How to reverse global wildlife declines by 2050

Michael Obersteiner, University of Oxford; David Leclère, International Institute for Applied Systems Analysis (IIASA), and Piero Visconti, International Institute for Applied Systems Analysis (IIASA)

Species are going extinct at an unprecedented rate. Wildlife populations have fallen by more than two-thirds over the last 50 years, according to a new report from the World Wildlife Fund. The sharpest declines have occurred throughout the world’s rivers and lakes, where freshwater wildlife has plummeted by 84% since 1970 – about 4% per year.

But why should we care? Because the health of nature is intimately linked to the health of humans. The emergence of new infectious diseases like COVID-19 tend to be related to the destruction of forests and wilderness. Healthy ecosystems are the foundation of today’s global economies and societies, and the ones we aspire to build. As more and more species are drawn towards extinction, the very life support systems on which civilisation depends are eroded.

Even for hard-nosed observers like the World Economic Forum, biodiversity loss is a disturbing threat with few parallels. Of the nine greatest threats to the world ranked by the organisation, six relate to the ongoing destruction of nature.

A digger tears down trees in a Malaysian rainforest. — New infectious diseases tend to emerge in places at the forefront of environmental destruction.
Rich Carey/Shutterstock

Economic systems and lifestyles which take the world’s generous stocks of natural resources for granted will need to be abandoned, but resisting the catastrophic declines of wildlife that have occurred over the last few decades might seem hopeless. For the first time, we’ve completed a science-based assessment to figure out how to slow and even reverse these trends.

Our new paper in Nature featured the work of 60 co-authors and built on efforts steered by the Intergovernmental Panel on Biodiversity and Ecosystem Services. We considered ambitious targets for rescuing global biodiversity trends and produced pathways for the international community to follow that could allow us to meet these goals.

Bending the curve

The targets of the UN Convention on Biological Diversity call for global trends of terrestrial wildlife to stop declining and start recovering by 2050 or earlier. Changes in how land is used – from pristine forest to cropland or pasture – rank among the greatest threats to biodiversity on land worldwide. So what are the necessary conditions for biodiversity to recover during the 21st century while still supporting growing and affluent human societies?

Two key areas of action stand out from the rest. First, there must be renewed ambition from the world’s governments to establish large-scale conservation areas, placed in the most valuable hotspots for biodiversity worldwide, such as small islands with species found nowhere else. These reserves, in which wildlife will live and roam freely, will need to cover at least 40% of the world’s land surface to help bend the curve from decline to recovery for species and entire ecosystems.

The location of these areas, and how well they are managed, is often more important than how big they are. Habitat restoration and conservation efforts need to be targeted where they are needed most – for species and habitats on the verge of extinction.

A downward sloping line showing wildlife declines splits into three alternative trajectories, where biodiversity increases, plateaus and crashes by 2050. — The next 30 years will prove pivotal for Earth’s biodiversity.
Leclère et al. (2020), Author provided

Second, we must transform our food systems to produce more on less land. If every farmer on Earth used the best available farming practices, only half of the total area of cropland would be needed to feed the world. There are lots of other inefficiencies that could be ironed out too, by reducing the amount of waste produced during transport and food processing, for example. Society at large can help in this effort by shifting towards healthier and more sustainable diets, and reducing food waste.

This should happen alongside efforts to restore degraded land, such as farmland that’s becoming unproductive as a result of soil erosion, and land that’s no longer needed as agriculture becomes more efficient and diets shift. This could return 8% of the world’s land to nature by 2050. It will be necessary to plan how the remaining land is used, to balance food production and other uses with the conservation of wild spaces.

Without a similar level of ambition for reducing greenhouse gas emissions, climate change will ensure the world’s wildlife fares badly this century. Only a comprehensive set of policy measures that transform our relationship with the land and rapidly scale down pollution can build the necessary momentum. Our report concludes that transformative changes in our food systems and how we plan and use land will have the biggest benefits for biodiversity.

But the benefits wouldn’t end there. While giving back to nature, these measures would simultaneously slow climate change, reduce pressure on water, limit nitrogen pollution in the world’s waterways and boost human health. When the world works together to halt and eventually reverse biodiversity loss, it’s not only wildlife that will thrive.

Michael Obersteiner, Director, Environmental Change Institute, University of Oxford; David Leclère, Researcher in Ecosystem Services and Management (ESM) Program, International Institute for Applied Systems Analysis (IIASA), and Piero Visconti, Research Scholar, Ecosystem Services and Management Programme, International Institute for Applied Systems Analysis (IIASA)

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

We accidentally found a whole new genus of Australian daisies. You’ve probably seen them on your bushwalks

Alexander Schmidt-Lebuhn, Author provided

Alexander Schmidt-Lebuhn, CSIRO and Ben Gooden, CSIRO

When it comes to new botanical discoveries, one might imagine it’s done by trudging around a remote tropical rainforest. Certainly, that does still happen. But sometimes seemingly familiar plants close to home hold unexpected surprises.

We recently discovered a new genus of Australian daisies, which we’ve named Scapisenecio. And we did so on the computer screen, during what was meant to be a routine analysis to test a biocontrol agent against a noxious weed originally from South Africa.

The term “genus” refers to groups of different, though closely related, species of flora and fauna. For example, there are more than 100 species of roses under the Rosa genus, and brushtail possums are members of the Trichosurus genus.

This accidental discovery shows how much is still to be learned about the natural history of Australia. Scapisenecio is a new genus, but thousands of visitors to the Australian Alps see one of its species flowering each summer. If this species was still misunderstood, surely similar surprises are still out there waiting for us.

How it began

It all started with a biocontrol researcher asking a plant systematist, who looks at the evolutionary history of plants, to help figure out the closest Australian native relatives of the weed, Cape ivy (Delairea odorata).

Cape ivy leaves covering a tree stump — Cape ivy is destructive to agriculture and native plants.
Murray Fagg/Australian Plant Image Index, Author provided

Weeds like Cape ivy cause major damage to agriculture in Australia, displace native vegetation and require extensive management. Biological control (biocontrol) is one way to reduce their impact. This means taking advantage of insects or fungi that attack a weed, generally after introducing them from the weed’s home range.

A well-known Australian example is the introduction of the Cactoblastis moth in 1926 to control prickly pear in Queensland and New South Wales. Even today it continues to keep that weed in check.

To minimise the risk of selecting a biocontrol agent that will damage native flora, ornamental plants or crops, it’s tested carefully against a list of species of varying degrees of relatedness to the target weed.

Authorities will approve the release of a biocontrol agent only if scientists can show it’s highly specific to the weed. Assembling a list of species to test therefore requires us to understand the evolutionary relationships of the target weed to other plant species.

If such relationships are poorly understood, we might fail to test groups of species that are closely related to the target.

Missing data

Our target weed Cape ivy is a climbing daisy that has become invasive in temperate forests and coastal woodlands throughout south-eastern Australia. One of us, Ben Gooden, is researching the potential use of Digitivalva delaireae — a stem-boring moth — for its biocontrol.

We tried to design a test list, but could not find up-to-date information on Cape ivy’s relatives. We already knew it is related to the large groundsel genus Senecio, but we didn’t know how closely. And no genetic data existed for many Australian native species of Senecio.

So, we set out to solve this problem together.

First, we assembled already-published DNA sequences for as many Senecio species and relatives as we could find, and then generated sequences for an additional 32 native Australian species.

We then united all these genetic data into a comprehensive phylogenetic analysis. “Phylogenetics” infers the evolutionary relatedness of organisms to each other.

Hidden in the evolutionary tree

The resulting “evolutionary tree” showed many of the native Senecio species where we expected them to be. More importantly, however, it showed us that Cape ivy is actually quite distantly related to Senecio.

To our surprise, the analysis also placed several Australian species traditionally belonging to the Senecio genus far outside of it, indicating they didn’t belong to Senecio at all and needed to be renamed.

Simplified phylogenetic tree of the daisy tribe *Senecioneae* showing the evolutionary distance between Senecio, Cape ivy, and the new genus. Unlabelled branches indicate other lineages of the same tribe.
Alexander Schmidt-Lebuhn, Author provided

The most interesting group of not-actually-Senecio are five species with leaf rosettes and one (or rarely, a few) flowerheads carried on distinctive stalks.

They’re all restricted to alpine or subalpine areas of south-eastern Australia, and all except one are found only in Tasmania. They turned out to be so unrelated, and so distinct from any other named plant genera, that they have to be recognised as a genus in its own right.

Introducing Scapisenecio

We have now named this new genus as Scapisenecio, after the long flower stalks (scapes) characterising the plants.

The most widespread and common species is Scaposenecio pectinatus, commonly known as the alpine groundsel, which is a familiar sight to hikers and bushwalkers in the Australian mainland alps and the central highlands of Tasmania.

Close-up of a single yellow daisy — Species belonging to this genus are a common sight to alpine hikers.
Alexander Schmidt-Lebuhn, Author provided

Apart from the excitement of finding a previously undescribed, distinctive genus, these results were also directly relevant to the original purpose of our work: informing a plant list to test possible biocontrol agents.

The traditional misclassification of these species would have misled us about their true relationships. Our new genetic data now allow us to test biocontrol agents on an appropriate sample of species, to minimise risks to our native flora.

It is not often we find that a new, unexpected lineage of plants has existed all along, right in front of us.

Alexander Schmidt-Lebuhn, Research Scientist, CSIRO and Ben Gooden, Plant ecologist, CSIRO

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

One of Earth’s most biodiverse habitats lies off the Scottish west coast – but climate change could wipe it out

Heidi Burdett, Heriot-Watt University and Cornelia Simon-Nutbrown, Heriot-Watt University

Maerl beds stud the ocean floor like underwater brambles. They’re pastel pink and, despite their knobbly appearance, made up of a red seaweed. This algae has a limestone skeleton which gives it a complex three-dimensional structure that is quite unlike the slimy seaweeds you may be more familiar with.

In fact, the closest thing to a maerl bed you’ve probably heard of is a coral reef. Like tropical reefs, the seaweeds in maerl beds interlock as they grow, creating nooks and crannies that serve as the perfect home for a huge range of sealife. Maerl beds are one of the world’s most biodiverse habitats, but unlike coral reefs, few people have heard of them and even fewer study them.

Also known as “rhodolith beds”, maerl beds are found in coastal waters all over the world, from the poles to the equator, but pockets of this habitat form European strongholds off Scotland’s west coast and islands. Sadly, our new research has revealed how climate change threatens to destroy much of this natural heritage before its wonders have been brought to light.

A clump of knobbly, pink, coralline seaweed. — A piece of Scottish maerl that is well over 100 years old.
Nick Kamenos, Author provided

Climate change and maerl beds

Maerl grows at a glacial pace – just 0.2 mm per year in Scotland. This makes it difficult for these habitats to respond to rapid changes in water temperature or ocean currents. But these are just the kind of environmental changes that are expected around Scotland over the coming century.

Until recently, scientists had only conducted small-scale experiments on maerl, so we knew very little about how Scotland’s beds would respond to climate change. To overcome this, we developed a computer model that can predict how the multiple changes to Scotland’s climate will affect the distribution of this habitat by 2100.

Astonishingly, even in the best-case scenario, where emissions are rapidly reduced from current levels, we predict that maerl bed distribution will shrink by 38% by the end of the century. If global emissions stick to their current trajectory, we predict a massive 84% decline in maerl bed distribution around Scotland. Without major changes we will likely follow this path, or worse.

Our research tells us that this would be devastating for the flora and fauna that call this habitat home, including commercially important species such as juvenile pollack, hake and scallops.

Scotland’s maerl beds under ‘worst-case’ warming scenario

Two maps comparing maerl bed distribution off the Scottish coast today and in 2100. — Simon-Nutbrown et al. (2020), Author provided

Refuge areas

Only international efforts to rapidly reduce greenhouse gas emissions could improve the situation for Scotland’s maerl beds. But managing the coastal ocean better – with regulation of trawling and pollution – could soften the blow. Since our model found that the rate of habitat decline will be fastest between now and 2050, the need for rapid action is even more urgent.

It’s unrealistic to expect the entire coastal ocean of a country to be placed under strict marine protection. After all, these regions are very valuable to a range of industries and interests, like tourism, shipping and fishing. Where then, should we focus our efforts? Our computer model helps with this too.

We have identified some key areas in which maerl populations are likely to persist in local micro-climates. Here, temperatures are not predicted to rise as much as the surrounding water and changes in waves and currents at the seafloor are expected to be less pronounced. This will allow maerl beds to remain in areas such as Loch Laxford, mainland Orkney and mainland Shetland. Protecting and monitoring these refuge areas could maximise the chances of these habitats surviving for future generations to enjoy.

Seafloor habitat with pink clumps of maerl, rocks and seaweed. — A Scottish maerl bed brimming with life.
Nick Kamenos, Author provided

Knowing where a habitat might continue to thrive in the future is crucial for planning how to manage coastal seas better, and being able to map these areas can help reconcile their protection with other activities. The refuge areas we found will now be considered as priority conservation areas by the Scottish Government.

Climate change is expected to affect maerl beds all around the world, so the computer model we’ve created can now find other areas where they may be able to cling on globally. Conservation can be long, gruelling work, so being able to focus marine protection efforts in areas with the highest chance of survival could help safeguard at least some of this habitat for future generations.

Heidi Burdett, Research Fellow, Lyell Centre for Earth and Marine Science and Technology, Heriot-Watt University and Cornelia Simon-Nutbrown, PhD Candidate in Marine Conservation, Heriot-Watt University

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

Australia’s natural history and native species should be on the citizenship test

Thomas M Wilson, University of Western Australia

Australia’s proposed changes to the citizenship test has raised questions about whether you can really evaluate someone’s “Australian values” via a set of exam questions.

But here’s another question not even considered by the test: should Australian citizenship entail a knowledge and appreciation of Australia’s unique wildlife and natural history?

At its heart, this is a question about what it truly means to be an Australian. Some would argue I’m not qualified even to ask it. My ancestors arrived in Perth in 1830 from England and unloaded plenty of inappropriate cultural baggage, including cats, onto the shores of Australia.

Modern Australia is both an ancient land of hundreds of different languages and cultures, and a creation of transplanted Europeans who have sought to establish Western democratic ideals such as freedom of speech. There have also been many waves of economic migrants or those fleeing persecution and violence in their homelands.

With democratic ideals attacked or disregarded in many parts of the world, Australia’s citizenship test aims to ensure new citizens have a shared knowledge of these values and responsibilities. The current test puts a lot of emphasis on knowing about free speech, the constitution, and how parliaments are organised.

But being Australian shouldn’t just mean agreeing with the principles of free speech and deliberative democracy. In 2006, the Australian author William J. Lines published Patriots: Defending Australia’s Natural Heritage. The title presupposes that being Australian is bound up with knowing and appreciating at least a little of Australia’s heritage of unique lifeforms and ecosystems.

My own book, Stepping Off: Rewilding and Belonging in the South West, published in 2017, also champions the idea of embracing the natural environment as part of one’s identity, with a particular focus on Perth and Australia’s southwest corner, an internationally recognised hotspot for unique plants and animals.

An appreciation of Australia

In my book I lament some aspects of the “Britanisation” of this country by my forebears. I also decry the smooth surface that corporate globalisation has more recently smeared over our modern cities.

As a counterbalance to these forces, I suggest other ways of “becoming Australian” that might help us live more gracefully and sustainably on this landscape.

What if we asked prospective Australian citizens to know and value the land on which we live, and the living things with which we share it? This might involve knowing facts such as:

much of southern Australia is geologically ancient, and broke from Antarctica around 40 million years ago before drifting north alone, evolving thousands of unique species
a eucalyptus leaf contains oils that can cause massive explosions in the forest canopy when fires tear through the environment, but which can also be used in kitchen detergents
Australia has about 70 species of macropod, of which kangaroos and wallabies are just two examples, and kangaroo meat is more sustainable than beef or lamb because of its low carbon footprint and its softer impact on the landscape compared with hoofed animals
a chuditch (or a quoll on the eastern side of the country), is a small carnivorous marsupial that is very friendly, although it’s (sadly) illegal to keep one as a pet.

Chuditch — Do you know a chuditch when you see one?
SJ Bennett/Wikimedia Commons, CC BY-SA

I’m not suggesting throwing the baby out with the bathwater. I appreciate many of the legacies of Western civilisation, including freedom of speech, deliberative democracy, and the rule of law by an independent judiciary. Of course being Australian should mean accepting these central tenets.

But we should expect new arrivals to our shores — including those whose ancestors have been here for a couple of centuries — to supplement this culture with an understanding and appreciation of land and ecosystem we live in. These values are also more aligned with those of Indigenous Australian cultures.

Being Australian shouldn’t just mean knowing about federation and the ANZACs, mateship and Vegemite. It should also mean knowing at least a little of the plants and animals, stones and clouds, smells and sights, of our wide shared land.

Thomas M Wilson, Honorary Research Fellow in Literature and Environment, University of Western Australia

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

The ocean is swimming in plastic and it’s getting worse – we need connected global policies now

Steve Fletcher, University of Portsmouth and Keiron Philip Roberts, University of Portsmouth

It seems you cannot go a day without reading about the impact of plastic in our oceans, and for good reason. The equivalent of a garbage truck of plastic waste enters the sea every minute, and this increases every day. If we do nothing, by 2040 the amount of plastic entering the ocean will triple from 13 million tonnes this year, to 29 million tonnes in 2040. That is 50kg of waste plastic entering the ocean for every metre of coastline.

Add to that almost all the plastic that has entered the ocean is still there since it takes centuries to break down. It is either buried or broken down into smaller pieces and potentially passes up the food chain creating further problems.

Despite this, plastic has also been a saviour. During the COVID-19 pandemic plastic used in face masks, testing kits, screens and to protecting food has enabled countries to come out of lockdown during and support social distancing. We still need to use these items until sustainable and “COVID safe” alternatives are available. But we also need to look to the future to reduce our dependence on plastic and its impact on the environment. With plastic in the ocean being a global problem, we need global agreements and policies to reverse the plastic tide.

Ambitious policies are needed

Environment ministers of the G20 group of the world’s most economically powerful countries and regions met on September 16 to discuss their immediate challenges, with marine plastic pollution a top priority. A key item for discussion was “safeguarding the planet by fostering collective efforts to protect our global commons”. This means working out how we can continue to use the planet’s resources sustainably without harming the environment.

A global analysis of plastics policies over the past two decades found that typical reactions to marine plastic litter were bans or taxes on individual or groups of plastic items within single countries. So far, 43 countries have introduced a ban, tax or levy on plastic bags. Other plastic packaging or single-use plastic products were banned in at least 25 countries, representing a population of almost 2 billion people in 2018.

But plastic waste doesn’t respect land or ocean borders, with mismanaged plastic waste easily migrating from country to country when leaked into the environment. Policies also need to consider the entire plastics life cycle to stand a chance of being effective. For example, the inclusion of easier to recycle plastics in consumer products sounds positive, but their actual recycling rate depends on effective sorting and collection of plastic waste, and appropriate infrastructure being in place.

Ultimately, a joined up but adaptable set of rules and guidelines are needed so all plastic producers and users can prevent its leakage across all stages of the plastics life cycle.

The G20 has sought to lead action on marine plastic litter through a 2017 Action Plan on Marine Litter which set out areas of concern and possible policy interventions, and through connections to initiatives such as the UN Environment Programme’s Global Partnership on Marine Litter and most recently the Osaka Blue Ocean Vision. The Osaka vision was agreed under the Japanese G20 presidency in 2019 and commits countries to “reduce additional pollution by marine plastic litter to zero by 2050”. Although an agreement led by the G20, it now has the support of 86 countries.

But even with these agreements in place, plastic entering the ocean will still only reduce by 7% by 2040. We need ambitious new agreements as current and emerging policies do not meet the scale of the challenge.

A consensus is forming that the G20 and other global leaders must focus on a systemic change of the plastics economy. This includes focusing on “designing out” plastics, promoting technical and business innovation, immediately scaling up actions known to reduce marine plastic litter, and transitioning to a circular economy in which materials are fully recovered and reused. These actions have the potential to contribute to the G20’s vision of net-zero plastics entering the ocean by 2050, but only if ambitious actions are taken now.

Steve Fletcher, Professor of Ocean Policy and Economy, University of Portsmouth and Keiron Philip Roberts, Research Fellow in Clean Carbon Technologies and Resource Management, University of Portsmouth

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

We looked at 35 years of rainfall and learnt how droughts start in the Murray-Darling Basin

Chiara Holgate, Australian National University; Albert Van Dijk, Australian National University, and Jason Evans, UNSW

The extreme, recent drought has devastated many communities around the Murray-Darling Basin, but the processes driving drought are still not well understood.

Our new study helps to change this. We threw a weather model into reverse and ran it back for 35 years to study the natural processes leading to low rainfall during drought.

And we found the leading cause for drought in the Murray-Darling Basin was that moisture from oceans didn’t reach the basin as often as normal, and produced less rain when it did. In fact, when moisture from the ocean did reach the basin during drought, the parched land surface actually made it harder for the moisture to fall as rain, worsening the already dry conditions.

These findings can help resolve why climate models struggle to simulate drought well, and ultimately help improve our ability to predict drought. This is crucial for our communities, farmers and bushfire emergency services.

There’s still a lot to learn about rain

The most recent drought was relentless. It saw the lowest rainfall on record in the Murray-Darling Basin, reduced agricultural output, led to increased food prices, and created tinder dry conditions before the Black Summer fires.

Drought in the Murray-Darling Basin is associated with global climate phenomena that drive changes in ocean and atmospheric circulation. These climate drivers include the El Niño and La Niña cycle, the Indian Ocean Dipole and the Southern Annular Mode.

Each influences the probability of rainfall over Australia. But drivers like El Niño can only explain around 20% of Australian rainfall — they only tell part of the story.

To fully understand the physical processes causing droughts to begin, persist and end, we need to answer the question: where does Australia’s rainfall come from? It may seem basic, but the answer isn’t so simple.

Where does Australia’s rainfall come from?

Broadly, scientists know rainfall derives from evaporation from two main sources: the ocean and the land. But we don’t know exactly where the moisture supplying Australia’s rainfall originally evaporates from, how the moisture supply changes between the seasons nor how it might have changed in the past.

To find out, we used a sophisticated model of Australia’s climate that gave data on atmospheric pressure, temperature, humidity, winds, rainfall and evaporation.

We put this data into a “back-trajectory model”. This traced the path of water from where it fell as rain, backwards in time through the atmosphere, to uncover where the water originally evaporated from. We did this for every day it rained over Australia between 1979 and 2013.

Not surprisingly, we found more than three-quarters of rain falling in Australia comes from evaporation from the surrounding oceans. So what does this mean for the Murray-Darling Basin?

Up to 18% of rain in the basin starts from the land

During the Millennium Drought and other big drought years (such as in 1982), the Murray-Darling Basin heavily relied on moisture transported from the Tasman and Coral seas for rain. Moisture evaporated off the east coast needs easterly winds to transport it over the Great Dividing Range and into the Murray-Darling Basin, where it can form rain.

This means low rainfall during these droughts was a result of anomalies in atmospheric circulation, which prevented the easterly flow of ocean moisture. The droughts broke when moisture could once again be transported into the basin.

A lack of vegetation on the land can exacerbate drought.
Shutterstock

The Murray-Darling Basin was also one of the regions in Australia where most “rainfall recycling” happens. This is when, following rainfall, high levels of evaporation from soils and plants return to the atmosphere, sometimes leading to more rain – particularly in spring and summer.

This means if we change the way we use the land or the vegetation, there is a risk we could impact rainfall. For example, when a forest of tall trees is replaced with short grass or crops, humidity can go down and wind patterns change in the atmosphere above. Both of these affect the likelihood of rain.

In the northern part of the basin, less evaporation from the dry land surface exacerbated the low rainfall.

On the other hand, when the drought broke, more moisture evaporated from the damp land surface, adding to the already high levels of moisture coming from the ocean. This meant the region got a surplus of moisture, promoting even more rain.

This relationship was weaker in the southern part of the basin. But interestingly, rainfall there relied on moisture originating from evaporation in the northern basin, particularly during drought breaks. This is a result we need to explore further.

Summer rain not so good for farmers

Rainfall and moisture sources for Australia and the Murray-Darling Basin are changing. In the past 35 years, the southeast of the country has been receiving less moisture in winter, and more in summer.

This is likely due to increased easterly wind flows of moisture from the Tasman Sea in summer, and reduced westerly flows of moisture from the Southern Ocean in winter.

This has important implications, particularly for agriculture and water resource management.

For example, more rainfall in summer can be a problem for horticultural farms, as it can make crops more susceptible to fungal diseases, decreases the quality of wine grape crops and affects harvest scheduling.

Less winter rain also means less runoff into creeks and rivers — a vital process for mitigating drought risk. And this creates uncertainty for dam operators and water resource managers.

Understanding where our rainfall comes from matters, because it can improve weather forecasts, seasonal streamflow forecasts and long-term rainfall impacts of climate change. For a drought-prone country like Australia — set to worsen under a changing climate — this is more crucial than ever.

Chiara Holgate, Hydrologist & PhD Candidate, Australian National University; Albert Van Dijk, Professor, Water and Landscape Dynamics, Fenner School of Environment & Society, Australian National University, and Jason Evans, Professor, UNSW

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

‘Like trying to find the door in a dark room while hearing your relatives scream for help’: Tasmania’s whale stranding tragedy explained

Olaf Meynecke, Griffith University

A desperate rescue effort is underway after hundreds of long-finned pilot whales (Globicephala melas) became stranded in Macquarie Harbour on Tasmania’s west coast.

Yesterday, more than 250 pilot whales were reported to have stranded, with one-third presumed dead. And this morning, rescuers found another 200 pilot whales stranded up to ten kilometres away from the first group — most are likely dead.

This brings the total number of stranded pilot whales in Tasmania to more than 450, and it’s believed to be the biggest ever recorded in the state. The Greens are calling on federal Environment Minister Sussan Ley to launch a national response.

The rescue mission aims to refloat the pilot whales that appear to still be in reasonable health. But their behaviour hampers rescue efforts: many pilot whales re-strand themselves to be with their family. This event likely means a number of generations of the local population will be lost.

How did they become stranded?

Despite its name, the long-finned pilot whale is actually a large oceanic dolphin. They cover vast areas of the Southern (Antarctic) Ocean, reaching between four and six metres in length and weighing up to one tonne.

They are well adapted to deeper oceans where they hunt for various species of squid in depths of between 600-1,000m, using echolocation to find their prey. Echolocation is a way of using sound to navigate in complete darkness.

They generally spend most of their lives offshore and it’s not well understood what conditions drive them close to shore, and to enter shallow embayments.

Some theories suggest food shortages are to blame, or changes in electromagnetic fields that disorient them. They may also be following a sick or distressed pod leader. And in some past cases strandings were related back to active sonar from ships and naval sonar interrupting their echolocation.

But once in shallow waters, it’s difficult to swim back out. As these whales mostly navigate with echolocation it’s not possible for them to use sonar effectively in shallow and muddy embayments.

It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help.

In fact, the stress is what many die from in the end. Other causes of death are overheating from sun exposure and drowning if they can’t move their bodies up to breach the surface in shallow water.

The rescue efforts

There are a number of strategies to refloat whales. In Macquarie Harbour, rescuers are using slings to tow the whales to deeper water, before releasing them.

Other options include multiple people pushing them off the beach during high tide into deeper water.

In this case, albeit potentially dangerous for the helpers, people power can make a big difference. After all, time is of immense importance for success, and to stop more whales beaching.

However, chances of survival plummet with long exposure to sun and extended periods of stress. What’s more, Macquarie Harbour is relatively remote and difficult to access, further complicating rescue efforts.

Dying together

But the biggest obstacle rescuers face is the whales’ social bonding. Long-finned pilot whales are highly intelligent and live in strong social units.

So when dealing with mass strandings, it’s important to realise the emotions and bonding between the whales are very likely beyond what humans can feel. One well-documented example of their emotional depth is the pilot whale seen carrying its dead calf for many days.

Mother pilot whale grieves over her dead calf.

This makes the stranding process extremely complex, as it unfolds over several hours to several days — the whales don’t all strand at the same time.

We know from killer whales, which also have strong social bonding, that if a close member of the group strands, others will attempt to join to die together.

The situation for pilot whale pods can be similar, but more complex as a result of having much larger pods. Pilot whale pods have multiple sub-units, which can consist of friends as well as family and they don’t have to be genetically related.

Social units get mixed up when they’re in shallow bays. This means individuals can become disconnected from their social units before the actual stranding occurs, causing stress and confusion prior the beaching.

Fewer pilot whales in the gene pool

There are an estimated 200,000 long-finned pilot whales in the Southern Ocean and Antarctica, but mass strandings like this can have a profound impact on sub-populations.

In Tasmania alone, 1,568 long-finned pilot whales have stranded between 1990 and 2008 in 30 stranding events.

Many similar sad events occured in New Zealand: hundreds of long-finned pilot whales stranded in 2018 and 2017, and the majority died.

To make matters worse, studies suggest the long-finned pilot whales in the Southeastern Pacific have low genetic diversity. There are similarities between this species found in Chile and New Zealand, but with surprisingly distinct differences between New Zealand and Tasmania.

Considering they can live up to 50 years and the fact only few survive when multiple generations strand, such events not only destroy entire generations but also remove them from the gene pool.

This puts local populations at further risk. Inbreeding is one consequence, but the biggest problem is their decreasing general fitness and ability to adapt to changes.

How to help

In the past, significant numbers of stranded whales have been successfully released, making it worth the effort. For example, in one of largest mass strandings in New Zealand in 2017, volunteers helped about 100 whales refloat, and made a human chain to try to stop them restranding.

Still, such events are likely to be more frequent in the future due to changing ocean conditions and increasing human activity such a noise pollution, commercial squid fisheries and deep sea mining.

Climate change shifts ocean currents as sea temperature rises. And with this, squid availability will change. A lack of food offshore can cause stress and drive them closer to shore.

We can help the whales not only by actively supporting rescue organisations such as ORRCA, but also by helping reduce carbon emissions, foster sustainable fisheries, reduce plastic pollution and advocate for marine sanctuaries.

Olaf Meynecke, Research Fellow in Marine Science, Griffith University

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

Bilbies Are Back

Malcolm Turnbull condemns Scott Morrison’s ‘gas, gas, gas’ song as ‘a fantasy’

Michelle Grattan, University of Canberra

Malcolm Turnbull has launched a swingeing attack on Scott Morrison’s gas-led recovery, labelling his threat to build a gas-fired power station “crazy stuff”, and his idea of gas producing a cheap energy boom “a fantasy”.

The former prime minister also claimed Morrison’s refusal to embrace a 2050 net zero emissions target was “absolutely” at odds with the Paris climate agreement. “That was part of the deal,” Turnbull said.

Morrison at the weekend would not commit to a 2050 target – endorsed by business, farming and other groups in Australia and very many countries – although he said it was achievable.

Turnbull also declared that Energy Minister Angus Taylor – who on Tuesday delivered his technology investment roadmap for low emissions – didn’t believe most of what he was saying on energy.

“Angus has got quite a sophisticated understanding of the energy market, and he is speaking through the political side of his brain rather than the economic side,” Turnbull told the ABC.

The energy/climate war was pivotal in Turnbull’s fall from the prime ministership in 2018, and from the opposition leadership in 2009. While Morrison is totally safe in his job, the battle over energy policy on the conservative side of politics has not been put to rest, although the prime minister is banking on his elevation of gas satisfying his Liberal parliamentarians.

Morrison’s gas policy, which the government spruiks as underpinning a manufacturing revival, is being seen as a walk away from coal.

It includes a threat to build a gas-fired power station in the Hunter region if private enterprise does not fill the gap left by the coming closure of the Liddell coal-fired station.

The debate about gas has produced an unexpected unity ticket between Turnbull and former resources minister, the Nationals Matt Canavan, on one key point – both insist gas prices won’t be as low as the policy assumes.

But Turnbull and Canavan go in opposite directions in their energy prescriptions – Turnbull strongly backs renewables and Canavan is a voice for coal.

While acknowledging gas had a role “as a peaking fuel”, Turnbull dismissed any prospect of a “gas nirvana”.

“There is no cheap gas on the east coast of Australia. It is cheap at the moment because there’s a global recession and pandemic and oil prices are down, but the equilibrium price of gas is too high to make it a cheap form of generating electricity.”

“The cheap electricity opportunities come from wind and solar, backed by storage, batteries and pumped hydro, and then with gas playing a role but it’s essentially a peaking role,” Turnbull said.

Writing in the Australian, Canavan said the Morrison gas plan would “keep the lights on but it is unlikely to lower energy prices to the levels needed to bring manufacturing back to Australia.

“If we were serious about getting [energy] prices down as low as possible, we would focus on the energy sources in which we have a natural advantage, and that is not gas. We face gas shortages in the years ahead.”

Former Nationals leader Barnaby Joyce said about the government’s power station threat, that it would be “peculiar” to build a gas-fired plant “in the middle of a coal field”.

Turnbull said of last week’s announcement, “I’m not going to sing the song but it’s a gas, gas, gas”.

The roadmap was “gas one minute, carbon capture and storage the next”.

“What you need is to set out some basic parameters, which deal with reliability, affordability and emissions reduction, and then let the market get to work. That’s what Liberal governments should do. Unfortunately, it’s just one random intervention after another,” Turnbull said.

He lamented that, for whatever reasons, there was a “body of opinion on the right of Australian politics in the Liberal party and the National party, the Murdoch press, which still clings to this fantasy that coal is best and if we can’t have coal we’ll burn gas – I mean, it’s bonkers. The way to cheaper electricity is renewables plus storage, which is why the big storage plan that we got started, Snowy 2, is so important.”

Turnbull said that unlike his own situation when PM, Morrison was “in a position with no internal opposition”. “Now is the time to deliver an integrated, coherent energy and climate policy which is what the whole energy sector has been crying out for.”

Taylor told the National Press Club the government’s determination to get the gap filled, whether by private investment or a government power station, when the Liddell coal fired station closes in 2023 “is partly about reliability, but it’s primarily about affordability.

“If you take that much capacity out of the market, it’s a huge amount in a short period of time. We saw what happened with Hazelwood. We saw very, very sharp increases in prices. We’re not prepared to accept that.”

Asked whether the government’s resistance to committing to the 2050 target was more about appeasing the right wing of the coalition rather than about the target itself, Taylor said: “Our focus is on our 2030 target in the Paris agreement…and in a few years time we will have to extend that out to 2035 …

“What we’re not going to do is impose a target that’s going to impose costs on the economy, destroy jobs, and stop investment. The Paris commitment, globally, is to net zero in the second half of the century and we would like that to happen as soon as possible.”

Michelle Grattan, Professorial Fellow, University of Canberra

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

Our new model shows Australia can expect 11 tropical cyclones this season

Andrew Magee, University of Newcastle and Anthony Kiem, University of Newcastle

Tropical cyclones are considered one of the most devastating weather events in Australia. But they’re erratic — where, when and how many tropical cyclones form each year is highly variable, which makes them difficult to predict.

In our new research published today, we created a statistical model that predicts the number of tropical cyclones up to four months before the start of the tropical cyclone season from November to April.

The model, the Long-Range Tropical Cyclone Outlook for Australia (TCO-AU), indicates normal to above normal tropical cyclone activity with 11 cyclones expected in total, Australia-wide. Though not all make landfall.

This is above Australia’s average of ten tropical cyclones per season, thanks to a climate phenomenon brewing in the Pacific that brings conditions favourable for tropical cyclone activity closer to Australia.

La Niña and tropical cyclones

As we’ve seen most recently with Tropical Storm Sally in the US, tropical cyclones can cause massive damage over vast areas. This includes extreme and damaging winds, intense rainfall and flooding, storm surges, large waves and coastal erosion.

Australian tropical cyclone behaviour is largely driven by the El Niño-Southern Oscillation (ENSO) — a global climate phenomenon that changes ocean and atmospheric circulation.

“La Niña” is one phase of ENSO. It’s typically associated with higher than normal tropical cyclone numbers in the Australian region. And the Bureau of Meteorology’s weather and climate model indicates there’s a 95% chance a La Niña will be established by October this year.

Around ten tropical cyclones occur in the Australian region every season, and about four of those usually make landfall.

Historically, La Niña has resulted in double the number of landfalling tropical cyclones in Australia, compared to El Niño phases. An “El Niño” event is associated with warmer and drier conditions for eastern Australia.

During La Niña events, the first tropical cyclone to make landfall also tends to occur earlier in the season. In fact, in Queensland, the only tropical cyclone seasons with multiple severe tropical cyclone landfalls have been during La Niña events.

Severe Tropical Cyclone Yasi, one of the most intense tropical cyclones to have hit Queensland, occurred during a La Niña in 2011. So did the infamous Severe Tropical Cyclone Tracy, which made landfall around Darwin in 1974, killing 71 people and leaving more than 80% of all buildings destroyed or damaged.

While naturally occurring climate drivers, such as La Niña, influence the characteristics of tropical cyclone activity, climate change is also expected to cause changes to future tropical cyclone risk, including frequency and intensity.

Australian tropical cyclone outlooks

Tropical cyclone outlooks provide important information about how many tropical cyclones may pass within the Australian region and subregions, before the start of the cyclone season. Decision-makers, government, industry and people living in tropical cyclone regions use them to prepare for the coming cyclone season.

The Australian Bureau of Meteorology has led the way in producing tropical cyclone outlooks for Australia, usually a couple of weeks before the official start of the tropical cyclone season.

But with monthly guidance up to four months before the start of the season, our new model, TCO-AU, is unmatched in lead time. It considers the most recent changes in ENSO and other climate drivers to predict how many tropical cyclones may occur in Australia and its sub-regions.

As a statistical model, TCO-AU is trained on historical relationships between ocean-atmosphere processes and the number of tropical cyclones per season.

For each region, hundreds of potential model combinations are tested, and the one that performs best in predicting historical tropical cyclone counts is selected to make the prediction for the coming season.

So what can we expect this season?

September’s TCO-AU guidance suggests normal to above normal risk for Australia for the coming tropical cyclone season (November 2020 – April 2021).

With an emerging La Niña and warmer than normal sea surface temperatures in the eastern Indian Ocean, 11 tropical cyclones are expected for Australia. There’s a 47% chance of 12 or more cyclones, and a probable range of between nine and 15.

For the Australian sub-regions, TCO-AU suggests the following:

above normal activity is expected for the Eastern region (eastern Australia) with four cyclones expected. Probable range between three and six cyclones; with a 55% chance of four or more cyclones
normal activity is expected for the Western region (west/northwest Western Australia) with six cyclones expected. Probable range between five and eight cyclones; 39% chance of seven or more cyclones
below normal activity is expected for the Northern region (northwest Queensland and Northern Territory) with three cyclones expected. Probable range between two and five cyclones; 37% chance of four cyclones or more
below normal activity is also expected for the Northwestern region (northwest Western Australia) with four cyclones expected. Probable range between three and six cyclones; 45% chance of five cyclones or more.

TCO-SP – Long-range Tropical Cyclone Outlook for the Southwest Pacific/The Conversation, CC BY-ND

Guidance from TCO-AU does not and should not replace advice provided by the Australian Bureau of Meteorology. Instead, it should be used to provide a complementary perspective to regional outlooks and provide a “heads-up” in the months leading up to the start of and within the cyclone season.

Regardless of what’s expected for the coming cyclone season, people living in tropical cyclone regions should always prepare for the cyclone season and follow the advice provided by emergency services.

Andrew Magee, Postdoctoral Researcher, University of Newcastle and Anthony Kiem, Associate Professor – Hydroclimatology, University of Newcastle

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

Kevin's Walk on the Wild Side

Environment, Wildlife and Wilderness – Articles and News

Monthly Archives for September 2020

How to reverse global wildlife declines by 2050

Bending the curve

We accidentally found a whole new genus of Australian daisies. You’ve probably seen them on your bushwalks

How it began

Missing data

Hidden in the evolutionary tree

Introducing Scapisenecio

One of Earth’s most biodiverse habitats lies off the Scottish west coast – but climate change could wipe it out

Climate change and maerl beds

Refuge areas

Australia’s natural history and native species should be on the citizenship test

An appreciation of Australia

The ocean is swimming in plastic and it’s getting worse – we need connected global policies now

Ambitious policies are needed

We looked at 35 years of rainfall and learnt how droughts start in the Murray-Darling Basin

There’s still a lot to learn about rain

Where does Australia’s rainfall come from?

Up to 18% of rain in the basin starts from the land

Summer rain not so good for farmers

‘Like trying to find the door in a dark room while hearing your relatives scream for help’: Tasmania’s whale stranding tragedy explained

How did they become stranded?

The rescue efforts

Dying together

Fewer pilot whales in the gene pool

How to help

Bilbies Are Back

Malcolm Turnbull condemns Scott Morrison’s ‘gas, gas, gas’ song as ‘a fantasy’

Our new model shows Australia can expect 11 tropical cyclones this season

La Niña and tropical cyclones

Australian tropical cyclone outlooks

So what can we expect this season?

Bending the curve

Share this:

How it began

Missing data

Hidden in the evolutionary tree

Introducing Scapisenecio

Share this:

Climate change and maerl beds

Refuge areas

Share this:

An appreciation of Australia

Share this:

Ambitious policies are needed

Share this:

There’s still a lot to learn about rain

Where does Australia’s rainfall come from?

Up to 18% of rain in the basin starts from the land

Summer rain not so good for farmers

Share this:

How did they become stranded?

The rescue efforts

Dying together

Fewer pilot whales in the gene pool

How to help

Share this:

Share this:

Share this:

La Niña and tropical cyclones

Australian tropical cyclone outlooks

So what can we expect this season?

Share this: