Australia’s preparedness

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The success in northern Australia is the result of sustained and arduous on-ground work by a range of landowners and managers. Of greatest significance is the fire management from Indigenous community-based ranger groups, which has led to one of the most significant greenhouse gas emissions reduction practices in Australia.

As Willie Rioli, a Tiwi Islander and Indigenous Carbon Industry Network steering committee member recently said:

Fire is a tool and it’s something people should see as part of the Australian landscape. By using fire at the right time of year, in the right places with the right people, we have a good chance to help country and climate.

Importantly, people need to listen to science – the success of our industry has been from a collaboration between our traditional knowledge and modern science and this cooperation has made our work the most innovative and successful in the world.

A tinder-dry season

The 2019 fire season was especially challenging in the north (as it was in the south), following years of low rainfall across the Kimberly and Top-End. Northern Australia endured tinder-dry conditions, severe fire weather in the late dry season, and a very late onset of wet-season relief.

Despite these severe conditions, extensive fuel management and fire suppression activities over several years meant northern Australia didn’t see the scale of destruction experienced in the south.

A comparison of two years with severe fire weather conditions. Extensive early dry season mitigation burns in 2019 reduced the the total fire-affected areas.

This is a huge success for biodiversity conservation under worsening, longer-term fire conditions induced by climate change. Indigenous land managers are even extending their knowledge of savanna burning to southern Africa.

Burn early in the dry season

The broad principles of northern Australia fire management are to burn early in the dry season when fires can be readily managed; and suppress, where possible, the ignition of uncontrolled fires – often from non-human sources such as lightning – in the late dry season.

Traditional Indigenous fire management involves deploying “cool” (low intensity) and patchy burning early in the dry season to reduce grass fuel. This creates firebreaks in the landscape that help stop larger and far more severe fires late in the dry season.

Relatively safe ‘cool’ burns can create firebreaks.
Author provided

Essentially, burning early in the dry season accords with tradition, while suppressing fires that ignite late in the dry season is a post-colonial practice.

Savannah burning is different to burn-offs in South East Australia, partly because grass fuel reduction burns are more effective – it’s rare to have high-intensity fires spreading from tree to tree. What’s more, these areas are sparsely populated, with less infrastructure, so there are fewer risks.

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Read more:
The burn legacy: why the science on hazard reduction is contested

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Satellite monitoring over the last 15 years shows the scale of change. We can compare the average area burnt across the tropical savannas over seven years from 2000 (2000–2006) with the last seven years (2013–2019). Since 2013, active fire management has been much more extensive.

The comparison reveals a reduction of late dry season wildfires over an area of 115,000 square kilometres and of all fires by 88,000 square kilometres.

How fire has changed in northern Australia.
Author provided

Combining traditional knowledge with western science

The primary goals of Indigenous savanna burning projects remain to support cultural reproduction, on-country living and “healthy country” outcomes.

Savanna burning is highly symbiotic with biodiversity conservation and landscape management, which is the core business of rangers.

Ensuring these gains are sustainable requires a significant amount of difficult on-ground work in remote and challenging circumstances. It involves not only Indigenous rangers, but also pastoralists, park rangers and private conservation groups. These emerging networks have helped build new savanna burning knowledge and innovative technologies.

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Read more:
Our land is burning, and western science does not have all the answers

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While customary knowledge underpins much of this work, the vast spatial extent of today’s savanna burning requires helicopters, remote sensing and satellite mapping. In other words, traditional burning is reconfigured to combine with western scientific knowledge and new tools.

For Indigenous rangers, burning from helicopters using incendiaries is augmented by ground-based operations, including on-foot burns that support more nuanced cultural engagement with country.

On-ground burns are particularly important for protecting sacred sites, built infrastructure and areas of high conservation value such as groves of monsoonal forest.

Who pays for it?

A more active savanna burning regime over the last seven years has led to a reduction in greenhouse gas emissions of more than seven million tonnes of carbon dioxide equivalent.

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Read more:
Savanna burning: carbon pays for conservation in northern Australia

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This is around 10% of the total emission reductions accredited by the Australian government through carbon credits units under Carbon Farming Initiative Act. Under the act, one Australian carbon credit unit is earned for each tonne of carbon dioxide equivalent that a project stores or avoids.

By selling these carbon credits units either to the government or on a private commercial market, land managers have created a A$20 million a year savanna burning industry.

How Indigenous Australians and others across Australia’s north are reducing emissions.

What can the rest of Australia learn?

Savanna fire management is not directly translatable to southern Australia, where the climate is more temperate, the vegetation is different and the landscape is more densely populated. Still, there are lessons to be learnt.

A big reason for the success of fire management in the north savannas is because of the collaboration with scientists and Indigenous land managers, built on respect for the sophistication of traditional knowledge.

This is augmented by broad networks of fire managers across the complex cross-cultural landscape of northern Australia. Climate change will increasingly impact fire management across Australia, but at least in the north there is a growing capacity to face the challenge.

Rohan Fisher, Information Technology for Development Researcher, Charles Darwin University and Jon Altman, Emeritus professor, School of Regulation and Global Governance, ANU, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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How the 2016 bleaching altered the shape of the northern Great Barrier Reef

Staghorn and tabular corals suffered mass die-offs, robbing many individual reefs of their characteristic shapes.
ARC Centre of Excellence for Coral Reef Studies/ Mia Hoogenboom

Selina Ward, The University of Queensland

In 2016 the Great Barrier Reef suffered unprecedented mass coral bleaching – part of a global bleaching event that dwarfed its predecessors in 1998 and 2002. This was followed by another mass bleaching the following year.

This was the first case of back-to-back mass bleaching events on the reef. The result was a 30% loss of corals in 2016, a further 20% loss in 2017, and big changes in community structure. New research published in Nature today now reveals the damage that these losses caused to the wider ecosystem functioning of the Great Barrier Reef.

Fast-growing staghorn and tabular corals suffered a rapid, catastrophic die-off, changing the three-dimensional character of many individual reefs. In areas subject to the most sustained high temperatures, some corals died without even bleaching – the first time that such rapid coral death has been documented on such a wide scale.

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Read more:
It’s official: 2016’s Great Barrier Reef bleaching was unlike anything that went before

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The research team, led by Terry Hughes of James Cook University, carried out extensive surveys during the two bleaching events, at a range of scales.

First, aerial surveys from planes generated thousands of videos of the reef. The data from these videos were then verified by teams of divers in the water using traditional survey methods.

Finally, teams of divers took samples of corals and investigated their physiology in the laboratory. This included counting the density of the microalgae that live within the coral cells and provide most of the energy for the corals.

The latest paper follows on from earlier research which documented the 81% of reefs that bleached in the northern sector of the Great Barrier Reef, 33% in the central section, and 1% in the southern sector, and compared this event with previous bleaching events. Another previous paper documented the reduction in time between bleaching events since the 1980s, down to the current interval of one every six years.

Different colour morphs of Acropora millepora, each exhibiting a bleaching response during mass coral bleaching event.
ARC Centre of Excellence for Coral Reef StudiesStudies/ Gergely Torda

Although reef scientists have been predicting the increased frequency and severity of bleaching events for two decades, this paper has some surprising and alarming results. Bleaching events occur when the temperature rises above the average summer maximum for a sufficient period. We measure this accumulated heat stress in “degree heating weeks” (DHW) – the number of degrees above the average summer maximum, multiplied by the number of weeks. Generally, the higher the DHW, the higher the expected coral death.

The US National Oceanic and Atmospheric Administration has suggested that bleaching generally starts at 4 DHW, and death at around 8 DHW. Modelling of the expected results of future bleaching events has been based on these estimates, often with the expectation the thresholds will become higher over time as corals adapt to changing conditions.

In the 2016 event, however, bleaching began at 2 DHW and corals began dying at 3 DHW. Then, as the sustained high temperatures continued, coral death accelerated rapidly, reaching more than 50% mortality at only 4-5 DHW.

Many corals also died very rapidly, without appearing to bleach beforehand. This suggests that these corals essentially shut down due to the heat. This is the first record of such rapid death occurring at this scale.

This study shows clearly that the structure of coral communities in the northern sector of the reef has changed dramatically, with a predominant loss of branching corals. The post-bleaching reef has a higher proportion of massive growth forms which, with no gaps between branches, provide fewer places for fish and invertebrates to hide. This loss of hiding places is one of the reasons for the reduction of fish populations following severe bleaching events.

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Read more:
The world’s coral reefs are in trouble, but don’t give up on them yet

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The International Union for Conservation of Nature (IUCN), which produces the Red List of threatened species, recently extended this concept to ecosystems that are threatened with collapse. This is difficult to implement, but this new research provides the initial and post-event data, leaves us with no doubt about the driver of the change, and suggests threshold levels of DHWs. These cover the requirements for such a listing.

Predictions of recovery times following these bleaching events are difficult as many corals that survived are weakened, so mortality continues. Replacement of lost corals through recruitment relies on healthy coral larvae arriving and finding suitable settlement substrate. Corals that have experienced these warm events are often slow to recover enough to reproduce normally so larvae may need to travel from distant healthy reefs.

Although this paper brings us devastating news of coral death at relatively low levels of heat stress, it is important to recognise that we still have plenty of good coral cover remaining on the Great Barrier Reef, particularly in the southern and central sectors. We can save this reef, but the time to act is now.

This is not just for the sake of our precious Great Barrier Reef, but for the people who live close to reefs around the world that are at risk from climate change. Millions rely on reefs for protection of their nations from oceanic swells, for food and for other ecosystem services.

This research leaves no doubt that we must reduce global emissions dramatically and swiftly if we are save these vital ecosystems. We also need to invest in looking after reefs at a local level to increase their chances of surviving the challenges of climate change. This means adequately funding improvements to water quality and protecting as many areas as possible.

Selina Ward, Senior Lecturer, School of Biological Sciences, The University of Queensland

This article was originally published on The Conversation. Read the original article.

How can we halt the feminisation of sea turtles in the northern Great Barrier Reef?

Ana Rita Patricio, University of Exeter

In the northern part of Australia’s Great Barrier Reef, the future for green sea turtles appears to be turning female.

A recent study has revealed that climate change is rapidly leading to the feminisation of green turtles in one of the world’s largest populations. Only about 1% of these juvenile turtles are hatching male.

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Read more: What does climate change mean for sea turtles?

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Among sea turtles, incubation temperatures above 29ºC produce more female offspring. When incubation temperatures approach 33ºC, 100% of the offspring are female. Cooler temperatures yield more males, up to 100% near a lower thermal limit of 23ºC. And if eggs incubate at temperatures outside the range of 23-33ºC the risk of embryo malformation and mortality becomes very high.

As current climate change models foresee increases in average global temperature of 2 to 3ºC by 2100, the future for these turtles is in danger. Worryingly, warmer temperatures will also lead to ocean expansion and sea-level rise, increasing the risk of flooding of nesting habitats.

How scientists are tackling the problem

Green sea turtles’ sensitivity to incubation temperatures is such that even a few degrees can dramatically change the sex ratio of hatchlings.

Sea turtles are particularly vulnerable because they have temperature-dependent sex determination, or TSD, meaning that the sex of the offspring depends on the incubation temperature of the eggs. This is the same mechanism that determines the sex of several other reptile species, such as the crocodilians, many lizards and freshwater turtles.

Scientists and conservationists are well aware of how future temperatures may threaten these species. For the past two decades they have been investigating the incubation conditions and resulting sex ratios at several sea turtle nesting beaches worldwide.

This is mostly done using temperature recording devices (roughly the size of an egg). These are placed inside nest chambers among the clutch of eggs, or buried in the sand at the same depth as the eggs. When a clutch hatches (after 50 to 60 days) the device is recovered and the temperatures recorded are analysed.

Research has revealed that most nesting beaches studied to date have sand temperatures that favour female hatchling production. But this female bias is not immediately a bad thing, because male sea turtles can mate with several females (polygyny). So having more females actually enhances the reproductive potential of a population (i.e. more females equals more eggs).

But given that climate change will likely soon increase this female bias, important questions arise. How much of a female bias is OK? Will there be enough males? What is the minimum proportion of males to keep a sustainable population?

These questions are being investigated. But, in the meantime, alarming reports of populations with more than 99% of hatchlings being female stress the urgency of science-based management strategies. These strategies must be designed to promote (or maintain) cooler incubation temperatures at key nesting beaches to prevent population decline or even extinction.

The challenge of reversing feminisation

There are two general approaches to the problem:

1. mitigate impacts at the most endangered nesting beaches
2. identify and protect sites that naturally produce higher proportions of males.

Several studies emphasise that the natural shading native vegetation provides is essential to maintain cooler incubation temperatures. Thus, a key conservation action is to protect beach vegetation, or reforest nesting beaches.

Coastal vegetation also protects the nesting beach against wave erosion during storms, which will worsen under climate change. This strategy further requires coastal development to allow for buffer zones. Construction setback regulations should be enforced or implemented.

When natural shading is not an option, clutches of eggs can be moved either to more suitable beaches, or to hatcheries with artificial shading. Researchers have tested the use of synthetic shade cloth and found it is effective in reducing sand and nest temperatures.

Other potential strategies involve adding light-coloured sand on top of nests. This can help by absorbing less solar radiation (heat) compared to darker sand. Beach sprinklers have also been tested to simulate the cooling effect of rainfall.

The effectiveness of these actions has yet to be fully tested, but there is concern about some potential negative side effects. For example, excess water from sprinklers may cause fungal infections on eggs.

Finally, as much as mitigation measures are important, these are always short-term solutions. In the long run, prevention is always the best strategy, i.e. protecting the nesting beaches that currently produce more males from deforestation, development and habitat degradation.

Our recent research on the largest green turtle population in Africa reports unusually high male hatchling production. We found almost balanced hatchling sex ratios (1 female to 1.2 males). We attributed this mostly to the cooling effect of the native forest.

This, and similar nesting beaches, should be designated as priority conservation sites, as they will be key to ensuring the future of sea turtles under projected global warming scenarios.

Sea turtles face an uncertain future

Sea turtles are resilient creatures. They have been around for over 200 million years, surviving the mass extinction that included the dinosaurs, and enduring dramatic climatic changes in the past.

There is potential for these creatures to adapt, as they did before. This could be through, for example, shifting the timing of nesting to cooler periods, changing their distribution to more suitable habitats, or evolution of critical incubation temperatures that produce males.

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But the climate today is changing at an unprecedented rate. Along with the feminisation of these turtles in the northern Great Barrier Reef, sea turtles globally face many threats from humans. These include problems associated with by-catch, poaching, habitat degradation and coastal development, plus a history of intense human exploitation.

In 2018, the prevalence of these species depends now more than ever on the effectiveness of conservation measures.

Ana Rita Patricio, Postdoctoral research fellow, University of Exeter

This article was originally published on The Conversation. Read the original article.

How we discovered a new species of orangutan in northern Sumatra

The new species has a smaller head, and a distinctly ‘cinnamon’ colour compared with other orangutans.
Maxime Aliaga, Author provided

Colin Groves, Australian National University and Anton Nurcahyo, Australian National University

We have discovered a new species of orangutan – the third known species and the first new great ape to be described since the bonobo almost a century ago.

The new species, called the Tapanuli orangutan (Pongo tapanuliensis), has a smaller skull than the existing Bornean and Sumatran orangutans, but has larger canines.

As we and our colleagues report in the journal Current Biology, the new species is represented by an isolated population of fewer than 800 orangutans living at Batang Toru in northern Sumatra, Indonesia.

Orangutan populations in Sumatra and Borneo – the new species’ distribution is shown in yellow.
Curr. Biol.

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Read more: The lengthy childhood of endangered orangutans is written in their teeth

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The existence of a group of orangutans in this region was first reported back in 1939. But the Batang Toru orangutans were not rediscovered until 1997, and then confirmed in 2003. We set about carrying out further research to see whether this isolated group of orangutans was truly a unique species.

On the basis of genetic evidence, we have concluded that they are indeed distinct from both the other two known species of orangutan: Pongo abelii from further north in Sumatra, and Pongo pygmaeus from Borneo.

The Batang Toru orangutans have a curious mix of features. Mature males have cheek flanges similar to those of Bornean orangutans, but their slender build is more akin to Sumatran orangutans.

The hair colour is more cinnamon than the Bornean species, and the Batang Toru population also makes longer calls than other orangutans.

Making sure

To make completely sure, we needed more accurate comparisons of their body dimensions, or “morphology”. It was not until 2013 that the skeleton of an adult male became available, but since then one of us (Anton) has amassed some 500 skulls of the other two species, collected from 21 institutions, to allow for accurate comparisons.

Analyses have to be conducted at a similar developmental stage on male orangutan skulls, because they continue growing even when adult. Anton found 33 skulls of wild males that were suitable for comparison. Of 39 different measurement characteristics for the Batang Toru skull, 24 of them fall outside of the typical ranges of northern Sumatran and Bornean orangutans.

The new orangutans have smaller heads – but some impressive teeth.
Matthew G Nowak, Author provided

Overall the Batang Toru male has a smaller skull, but bigger canines. Combining the genetic, vocal, and morphological sources of evidence, we have confidently concluded that Batang Toru orangutan population is a newly discovered species – and one whose future is already under threat.

Under threat as soon as they’re discovered.
Maxime Aliaga, Author provided

Despite the heavy exploitation of the surrounding areas (hunting, habitat
alteration and other illegal activities), the communities surrounding the habitat of the Tapanuli orangutan still give us the opportunity to see and census the surviving population. Unfortunately, we believe that the population is fewer than 800 individuals.

Of the habitat itself, no more than 10 square km remains. Future development has been planned for that area, and about 15% of the orangutans’ habitat has non-protected forest status.

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The discovery of the third orangutan in the 21st century gives us an understanding that the great apes have more diversity than we know, making it all the more important to conserve these various groups.

Without the strong support of, and participation from, the communities surrounding its habitat, the future of the Tapanuli orangutan will be uncertain. Government, researchers and conservation institutions must make a strong collaborative effort to make sure that this third orangutan will survive long after its discovery.

Colin Groves, Professor of Bioanthropology, Australian National University and Anton Nurcahyo, , Australian National University

This article was originally published on The Conversation. Read the original article.

Mercury from the northern hemisphere is ending up in Australia

Mercury pollution, often released from gold mining and coal power stations, is a global problem.
Shutterstock

Jenny Fisher, University of Wollongong; Dean Howard, Macquarie University; Grant C Edwards, Macquarie University, and Peter Nelson, Macquarie University

Mercury pollution has a long legacy in the environment. Once released into the air, it can cycle between the atmosphere and ecosystems for years or even decades before ending up deep in the oceans or land.

The amount of mercury in the ocean today is about six times higher than it was before humans began to release it by mining. Even if we stopped all human mercury emissions now, ocean mercury would only decline by about half by 2100.

To address the global and long-lasting mercury problem, a new United Nations treaty called the Minamata Convention on Mercury came into effect last month. The treaty commits participating countries to limit the release of mercury and monitor the impacts on the environment. Australia signed the Convention in 2013 and is now considering ratification.

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Read more: Why won’t Australia ratify an international deal to cut mercury pollution?

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Until now, we have only been able to guess how much mercury might be in the air over tropical Australia. Our new research, published in the journal Atmospheric Chemistry and Physics, shows that there is less mercury in the Australian tropics than in the northern hemisphere – but that polluted northern hemisphere air occasionally comes to us.

A global problem

While most of mercury’s health risks come from its accumulation in ocean food webs, its main entry point into the environment is through the atmosphere. Mercury in air comes from both natural sources and human activities, including mining and burning coal. One of the biggest mercury sources is small-scale gold mining – a trade that employs millions of people in developing countries but poses serious risks to human health and the environment.

Small-scale gold mining is an economic mainstay for millions of people, but it releases mercury directly into the air and water sources.

Once released to the air, mercury can travel thousands of kilometres to end up in ecosystems far away from the original source.

Measuring mercury in the tropics

While the United Nations was gathering signatures for the Minamata Convention, we were busy measuring mercury at the Australian Tropical Atmospheric Research Station near Darwin. Our two years of measurements are the first in tropical Australia. They are also the only tropical mercury measurements anywhere in the Maritime Continent region covering southeast Asia, Indonesia, and northern Australia.

We found that mercury concentrations in the air above northern Australia are 30-40% lower than in the northern hemisphere. This makes sense; most of the world’s population lives north of the Equator, so most human-driven emissions are there too.

More surprising is the seasonal pattern in the data. There is more mercury in the air during the dry season than the wet season.

The Australian monsoon appears to be partly responsible for the seasonal change. The amount of mercury jumps up sharply at the start of the dry season when the winds shift from blowing over the ocean to blowing over the land.

In the dry season the air passes over the Australian continent before arriving at the site, while in the wet season the air usually comes from over the ocean to the west of Darwin.
Howard et al., 2017 (modified)

But wind direction can’t explain the whole story. Mercury is likely being removed from the air by the intense rains that characterise the wet season. In other words, the lower mercury in the air during the wet season may mean more mercury is being deposited to the ocean and the land at this time of year. Unfortunately, there simply isn’t enough information from Australian ecosystems to know how this impacts local plants and wildlife.

Fires also play a role. Mercury previously absorbed by grasses and trees can be released back to the atmosphere when the vegetation burns. In our data, we see occasional large mercury spikes associated with dry season fires. As we move into a bushfire season predicted to be unusually severe, we may see even more of these spikes.

Air from the north

Although mercury levels were usually low in the wet season, on a few days each year the mercury jumped up dramatically.

To figure out where these spikes were coming from, we used two different models. These models combine our understanding of atmospheric physics with real observations of wind and other meteorological parameters.

Both models point to the same source: air transported from the north.

Australia is usually shielded from northern hemispheric air by a “chemical equator” that stops air from mixing. This barrier isn’t static – it moves north and south throughout the year as the position of the sun changes.

A few times a year, the chemical equator moves so far south that the top end of Australia actually falls within the atmospheric northern hemisphere. When this happens, polluted northern hemisphere air can flow directly to tropical Australia.

We observed 13 days when our measurement site near Darwin sampled more northern hemisphere air than southern hemisphere air. On each of these days, the amount of mercury in the air was much higher than on the days before or after.

Tracing the air backwards in time showed that the high-mercury air travelled over the Indonesian archipelago before arriving in Australia. We don’t yet know whether that mercury came from pollution, fires, or a mix of the two.

The highest mercury is observed when the air comes from the northern hemisphere.
Howard et al., 2017 (modified)

A global solution

To effectively reduce mercury exposure in sensitive ecosystems and seafood-dependent populations around the world, aggressive global action is necessary.

The cross-boundary influences on mercury that we have observed in northern Australia highlight the need for the type of multinational collaboration that the Minamata Convention will foster.

Our new data establish a baseline for monitoring the effectiveness of new actions taken under the Minamata Convention. With the first Conference of the Parties having taken place last week, hopefully it will only be a matter of time before we begin to see the benefit.

Jenny Fisher, Senior Lecturer in Atmospheric Chemistry, University of Wollongong; Dean Howard, , Macquarie University; Grant C Edwards, Senior lecturer, Macquarie University, and Peter Nelson, Pro Vice Chancellor (Research Performance and Innovation), Macquarie University

This article was originally published on The Conversation. Read the original article.

Extreme weather likely behind worst recorded mangrove dieback in northern Australia

Penny van Oosterzee, James Cook University and Norman Duke, James Cook University

One of the worst instances of mangrove forest dieback ever recorded globally struck Australia’s Gulf of Carpentaria in the summer of 2015-16. A combination of extreme temperatures, drought and lowered sea levels likely caused this dieback, according to our investigation published in the journal Marine and Freshwater Research.

The dieback, which coincided with the Great Barrier Reef’s worst ever bleaching event, affected 1,000km of coastline between the Roper River in the Northern Territory and Karumba in Queensland.

Views of mangrove shorelines impacted by dieback event in late 2015, east of Limmen Bight River, Northern Territory (imagery: NC Duke, June 2016).

About 7,400 hectares, or 6%, of the gulf’s mangrove forest had died. Losses were most severe in the NT, where around 5,500ha of mangroves suffered dieback. Some of the gulf’s many catchments, such as the Robinson and McArthur rivers, lost up to 26% of their mangroves.

Views of seaward mangrove fringes showing foreshore sections of minor (left side) and extreme (right side) damage as observed in June 2016 between Limmen and MacArthur rivers, NT. These might effectively also represent before and after scenarios, but together show how some shoreline sections have been left exposed and vulnerable.
NC Duke

The gulf, a remote but valuable place

The Gulf of Carpentaria is a continuous sweep of wide tidal wetlands fringed by mangroves, meandering estuaries, creeks and beaches. Its size and naturalness makes it globally exceptional.

An apron of broad mudflats and seagrass meadows supports thousands of marine turtles and dugongs. A thriving fishing industry worth at least A$30 million ultimately depends on mangroves.

Dieback of mangroves around Karumba in Queensland, with surviving saltmarsh, October 2016.
NC Duke

Mangroves and saltmarsh plants are uniquely adapted to extreme and fickle coastal shoreline ecosystems. They normally cope with salt and daily inundation, having evolved specialised physiological and morphological traits, such as salt excretion and unique breathing roots.

But in early 2016, local tour operators and consultants doing bird surveys alerted authorities to mangroves dying en masse along entire shorelines. They reported skeletonised mangroves over several hundred kilometres, with the trees appearing to have died simultaneously. They sent photos and even tracked down satellite images to confirm their concerns. The NT government supported the first investigative surveys in June 2016.

Areas affected by severe mangrove dieback in late 2015 (grey shaded) along southern shorelines of Australia’s Gulf of Carpentaria from Northern Territory to Queensland. Aerial surveys (red lines) were undertaken on three occasions during 2016 to cover around 600km of the 1000km impacted.
NC Duke

In the end, the emails from citizen scientists nailed the timing: “looks like it started maybe December 2015”; the severity: “I’ve seen dieback before, but not like this”; and the cause: “guessing it may be the consequence of the four-year drought”.

Our investigation used satellite imagery dating back to 1972 to confirm that the dieback was an unparalleled event. Further aerial helicopter surveys and mapping during 2016, after the dieback, validated the severity of the event extending across the entire gulf. Mangrove dieback has been recorded in Australia in the past but over decades, not months.

Mangroves losses (red) and surviving mangroves (green) around the shoreline and mouth of the Limmen Bight River, south-western Gulf of Carpentaria, April 2015 to April 2016.
NC Duke, J. Kovacs

Mysterious patterns in the dieback

We still don’t fully understand what caused the dieback. But we can rule out the usual suspects of chemical or oil spills, or severe storm events. It was also significant that losses occurred simultaneously across a 1,000km front.

There were also a number of tell-tale patterns in the dieback. The worst-impacted locations had more or less complete loss of shoreline-fringing mangroves. This mirrored a general loss of mangroves fringing tidal saltpans and saltmarshes along this semi-arid coast.

Mangroves were unaffected where they kept their feet wet along estuaries and rivers. This, as well as the timing and severity of the event, points to a connection with extreme weather and climate patterns, and particularly the month-long drop of 20cm in local sea levels.

Extreme weather the likely culprit

We believe the dieback is best explained by drought, hot water, hot air and the temporary drop in sea level. Each of these was correlated with the strong 2015-16 El Niño. Let’s take a look at each in turn.

First, the dieback happened at the end of an unusually long period of severe drought conditions, which prevailed for much of 2015 following four years of below-average rainfall. This caused severe moisture stress in mangroves growing alongside saltmarsh and saltpans.

Second, the dieback coincided with hot sea temperatures that also caused coral bleaching along the Great Barrier Reef. While mangroves are known to be relatively heat-tolerant, they have their limits.

The air temperatures recorded at the time of the mangrove dieback, particularly from February to September 2015, were also exceptionally high.

Views of mangrove shorelines impacted by dieback event in late 2015, north of Karumba, Queensland (imagery: NC Duke, Oct 2016).

Third, the sea level dropped by up to 20cm at the time of the dieback when the mangroves were both heat- and moisture-stressed. Sea levels commonly drop in the western Pacific (and rise in the eastern Pacific) during strong El Niño years: and the 2015-2016 El Niño was the third-strongest recorded.

The mangroves appear to have died of thirst. Mangroves may be hardy plants, but when sea levels drop, reducing inundation, coupled with already heat-and-drought-stressed weather conditions, then the plants will die – much like your neglected pot plants.

We don’t yet know what role human-caused climate change played in these particular weather events or El Niño. But the unprecedented extent of the dieback, the confluence of extreme climate events and the coincidence with the bleaching of the Great Barrier Reef mean the role of climate change will be of critical interest in the global response to mangrove decline.

What future for mangroves?

The future for mangroves around the world is mixed. Thanks to climate change, droughts are expected to become hotter and more frequent. If the gulf’s mangroves experience further dieback in the future, this will have serious implications for Australia’s northern fisheries including the iconic prawn fishery, mudcrab and fin fish fisheries. All species are closely associated with healthy mangroves.

We don’t know whether the mangroves will recover or not. But there is now a further risk of shoreline erosion and retreat, particularly if the region is struck by a cyclone – and this may have already begun with recent cyclonic weather and flooding in the gulf. The movement of mangrove sediments will lead to massive releases of carbon uniquely buried among their roots.

Mangroves are among the most carbon-rich forests in the tropics and semi-tropics and much of this carbon could enter the atmosphere.

Aerial view of severe mangrove dieback near Karumba in Queensland, October 2016.
NC Duke

Now we urgently need to understand how mangroves died at large and smaller scales (such as river catchments), so we can develop strategies to help them adapt to future change.

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Australia’s top specialists and managers will be reviewing the current situation at a dedicated workshop during next week’s Australian Mangrove and Saltmarsh Network annual conference in Hobart.

Penny van Oosterzee, Principal Research Adjunct James Cook University and University Fellow Charles Darwin University, James Cook University and Norman Duke, Professor of Mangrove Ecology, James Cook University

This article was originally published on The Conversation. Read the original article.

EcoCheck: Australia’s vast, majestic northern savannas need more care

Euan Ritchie, Deakin University and Brett Murphy, Charles Darwin University

Our EcoCheck series takes the pulse of some of Australia’s most important ecosystems to find out if they’re in good health or on the wane.

Australia’s Top End, Kimberley and Cape York Peninsula evoke images of vast, awe-inspiring and ancient landscapes. Whether on the hunt for a prized barramundi, admiring some of the oldest rock art in the world, or pursuing a spectacular palm cockatoo along a pristine river, hundreds of thousands of people flock to this region each year. But how are our vast northern landscapes faring environmentally, and what challenges are on the horizon?

Above 17° south, bounded by a rough line from Cairns, Queensland, to Derby, Western Australia, are the high-rainfall (more than 1,000mm a year) tropical savannas. These are the largest and most intact ecosystem of their kind on Earth. With the exception of some “smaller” pockets of rainforest (such as Queensland’s Kutini-Payamu (Iron Range) National Park), the vegetation of the region is dominated by mixed Eucalyptus forest and woodland with a grassy understorey.

Within the fire-prone Great Northern Savannas exist fire-sensitive communities such as these Allosyncapria ternata rainforests along the edge of the Arnhem Plateau in Kakadu National Park.
Brett Murphy

There is a distinct monsoonal pattern of rainfall. Almost all of it falls during the wet season (December-March), followed by an extended dry (April-November). Wet-season rains drive abundant grass growth, which subsequently dries and fuels regular bushfires – making these landscapes among the most fire-prone on Earth. The dominant land tenures of the region are Indigenous, cattle grazing and conservation.

Cattle grazing is widespread in the Great Northern Savannas.
Mark Ziembicki

These savannas are home to a vast array of plant and animal species. The Kimberley supports at least 2,000 native plant species, while the Cape York Peninsula has some 3,000. More than 400 bird and 100 mammal species call the region home, along with invertebrates such as moths, butterflies, ants and termites, and spiders. Many of the latter are still undescribed and poorly studied.

Many species, such as the scaly-tailed possum, are endemic to the region, meaning they are found nowhere else.

A large male antilopine wallaroo, endemic to tropical Australia.
Euan Ritchie

The general lack of extensive habitat loss and modification, as compared to the broad-scale land clearing in southern Australia since European arrival, can give a false impression that the tropical savannas and their species are in good health. But research suggests otherwise, and considerable threats exist.

Fire-promoting weeds such as gamba grass, widely sown until very recently as fodder for cattle, are transforming habitats from diverse woodlands to burnt-out, low-diversity grasslands. Indeed, the fires themselves, which are considered too frequent and too late in the dry season at some locations, are now thought to be a primary driver of species loss.

Notable examples of wildlife in trouble include declines of many seed-eating birds, such as the spectacular Gouldian finch, and the catastrophic decline of native mammal species, most prominently in Australia’s largest national park, Kakadu.

Bauxite mining threatens the habitat of vulnerable Cape York palm cockatoos.
Mark Ziembicki

Added pressures include bauxite mining, forestry and cattle grazing. The latter activity exerts strong pressures on the characteristically leached, nutrient-poor, tropical soils. Most recently, changes to Queensland’s land-clearing laws have led to virgin savanna woodland being cleared.

It is likely some threats may also combine to make matters worse for certain species. For instance, frequent fires, intensive cattle grazing and the overabundance of introduced species such as feral donkeys and horses all combine to remove vegetation cover. This, together with the presence of feral cats, makes some native animals more vulnerable to predation.

New threats

This globally significant ecosystem, already under threat, is facing new challenges too. Proposals to use the region as a food bowl for Asia are associated with calls for the damming of waterways and land clearing for agriculture.

This is against a backdrop of climate change, which among other effects may bring less predictable wet seasons, more frequent and intense storms (cyclones) and fires, and hotter, longer dry seasons. Such changes are not only likely to harm some species, but could also make those much-touted agricultural goals far more difficult to achieve.

Great opportunities exist in northern Australia, but we need to avoid the mistakes of the past.
Mark Ziembicki

Great opportunities do exist in northern Australia, including carbon farming and expanded tourism enterprises. In some cases this might require difficult transitions, as already seen in parts of Cape York Peninsula, where often economically unviable cattle stations have become joint Indigenous and conservation-managed lands.

A key priority for the Great Northern Savannas should be to maintain people on country. It’s often thought that the solution to reducing environmental impacts is removing people from landscapes, but as people disappear so too does their stewardship and ability to manage and care for the land.

Importantly, and finally, we must also learn the historical lessons from southern Australia if we are to avoid making similar mistakes all over again, jeopardising the unique and precious values of the north.

Are you a researcher who studies an iconic Australian ecosystem and would like to give it an EcoCheck? Get in touch.

Euan Ritchie, Senior Lecturer in Ecology, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University and Brett Murphy, Research Fellow, Charles Darwin University

This article was originally published on The Conversation. Read the original article.

Rush to dam northern Australia comes at the expense of sustainability

Barry Hart, Monash University; Avril Horne, University of Melbourne, and Erin O’Donnell, University of Melbourne

Ahead of the election, the major parties have released different visions for developing northern Australia. The Coalition has committed to dam projects across Queensland; Labor has pledged to support the tourism industry.

These pledges build on the Coalition’s A$5 billion Northern Australia Infrastructure Facility, a fund to support large projects, starting on July 1.

The Coalition has pledged A$20 million to support 14 new or existing dams across Queensland should the government be returned to power, as part of a A$2.5 billion plan for dams across northern Australia.

Labor, meanwhile, will redirect A$1 billion from the fund towards tourism, including eco-tourism, indigenous tourism ventures and transport infrastructure (airports, trains, and ports).

It is well recognised that the development of northern Australia will depend on harnessing the north’s abundant water resources. However, it’s also well recognised that the ongoing use of water resources to support industry and agriculture hinges on the health and sustainability of those water resources.

Northern Australia is home to diverse ecosystems, which support a range of ecosystem services and cultural values, and these must be adequately considered in the planning stages.

Sustainability comes second

The white paper for northern Australia focuses almost solely on driving growth and development. Current water resource management policy in Australia, however, emphasises integrated water resource planning and sustainable water use that protects key ecosystem functions.

Our concern is that the commitment to sustainability embedded in the National Water Initiative (NWI), as well as Queensland’s water policies, may become secondary in the rush to “fast track” these water infrastructure projects.

Lessons from the past show that the long-term success of large water infrastructure projects requires due process, including time for consultation, environmental assessments and investigation of alternative solutions.

What is on the table?

The Coalition proposes providing funds to investigate the feasibility of a range of projects, including upgrading existing dams and investigating new dams. The majority of these appear to be focused on increasing the reliability of water supplies in regional urban centres. Few target improved agricultural productivity.

These commitments add to the already proposed feasibility study (A$10 million) of the Ord irrigation scheme in the Northern Territory and the construction of the Nullinga Dam in Queensland. And the A$15 million northern Australia water resources assessment being undertaken by CSIRO, which is focused on the Fitzroy river basin in Western Australia, the Darwin river basins in Northern Territory and the Mitchell river basin in Queensland.

Rethinking dams

New water infrastructure in the north should be part of an integrated investment program to limit overall environmental impacts. Focusing on new dams applies 19th-century thinking to a 21st-century problem, and we have three major concerns about the rush to build dams in northern Australia.

First, the process to establish infrastructure priorities for federal investment is unclear. For instance, it’s uncertain how the projects are connected to Queensland’s State Infrastructure Plan.

Investment in new water infrastructure across northern Australia needs to be part of a long-term water resource plan. This requires clearly articulated objectives for the development of northern Australia, along with assessment criteria that relate to economic, social and environmental outcomes, such as those used in the Murray-Darling Basin Plan.

Second, the federal government emphasises on-stream dams. Dams built across the main river in this way have many well-recognised problems, including:

• lack of environmental flows (insufficient water at the appropriate frequency and duration to support ecosystems)

• flow inversion (higher flows may occur in the dry season than in the wet, when the bulk of rainfall occurs)

• barriers to fish movement and loss of connectivity to wetlands

• water quality and temperature impacts (unless there is a multi-level off-take).

As a minimum, new dams should be built away from major waterways (such as on small, tributary streams) and designed to minimise environmental impacts. This requires planning in the early stages, as such alternatives are extremely difficult to retrofit to an existing system.

Finally, the federal government proposals make no mention of climate change impacts. Irrigation and intensive manufacturing industries demand highly reliable water supplies.

While high-value use of water should be encouraged, new industries need to be able to adapt for the increased frequency of low flows; as well as increased intensity of flood events. Government investment needs to build resilience as well as high-value use.

Detailed planning, not press releases

In place of the rather ad hoc approach to improvements in water infrastructure, such as the projects announced by the federal government in advance of the election, we need a more holistic and considered approach.

The A$20 million investment for 14 feasibility studies and business cases in Queensland represents a relatively small amount of money for each project, and runs the risk of having them undertaken in isolation. The feasibility studies should be part of the entirety of the government’s plan for A$2.5 billion in new dams for northern Australia.

Water resource planning is too important and too expensive to cut corners on planning. Investment proposals for Queensland need to be integrated with water resource planning across the state, and across northern Australia, and with appropriate consideration of climate change impacts.

Fast tracking dams without considering ecosystem impacts, future variability in water supplies, and resilience in local communities merely sets the scene for future problems that will likely demand another round of intervention and reform.

Barry Hart, Emeritus Professor Water Science, Monash University; Avril Horne, Research fellow, Department of Infrastructure Engineering, University of Melbourne, and Erin O’Donnell, Senior Fellow, Centre for Resources, Energy and Environment Law, University of Melbourne

This article was originally published on The Conversation. Read the original article.

Damming northern Australia: we need to learn hard lessons from the south

Erin O’Donnell, University of Melbourne and Barry Hart, Monash University

The push for development in northern Australia is gathering momentum, with the government recently releasing a draft of its Northern Australia Infrastructure Facility to help finance large projects.

The development of northern Australia will crucially depend on harnessing the north’s abundant available water resources. Over the next five years the government will develop plans to manage these water resources.

However we have to get these plans right from the start to ensure the north’s waters are developed sustainably. To do so, we can start by looking south.

Full steam ahead

In June 2015, the federal government released its long-awaited northern Australia White Paper. Among commitments to agriculture in northern Australia, the white paper targets more efficient use of water resources across the north.

Over 60% of Australia’s total surface water runoff occurs north of the Tropic of Capricorn. A 2014 CSIRO review indicates that this could potentially support up to 1.4 million hectares of irrigated land, increasing Australia’s irrigated area by 50%.

Reaching this potential, however, would come at the financial and environmental cost of around 90 new dams and many weirs and other infrastructure.

The white paper promises sustainable development, but the problem is the timeframe. The paper commits, over the next two years, to assessment of the water resources in the initial priority catchments, and within five years, to the development of water resource plans. These plans will include a cap on water use, and a water market to trade water allocations.

But the paper is silent on what we know about northern ecosystems and how water infrastructure might affect them, and makes no allowance for climate change.

Learning from the south

There is much to be learned from the current implementation of the Murray-Darling Basin Plan, which will result in upgrades to existing water plans in Queensland, New South Wales, South Australia, Victoria and the Australian Capital Territory.

The past 20 years have seen almost continual reform in Murray-Darling, demonstrating how hard it is to achieve sustainability when water resources are over-used.

Australia is currently spending over A$13 billion to restore the Murray-Darling Basin catchments to something approaching the minimum needed to maintain the ecological health of the system.

Avoiding this will avoid a major overhaul in the future and provide investor confidence.

Managing this risk to wildlife

Northern Australia is home to 301 nationally threatened species, as well as the iconic Great Barrier Reef, already under threat.

In 2004 one of us (Barry) looked at environmental risks of new irrigation schemes then proposed for the north.

He identified four factors for sustainable irrigation, including urgently better understanding the north’s freshwater ecosystems, and developing a risk-based approach to making decisions on infrastructure.

Over the past decade we’ve considerably improved our knowledge of northern ecosystems, for example the Ord river system in Western Australia, Kakadu and the Daly river in Norther Territory, and the Mitchell, Burdekin and other coastal rivers and wetlands in Queensland. Although we know more, this knowledge needs to be synthesised before it can be used for planning.

We still don’t know exactly how irrigation projects might affect these ecosystems. To deal with this we suggest adopting an ecological risk-based approach to planning.

It is trite, but true, that one needs to know the risks before one can set about managing them. Ecological risk assessments assist in identifying the risks, assessing their relative importance, and identifying possible ways to mitigate the risks. This sort of process is a basic component of the requirements for plans being developed as part of the Murray-Darling Basin Plan.

Dealing with dams

The White Paper clearly sees new on-stream dams as part of increasing water use in northern Australia.

The planning process will set a cap on how much water can be used. But current evidence regarding the impact of dams on river flows shows that this will not be enough.

From the start, plans need to include environmental flow: sufficient water at the appropriate frequency and duration to support ecosystems. As well as a cap, this might mean creating legal rights for water held in the storage for the environment.

One of the intractable problems caused by dams in southern Australia has been seasonal flow inversion. River flows are higher in summer and lower in winter than the ecosystem needs.

In the north, flow inversion may occur with higher flows occurring in the dry season rather than in summer when the bulk of the rainfall occurs.

To avoid this, new water infrastructure in the north could be built off stream. This system is currently used in the Queensland section of the Murray-Darling Basin. But, unless planned for at the outset, these alternatives are extremely difficult to retrofit to an existing system.

Figuring out the sustainable level of water extraction for an aquatic ecosystem depends on considerable technical work (hydrological, ecological and modelling). This technical work needs to be guided by a clear set of objectives for each development, including the value the community (including Indigenous Australians) places on the local ecosystems.

The water market

The Murray-Darling Basin demonstrates that water markets are a highly efficient means for ensuring that the available water resource is effectively used. Additionally, the water market is also an efficient means for recovering water for the environment (although the overall process remains costly), and can also increase efficiency of environmental water management.

But to make the most of the opportunities created by water markets, the environment needs the institutional capacity to enter the market. In the south, the Commonwealth Environmental Water Holder owns and manages large volumes of water across the Murray-Darling Basin. At the state level, the Victorian Environmental Water Holder has also proved effective at streamlining decision-making and using the market to manage its holdings.

If environmental water in the north is to be managed efficiently in the context of a future water market, establishing a legal entity with the capacity to hold water, enter contracts and make decisions will be an essential piece of the puzzle.

The White Paper is a bold vision for developing northern Australia. Australia has learned many lessons about sustainable water allocation the hard way, at the cost of a great deal of time, money and ecosystem degradation.

We need to apply these lessons from the south to the north. Failing to adequately invest in new water resource development plans in northern Australia is effectively planning to fail. And we should know better.

Erin O’Donnell, Senior Fellow, Centre for Resources, Energy and Environment Law, University of Melbourne and Barry Hart, Emeritus Professor Water Science, Monash University

This article was originally published on The Conversation. Read the original article.