Climate change - marine heatwaves cooking the oceans

The impact of marine heatwaves is most publicly visible and recognised in the coral reef systems across the planet. Yet the impact is far wider and damaging across the marine environment as this article covers -

Marine heatwaves are cooking our ocean ecosystems – and will only become more common

Canva, Pixabay, The Conversation, CC BY-NC-SA

Sina Pinter, The University of Western Australia and Nicole L. Jones, The University of Western Australia

You may have heard reports of fish die-offs or seen photos of hauntingly bleached coral.

Those are just two signs a marine heatwave has swept through the sea.

Marine heatwaves happen when the ocean remains abnormally hot for an extended period. While they may be invisible from the shore, their impacts can wreak havoc underwater – killing various kinds of coral, seagrass and fish.

As climate change continues to warm the ocean, marine heatwaves will only become more frequent and severe. While we cannot stop these marine disasters happening, we can work to better understand them and reduce their impacts on vulnerable ocean ecosystems.

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Our climate is rapidly warming, dramatically reshaping weather around the globe. In this three-part series, we explore a range of emerging climate phenomena and consider how to respond to their destructive effects.

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The science of marine heatwaves

Marine heatwaves are naturally occurring weather patterns that can form when hotter water near the surface of the ocean doesn’t mix with cooler water below. This is most common when conditions are hot, dry and windless. However, marine heatwaves can also develop when unusually strong currents carry extra heat from the tropics to colder ocean areas.

To identify a marine heatwave, scientists measure ocean temperatures and compare those observed ocean temperatures with the historical average temperature – the baseline or “normal” temperature of that location at a specific time of year.

Marine heatwaves occur when the ocean is hotter than 90% of historical temperature records. To be considered a heatwave, this abnormal heat must last for at least five consecutive days.

Ocean temperatures vary according to local conditions. Given marine heatwaves are measured in relation to a region’s normal seasonal ocean temperatures, they can happen anywhere and at any time of year. For example, a water temperature of 25°C at Western Australia’s Ningaloo Reef might not seem warm for that tropical area. However, 25°C in the waters around Tasmania would be considered extreme.

Terrestrial heatwaves follow the same logic as marine heatwaves. But a land-based heatwave only needs to last three days to be classified as a heatwave. Minimum night and maximum day temperatures must also be unusually hot.

An underwater disaster

Given marine heatwaves can happen in any part of the ocean, all marine ecosystems are at risk.

However, marine species cope in different ways. Those that are mobile, such as fish, can swim to cooler waters. In contrast, coral, kelp or bottom-dwelling creatures such as sea urchins can’t relocate. This means they are directly impacted by marine heatwaves. For example, they may struggle to reproduce due to heat stress. They also suffer indirect impacts, such as a lack of food if species further down the food chain are wiped out by a marine heatwave.

On land, marine heatwaves can be economically and culturally devastating for coastal communities. They can cost fisheries, aquaculture businesses and tourism operators billions of dollars in lost income. Marine heatwaves may also damage culturally significant sites, as in the case of Shark Bay, a World Heritage-listed marine ecosystem off the WA coast. They may also destroy blue carbon habitats. These are ocean-based habitats, such as mangroves and seagrass, that absorb carbon and help cool the planet.

In February 2011, a massive compound heatwave – where a marine and a terrestrial heatwave happened together – decimated ecosystems across WA. On land, it killed trees and caused the endangered cockatoo population to crash. Beneath the sea, it triggered widespread coral bleaching in the Pilbara, Ningaloo and Houtman Abrolhos Islands regions.

In September 2024, another marine heatwave swept through the waters off the coast of WA lasting several months. It was the state’s longest, largest and most severe marine heatwave ever. It killed about half of the coral in the North West Shelf region.

Most recently, sea surface temperatures have surged during the 2026 European summer, in some places by up to 5°C higher than average. This threatens marine ecosystems across the Mediterranean Sea, North Sea and Baltic Sea.

Worse under climate change

Marine heatwaves are a natural part of our planet’s variable climate system.

But climate change means they are becoming more common and severe. They are also lasting longer. The ocean’s thermal baseline – or the natural temperature of the ocean – is rising due to climate change. This means any temperature fluctuations compound the effects of this background warming.

Other climate drivers, including the El Niño and La Niña climate patterns, can also intensify marine heatwaves. In Australia, El Niño typically warms the waters off the east coast, heightening the risk of severe marine heatwaves there. La Niña tends to push warm water towards the west coast, driving extreme ocean temperatures off WA.

However, because of climate change, large-scale climate patterns like El Niño and La Niña are no longer necessary to trigger marine heatwaves. This means even the slightest change in these climate drivers might bring extreme heat to either coast.

Where to from here

To better understand the factors that drive marine heatwaves, we need further research that analyses changes in air and ocean currents. We should also prioritise research investigating the sub-surface ocean. Satellites monitor the surface but many severe marine heatwaves remain hidden underwater, devastating marine life without detection.

The most important step to reduce the impacts of marine heatwaves is to cut greenhouse gas emissions, limiting further ocean warming. At the same time, researchers are exploring other ways to help ecosystems adapt. These include introducing thermal tolerant species to vulnerable regions. Marine cloud brightening, which aims to temporarily reduce ocean heating by making clouds more reflective, is another option being investigated.

We must also invest in modelling to predict when future marine heatwaves may hit. Early warning systems are also vital to ensure fisheries and conservation zones can prepare for these increasingly common underwater disasters.

Sina Pinter, PhD Candidate in Ocean Dynamics, The University of Western Australia and Nicole L. Jones, Professor of Physical Oceanography, The University of Western Australia

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

Climate change - the new terminology of 'climate whiplash'

 

‘Climate whiplash’ is not simply a buzzword, but a symptom of a warming planet

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Linden Ashcroft, The University of Melbourne

What flashes to mind when you hear the word “whiplash”?

Perhaps you picture someone’s head rocking back and forth during a car crash – a jarring and often painful experience. Climate whiplash is no different.

Scientists use the terms “weather whiplash” and “climate whiplash” to describe dramatic swings between different kinds of extreme weather. And as the world continues to warm, research suggests these whiplash events will only become more common and severe.

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CC BY-NC-ND

Our climate is rapidly warming, dramatically reshaping weather around the globe. In this three-part series, we explore a range of emerging climate phenomena and consider how to respond to their destructive effects.

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Not just buzzwords

In general, the term weather whiplash refers to abrupt weather changes that happen on a daily to weekly scale. For example, a downpour may immediately follow a heatwave, or temperatures could be freezing one day and baking hot the next.

At the start of 2026, the Otways region in southern Victoria experienced weather whiplash. In the space of two weeks, a huge bushfire gave way to a record-breaking flood and then an historic heatwave.

Climate whiplash is sometimes used to describe these rapid shifts. However, because climate relates to the long-term average of weather, climate whiplash more accurately describes changes on a monthly to annual scale. Another term scientists use is “climate volatility”.

The current drought afflicting the United Kingdom is a prime example of climate whiplash. After an unusually wet start to the year, parts of the UK endured their driest July on record, with farmers struggling to keep their crops and pastures alive.

Researchers and emergency responders are increasingly concerned by “compound disasters”, which include whiplash events. These occur when multiple kinds of extreme weather collide, and can happen at the same place and time or back-to-back. This compounding makes the events much more destructive than any single disaster.

A temperamental country

In Australia, we are all too familiar with both climate and weather whiplash.

From year to year, our rainfall can swing violently between soaking wet and alarmingly dry. In fact, Australia’s precipitation patterns are among the most variable on Earth. This is largely due to temperature seesaws in the nearby Indian and Pacific Oceans that affect weather patterns and moisture availability over Australia.

Parts of Australia are also known for their temperamental temperatures. Melbourne, for example, is famous for cycling through four seasons in one day. This happens most often when hot air from Australia’s arid centre is shoved out of the way by cold air from Antarctica. This air-mass replacement leads to remarkable drops in temperature, otherwise known as a cool change.

Overseas, the United States and continental Europe are other whiplash hotspots, particularly for rapid temperature changes. In these parts of the northern hemisphere, the jet stream that keeps polar air up near the Arctic can wiggle and weaken, allowing freezing temperatures to spill out onto temperate regions.

Are things getting more ‘whiplashy’?

Research reveals whiplash-like weather is increasing in frequency and intensity.

Globally, extreme temperature variability and sudden swings from wet to dry or dry to wet are becoming more frequent and intense.

What’s more, computer simulations reveal these trends will only worsen if we keep heating the planet by adding more greenhouse gases into the atmosphere. A major reason for this is climatic extremes are more dramatic than they were when our planet was cooler. Heatwaves are hotter, heavy rainfall is heavier and droughts are even drier.

Research suggests a warming planet is altering the speed and behaviour of the weather systems that drive these extremes. For example, the polar regions are warming faster than the tropics, particularly in the northern hemisphere. This uneven warming reduces the temperature change between the equator and the poles, which in turn weakens large-scale wind and pressure patterns that are driven by these temperature differences.

Why whiplash matters

Rapidly changing weather places immense strain on our communities, ecosystems and emergency services.

Quick shifts between hot and cold temperatures affect human health and whole economies. Dramatic shifts between wet and dry conditions have been found to damage soil health, increase water contamination and fuel fast-moving bush and wildfires.

The phrases weather and climate whiplash give scientists another way to communicate just how extreme our weather is becoming. They also enable emergency responders and health services to better plan for back-to-back extremes, and communicate with vulnerable communities.

Weather and climate whiplash may sound like buzzwords. But these terms are a visceral expression of a worrying reality: the more we keep burning coal, oil and gas, the more chaotic and dramatic our weather will become.

Linden Ashcroft, Senior Lecturer, Climate Science and Science Communication, The University of Melbourne

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

Environment - Mangrove swamps are improving despite climate change

 

The world’s mangrove forests are bouncing back. That’s good news for our coasts and climate

talented young photographer/Getty

Catherine Lovelock, The University of Queensland

Mangroves are perplexing plants.

They breathe through their roots, appear to stand on stilts and grow best in hot, salty seawater drawn in and out by the tide.

Historically, mangrove forests have been dismissed as inhospitable places to avoid and have been extensively cleared. But these fascinating trees are now gaining attention for how they support biodiversity, store carbon and buffer the effects of storms, cyclones and tsunamis.

Since 1984, scientists have been monitoring the growth and geographical reach of mangrove forests using satellites. And for the first time, these unique ecosystems are expanding at a faster rate than they are declining.

So what’s driving this? And could it help curb climate change?

Mangroves thrive in coastal environments, where the tide comes in and out. Vicki Smith

Why mangroves matter

Mangrove forests were long viewed as largely expendable places. Research shows people were quick to convert them into rice paddies, oil palm plantations and aquaculture operations. Some were even used as rubbish tips.

However, mangrove forests are now recognised as a vital part of our coastal environments. They provide habitat for a wealth of plants and animals including fish such as barramundi and giant shovelnose rays, reptiles such as seasnakes and even mammals such as the proboscis monkey and water mouse. They are crucial carbon stores, locking up roughly four times more carbon than other land-based forests. Mangroves can also shelter coastal communities and ecosystems from natural disasters by reducing the risk of flooding and erosion.

From an economic perspective, mangrove forests allow millions of fishers to earn a living as well as supporting commercial fisheries. These forests are also of immense cultural value to First Nations communities, many of which associate mangroves with certain religious gods or cultural practices.

Mangrove seedlings growing in the tidal flats of the Narrawallee estuary in NSW. lynnebeclu/Getty

Mangroves are bouncing back

For decades, mangrove forests have been systematically cleared and destroyed. Between the 1980s and 2010, we lost more than 12,000 square kilometres – an area the size of Jamaica – of mangroves worldwide. That means there are far fewer mangroves that can trap harmful greenhouse gas emissions and slow the effects of climate change.

However, this trend may be reversing. A recent study analysed four decades of global data documenting the reach and growth of mangroves. It had three key – and somewhat surprising – findings.

Mangroves are rebounding despite climate change

Human-induced climate change is putting immense pressure on our mangrove forests. It is driving more severe and frequent droughts and storms that can damage or kill mangroves. It is also accelerating sea level rise, potentially drowning mangroves.

This study shows the world’s mangrove forests are rebounding, even as our planet rapidly warms. Since 2010, they have expanded by more than 2,000 square kilometres.

Importantly, the reasons for this vary between regions. Before 2010, Myanmar and Indonesia were hot-spots of mangrove loss. But this trend has now stabilised, with policymakers strengthening the laws around mangrove protection following the catastrophic 2004 Indian Ocean tsunami and 2008 cyclone Nargis.

Australia’s mangrove forests are also expanding. However, research suggests this is because mangroves are increasingly growing on floodplains. Rising sea levels allow tides to reach further inland, creating the salty conditions in which mangroves thrive.

In some places – such as where mangroves regenerate in unused aquaculture ponds – this shift inland is positive. In northern Australia, however, it threatens to degrade freshwater ecosystems and is an urgent concern for Traditional Owners.

Mangroves are shifting closer to the sea

This new study suggests mangroves are increasingly growing on newly formed mud flats.

This is counter intuitive because rising sea levels should, in theory, restrict mangrove growth. It may be happening because rivers are carrying soil and sand from deforested areas to the coast, creating new habitat for mangroves.

This demonstrates the resilience of mangrove ecosystems. However, it seems mangroves aren’t regenerating rapidly in the coastal regions where they once thrived – an indicator of successful restoration.

Mangroves are expanding and retreating at the same time

The authors of this study also examined trends in mangrove degradation.

Degradation occurs when mangrove canopies become less dense – a sign they are not as healthy as before. The researchers point to human activities, such as harvesting or pollution, and extreme weather as the main factors driving mangrove degradation.

However, exact causes will differ between regions.

Mangroves have very recognisable roots. Dulyanut Swdp/Getty

More work needed

The expansion of the world’s mangrove forests is promising – and perhaps unexpected – news. However, we can’t be complacent. Current evidence suggests mangrove forests are still thinning overall, putting coastal ecosystems and climate action efforts at risk.

To combat this trend of mangrove degradation, we should support policies that strengthen mangrove protection and restoration.

Organisations such as the Global Mangrove Alliance and Mangrove Breakthrough are also raising the profile of these fascinating ecosystems.

Further research is needed to monitor the varying impacts of climate change on mangroves.

Mangroves at Cullendulla Creek Nature Reserve, New South Wales at low tide. Simon McGill/Getty

Catherine Lovelock, Professor of Biology, The University of Queensland

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

Environment - H5N1 bird flu - survival insights needed

 

We don’t know how well threatened species fight off bird flu – but we need to

Katherine Belov, University of Sydney and Carolyn Hogg, University of Sydney

Lethal bird flu is now spreading in Australia. This is bad news for many native species.

New federal government analysis suggests close to one in five Australian bird and mammal species is at high, very high or extreme risk. But this risk assessment omits something vital – how genetically well-equipped the species is to fight the virus.

While species such as black swans are likely to be very hard-hit, others such as wild ducks are expected to be less affected. One reason for this is different immune systems – some are more or less able to fight the virus. But there’s a more significant factor – how much variation there is in key immune system genes across populations.

Right now, we don’t have an overview of which threatened species are at highest risk based on this. If we urgently create a national immune-risk map for species at risk, we can act to protect those in most danger.

Black swans are likely to be hard hit by bird flu, unlike wild duck species. The difference lies in their immune systems. irmaferreira/Getty

Why immune gene variations matter

When a virus enters an animal’s body, its immune system must first detect it, then respond. Key immune genes help determine if an animal fights off infection, becomes seriously ill or dies.

Different individuals will have slightly different immune responses based on variations at different immune genes. Some variants will allow an individual to survive the virus, and others won’t. This is why diversity in these genes is critical across the species.

Large wildlife populations often have a wide array of variants at each immune gene. This acts as biological insurance – when a new disease arrives, some individuals will be more able to survive. But if a species becomes threatened and its population falls, it’s likely to lose much of this protective diversity.

If the remaining individuals share similar vulnerabilities, a lethal disease such as H5N1 bird flu could be enough to push the species closer to extinction.

Threatened species are often immunologically fragile

Australia’s wildlife faces threats such as habitat loss, climate change, invasive species, pollution and disease. These threats not only reduce population size – they erode genetic diversity.

Small, fragmented populations may have enough genetic diversity to look viable in the short term. But when a new disease arrives, they may lack the breadth of variation at the immune genes needed to survive the new disease. This is a large, hidden vulnerability.

The orange-bellied parrot is a species that worries us deeply. The small, migratory parrot is one of Australia’s most endangered birds. Just 86 birds are left in the wild, with a few hundred more in captive breeding populations.

Our previous research found the parrot has suffered a dramatic loss of genome-wide diversity over the past century – including variation in immune genes.

If H5N1 infects these parrots, they may lack the immune gene variants needed to buffer the species against severe disease.

Many orange-bellied parrots are being reared in captive breeding programs. Outback to Coast/Getty

Tasmanian devils are similarly at risk. These iconic marsupials have critically low immune gene diversity due to population bottlenecks over the past 5,000 years. This left them vulnerable to the contagious devil facial tumour disease, which saw populations plummet with local declines of 95%, and an estimated 80% decline across Tasmania since the disease arose in the 1990s. Our preprint research shows facial tumour disease is still eroding immune gene diversity.

These scavengers are likely to be exposed to bird flu by eating carcasses, and we know which devil populations eat seabirds. The question will be whether devils have enough immune variation to respond to H5N1.

How a national immune-risk map could help

While we know how some species are likely to respond to the virus, the picture is far from complete.

We could fill in the blanks quickly, using DNA samples held in museums or from animals in zoos to generate genomic data on many more species.

We could then analyse immune gene variation across different populations of each species to measure how diverse they are. This approach could reveal populations that have lost important immune variants and may be particularly vulnerable to bird flu.

The Threatened Species Initiative, has collected this data for more than 125 threatened species. But there are hundreds more threatened animal species for which we have no data and no samples.

If we worked quickly to create a national immune-risk map, wildlife managers could focus surveillance, vaccination and protection efforts on the populations likely to be at most risk.

Importantly, they could establish new captive populations before the virus arrives, using breeding programs to maximise immune fitness and keep inbreeding to a minimum.

This is not science fiction. We led immune-guided conservation work in Tasmanian devils, where data on immune genes shape decisions around breeding. The end result: devil joeys with stronger immune systems.

If we use this approach for more at-risk species, we could better protect wildlife from bird flu and future diseases.

No time to waste

Responses to wildlife diseases are often reactive. Animals start dying in large numbers and then we investigate. This approach will be much too slow to respond to the fast-moving H5N1 strain.

Australia has world-leading wildlife genomics expertise, valuable museum and zoo collections, threatened species recovery programs and growing genome resources.

What’s missing is a coordinated way to translate immune gene data into practical action.

It’s not too late. But we have to act fast to identify species and populations with low immune diversity and roll out measures before irreversible losses occur.

Katherine Belov, Professor of Comparative Genomics, University of Sydney and Carolyn Hogg, Professor of Biodiversity & Conservation and Co-Lead, Australasian Wildlife Genomics Group, University of Sydney

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

Environment - Bird Flu H5N1 - managing the threat

 

Powerless against bird flu? Not entirely. Here are 8 ways to help protect Australia’s birds and mammals

Philip Thurston/Getty, CC BY

John Woinarski, Charles Darwin University; Euan Ritchie, Deakin University, and Stephen Garnett, Charles Darwin University

The deadly H5N1 strain of bird flu has now spread from migratory birds to infect resident Australian birds. Clusters of dead birds have been found in several locations. The virus will inevitably infect other wildlife, most notably mammals.

Death rates range from 75-100% in poultry and some wild bird species. There’s great uncertainty about how big the death toll will be over both the short and long-term. Native species such as the black swan are highly vulnerable, while others may prove more resilient.

Based on overseas experience, we can expect many thousands, if not millions, of Australian birds, and large numbers of mammals, to perish. Poultry will likely become infected, while some beloved pets may die.

Overall, the populations of many Australian species will likely plummet. Some threatened species will move closer to extinction, and relatively safe species could become threatened. As the virus spreads through widespread species such as silver gulls, white ibis, pigeons, ducks and crows, many of us will be confronted by wildlife deaths close to home.

Facing a threat like this can make us feel powerless. But there are actions we can take.

Blow after blow for wildlife

Over the 2019-20 summer, megafires incinerated forests and wildlife. In 2025, the lethal South Australian algal bloom denuded large marine areas.

The prospect of yet another hammer blow to wildlife is haunting and emotionally triggering for conservationists, wildlife carers and people who love nature.

To date, the official messaging asks us to watch for, report and record sick birds and mammals. This is important, but it risks leaving the community feeling disempowered witnesses to catastrophe. The situation is far from hopeless. Now is the time to act.

What can be done?

Following overseas work on ways to reduce the toll, we have come up with eight actions.

1. Tackle other threats to give species a fighting chance

While federal, state and territory response plans are not public, what we do know suggests a focus on controlling threats other than bird flu, especially for species that are threatened.

For example, locally eradicating predators such as cats and foxes could give more individuals a chance to get through the first wave of bird flu. Banning duck hunting could also reduce one threat to wildlife.

Working to reduce other threats such as feral cats will boost resilience to the virus at a species level. Pictured: a cat stalking a red-tailed tropic-bird chick on Christmas Island. Janos Hennicke, CC BY

2. Secure insurance populations

Threatened birds and mammals with populations in captivity provide some security. We can boost these insurance populations by increasing their genetic diversity and the number of individuals kept.

For at-risk species without these populations, we may have to collect wild animals before infection reaches them (where practical). Zoos may offer the most protection, but there’s scope to translocate species (such as northern quolls) to safer wild places.

3. Vaccinate species at risk

New Zealand authorities are already giving vaccines to birds at risk. To date, Australia is not doing so, though policymakers are exploring the option. Limited trials in mammals have been undertaken in the United States.

Wild animals have to be caught, given the vaccine, and recaptured for a booster 4-6 weeks later. This is challenging but often feasible. In the US, authorities captured and vaccinated endangered Californian condors, then released them back to the wild.

We need to explore new vaccines, especially for mammals.

4. Widen monitoring

We need good monitoring to track the spread, understand whether our efforts have helped and plan future actions. Monitoring will show what the virus has done to species, track viral mutations and assess survival rates.

For many seabirds and waterbirds, existing programs give us good estimates of current population size. This will let us estimate declines and any recoveries. But we don’t have robust estimates for other at-risk bird and mammal species. This gap needs to be rapidly filled with funding for targeted monitoring. Citizen scientists can also help.

Citizen scientists can play a key role in monitoring population declines and – hopefully – recovery through platforms such as iNaturalist and Birdata. Renee Mead, CC BY

5. Expand research

Much Australian fauna is very distinct from species overseas, meaning lessons learned elsewhere won’t necessarily apply. We need to know which species are most vulnerable, which species spread the virus most effectively, whether survivors have compromised immune systems and how much genetic diversity has been lost.

6. Slow the spread

The virus spreads rapidly in contaminated water and through the movements of infected birds and mammals. Even so, we can slow the spread. In some situations, authorities can remove sick or dead animals to reduce the chance of scavenging birds and animals eating them and contracting then spreading the virus.

Some areas may need to be closed to the public to reduce infection risks through disturbance or contamination. It may be necessary to shut down some water sources or make them less attractive to waterfowl, who are often good carriers of the virus. Poultry farmers will need to control water sources too, to avoid attracting infected birds.

7. Involve interested groups

Authorities must ensure community members, land-owners, First Nations groups and conservationists are involved in creating response plans. Bird flu is a shared problem. Governments cannot respond alone.

8. Look for some silver linings

This virus will likely have dire consequences for many species. But it could also kill introduced predators and scavengers such as feral pigs, cats, foxes and common mynahs.

Time to act

The damage this virus will do isn’t set. We can shape some outcomes. We believe this package of actions could help avert the worst future for Australian birds and mammals – and encourage their recovery.

Acknowledgements: Ecologist Tanya Loos provided helpful feedback.

John Woinarski, Professor of Conservation Biology, Charles Darwin University; Euan Ritchie, Professor in Wildlife Ecology and Conservation, School of Life & Environmental Sciences, Deakin University, and Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University

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

Health - Less than 10,000 steps a day is optimum for good health

 

In recent years increasing attention has been paid to the value of walking and 'step counts' with varying numbers quoted as to the number of steps per day that is optimum for health. This blog has previously published recent research on this subject that can be found at these links:

• Recommended steps by age group

• Exercise and walking to avoid Alzheimers disease

Further insights are provided in this article -

Do we really need 10,000 steps a day?

Canva, Ono Kosuki/Pexels, Billion Photos/Canva, Josh Blake/Canva, The Conversation

Hunter Bennett, Adelaide University

You’ve probably heard that hitting 10,000 steps a day is the key to health and longevity.

This magic number feels like a medical rule, handed down by doctors across the globe.

But where did it come from? And is it even true?

Let’s step back to Japan in 1964

Believe it or not, but the infamous 10,000 steps a day recommendation didn’t come from a research laboratory.

In fact, it is not scientific at all.

It came from a Japanese pedometer called the manpo-kei which translates to “10,000-step meter”.

This pedometer went on sale just after the 1964 Tokyo Olympics, at a time when there was a growing worry people in Japan weren’t moving enough.

The number was mainly chosen was because it was catchy and easy to remember. The Japanese kanji character for 10,000 – 万 – even looks a little like a walking person, which may have played a role in deciding on the number.

So 10,000 was a slogan to sell a step-counter, not an evidence-based recommendation.

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So many ideas about what makes us sick, or keeps us well, sound plausible. Early studies might sound promising. But then something gets twisted. In this series, we investigate how a grain of truth ends up as a common health myth. And we untangle what went wrong along the way.

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So what does the research say?

Getting 10,000 steps a day can be a useful goal, and it will have a positive impact on your health. But you can reap health benefits from even less.

A recently published systematic review combined the results of 57 studies and more than 160,000 adults to examine the relationship between daily steps and health. Interestingly, they found 7,000 steps a day was where health benefits were maximised.

Reaching 7,000 steps a day was linked to a 47% lower risk of dying early, a 25% lower risk of cardiovascular disease (heart disease and stroke), a 14% lower risk of type 2 diabetes, a 38% lower risk of dementia, a 22% lower some of depression and a 28% lower risk of falls.

Some health benefits started well before 7,000 steps.

The researchers found going from about 2,000 to 4,000 steps a day makes a real difference. These health benefits then increase again slightly from 4,000 to 7,000 steps a day, after which the benefits start to plateau.

These results align closely with other research looking at all types of physical activity, where going from being inactive to moderately active yields the largest health improvements. Moving from a moderate to high level of activity does provide additional benefits, but these are much smaller in magnitude.

Why walking is good for you

Walking is a form of “aerobic” exercise. It raises your heart rate and places stress on your respiratory, muscular and cardiovascular systems.

If you do it regularly, it can improve your heart and metabolic health, and reduce your bodyweight.

Walking can also reduce stress and improve mental health, possibly due improvements in feelings of self-esteem and self-efficacy that comes with regular movement.

Steps versus minutes

There is some additional nuance that needs to be considered when discussing how far you walk each day: how hard you walk.

Most people choose a walking pace that pushes them into the realm of “moderate intensity” exercise. However, the health benefits of exercise scale up with exercise intensity: you get more bang for your buck from more intense exercise.

So, if you pick up the pace and move towards a vigorous exercise intensity (where it’s hard to maintain a conversation), you will get larger health benefits in less time. This is why official exercise guidelines treat 75 minutes of vigorous activity as roughly equal to 150 minutes of moderate activity.

With this in mind, rather than focusing on steps, you might be better off focusing on the number of minutes you accumulate each week.

Recent research even suggests short bursts of high-intensity exercise spread across the day can have surprising health benefits.

So, if you’re short on time, walking faster is one of the simplest ways to get more out of that same walk.

But walking alone isn’t enough

Walking covers the “aerobic” side of fitness well. However, it doesn’t really address the “anaerobic” side.

Anaerobic fitness refers to your muscle mass, muscle strength, and power. Having higher anaerobic fitness is linked to having a better quality of life and lower risk of mortality as you get older.

This is why most health authorities recommend muscle-strengthening activities (such as lifting weights) at least two days a week.

This will also help reduce your risk of type 2 diabetes, while also helping you avoid falls and stay independent for longer as you get older.

If you can aim to hit 7,000 steps each day, and add in weight training twice per week, you’re going to have most of your bases covered from a health perspective.

Hunter Bennett, Lecturer in Exercise Science, Adelaide University

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

Climate change - fires intensify after flash droughts

 

Flash droughts pull ‘alarming’ amounts of moisture from the landscape and intensify wildfires: new research

Abhirup Dikshit, UNSW and Jason Evans, UNSW

When catastrophic wildfires capture global headlines, such as the unprecedented blazes sweeping through southern Europe this summer or the devastating 2019–20 “Black Summer” in Australia, they are almost always preceded by severe drought. Dry vegetation and parched landscapes are necessary ingredients for infernos.

But not all droughts are created equal – the way a drought evolves can drastically alter how a fire behaves once it ignites. As global temperatures rise, a new and dangerous phenomenon is becoming increasingly common: the “flash drought”.

Unlike standard droughts, which take place over months or years, flash droughts are rapidly occurring dry spells, driven by intense heat and unusually low humidity. They suck moisture out of the landscape at an alarming rate.

While scientists know standard droughts increase fire risks, a critical question has remained unanswered: do flash droughts further increase this risk, and what happens when these two drought types collide?

Our latest research mapped two decades of global satellite data to answer this question. We found when landscapes transition from a prolonged standard drought into a rapid flash drought – or when the two overlap – they create a “hyper-flammable” state. This acts as a massive fire accelerant; they spread faster, last longer and grow significantly larger than other wildfires.

How hyper-flammability works

To understand why this happens, we have to look at how different droughts affect the environment. The major difference is the speed at which they occur.

A standard drought acts like a slow, relentless oven. Over months, it gradually dries out vegetation and severely reduces soil moisture, leaving a dry environment primed to burn.

A flash drought, on the other hand, is like hitting the landscape with a high-powered hairdryer. The atmospheric dryness rapidly increases, characterised by extreme heat and low humidity, and quickly depletes remaining soil moisture.

When a standard drought turns into a flash drought, the effects don’t just add up; they multiply. Combined, they cause the fire danger to skyrocket, setting the perfect stage for fast-spreading and intense wildfires. Short-lived weather anomalies such as flash droughts generate disproportionately severe and extreme fires.

Tracking two decades of global fires

To uncover this pattern, we analysed global drought and satellite-based fire data sets from 2002 to 2021. Global wildfires were categorised into four distinct groups: fires occurring under normal (no drought) conditions; fires occurring during flash droughts; fires occurring during isolated standard droughts; and fires occurring where the two drought types overlapped or followed one another.

Across every single fire metric we measured, including speed, size, duration and spread, fires burning under combined drought conditions were the most extreme. The median size of these fires was 65% larger than fires in normal conditions, and 21% larger than those occurring during standard droughts alone. They spread 35% faster and burned 19% longer.

We also discovered that regions experiencing combined drought conditions endured significantly longer dry spells before a fire actually started. On average, 72 days passed between the onset of a combined drought and the start of a fire. This compared with only 17 days for flash droughts and 56 days for standard droughts. This prolonged period allows severe dryness to develop before fires start.

Global fire hotspots

While fires that follow standard droughts are widespread across the globe’s arid and semi-arid zones, we found fires following flash droughts and, particularly, combined droughts, clustered in distinct geographic hotspots.

The most extreme are heavily concentrated in highly vulnerable communities of plants and animals, including the savannas of South America and Africa, northern Australia, and the western United States.

These regions are highly susceptible to rapid-onset heat and moisture stress, making them ground zero for compounding climate extremes. The presence of both slow-moving and flash droughts causes the most extreme fire behaviour, thus amplifying the fire’s intensity.

Rethinking wildfire preparation

As the climate continues to heat up, the rate of evaporation increases worldwide. This means the frequency and extent of combined droughts are likely to increase across fire-prone regions around the world.

Crucially, we must stop viewing droughts simply as a static state of reduced moisture. Instead, we must recognise them as evolving processes, in which the shift from one type of drought to another can fundamentally change wildfire severity.

Unfortunately, many current global drought and fire monitoring systems emphasise real-time conditions, or look at drought severity as an aggregated whole. To better protect communities and nature, these systems urgently need to integrate information on how droughts evolve. This would enable us to better detect emerging hyper-flammable landscapes before the first spark.

Abhirup Dikshit, ARC DECRA Fellow, Climate Change Research Centre, UNSW and Jason Evans, Professor, Climate Change Research Centre, UNSW

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

Satellites in orbit and many more to come

 

There are already 16,000 satellites in Earth’s orbit. How will we manage the next 100,000?

Visualisation of objects in Earth’s orbit. LeoLabs

Tony Jan, Torrens University Australia

Earth’s orbit is getting crowded.

About 16,000 satellites currently circle our planet, supporting everything from GPS navigation and weather forecasting to banking, emergency services and internet communications.

Dozens more are launched every few weeks. Some estimates suggest the total number of satellites could exceed 100,000 within this decade, with more conservative estimates landing on up to 60,000 satellites by 2030 – still a staggering amount.

This rapid growth is creating an important challenge. How do we safely manage an increasingly crowded orbital environment while ensuring the satellites we depend on continue to work reliably?

The risks are not difficult to imagine. Large satellite constellations increase light pollution and other disruptions to astronomy and the night sky. More satellites mean more traffic, a greater chance of collisions and an increasing amount of space debris.

In a worst-case scenario, space debris can cause a runaway chain reaction known as Kessler syndrome, which would ensconce Earth in a cloud of debris and render its orbit unusable, without the ability to launch satellites or any other space missions.

Even short of this, ageing or damaged satellites can become hazards if they stop working, collide with other objects, or eventually make uncontrolled re-entries through the atmosphere.

This raises a practical question – satellites can’t simply be brought home for repairs. So how do we maintain tens of thousands of machines that are hundreds of kilometres above Earth?

The Conversation, CC BY-SA

Satellites don’t last forever

The challenge of satellite maintenance became more visible in March this year when a large NASA satellite made an uncontrolled re-entry into Earth’s atmosphere.

The US Space Force confirmed the spacecraft re-entered over the eastern Pacific Ocean, and NASA expected most of it to burn up, though some components may have survived. The event attracted worldwide attention as experts tracked its descent and estimated where debris might land, including the possibility that large debris could one day cause damage in populated areas.

The incident was a reminder that satellites don’t last forever. Like any machine, they age. Batteries degrade, electronic components wear out and harsh space conditions gradually take their toll.

Unlike aircraft or cars, however, we can’t easily take satellites to a repair workshop.

Once launched, they must continue operating in an environment of intense radiation, extreme temperature changes and constant mechanical stress. Servicing missions are technically possible, but remain expensive and relatively uncommon.

How do we keep satellites ‘healthy’?

Today, satellite health is monitored largely from the ground.

Engineers receive streams of telemetry data showing battery performance, temperatures, power consumption and the status of onboard systems. They analyse this information and look for warning signs that something may be going wrong.

This approach has worked well for decades. But it may become increasingly difficult as satellite constellations grow from dozens of spacecraft to hundreds or even thousands. Human operators can only monitor so much information at once.

This is where recent advances in artificial intelligence (AI) may help. Researchers have been investigating how AI can identify early signs of satellite degradation before they become mission-threatening failures.

One important example involves batteries. Satellite batteries gradually lose performance over time, much like the battery in a smartphone or electric vehicle.

If this degradation can be detected early, operators may be able to adjust how a satellite is used, extend its operational life or avoid unexpected failures. They could do this by sending new instructions to the satellite, such as reducing power-hungry activities, changing when data are processed or transmitted, or placing non-essential systems into standby.

Our recent research used publicly available NASA satellite battery data to explore how machine learning (a type of artificial intelligence) can recognise patterns associated with battery ageing and predict future performance.

The goal is similar to predictive maintenance systems already used in modern aircraft, wind farms and manufacturing plants. Rather than waiting for equipment to fail, AI looks for subtle changes that suggest problems may be developing.

Satellites can learn from each other

In our approach, we also considered federated learning.

Normally, enormous amounts of satellite data would need to be transmitted back to Earth for analysis. This requires time, bandwidth and energy. Federated learning offers a different approach. Individual satellites can “learn” from their own experience and share useful insights with other satellites or ground systems without constantly sending every piece of raw data.

In simple terms, satellites could help each other become better at recognising potential faults. Over time, this could support continuous self-monitoring across large satellite networks.

There are, however, important limitations.

AI can’t prevent every satellite failure. It can’t eliminate space debris or solve orbital congestion on its own. Predictive models require extensive testing, such as checking them against historical satellite data, simulated faults and laboratory battery experiments before they are trusted in orbit. And any autonomous decision-making systems must be reliable enough for safety-critical applications while remaining under human oversight.

The next great challenge of the new space age may not simply be launching another 100,000 satellites. It may be ensuring those satellites are intelligent enough to monitor their own condition, detect problems early and help keep the space services we rely on running safely and reliably.

Tony Jan, Professor of Information Technology and Director of Artificial Intelligence Research and Optimization (AIRO) Centre, Torrens University Australia

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