Headphones, saw blades, coat hangers: how human trash in Australian bird nests changed over 195 years


This, if you can believe it, is part of a magpie nest.
Kathy Townsend, Author provided

Kathy Ann Townsend, University of the Sunshine Coast and Dominique Potvin, University of the Sunshine CoastEnvironmental scientists see flora, fauna and phenomena the rest of us rarely do. In this series, we’ve invited them to share their unique photos from the field.


When we opened a box supplied by museum curators, our research team audibly gasped. Inside was a huge Australian magpie nest from 2018.

It was more than a metre wide and made up of the strangest assortment of items, including wire coat hangers, headphones, saw blades and plastic 3D glasses — a mix of detritus reflecting our modern lifestyle.

This was one of almost 900 Australian nest specimens dating back over 195 years that we inspected for our recent, world-first study.

We estimate that today, around 30% of Australian bird nests incorporate human-made materials (primarily plastics). We also noted a steady increase in nest parasites over this period.

It’s clear the types of debris the birds use has reflected changes in society over time. They highlight the unexpected and far-reaching ways Australians impact their environment, and put birds in danger.

The full magpie nest from 2018 that was collected outside a construction site.
Kathy Townsend, Author provided

The first synthetic item

Birds and humans have been sharing spaces and habitats throughout history.

It’s well known birds incorporate material from their environment into their nests, making them ideal indicators of environmental changes and human activity. It’s also well known, particularly among scientists, that museum collections can provide unique insight into environmental changes through time and space.

Compare the magpie nest above to this natural butcherbird nest from 1894. Butcherbirds are in the same family as magpies.
Dominique Potvin, Author provided

With this in mind, our international team investigated Australian museum bird nest specimens collected between 1823 and 2018. Sourced from Museums Victoria and CSIRO’s Crace Site in Canberra, we inspected a total of 892 nests from 224 different bird species.

Australian birds generate an amazing array of nest types. Rufous fantails, for example, build delicately woven structures made of fine grass and spiderwebs, while welcome swallows and white-winged choughs create nests out of mud, which dry incredibly hard and can be used year after year.

A woven egg cup nest from 1870, made of grass and spiderwebs, by the rufous fantail.
Kathy Townsend, Author provided
Fabiola Opitz, a member of our research team, measuring mudnest collected circ. 1933 of a whitewinged chough. These mudnests can last for years.
Dominique Potvin, Author provided

Before the 1950s, human-made debris found in the nests consisted of degradable items such as cotton thread and paper.

This changed in 1956, when we found the first synthetic item in a bird nest from Melbourne: a piece of polyester string. This appearance correlates with the increased availability of plastic polymers across Australian society, seven years after the end of the second world war.

Australian magpies earn their name

We also determined, based on collection date and using historical maps, whether the nests came from natural, rural or urban landscapes. And it turns out the nest’s location, when it was built, and the species that made it largely determined whether human-made materials were present.

Brown nest with blue string
The nest of a noisy miner found on the Sunshine Coast, Queensland, in 2020 with plastic string.
Kathy Townsend, Author provided

Our study found nests built close to urban areas or farmland after the 1950s by birds from the families Craticidae (Australian magpies and butcherbirds), Passeridae (old world or “true” sparrows) and Pycnonotidae (bulbuls) had significantly more human-made debris.

Familiar to many an urban bird enthusiast, these species tend to adapt quickly to new environments. The incorporation of human materials in nests is likely one example of this behavioural flexibility.

The research team also had access to ten bowerbird bowers from the family Ptilonorhynchidae, spanning more than 100 years. Male bowerbirds are known for creating elaborate structures, decorated with a range of colourful items to attract a mate.

A silvereye or gerygong nest from 2019.
Kathy Townsend, Author provided

In the 1890s, the birds decorated their bowers with natural items such as flowers and berries. Newspaper scraps were the only human-produced items we identified.

This changed dramatically 100 years later, where the most sought-after items included brightly coloured plastics, such as straws, pen lids and bottle caps.

A satin bowerbird collecting blue junk. Video: BBC Wildlife.

But there are tragic consequences

When birds weave non-biodegradable materials — such as fishing line and polymer rope — into their nests, it increases the risk of entanglement, amputation and even accumulation of plastics in the gut of nestlings.

For example, we found evidence of one pallid cuckoo juvenile dying in 1981 after it was entangled in plastic twine used by its adoptive bell miner parents.

This is the bell miner nest with twine that caused the cuckoo chick to die, according to the museum notes.
Dominique Potvin, Author provided

Plastic was not the only issue. We found the prevalence of nest parasites that attack the young chicks also increased by about 25% over the last 195 years.

Nest parasites can kill huge numbers of nestlings. Recent research into the forty-spotted pardalote in Tasmania, a threatened species, has shown nest parasites kill up to 81% of its nestlings.

What has caused this increase isn’t clear. However, the team determined it wasn’t directly linked to urban or rural habitat type, or the presence of human-made materials in the nest. This goes against the findings of other studies, which show a decrease of parasites in nests that incorporated items such as cigarettes.

Interestingly, we did find eucalyptus leaves might deter parasites, as nests that incorporated them were less likely to show evidence of parasitism.

An eastern yellow robin nest from 2003, with eucalyptus leaves, lichen, spider webs and no parasites. Eastern yellow robins are specialist nest builders that don’t tend to stray from using specific natural items.
Kathy Townsend, Author provided
This nest from 1932 is from an Australian magpie, using eucalyptus leaves.
Kathy Townsend, Author provided

It may be, therefore, that sticking with certain natural materials is not only better for the safety of nest inhabitants, but also may have an added effect of pest control.

Stop littering, please

While most are aware of how plastics harm sea life, our study is one of the first to show the impact goes further to harm animals living in our own backyard. If the trend continues, the future for Australian birds looks bleak.

However, we can all do something about it.

A weebill or mistletoe bird’s woven nest from 1941, with tufts of spider webs and plant fluff.
Kathy Townsend, Author provided

It is as simple as being responsible for our rubbish and supporting proposed legislation and campaigns for moving away from single-use plastics.

The team had access to nests from 224 different species, which equates to only about a quarter of Australia’s total of 830 bird species.

There is still plenty more to discover.




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The Conversation


Kathy Ann Townsend, Senior Lecturer in Animal Ecology, University of the Sunshine Coast and Dominique Potvin, Lecturer in Animal Ecology, University of the Sunshine Coast

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

Don’t hike so close to me: How the presence of humans can disturb wildlife up to half a mile away


What are you looking at? Greg Shine, BLM/Flickr, CC BY

Jeremy Dertien, Clemson University ; Courtney Larson, University of Wyoming, and Sarah Reed, Colorado State University

Millions of Americans are traveling this summer as pandemic restrictions wind down. Rental bookings and crowds in national parks show that many people are headed for the great outdoors.

Seeing animals and birds is one of the main draws of spending time in nature. But as researchers who study conservation, wildlife and human impacts on wild places, we believe it’s important to know that you can have major effects on wildlife just by being nearby.

In a recent review of hundreds of studies covering many species, we found that the presence of humans can alter wild animal and bird behavior patterns at much greater distances than most people may think. Small mammals and birds may change their behavior when hikers or birders come within 300 feet (100 meters) – the length of a football field. Large birds like eagles and hawks can be affected when humans are over 1,300 feet (400 meters) away – roughly a quarter of a mile. And large mammals like elk and moose can be affected by humans up to 3,300 feet (1,000 meters) away – more than half a mile.

Elk viewed over a hiker's shoulder.
A hiker about 75 feet from a bull elk in Yellowstone National Park. Jacob W. Frank, NPS/Flickr

Many recent studies and reports have shown that the world is facing a biodiversity crisis. Over the past 50 years, Earth has lost so many species that many scientists believe the planet is experiencing its sixth mass extinction – due mainly to human activities.

Protected areas, from local open spaces to national parks, are vital for conserving plants and animals. They also are places where people like to spend time in nature. We believe that everyone who uses the outdoors should understand and respect this balance between outdoor recreation, sustainable use and conservation.

How human presence affects wildlife

Pandemic lockdowns in 2020 confined many people indoors – and wildlife responded. In Istanbul, dolphins ventured much closer to shore than usual. Penguins explored quiet South African Streets. Nubian ibex grazed on Israeli playgrounds. The fact that animals moved so freely without people present shows how wild species change their behavior in response to human activities.

Decades of research have shown that outdoor recreation, whether it’s hiking, cross-country skiing or riding all-terrain vehicles, has negative effects on wildlife. The most obvious signs are behavioral changes: Animals may flee from nearby people, decrease the time they feed and abandon nests or dens.

Other effects are harder to see, but can have serious consequences for animals’ health and survival. Wild animals that detect humans can experience physiological changes, such as increased heart rates and elevated levels of stress hormones.

And humans’ outdoor activities can degrade habitat that wild species depend on for food, shelter and reproduction. Human voices, off-leash dogs and campsite overuse all have harmful effects that make habitat unusable for many wild species.

Disturbing shorebirds can cause them to stop eating, stop feeding their young or flee their nests, leaving chicks vulnerable.

Effects of human presence vary for different species

For our study we examined 330 peer-reviewed articles spanning 38 years to locate thresholds at which recreation activities negatively affected wild animals and birds. The main thresholds we found were related to distances between wildlife and people or trails. But we also found other important factors, including the number of daily park visitors and the decibel levels of people’s conversations.

The studies that we reviewed covered over a dozen different types of motorized and nonmotorized recreation. While it might seem that motorized activities would have a bigger impact, some studies have found that dispersed “quiet” activities, such as day hiking, biking and wildlife viewing, can also affect which wild species will use a protected area.

Put another way, many species may be disturbed by humans nearby, even if those people are not using motorboats or all-terrain vehicles. It’s harder for animals to detect quiet humans, so there’s a better chance that they’ll be surprised by a cross-country skier than a snowmobile, for instance. In addition, some species that have been historically hunted are more likely to recognize – and flee from – a person walking than a person in a motorized vehicle.

Generally, larger animals need more distance, though the relationship is clearer for birds than mammals. We found that for birds, as bird size increased, so did the threshold distance. The smallest birds could tolerate humans within 65 feet (20 meters), while the largest birds had thresholds of roughly 2,000 feet (600 meters). Previous research has found a similar relationship. We did not find that this relationship existed as clearly for mammals.

We found little research on impact thresholds for amphibians and reptiles, such as lizards, frogs, turtles and snakes. A growing body of evidence shows that amphibians and reptiles are disturbed and negatively affected by recreation. So far, however, it’s unclear whether those effects reflect mainly the distance to people, the number of visitors or other factors.

Graphic showing distances at which human presence affects animals' behavior.
Human recreation starts to affect wild creatures’ behavior and physical state at different distances. Small mammals and birds tolerate closer recreation than do larger birds of prey and large mammals. Sarah Markes, CC BY-ND

How to reduce your impact on wildlife

While there’s much still to learn, we know enough to identify some simple actions people can take to minimize their impacts on wildlife. First, keep your distance. Although some species or individual animals will become used to human presence at close range, many others won’t. And it can be hard to tell when you are stressing an animal and potentially endangering both it and yourself.

Second, respect closed areas and stay on trails. For example, in Jackson Hole, Wyoming, wildlife managers seasonally close some backcountry ski areas to protect critical habitat for bighorn sheep and reduce stress on other species like moose, elk and mule deer. And rangers in Maine’s Acadia National Park close several trails annually near peregrine falcon nests. This reduces stress to nesting birds and has helped this formerly endangered species recover.

 

 

 

Getting involved with educational or volunteer programs is a great way to learn about wildlife and help maintain undisturbed areas. As our research shows, balancing recreation with conservation means opening some areas to human use and keeping others entirely or mostly undisturbed.

As development fragments wild habitat and climate change forces many species to shift their ranges, movement corridors between protected areas become even more important. Our research suggests that creating recreation-free wildlife corridors of at least 3,300 feet (1,000 meters) wide can enable most species to move between protected areas without disturbance. Seeing wildlife can be part of a fun outdoor experience – but for the animals’ sake, you may need binoculars or a zoom lens for your camera.

[Get our best science, health and technology stories. Sign up for The Conversation’s science newsletter.]The Conversation

Jeremy Dertien, PhD Candidate in Forestry and Environmental Conservation, Clemson University ; Courtney Larson, Adjunct Assistant Professor, University of Wyoming, and Sarah Reed, Affiliate Faculty in Fish, Wildlife and Conservation Biology, Colorado State University

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

When coral dies, tiny invertebrates boom. This could dramatically change the food web on the Great Barrier Reef


Shutterstock

Kate Fraser, University of TasmaniaThis week, international ambassadors will take a snorkelling trip to the Great Barrier Reef as part of the Australian government’s efforts to stop the reef getting on the world heritage “in danger” list.

The World Heritage Centre of UNESCO is set to make its final decision on whether to officially brand the reef as “in danger” later this month.

To many coral reef researchers like myself, who have witnessed firsthand the increasing coral bleaching and cyclone-driven destruction of this global icon, an in-danger listing comes as no surprise.

But the implications of mass coral death are complex — just because coral is dying doesn’t mean marine life there will end. Instead, it will change.

In recent research, my colleagues and I discovered dead coral hosted 100 times more microscopic invertebrates than healthy coral. This means up to 100 times more fish food is available on reefs dominated by dead coral compared with live, healthy coral.

This is a near-invisible consequence of coral death, with dramatic implications for reef food webs.

When coral dies

Tiny, mobile invertebrates — between 0.125 and 4 millimetres in size — are ubiquitous inhabitants of the surfaces of all reef structures and are the main food source for approximately 70% of fish species on the Great Barrier Reef.

These invertebrates, most visible only under a microscope, are commonly known as “epifauna” and include species of crustaceans, molluscs, and polychaete worms.




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When corals die, their skeletons are quickly overgrown by fine, thread-like “turfing algae”. Turf-covered coral skeletons then break down into beds of rubble.

We wanted to find out how the tiny epifaunal invertebrates — upon which many fish depend – might respond to the widespread replacement of live healthy coral with dead, turf-covered coral.

A sample of epifauna under the microscope.
Kate Fraser

I took my SCUBA gear and a box of lab equipment, and dived into a series of reefs across eastern Australia, from the Solitary Islands in New South Wales to Lizard Island on the northern Great Barrier Reef.

Underwater, I carefully gathered into sandwich bags the tiny invertebrates living on various species of live coral and those living on dead, turf-covered coral.

But things really got interesting back in the laboratory under the microscope. I sorted each sandwich bag sample of epifauna into sizes, identified them as best I could (many, if not most, species remain unknown to science), and counted them.

I quickly noticed samples taken from live coral took just minutes to count, whereas samples from dead coral could take hours. There were exponentially more animals in the dead coral samples.

The Great Barrier Reef may soon be listed as ‘in danger’
Rick Stuart-Smith

Why do they prefer dead coral?

Counting individual invertebrates is only so useful when considering their contribution to the food web. So we instead used the much more useful metric of “productivity”, which looks at how much weight (biomass) of organisms is produced daily for a given area of reef.

We found epifaunal productivity was far greater on dead, turf-covered coral. The main contributors were the tiniest epifauna — thousands of harpacticoid copepods (a type of crustacean) an eighth of a millimetre in size.

In contrast, coral crabs and glass shrimp contributed the most productivity to epifaunal communities on live coral. At one millimetre and larger, these animals are relative giants in the epifaunal world, with fewer than ten individuals in most live coral samples.

Dead coral rubble overgrown with turfing algae.
Rick Stuart-Smith

These striking differences may be explained by two things.

First: shelter. Live coral may look complex to the naked eye, but if you zoom in you’ll find turfing algae has more structural complexity that tiny epifauna can hide in, protecting them from predators.

A coral head is actually a community of individual coral polyps, each with a tiny mouth and fine tentacles to trap prey. To smaller epifauna, such as harpacticoid copepods, the surface of live coral is a wall of mouths and a very undesirable habitat.




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Second: food. Many epifauna, regardless of size, are herbivores (plant-eaters) or detritivores (organic waste-eaters). Turfing algae is a brilliant trap for fine detritus and an excellent substrate for growing films of even smaller microscopic algae.

This means dead coral overgrown by turfing algae represents a smorgasbord of food options for the tiniest epifauna through to the largest.

Meanwhile, many larger epifauna like coral crabs have evolved to live exclusively on live coral, eating the mucus that covers the polyps or particles trapped by the polyps themselves.

Harpacticoid copepod are just an eighth of a millimetre in size.
Naukhan/Wikimedia, CC BY

What this means for life on the reef?

As corals reefs continue to decline, we can expect increased productivity at the base level of reef food webs, with a shift from larger crabs and shrimp to small harpacticoid copepods.

This will affect the flow of food and energy throughout reef food webs, markedly changing the structure of fish and other animal communities. The abundance of animals that eat invertebrates will likely boom with increased coral death.

We might expect higher numbers of fish such as wrasses, cardinalfish, triggerfish, and dragonets, with species preferring the smallest epifauna most likely to flourish.

The dragonet species, mandarinfish, feeds on the smallest harpacticoid copepod prey.
Rick Stuart-Smith

Invertebrate-eating animals are food for a diversity of carnivores on a coral reef, and most fish Australians want to eat are carnivores, such as coral trout, snapper, and Spanish mackerel.

While we didn’t investigate exactly which species are likely to increase following widespread coral death, it’s safe to say populations of fish targeted by recreational and commercial fisheries on Australia’s coral reefs are likely to change as live coral is lost, some for better and some for worse.




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The Great Barrier Reef is undoubtedly in danger, and it’s important that we make every effort to protect and conserve the remaining live, healthy coral. However, if corals continue to die, there will remain an abundance of life in their absence, albeit very different life from that to which we are accustomed.

As long as there is hard structure for algae to grow on, there will be epifauna. And where there is epifauna, there is food for fish, although perhaps not for all the fish we want to eat.The Conversation

Kate Fraser, Marine Ecologist, University of Tasmania

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

Repeating mistakes: why the plan to protect the world’s wildlife falls short


The forty-spotted pardalote is one of Australia’s rarest birds.
Shutterstock

Michelle Lim, Macquarie UniversityIt’s no secret the world’s wildlife is in dire straits. New data shows a heatwave in the Pacific Northwest killed more than 1 billion sea creatures in June, while Australia’s devastating bushfires of 2019-2020 killed or displaced 3 billion animals. Indeed, 1 million species face extinction worldwide.

These numbers are overwhelming, but a serious global commitment can help reverse current tragic rates of biodiversity loss.

This week the UN’s Convention on Biological Diversity released a draft of its newest ten-year global plan. Often considered to be the Paris Agreement of biodiversity, the new plan aims to galvanise planetary scale action to achieve a world “living in harmony with nature” by 2050.

But if the plan goes ahead in its current form, it will fall short in safeguarding the wonder of our natural world. This is primarily because it doesn’t legally bind nations to it, risking the same mistakes made by the last ten-year plan, which didn’t stop biodiversity decline.

A lack of binding obligations

The Convention on Biological Diversity is a significant global agreement and almost all countries are parties to it. This includes Australia, which holds the unwanted record for the greatest number of mammal extinctions since European colonisation.

However, the convention is plagued by the lack of binding obligations. Self-reporting to the convention secretariat is the only thing the convention makes countries do under international law.

All other, otherwise sensible, provisions of the convention are limited by a series of get-out-of-jail clauses. Countries are only required to implement provisions “subject to national legislation” or “as far as possible and as appropriate”.

The convention has used non-binding targets since 2000 in its attempt to address global biodiversity loss. But this has not worked.

Kangaroo in burnt bushland
More than 3 billion animals were killed or displaced as a result of the 2019-2020 bushfires.
Shutterstock

The ten-year term of the previous targets, the Aichi Targets, came to an end in 2020, and included halving habitat loss and preventing extinction. But these, alongside most other Aichi targets, were not met.

In the new draft targets, extinction is no longer specifically named — perhaps relegated to the too hard basket. Pollution appears again in the new targets, and now includes a specific mention of eliminating plastic pollution.

Is this really a Paris-style agreement?

I wish. Calling the plan a Paris-style agreement suggests it has legal weight, when it doesn’t.

The fundamental difference between the biodiversity plan and the Paris Agreement is that binding commitments are a key component of the Paris Agreement. This is because the Paris Agreement is the successor of the legally binding Kyoto Protocol.

The final Paris Agreement legally compels countries to state how much they will reduce their emissions by. Nations are then expected to commit to increasingly ambitious reductions every five years.




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If they don’t fulfil these commitments, countries could be in breach of international law. This risks damage to countries’ reputation and international standing.

The door remains open for some form of binding commitment to emerge from the biodiversity convention. But negotiations to date have included almost no mention of this being a potential outcome.

Bleached coral
Ecosystems humans rely on are in peril, such as the Great Barrier Reef which was recently recommended to be placed on the world heritage ‘in danger’ list.
Shutterstock

So what else needs to change?

Alongside binding agreements, there are many other aspects of the convention’s plan that must change. Here are three:

First, we need truly transformative measures to tackle the underlying economic and social causes of biodiversity loss.

The plan’s first eight targets are directed at minimising the threats to biodiversity, such as the harvesting and trade of wild species, area-based conservation, climate change and pollution.

While this is important, the plan also needs to call out and tackle dominant worldviews which equate continuous economic growth with human well-being. The first eight targets cannot realistically be met unless we address the economic causes driving these threats: materialism, unsustainable production and over-consumption.




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‘Revolutionary change’ needed to stop unprecedented global extinction crisis


Second, the plan needs to put Indigenous peoples’ knowledge, science, governance, rights and voices front and centre.

An abundance of evidence shows lands managed by Indigenous and local communities have significantly better biodiversity outcomes. But biodiversity on Indigenous lands is decreasing and with it the knowledge for continued sustainable management of these ecosystems.

Indigenous peoples and local communities have “observer status” within the convention’s discussions, but references to Indigenous “knowledges” and “participation” in the draft plan don’t go much further than in the Aichi Targets.

A mother orangutan carrying its baby
Actions in one part of the globe can have significant impacts to biodiversity in other parts.
Shutterstock

Third, there must be cross-scale collaborations as global economic, social and environmental systems are connected like never before.

The unprecedented movement of people and goods and the exchange of money, information and resources means actions in one part of the globe can have significant biodiversity impacts in faraway lands. The draft framework does not sufficiently appreciate this.

For example, global demand for palm oil contributes to deforestation of orangutan habitat in Borneo. At the same time, consumer awareness and social media campaigns in countries far from palm plantations enable distant people to help make a positive difference.

The road to Kunming

The next round of preliminary negotiations of the draft framework will take place virtually from August 23 to September 3 2021. And it’s likely final in-person negotiations in Kunming, China will be postponed until 2022.

It’s not all bad news, there is still much to commend in the convention’s current draft plan.

For example, the plan facilitates connections with other global processes, such as the UN’s Sustainable Development Goals. It recognises the contributions of biodiversity to, for instance, nutrition and food security, echoing Sustainable Development Goal 2 of “zero hunger”.

The plan also embraces more inclusive language, such as a shift from saying “ecosystem services” to “Nature’s Contribution to People” when discussing nature’s multiple values.




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But if non-binding targets didn’t work in the past, then why does the convention think this time will be any different?

A further set of unmet biodiversity goals and targets in 2030 is an unacceptable scenario. At the same time, there’s no point aiming at targets that merely maintain the status quo.

We can change the current path of mass extinction. This requires urgent, concerted and transformative action towards a thriving planet for people and nature.The Conversation

Michelle Lim, Senior Lecturer, Macquarie Law School, Macquarie University

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

India’s wicked problem: how to loosen its grip on coal while not abandoning the millions who depend on it


Anupam Nath/AP

Vigya Sharma, The University of QueenslandIndia is the world’s third largest emitter of greenhouse gases, and its transition to a low-carbon economy is crucial to meeting the goals of the Paris Agreement. But unfortunately, the nation is still clinging firmly to coal.

Our new research considered this problem, drawing on a case study in the Angul district, India’s largest coal reserve in the eastern state of Odisha.

We found three main factors slowing the energy transition: strong political and community support for coal, a lack of alternative economic activities, and deep ties between coal and other industries such as rail.

India must step away from coal, while maintaining economic growth and not leaving millions of people in coal-mining regions worse off. Our research probes this wicked problem in detail and suggests ways forward.

people carry baskets filled with coal
India’s energy transition must ensure those living in poverty are not left behind.
Shutterstock

Why India matters

India’s population will soon reach 1.4 billion and this decade it is expected to overtake China as the world’s most populous nation. This, combined with a young population, growing economy and rapid urbanisation, means energy consumption in India has doubled since 2000.

The International Energy Agency (IEA) estimates India will have the largest increase in energy demand of any country between now and 2040.

An affordable, reliable supply of energy is central to raising the nation’s living standards. A recent World Bank analysis found up to 150 million people in India are poor.

Alongside its massive reliance on coal, India has one of the world’s most ambitious renewable energy plans, including an aim to quadruple renewable electricity capacity by 2030.

The IEA says coal accounts for about 70% of India’s electricity generation. And as the nation rebounds from the coronavirus pandemic this year, the rise in coal-fired electricity production is expected to be three times that from cleaner sources.

Coal-powered generation is anticipated to grow annually by 4.6% to 2024, and coal is expected to remain a major emitter of greenhouse gases to 2040.

While India’s energy trajectory remains aligned with its commitments under the Paris Agreement, the speed and readiness of its transition remains a complex, divisive issue. The World Economic Forum’s 2021 Energy Transition Index ranks India 87th out of 115 countries analysed.




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students hold lights
India’s young, growing population is fuelling the nation’s energy demand.
EPA

Bottlenecks in the transition

Our research involved visits to the Angul district in Odisha in 2018 and 2019, where we conducted focus groups and interviews. Angul is home to 11 coal mines.

We found three crucial bottlenecks to the energy transition, which arguably exist in India’s other coal belts and could derail the nation’s decarbonisation efforts.

First, the Odisha government has historically been very pro-business. Politicians across the spectrum support coal mining and seek to position it as the region’s primary economic lifeline.

The official pro-coal position receives little pushback from Angul residents, who are largely unaware of Odisha’s contribution to national greenhouse gas emissions. Any local opposition to coal usually stems from concern about environmental degradation such as air, water and land pollution.

Most of Angul’s residents felt a deep connection to coal because their livelihood depends on it. One participant told us:

even if all the water is polluted and five inches of dust settles on our well, we would prefer mining to continue as my family’s survival depends on (the contract with the mining company).

Most participants considered their farming land as an asset to be sold to the mining companies for a significant sum. The money would, in turn, allow them to start a business, buy a car or arrange a marriage in the family.

people sit in dark room
Coal is important to the livelihoods of millions of Indian people.
AP

Second, the heavy reliance on coal means efforts to diversify the region’s economy have been grossly neglected.

In Angul, mining zones and coal-dedicated railway lines passing through paddy fields mean agricultural productivity has declined over time. Rural development agendas have been short-lived, often set within six months of an election deadline then changed or abandoned.

Skill-development programs in non-coal vocations have also been limited. This lack of viable alternatives implicitly generates local support for coal.

And third, a suite of industries in Odisha – such as steel, cement, fertiliser and bauxite – depend on cheap coal for power. This is reflected across India, where coal has deep ties with other industries in ways not seen elsewhere.

For example, in 2016 Indian Railways earned 44% of its freight revenue from transporting coal. Indian Railways is India’s largest employer and coal revenue helps keep passenger fares low. So in this way, a potential coal phaseout in India would have far-reaching effects.

people look out train window
Coal revenue helps subsidise train fares in India.
EPA

The way forward

We offer these pathways to ensure a steady, just energy transition in India:

  • India must help its coal regions diversify their economic activities
  • bipartisan support for a coal-free India is needed. Transition champions such as Germany can show India’s leaders the way
  • a national taskforce for energy transition should be established. It should include representatives from across industry and academia, as well as climate policymakers and grassroots organisations
  • India’s coal regions are endowed with metals needed in the energy transition, including iron ore, bauxite and manganese. With improved regulatory standards, these offer economic alternatives to coal
  • concerns about the coal phase-out from communities in coal regions should be addressed fairly and in a timely way.

The world’s emerging economies are responsible for two-thirds of global greenhouse gas emissions. The energy transition in India, if done well, could show the way for other developing nations.

But as new industrial sectors emerge and clean energy jobs grow, India must ensure those in coal-dependent regions are not left behind.




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The Conversation


Vigya Sharma, Senior Research Fellow, Sustainable Minerals Institute, The University of Queensland

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

5 rocks any great Australian rock collection should have, and where to find them


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Emily Finch, Monash UniversityRoad tripping with a geologist is a little different. While you’re probably reading road signs and dodging roadkill, we’re reading road cuttings and deciphering the history of the area over the previous millions — or even billions — of years.

Geology has shaped the Australian landscape. In Victoria where I live, for example, the western plains are pockmarked by Australia’s youngest volcanoes, while the east of the state has been pushed up to form the mountains of the Great Dividing Range.

Along the southern margin of the state are fossilised braided rivers, relics of when Australia drifted away from Antarctica. Evidence of this event extends into Tasmania, where dolerite, a rock that signifies this rift, looms in enormous columns over Hobart from Mount Wellington.

This probably won’t surprise anyone who knows me, but I have rocks peppered around my house that I’ve collected on my travels. Every time I look at them, I not only think about how the rocks were formed, I’m also reminded of the trip when I collected them.

With international and even state borders set to remain closed for a while longer, this is the perfect time to take a great Australian road trip, become a rock detective, and build up your rock collection while you’re at it.

To help you get started, I’ve listed five rocks any great Australian rock collection should have.

Green, volcanic crater
The crater of an erupted volcano near Mount Gambier in Victoria.
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1. Mantle xenoliths

Western Victoria

The youngest rocks in Australia are those that erupted out of Australia’s youngest volcano in Mount Gambier, South Australia, 4,000 to 8,000 years ago. That volcano is the culmination of an enormous field of volcanoes that span central and western Victoria.




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Photos from the field: the stunning crystals revealing deep secrets about Australian volcanoes


In western Victoria, the volcanoes were formed from magma that ascended from the Earth’s mantle — the layer between the Earth’s core and crust. While the magma was rising, it tore off chunks of the surrounding mantle rock and transported it to the surface. We can find these chunks of the mantle — or mantle xenoliths (xeno = foreign, lith = rock) — in cooled lava today in western Victoria.

At first, these rocks look like any other piece of black or brown basalt, but then you turn them over or crack them open and there’s a blob of bright green rock staring back at you. The mantle rock inside is comprised mainly of olivine, which is a green mineral, and some black/brown pyroxene.

Green rock blob encased in black rock
Green mantle xenolith (xeno = foreign, lith = rock) encased in cooled basaltic lava from Mount Shadwell, Victoria.
Dr Melanie Finch, Author provided

Mantle xenoliths are a great place to start your rock collection because not only will they be your very own piece of Earth’s mantle, but you can find them yourself through a bit of fossicking around some of the volcanoes in western Victoria.

2. Meteorites

The Nullarbor Desert, South Australia and Western Australia

The Nullarbor is a desert plain region which straddles the border of South Australia and Western Australia.

The dry environment is ideal for preserving meteorites that fall to Earth, and the light colour of the limestone country rock and lack of vegetation means the black and brown meteorites are easier to see.

A black meteorite standing out against the white limestone of the Nullarbor Plain.
Professor Andy Tomkins, Author provided

Even if you don’t have a great eye for spotting meteorites hiding in plain sight, you can do as the geologists do and use a magnet on a stick to help you. Most meteorites are iron-rich, so wandering around with a magnet hovering over the surface is a good way to pick them up.

Thousands of meteorites have been found in the Nullarbor, some up to 40,000 years old.

3. Metamorphic rocks

Broken Hill, New South Wales

You’ve probably heard of Broken Hill because of the large silver, lead and zinc mine there. But the geological conditions that created the ore deposit around 1.7 billion years ago also made some beautiful rocks.

A visit to Broken Hill’s Albert Kersten Mining and Minerals Museum will demonstrate the vast array of unusual minerals found in the region, some of them described for the first time at this locality.

If you’re seeking your own chunk of Broken Hill’s geological history, Round Hill is the place for you. Just a short way out of the town centre, you’ll find beautiful red garnets surrounded by patches of white minerals (quartz and feldspar).

A geologist holding a rock with various colours
A large garnet from the Broken Hill region.
Professor Andy Tomkins, Author provided

These rocks started out as sand and mud, and record the history of being buried and heated to over 700℃ deep below the Earth’s surface. This process caused the rock to start melting and created the striking stripey, garnet-rich rocks we find there today.

4. Banded iron formation

Western Australia

Banded iron formation is a layered sedimentary rock mainly comprised of alternating bands of chert (a sedimentary rock made of quartz) that’s often red in colour and silver to black iron oxide. It is the main host of iron ore, and can be found in several regions in Western Australia.

The Hamersley Province in the northwestern part of Western Australia has the thickest and most extensive banded iron formations in the world. They are about 2.45 to 2.78 billion years old.

Red and brown bands along a rock face
Banded iron formation at Forescue Falls, WA.
Graeme Churchard/Flickr, CC BY

Geologists believe they formed on a continental shelf, where thick continental crust extends out into the ocean and then drops away to oceanic crust.

Banded iron formation is exciting because it no longer forms on Earth today, meaning it records an ancient process that we no longer see happening.

It is thought to have formed in ancient oceans, which were starting to increase in oxygen content at the time. It records the chemical input of these oceans, as well as sediments from the continent and volcanoes on the ocean floor.

5. Dinosaur fossils

Central and western Queensland

Oh to have been in Queensland 100 million years ago! Judging by the fossils found in parts of the state, it would have been a cornucopia of dinosaur activity.

From an unlikely duo of dinosaurs in a 98-million-year-old billabong in Winton, to fossilised evidence of a dinosaur herd at Lark Quarry, Queensland is the place to go to peer back in time to the Mesozoic Era between 252 and 66 million years ago.

And if you’re really lucky, you might even have dinosaur bones on your property, like the huge, long-necked sauropod discovered just this year on a Queensland cattle farm.

An outback museum with a dinosaur statue in front
The Australian Age of Dinosaurs Museum in Winton, Queensland, is home to the largest collection of Australian dinosaur fossils. (Note: not a real dinosaur.)
Shutterstock

When building your Australian rock collection, remember to check first if fossicking is allowed in the area. When you find an interesting rock, your state or territory geological survey might be able to help with identifying it.

Happy hunting!




Read more:
How to hunt fossils responsibly: 5 tips from a professional palaeontologist


The Conversation


Emily Finch, Beamline Scientist at ANSTO, and Research Affiliate, Monash University

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

‘Environmental accounting’ could revolutionise nature conservation, but Australia has squandered its potential


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Peter Burnett, Australian National University and Michael Vardon, Australian National UniversityLet’s say a new irrigation scheme is proposed and all the land it’ll take up needs to be cleared — trees felled, soil upturned, and habitats destroyed. Water will also have to be allocated. Would the economic gain of the scheme outweigh the damage to the environment?

This is the kind of question so-called “land accounts” grapple with. Land accounts are a type of “environmental account”, which measures our interactions with the environment by recording them as transactions. They help us understand the environmental and economic outcomes of land use decisions.

Environmental accounting, for which Australia has a national strategy, seeks to integrate environmental and economic data to ensure sustainable decision making. Last month, the Australian Bureau of Statistics released the country’s first national land account under the strategy, describing it as “experimental”.

Environmental accounting could be a game changer for conserving nature, but the account released by the ABS falls flat. It’s yet another example of Australia’s environmental policy culture: we develop or adopt good ideas, but then just tinker with them, or even discard them.

A (really) long time coming

Environmental accounting has been a long time coming and dates back to the 1980s. It’s closely related to sustainable development, and in fact, the two ideas developed in parallel.

In 1992, the Rio Earth Summit endorsed both, and nations agreed to develop an international system of environmental accounting.

But it took the UN 20 years to endorse the System of Environmental Economic Accounting (SEEA) — the rules for developing accounts — as an international statistical standard. This endorsement means they’re authoritative and compatible with national accounts.

Then, in March this year, the international standard was finally extended to cover ecosystem accounting.

So, how are environmental accounts used?

“National accounts” are a way to measure the economic activity of Australia and they tell us our gross domestic product (GDP). Linking existing national accounts to environmental accounts means important decisions can capture environmental and economic outcomes, obviously making for better decisions.

For example, the case for orienting a stimulus package towards investing in renewable energy and land restoration will be much stronger if it can quantify not only economic benefits, but gains to natural assets, such as through revegetation.

Revegetation
Gains to natural assets, such as revegetation, should be measured alongside economic gains.
Shutterstock

Stuck in ‘experimental’ mode

Australia, through the ABS, was an early mover in developing environmental accounting. It has produced experimental accounts since the mid-1990s.

Some countries are now taking significant steps to produce and apply accounts. And a communiqué issued by the G7 in May endorses the UN’s SEEA and encourages making nature a regular part of all decision-making – in other words, “mainstreaming nature”. This is something for which SEEA is ideal.




Read more:
You probably missed the latest national environmental-economic accounts – but why?


It’s no accident this communiqué emerged from London. The UK is a leader in the field of applying accounting to environmental and economic management. It had a Natural Capital Committee for some years and its 25-year environmental plan provides for further account development, including for urban areas, fisheries and forestry.

Australian governments, on the other hand, have been slow to use environmental accounts. They took until 2018 to agree on an unambitious national strategy, which specified “intermediate” outcomes, only to 2023.

These targets include such policy basics as making environmental information for accounts “findable” and “accessible”. This is not far removed from what federal and state governments first signed up to in an agreement 30 years ago.

And the strategy places the holy grail of policy integration “into the future” beyond 2023 — for example, off into the never-never. As a result, we are on a slow track and seemingly stuck in “experimental” mode.

So, what’s the problem with the new land account?

The new land account is a very small step. While it has gathered a lot of information in one place, it tells us little, and essentially repackages old information (the newest data is for 2016).

It’s also in a format that cannot be integrated with national accounts, or even with other environmental accounts so far produced in Australia, such as those covering waste, water, energy and greenhouse gas emissions.

Integration of environmental and economic information is the raison d’etre for the international system. So how did this happen?

Coal plant
The new land account from the ABS can’t be integrated with other environmental accounts, such as accounts for greenhouse gas emissions. So what’s the point of it?
Shutterstock

For accounts produced outside the ABS (such as for greenhouse gas emissions), different accounting frameworks were used, so this is understandable, though unfortunate. For the land accounts, it is less understandable and we can only speculate.

Not being able to integrate the land, water and national accounts means the environmental-economic trade-offs cannot be assessed. It seems the government is struggling to integrate an exercise of integration!

Governments fiddle while the planet burns

Australia’s 2021 intergenerational report, released last month, shows how far we are from producing good environmental information.

The environment section of the report acknowledges climate change and biodiversity loss as major problems, and the need to account for and maintain natural capital. But it goes on to do little more than make general observations and recite standard government talking points about existing policies.




Read more:
Intergenerational reports ought to do more than scare us — they ought to spark action


If the report was informed by comprehensive environmental accounts, it could support the modelling of environmental trends going forward. This would give us a real sense of likely changes to natural capital and its impact on the economy.

But there are no plans for such an approach. In fact, this kind of “high potential, low ambition” approach to environmental policy is something of a trademark for this government. Another example is the recent cherry picking of recommendations from an independent review of Australia’s environment law.

While such an approach may deliver a successful political placebo, it is a formula for policy failure.

Just how loud will the wake-up call have to be? Recently, a climate-change-induced “heat dome” hit western North America. Lytton, Canada, which is closer to the North Pole than the equator, shattered temperature records with a staggering 49.6℃, before being decimated by wildfire.

If only such disasters, including our own Black Summer, would raise policy ambition more than the temperature.




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The government’s idea of ‘national environment standards’ would entrench Australia’s global pariah status


The Conversation


Peter Burnett, Honorary Associate Professor, ANU College of Law, Australian National University and Michael Vardon, Associate Professor at the Fenner School, Australian National University

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

Climate explained: is New Zealand losing or gaining native forests?


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Sebastian Leuzinger, Auckland University of Technology


CC BY-ND

Climate explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz


In recent decades, has New Zealand lost forest (both native and exotic) or gained it, courtesy of the One Billion Trees programme? What about natural habitats like wetlands?

Apart from wetlands, land above the treeline, coastal dunes and a few other exceptions, New Zealand was once covered in forests from Cape Reinga to Bluff.

So was Europe, which basically consisted of a single forest from Sicily in southern Italy to the North Cape in Norway, before human intervention.

But since people arrived in New Zealand some 850 years ago, about three quarters of the country’s native forest area has been lost. About half of the loss happened before Europeans arrived, mostly through burning to clear large areas of native bush.

Most of New Zealand was once covered in native forest.
Shutterstock/Latitude Creative

In recent decades, the loss of native forest has slowed down. For example, in the first decade of the 21st century, we lost roughly 16,000 hectares of native forest, which translates to a loss of about 0.2% of the remaining total area covered in native forest (about 7.5 million hectares). The error associated with such estimates is considerable, though, because land cover is complex and highly fragmented.




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A billion trees

According to Global Forest Watch, the drivers behind the more recent losses of native forests include exotic plantation forests, urban developments and wildfires. Indeed, the total land area dedicated to exotic plantation forests increased by about 200,000 hectares per decade between 1990 and 2017.

Commercial plantations of exotic pines have replaces native forests.
Shutterstock/Cloudia Spinner

So what has the One Billion Trees Programme achieved in comparison to these changes?

The project’s aim is to double the current planting rate and plant one billion trees between 2018 and 2028. The latest report shows about a quarter of this goal has been achieved in terms of the number of trees planted. In regards to forest area, 25,557 hectares have been reforested, about half of it with natives.

This is a remarkable achievement in light of the losses cited above and the short duration of the programme.

About a quarter of a billion trees have been planted so far, half of it native species.
Shutterstock/Kira Volkov

Saving remaining peat bogs

We think of forests as our guardians of carbon — and indeed, an aged New Zealand forest can hold about 350 tonnes of carbon per hectare. But intact peat bogs, such as the Kopuatai dome in the Waikato region, can hold up to 1,400 tonnes of carbon per hectare.

But peat bogs only store carbon if they remain wet. Once drained, they begin to emit carbon dioxide. Almost half of New Zealand’s peatlands are in the Waikato, but of a total of 89,000 hectares only 19,400 hectares remain in a natural state.

Aerial view of the Kopuatai bog.
The Kopuatai dome is New Zealand’s largest intact peat bog.
Georgie Glover-Clark, CC BY-SA

The Kopuatai bog itself is surrounded by dairy farms operating on drained peat. Collectively, the Waikato’s drained peatlands produce 10-33 tonnes of CO₂-equivalent emissions per hectare each year.

The draining of peatlands in the Waikato region did far more damage, in terms of carbon emissions, than a small loss of forest area.




Read more:
Peat bogs: restoring them could slow climate change – and revive a forgotten world


But nevertheless, planting trees and increasing our forest area is an important and necessary contribution to climate mitigation, and often comes with a myriad of other benefits, far beyond carbon sequestration.

Sometimes it’s as easy as planting your own fruit trees around your house. They will capture carbon for years to come, and keep you from buying fruit that has been transported thousands of kilometres.

They might even motivate you to reduce food waste. Globally, about 25-30% of food goes to waste. If we reduced food waste, we could save agricultural land multiple times the size of New Zealand and plant trees there instead.The Conversation

Sebastian Leuzinger, Professor, Auckland University of Technology

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

Almost 60 coral species around Lizard Island are ‘missing’ – and a Great Barrier Reef extinction crisis could be next


Michael Emslie

Zoe Richards, Curtin UniversityThe federal government has opposed a recommendation by a United Nations body that the Great Barrier Reef be listed as “in danger”. But there’s no doubt the natural wonder is in dire trouble. In new research, my colleagues and I provide fresh insight into the plight of many coral species.

Worsening climate change, and subsequent marine heatwaves, have led to mass coral deaths on tropical reefs. However, there are few estimates of how reduced overall coral cover is linked to declines in particular coral species.

Our research examined 44 years of coral distribution records around Lizard Island, at the northern end of the Great Barrier Reef. We found 16% of coral species have not been seen for many years and are at risk of either local extinction, or disappearing from parts of their local range.

This is alarming, because local extinctions often signal wider regional – and ultimately global – species extinction events.

Healthy coral near Lizard Island in 2011, top, then six years later after two bleaching events, bottom.
Healthy coral near Lizard Island in 2011, top, then six years later after two bleaching events, bottom.
Zoe Richards

Sobering findings

The Lizard Island reef system is 270 kilometres north of Cairns. It has suffered major disturbances over the past four decades: repeated outbreaks of crown-of-thorns seastars, category 4 cyclones in 2014 and 2015, and coral bleaching events in 2016, 2017 and 2020.

Our research focused on “hermatypic” corals around Lizard Island. These corals deposit calcium carbonate and form the hard framework of the reef.

We undertook hard coral biodiversity surveys four times between 2011 and 2020, across 14 sites. We combined the results with published and photographic species records from 1976 to 2020.

red fleshy coral with blue spots
Micromussa lordhowensis is popular in the aquarium trade.
Zoe Richards

Of 368 hard coral species recorded around Lizard Island, 28 (7.6%) have not been reliably recorded since before 2011 and may be at risk of local extinction. A further 31 species (8.4%) have not been recorded since 2015 and may be at risk of range reduction (disappearance from parts of its local range).

The “missing” coral species include:

  • Acropora abrotanoides, a robust branching shallow water coral that lives on the reef crest and reef flat has not been since since 2009
  • Micromussa lordhowensis, a low-growing coral with colourful fleshy polyps. Popular in the aquarium trade, it often grows on reef slopes but has not been seen since 2005
  • Acropora aspera, a branching coral which prefers very shallow water and has been recorded just once, at a single site, since 2011.

The finding that 59 coral species are at risk of local extinction or range reduction is significant. Local range reductions are often precursors to local species extinctions. And local species extinctions are often precursors to regional, and ultimately global, extinction events.

Each coral species on the reef has numerous vital functions. It might provide habitat or food to other reef species, or biochemicals which may benefit human health. One thing is clear: every coral species matters.




Read more:
The outlook for coral reefs remains grim unless we cut emissions fast — new research


reddish coral underwater
Acropa abrotanoides, one of the corals ‘missing’ from around Lizard Island.
Zoe Richards

A broader extinction crisis?

As human impacts and climate threats mount, there is growing concern about the resilience of coral biodiversity. Our research suggests such concerns are well-founded at Lizard Island.

Coral reef communities are dynamic, and so detecting species loss can be difficult. Our research found around Lizard Island, the diversity of coral species fluctuated over the past decade. Significant declines were recorded from 2011 to 2017, but diversity recovered somewhat in the three following years.

Local extinctions often happen incrementally and can therefore be “invisible”. To detect them, and to account for natural variability in coral communities, long-term biodiversity monitoring across multiple locations and time frames is needed.

Green coral
Acropora aspera has been recorded just once, at a single location, since 2011.
Anne Hoggett

In most locations however, data on the distribution and abundance of all coral species in a community is lacking. This means it can be hard to assess changes, and to understand the damage that climate change and other human-caused stressors are having on each species.

Only with this extra information can scientists conclusively say if the level of local extinction risk at Lizard Island indicates a risk that coral species may become extinct elsewhere – across the Great Barrier Reef and beyond.




Read more:
Is Australia really doing enough for the Great Barrier Reef? Why criticisms of UNESCO’s ‘in danger’ recommendation don’t stack up


The Conversation


Zoe Richards, Senior Research Fellow, Curtin University

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

The North American heatwave shows we need to know how climate change will change our weather


NASA

Christian Jakob, Monash University and Michael Reeder, Monash UniversityEight days ago, it rained over the western Pacific Ocean near Japan. There was nothing especially remarkable about this rain event, yet it made big waves twice.

First, it disturbed the atmosphere in just the right way to set off an undulation in the jet stream – a river of very strong winds in the upper atmosphere – that atmospheric scientists call a Rossby wave (or a planetary wave). Then the wave was guided eastwards by the jet stream towards North America.

Along the way the wave amplified, until it broke just like an ocean wave does when it approaches the shore. When the wave broke it created a region of high pressure that has remained stationary over the North American northwest for the past week.

This is where our innocuous rain event made waves again: the locked region of high pressure air set off one of the most extraordinary heatwaves we have ever seen, smashing temperature records in the Pacific Northwest of the United States and in Western Canada as far north as the Arctic. Lytton in British Columbia hit 49.6℃ this week before suffering a devastating wildfire.

What makes a heatwave?

While this heatwave has been extraordinary in many ways, its birth and evolution followed a well-known sequence of events that generate heatwaves.

Heatwaves occur when there is high air pressure at ground level. The high pressure is a result of air sinking through the atmosphere. As the air descends, the pressure increases, compressing the air and heating it up, just like in a bike pump.

Sinking air has a big warming effect: the temperature increases by 1 degree for every 100 metres the air is pushed downwards.

The North American heatwave has seen fires spread across the landscape.
NASA

High-pressure systems are an intrinsic part of an atmospheric Rossby wave, and they travel along with the wave. Heatwaves occur when the high-pressure systems stop moving and affect a particular region for a considerable time.

When this happens, the warming of the air by sinking alone can be further intensified by the ground heating the air – which is especially powerful if the ground was already dry. In the northwestern US and western Canada, heatwaves are compounded by the warming produced by air sinking after it crosses the Rocky Mountains.

How Rossby waves drive weather

This leaves two questions: what makes a high-pressure system, and why does it stop moving?

As we mentioned above, a high-pressure system is usually part of a specific type of wave in the atmosphere – a Rossby wave. These waves are very common, and they form when air is displaced north or south by mountains, other weather systems or large areas of rain.




Read more:
We’ve learned a lot about heatwaves, but we’re still just warming up


Rossby waves are the main drivers of weather outside the tropics, including the changeable weather in the southern half of Australia. Occasionally, the waves grow so large that they overturn on themselves and break. The breaking of the waves is intimately involved in making them stationary.

Importantly, just as for the recent event, the seeds for the Rossby waves that trigger heatwaves are located several thousands of kilometres to the west of their location. So for northwestern America, that’s the western Pacific. Australian heatwaves are typically triggered by events in the Atlantic to the west of Africa.

Another important feature of heatwaves is that they are often accompanied by high rainfall closer to the Equator. When southeast Australia experiences heatwaves, northern Australia often experiences rain. These rain events are not just side effects, but they actively enhance and prolong heatwaves.

What will climate change mean for heatwaves?

Understanding the mechanics of what causes heatwaves is very important if we want to know how they might change as the planet gets hotter.

We know increased carbon dioxide in the atmosphere is increasing Earth’s average surface temperature. However, while this average warming is the background for heatwaves, the extremely high temperatures are produced by the movements of the atmosphere we talked about earlier.

So to know how heatwaves will change as our planet warms, we need to know how the changing climate affects the weather events that produce them. This is a much more difficult question than knowing the change in global average temperature.

How will events that seed Rossby waves change? How will the jet streams change? Will more waves get big enough to break? Will high-pressure systems stay in one place for longer? Will the associated rainfall become more intense, and how might that affect the heatwaves themselves?




Read more:
Explainer: climate modelling


Our answers to these questions are so far somewhat rudimentary. This is largely because some of the key processes involved are too detailed to be explicitly included in current large-scale climate models.

Climate models agree that global warming will change the position and strength of the jet streams. However, the models disagree about what will happen to Rossby waves.

From climate change to weather change

There is one thing we do know for sure: we need to up our game in understanding how the weather is changing as our planet warms, because weather is what has the biggest impact on humans and natural systems.

To do this, we will need to build computer models of the world’s climate that explicitly include some of the fine detail of weather. (By fine detail, we mean anything about a kilometre in size.) This in turn will require investment in huge amounts of computing power for tools such as our national climate model, the Australian Community Climate and Earth System Simulator (ACCESS), and the computing and modelling infrastructure projects of the National Collaborative Research Infrastructure Strategy (NCRIS) that support it.

We will also need to break down the artificial boundaries between weather and climate which exist in our research, our education and our public conversation.The Conversation

Christian Jakob, Professor in Atmospheric Science, Monash University and Michael Reeder, Professor, School of Earth, Atmosphere and Environment, Monash University

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