We found methane-eating bacteria living in a common Australian tree. It could be a game changer for curbing greenhouse gases


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Luke Jeffrey, Southern Cross UniversityTrees are the Earth’s lungs – it’s well understood they drawdown and lock up vast amounts of carbon dioxide from the atmosphere. But emerging research is showing trees can also emit methane, and it’s currently unknown just how much.

This could be a major problem, given methane is a greenhouse gas about 45 times more potent than carbon dioxide at warming our planet.

However, in a world-first discovery published in Nature Communications, we found unique methane-eating communities of bacteria living within the bark of a common Australian tree species: paperbark (Melaleuca quinquenervia). These microbial communities were abundant, thriving, and mitigated about one third of the substantial methane emissions from paperbark that would have otherwise ended up in the atmosphere.

Because research on tree methane (“treethane”) is still in its relative infancy, there are many questions that need to be resolved. Our discovery helps fill these critical gaps, and will change the way we view the role of trees within the global methane cycle.

Wait, trees emit methane?

Yes, you read that right! Methane gas within cottonwood trees was first reported in 1907, but has been largely overlooked for almost a century.

Only in 2018 was a tree methane review published and then a research blueprint put forward, labelling this as “a new frontier of the global carbon cycle”. It has since been gaining rapid momentum, with studies now spanning the forests of Japan, UK, Germany, Panama, Finland, China, Australia, US, Canada, France and Borneo just to name a few.

Research on tree methane is still in its relative infancy.

In some cases, treethane emissions are significant. For example, the tropical Amazon basin is the world largest natural source of methane. Trees account for around 50% of its methane emissions.

Likewise, research from 2020 found low-lying subtropical Melaleuca forests in Australia emit methane at similar rates to trees in the Amazon.

Dead trees can emit methane, too. At the site of a catastrophic climate-related mangrove forest dieback in the Gulf of Carpentaria, dead mangrove trees were discovered to emit eight times more methane than living ones. This poses new questions for how climate change may induce positive feedbacks, triggering potent greenhouse gas release from dead and dying trees.

Aerial shot of river through trees in the Amazon
Trees account for around 50% of the total Amazon basin methane emissions.
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Treethane emissions most likely account for some of the large uncertainties within the most recent global methane budget, which tries to determine where all the methane in the atmosphere comes from. But we’re still a long way from refining an answer to this question. Currently, trees are not yet included as a distinct emissions category.

So where exactly is the treethane coming from?

Within wetland forests, scientists assumed most treethane emissions originate from the underlying soils. The methane is transported upwards via the tree roots and stems, then through to the atmosphere via their bark.

We confirmed, in other recent research, that wetland soils were indeed the source of methane emissions in lowland forest trees. But this wasn’t always the case.

Some lowland forest trees such as cottonwood can emit flammable methane directly from their stems, which is likely produced by microbes living within the moist trees themselves. Dry upland forest trees are also emerging as methane emitters too — albeit at much lower rates.

Paperbark trees surround a body of water
Paperbark forest in a wetland, where bark-dwelling methane-eating microbes were discovered.
Luke Jeffrey, Author provided

Discovering methane-eating bacteria

For our latest research, we used microbiological extraction techniques to sample the diverse microbial communities that live within trees.

We discovered the bark of paperbark trees provide a unique home for methane-oxidizing bacteria — bacteria that “consumes” methane and turns it into carbon dioxide, a far less potent greenhouse gas.

Remarkably, these bacteria made up to 25% of total microbial communities living in the bark, and were consuming around 36% of the tree’s methane. It appears these microbes make an easy living in the dark, moist and methane-rich environments.




Read more:
Emissions of methane – a greenhouse gas far more potent than carbon dioxide – are rising dangerously


This discovery will revolutionise the way in which we view methane emitting trees and the novel microbes living within them.

Only through understanding why, how, which, when and where trees emit the most methane, may we more effectively plant forests that effectively draw down carbon dioxide while avoiding unwanted methane emissions.

Author sampling microbes from paperbark tree
Microbe sampling techniques have advanced within the last few decades, allowing us to understand the diverse microbial communities living within trees.
Luke Jeffrey, Author provided

Our discovery that bark-dwelling microbes can mitigate substantial treethane emissions complicates this equation, but provides some reassurance that microbiomes have evolved within trees to consume methane as well.

Future work will undoubtedly look further afield, exploring the microbial communities of other methane-emitting forests.

A trillion trees to combat climate change

We must be clear: trees are in no way shape or form bad for our climate and provide a swath of other priceless ecosystem benefits. And the amount of methane emitted from trees is generally dwarfed by the amount of carbon dioxide they will take in over their lifetime.

However, there are currently 3.04 trillion trees on Earth. With both upland and lowland forests capable of emitting methane, mere trace amounts of methane on a global scale may amount to a substantial methane source.

As we now have a global movement aiming to reforest large swaths of the Earth with 1 trillion trees, knowledge surrounding methane emitting trees is critical.




Read more:
Half of global methane emissions come from aquatic ecosystems – much of this is human-made


The Conversation


Luke Jeffrey, Postdoctoral Research Fellow, Southern Cross University

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

Cyclone Seroja just demolished parts of WA – and our warming world will bring more of the same


Bureau of Meteorology

Jonathan Nott, James Cook UniversityTropical Cyclone Seroja battered parts of Western Australia’s coast on Sunday night, badly damaging buildings and leaving thousands of people without power. While the full extent of the damage caused by the Category 3 system is not yet known, the event was unusual.

I specialise in reconstructing long-term natural records of extreme events, and my historic and prehistoric data show cyclones of this intensity rarely travel as far south as this one did. In fact, it has happened only 26 times in the past 5,000 years.

Severe wind gusts hit the towns of Geraldton and Kalbarri – towns not built to withstand such conditions.

Unfortunately, climate change is likely to mean disasters such as Cyclone Seroja will become more intense, and will be seen further south in Australia more often. In this regard, Seroja may be a timely wake-up call.

Seroja: bucking the cyclone trend

Cyclone Seroja initially piqued interest because as it developed off WA, it interacted with another tropical low, Cyclone Odette. This rare phenomenon is known as the Fujiwhara Effect.

Cyclone Seroja hit the WA coast between the towns of Kalbarri and Gregory at about 8pm local time on Sunday. According to the Bureau of Meteorology it produced wind gusts up to 170 km/hour.

Seroja then moved inland north of Geraldton, weakening to a category 2 system with wind gusts up to 120 km/hour. It then tracked further east and has since been downgraded to a tropical low.

The cyclone’s southward track was historically unusual. For Geraldton, it was the first Category 2 cyclone impact since 1956. Cyclones that make landfall so far south on the WA coast are usually less intense, for several reasons.

First, intense cyclones draw their energy from warm sea surface temperatures. These temperatures typically become cooler the further south of the tropics you go, depleting a cyclone of its power.

Second, cyclones need relatively low speed winds in the middle to upper troposphere – the part of the atmosphere closest to Earth, where the weather occurs. Higher-speed winds there cause the cyclone to tilt and weaken. In the Australian region, these higher wind speeds are more likely the further south a cyclone travels.

Third, most cyclones make landfall in the northern half of WA where the coast protrudes far into the Indian Ocean. Cyclones here typically form in the Timor Sea and move southward or south-west away from WA before curving southeast, towards the landmass.

For a cyclone to cross the coast south of about Carnarvon, it must travel a considerable distance towards the south-west into the Indian Ocean. This was the case with Seroja – winds steered it away from the WA coast before they weakened, allowing the cyclone to curve back towards land.

Reading the ridges

My colleagues and I have devised a method to estimate how often and where cyclones make landfall in Australia.

As cyclones approach the coast, they generate storm surge – abnormal sea level rise – and large waves. The surge and waves pick up sand and shells from the beaches and transport them inland, sometimes for several hundred metres.

These materials are deposited into ridges which stand many metres above sea level. By examining these ridges and geologically dating the materials within them, we can determine how often and intense the cyclones have been over thousands of years.




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


At Shark Bay, just north of where Seroja hit the coast, a series of 26 ridges form a “ridge plain” made entirely of one species of a marine cockle shell (Fragum eragatum). The sand at beaches near the plain are also made entirely of this shell.

The ridge record shows over the past 5,000 years, cyclones of Seroja’s intensity, or higher, have crossed the coast in this region about every 190 years – so about 26 times. Some 14 of these cyclones were more intense than Seroja.

The record shows no Category 5 cyclones have made landfall here over this time. The ridge record prevents us from knowing the frequency of less intense storms. But Bureau of Meteorology cyclone records since the early 1970s shows only a few crossed the coast in this region, and all appear weaker than Seroja.

Emergency services crews in the WA town of Geraldton, preparing ahead of the arrival of Tropical Cyclone Seroja
Emergency services crews in the WA town of Geraldton, preparing ahead of the arrival of Tropical Cyclone Seroja – an event rarely seen this far south.
Department of Fire and Emergency Services WA

Cyclones under climate change

So why does all this matter? Cyclones can kill and injure people, damage homes and infrastructure, cause power and communication outages, contaminate water supplies and more. Often, the most disadvantaged populations are worst affected. It’s important to understand past and future cyclone behaviour, so communities can prepare.

Climate change is expected to alter cyclone patterns. The overall number of tropical cyclones in the Australian region is expected to decrease. But their intensity will likely increase, bringing stronger wind and heavier rain. And they may form further south as the Earth warms and the tropical zone expands poleward.

This may mean cyclones of Seroja’s intensity are likely to become frequent, and communities further south on the WA coast may become more prone to cyclone damage. This has big implications for coastal planning, engineering and disaster management planning.

In particular, it may mean homes further south must be built to cope with stronger winds. Storm surge may also worsen, inundating low-lying coastal land.

Global climate models are developing all the time. As they improve, we will gain a more certain picture of how tropical cyclones will change as the planet warms. But for now, Seroja may be a sign of things to come.




Read more:
Wetlands have saved Australia $27 billion in storm damage over the past five decades


This article is part of Conversation series on the nexus between disaster, disadvantage and resilience. Read the rest of the stories here.The Conversation

Jonathan Nott, Professor of Physical Geography, James Cook University

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

Climate change is a security threat the government keeps ignoring. We’ll show up empty handed to yet another global summit


Cheryl Durrant, UNSWClimate change is a hot topic in Australian security circles, as it poses an emerging threat to our national resilience and way of life. As a new report from the Australian Strategic Policy Institute (ASPI) last week warned, the federal government is unprepared to meet these challenges.

The report, authored by Dr Robert Glasser, said the government has largely overlooked the security threat posed by rising seas, climate-induced famine, extreme weather events, mass migrations and other climate change damage in Southeast Asia. Australia is sitting on the frontline of this vulnerable region.

Glasser’s report focuses on Southeast Asia, but in the bigger picture, climate security is an existential global risk which the Australian government is yet to fully grasp. It is this global aspect of climate and security which will be on the agenda in two weeks time at the Biden Leaders Summit in the US.

Why should we be worried?

The global risk is broader than traditional security threats, such as the rise of China, terrorism and separatist movements. As the ASPI report emphasises, there is a relationship between climate security and other sectors such as food, health and environmental security.

Unlike traditional national security threats, climate threats have no respect for national or sector borders and cannot be solved with missiles.

The threat is urgent. With the end of the Donald Trump presidency, climate change is back on regional and international security action agendas. The penny has dropped on how little time is left to take action to prepare for the worst of consequences.

This is especially the case when there are long lead times to implement action, such as infrastructure development and military capability development.




Read more:
Climate change poses a ‘direct threat’ to Australia’s national security. It must be a political priority


ASPI’s key recommendations to the government include:

  • improving understanding of climate change risks through a broad whole-of-government process
  • building capacity in government agencies to assess ongoing risks
  • identifying opportunities for regional aid and investments.

These make sense, as the first step of preparedness is understanding the risk.

Security risks go beyond natural disasters

The ASPI report notes Southeast Asia “has the world’s highest sea-level rise per kilometre of coastline and the largest coastal population affected by it”. The region is a hot spot for cyclones, with some nations vulnerable to catastrophic heat or fires.

The ASPI report notes:

Those hazards will not only exacerbate the traditional regional security threats […] but also lead to new threats and the prospect of multiple, simultaneous crises, including food insecurity, population displacement and humanitarian disasters that will greatly test our national capacities, commitments and resilience.

The report focuses on Southeast Asia and natural disasters, but the risks and the affected regions are bigger than that.

The Indo-Pacific region may see the displacement of millions of people due to climate change-related extreme weather events, heatwaves, droughts, rising seas and floods. We’re already seeing this occur in Bangladesh and small island developing states.

We could also see conflict arise as climate change affects global food or water resources. A particular concern is the potential geopolitical tensions between India and China over dwindling Tibetan water resources.

Australia is getting left behind

Urgency and risk are central to an executive order from President Joe Biden in January. The order requires a US national security estimate on the economic and national security impacts of climate change by June. The US Department of Defence must also complete an analysis of the security implications of climate change in the same timeframe.




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Biden says the US will rejoin the Paris climate agreement in 77 days. Then Australia will really feel the heat


Most tellingly, the US is taking an integrated approach to climate security. Foreign policy, defence and economic risk analysis are being conducted in a joined-up, systemic way.

In contrast, the Australian Defence Strategic Update 2020 was conducted in isolation from foreign policy and economic reviews. Taking a narrow military perspective, it does mention climate change, but only once, as a subset of human security threats.

Australia risks being left behind as other countries follow the US lead. Across the Tasman, our Kiwi friends are already well advanced in turning risk awareness into action. The New Zealand government completed its first national climate risk assessment last year, with a national adaptation plan to be completed by August 2022.

What are the consequences?

Being left behind has consequences for Australia’s international standing, national resilience and economic position.

From a diplomatic perspective, Australia’s influence in the Indo-Pacific region is diminished, relative to other actors, especially in states where climate change risk is a top priority, such as Vanuatu or Kiribati.

Risks offer opportunities as well. For example, Australia has an abundance of critical minerals and rare earths needed for modern communications, space technologies, and renewable energy generation and transmission. These are key for business, as well as critical for defence forces.




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Critical minerals are vital for renewable energy. We must learn to mine them responsibly


However, processing and manufacturing is largely conducted offshore — in countries vulnerable to climate risks such as Malaysia — before returning to Australia as finished products.

This puts Australian defence and space and energy sectors at risk of disruption, and Australian businesses at risks of economic loss.

What needs to happen next?

ASPI’s report echoes the earlier recommendation from a 2018 Senate inquiry into the implications of climate change for Australia’s national security. The inquiry also called for a coordinated whole-of-government response to climate change risks.

Three years later, the federal government has yet to act on its recommendations.

The Australian government now needs to have a greater sense of urgency to act on the growing national and international calls to act on climate risk. But first, our leaders need a changed mindset. They must accept that climate change is an immediate threat to Australia.




Read more:
Senate report: climate change is a clear and present danger to Australia’s security


The Conversation


Cheryl Durrant, Adjunct Associate Professor, UNSW

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

Half of global methane emissions come from aquatic ecosystems – much of this is human-made


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Judith Rosentreter, Yale University; Alberto Borges, Université de Liège; Ben Poulter, NASA, and Bradley Eyre, Southern Cross UniversityMethane — a greenhouse gas far more potent than carbon dioxide — plays a major role in controlling the Earth’s climate. But methane concentrations in the atmosphere today are 150% higher than before the industrial revolution.

In our paper published today in Nature Geoscience, we show as much as half of global methane emissions come from aquatic ecosystems. This includes natural, human-created and human-impacted aquatic ecosystems — from flooded rice paddies and aquaculture ponds to wetlands, lakes and salt marshes.

Our findings are significant. Scientists had previously underestimated this global methane contribution due to underaccounting human-created and human-impacted aquatic ecosystems.

It’s critical we use this new information to stop rising methane concentrations derailing our attempts to stabilise the Earth’s temperature.

From underwater sediment to the atmosphere

Most of the methane emitted from aquatic ecosystems is produced by micro-organisms living in deep, oxygen-free sediments. These tiny organisms break down organic matter such as dead algae in a process called “methanogenesis”.

Flooded rice paddies
Rice farming releases more methane per year than the entire open ocean.
Shutterstock

This releases methane to the water, where some is consumed by other types of micro-organisms. Some of it also reaches the atmosphere.

Natural systems have always released methane (known as “background” methane). And freshwater ecosystems, such as lakes and wetlands, naturally release more methane than coastal and ocean environments.

Human-made or human-impacted aquatic ecosystems, on the other hand, increase the amount of organic matter available to produce methane, which causes emissions to rise.




Read more:
Emissions of methane – a greenhouse gas far more potent than carbon dioxide – are rising dangerously


Significant global contribution

Between 2000 and 2006, global methane emissions stabilised, and scientists are still unsure why. Emissions began steadily rising again in 2007.

There’s active debate in the scientific community about how much of the renewed increase is caused by emissions or by a decline of “methane sinks” (when methane is eliminated, such as from bacteria in soil, or from chemical reactions in the atmosphere).

We looked at inland, coastal and oceanic ecosystems around the world. While we cannot resolve the debate about what causes the renewed increase of atmospheric methane, we found the combined emissions of natural, impacted and human-made aquatic ecosystems are highly variable, but may contribute 41% to 53% of total methane emissions globally.




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Feeding cows a few ounces of seaweed daily could sharply reduce their contribution to climate change


In fact, these combined emissions are a larger source of methane than direct anthropogenic methane sources, such as cows, landfill and waste, and coal mining. This knowledge is important because it can help inform new monitoring and measurements to distinguish where and how methane emissions are produced.

Water is a big part of much of our landscape, from mountain rivers to the coastal ocean. This aerial image shows Himalaya rivers, wetlands, lakes and ponds, and the world’s largest mangrove forest (the Sundarbans) at the coast of the tropical Bay of Bengal.
George Allen, Author provided

The alarming human impact

There is an increasing pressure from humans on aquatic ecosystems. This includes increased nutrients (like fertilisers) getting dumped into rivers and lakes, and farm dam building as the climate dries in many places.

In general, we found methane emissions from impacted, polluted and human-made aquatic ecosystems are higher than from more natural sites.

For example, fertiliser runoff from agriculture creates nutrient-rich lakes and reservoirs, which releases more methane than nutrient-poor (oligotrophic) lakes and reservoirs. Similarly, rivers polluted with nutrients also have increased methane emissions.

An aquaculture farm
Coastal aquaculture farms emit up to 430 times more methane per area than coastal habitats.
Shutterstock

What’s particularly alarming is the strong methane release from rice cultivation, reservoirs and aquaculture farms.

Globally, rice cultivation releases more methane per year than all coastal wetlands, the continental shelf and open ocean together.

The fluxes in methane emissions per area of coastal aquaculture farms are 7-430 times higher than from coastal habitats such as mangrove forests, salt marshes or seagrasses. And highly disturbed mangroves and salt marsh sites have significantly higher methane fluxes than more natural sites.

So how do we reduce methane emissions?

For aquatic ecosystems, we can effectively reduce methane emissions and help mitigate climate change with the right land use and management choices.

For example, managing aquaculture farms and rice paddies so they alternate between wet and dry conditions can reduce methane emissions.




Read more:
Climate explained: methane is short-lived in the atmosphere but leaves long-term damage


Restoring salt marsh and mangrove habitats and the flow of seawater from tides is another promising strategy to further reduce methane emissions from degraded coastal wetlands.

We should also reduce the amount of nutrients coming from fertilisers washing into freshwater wetlands, lakes, reservoirs and rivers as it leads to organic matter production, such as toxic algal blooms. This will help curtail methane emissions from inland waters.

These actions will be most effective if we apply them in the aquatic ecosystems that have the greatest contribution of aquatic methane: freshwater wetlands, lakes, reservoirs, rice paddies and aquaculture farms.

This will be no small effort, and will require knowledge across many disciplines. But with the right choices we can create conditions that bring methane fluxes down while also preserving ecosystems and biodiversity.The Conversation

Judith Rosentreter, Postdoctoral Research Fellow, Yale University; Alberto Borges, Research Director FRS-FNRS, Associate Professor at ULiège, Université de Liège; Ben Poulter, Research scientist, NASA, and Bradley Eyre, Professor of Biogeochemistry, Director of the Centre for Coastal Biogeochemistry, Southern Cross University

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

Climate explained: rising carbon emissions (probably) won’t make the Earth uninhabitable


Shutterstock/Jurik Peter

Laura Revell, University of Canterbury


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


Even with all humanity’s carbon emissions to date, there’s a lot less carbon dioxide in Earth’s atmosphere than Venus, and Earth is further away from the Sun. But if carbon emissions continue at the current rate, is there any risk of reaching a tipping point at which a runaway greenhouse effect takes over, making Earth uninhabitable for any form of life?

When sunlight enters the Earth’s atmosphere, some is reflected back to space by clouds, some is reflected by bright surfaces such as ice and snow and some is absorbed by the land surface and ocean.

To maintain a balance, the Earth emits energy back to space in the form of infrared, or longwave, radiation. Some longwave radiation is absorbed in the atmosphere by heat-trapping gases, such as carbon dioxide.

This is the well-known greenhouse effect.




Read more:
Climate Explained: what Earth would be like if we hadn’t pumped greenhouse gases into the atmosphere


As is already well established, concentrations of carbon dioxide have increased over the past 250 years, causing the average surface temperature to increase.

One consequence of increasing atmospheric carbon dioxide concentrations is that, as the atmosphere warms, it can contain more water vapour. Since water vapour is itself a greenhouse gas, this can create an amplifying effect.

In general, as surface temperature increases, the Earth emits more longwave radiation to space to maintain the energy balance. But there is a limit to how much longwave radiation can be emitted.

If the atmosphere becomes completely saturated with water vapour, the Earth’s surface and lower atmosphere warm up, but further increases in emission of longwave radiation are not possible.

The runaway greenhouse

This is termed a runaway greenhouse and would mean the Earth would become lethally hot and unable to cool itself by emitting heat to space.

Ultimately, this is the fate of the Earth. In billions of years from now the Sun will become brighter and grow into a Red Dwarf. As the Sun’s luminosity increases, the Earth will become hotter and its oceans will evaporate.

We’re doomed … but not for billions of years.

The hot and steamy atmosphere will ensure the Earth is just as uninhabitable to current life-forms as Venus is today.

But could we bring such a situation about on a shorter timeframe through continued carbon dioxide emissions? The good news is, probably not.

We’re safe, for now

Previous research has found that, due to differences in the properties of water vapour and carbon dioxide as greenhouse gases, adding carbon dioxide to the atmosphere is likely insufficient to trigger a runaway greenhouse.

Atmospheric carbon dioxide is currently around 416 parts per million (ppm) – up from approximately 280 ppm since the first industrial revolution began, some 250 years ago.

In geological terms, this is a very large increase to take place over a short period of time. Yet human emissions of carbon dioxide are considered insufficient to trigger a runaway greenhouse, given the fossil fuel reserves available.

The Earth should be safe from a runaway greenhouse developing for at least another 1.5 billion years.

But then …

The caveat to all the above is that the models scientists use to study future climate are built based on past, known conditions. It is therefore difficult to predict how certain parts of the climate system might operate under extremely high greenhouse gas emissions scenarios.

Clouds hiding the Sun but with rays of light emerging from behind top.
Clouds can reflect sunlight back to space.
Flickr/scheendijk, CC BY

For example, clouds can reflect sunlight back to space, or they can trap heat emitted by the Earth. In a warming world, scientists are still unclear on the role clouds will play.




Read more:
Expect the new normal for NZ’s temperature to get warmer


While a runaway greenhouse would make Earth completely uninhabitable to life as we know it, the losses that may accrue from just a few degrees Celsius of global warming are serious and must not be discounted.

Sea level rise, increased frequency and intensity of extreme weather events, threats to endangered species and unique ecosystems are just a few of the many reasons we have to be concerned.

The silver lining is we (probably) don’t need to worry about becoming like our neighbour Venus any time soon.The Conversation

We’re not heading this way just yet.

Laura Revell, Senior Lecturer in Environmental Physics, University of Canterbury

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

Is Malcolm Turnbull the only Liberal who understands economics and climate science – or the only one who’ll talk about it?


Darren England/AAP

Richard Denniss, Crawford School of Public Policy, Australian National UniversityYesterday, former Liberal prime minister Malcolm Turnbull was unceremoniously dumped as chair of the New South Wales government’s climate advisory board, just a week after being offered the role. His crime? He questioned the wisdom of building new coal mines when the existing ones are already floundering.

No-one would suggest building new hotels in Cairns to help that city’s struggling tourism industry. But among modern Liberals it’s patently heresy to ask how rushing to green light 11 proposed coal mines in the Hunter Valley helps the struggling coal industry.

Coal mines in the Hunter are already operating well below capacity and have been laying off workers in the face of declining world demand for coal, plummeting renewable energy prices and trade sanctions imposed by China. The problem isn’t a shortage of supply, but an abundance.

The simple truth is building new coal mines will simply make matters worse, especially for workers in existing coal mines that have already been mothballed or had their output scaled back.

coal mine in the Hunter Valley
Turnbull has called for a moratorium on new coal mines in the Hunter Valley, such as the one pictured above.
Dean Lewins/AAP

It gets worse. Once an enormous, dusty, noisy open cut coal mine is approved, the agriculture, wine, tourism and horse breeding industries – all major employers in the Hunter Valley – are reluctant to invest nearby. While building new coal mines hurts workers in existing coal mines, the mere act of approving new coal mines harms investment in job creation in the industries that offer the Hunter a smooth transition from coal.

The NSW planning department doesn’t have a plan for how many new coal mines are needed to meet world demand. Nor does it have a plan for how much expansion of rail and port infrastructure is required to meet the output of all the new mines being proposed.




Read more:
Forget about the trade spat – coal is passé in much of China, and that’s a bigger problem for Australia


That’s why my colleagues and I recently called for a moratorium on new coal mines in the Hunter until such plans were made explicit. Just as you wouldn’t approve 1,000 new homes in a town where the sewerage system was already at capacity, it makes no sense to approve 11 new coal mines in a region that couldn’t export that much coal if it tried.

But if there’s one thing that defines the debate about coal in Australia, its that it makes no sense.

Just as it made no sense for then-treasurer Scott Morrison to wave a lump of coal around in parliament in 2017, it makes no sense for right-wing commentators to pretend approving new mines will help create jobs in coal mining. And it makes no sense for the National Party to ignore the pleas of farmers to protect their land from the damage coal mines do.

Scott Morrison with a lump of coal to Question Time in 2017.
Scott Morrison took a lump of coal to Question Time in 2017.
Lukas Coch/AAP

On the surface, Turnbull’s support for a pause on approving new mines while a plan is developed is old-fashioned centrism. It protects existing coal workers from new, highly automated mines, it protects farmers and it should make those concerned with climate change at least a bit happy. Win. Win. Win.

But there’s no room for a sensible centre in the Australian coal debate. And when someone even suggests the industry might not be set to grow, its army of loyal parliamentary and media supporters swing into action.

Labor’s Joel Fitzgibbon said Turnbull “wants to make the Upper Hunter a coal-mine-free zone”. The Nationals’ Matt Canavan suggested stopping coal exports was “an inhumane policy to keep people in poverty”. The head of the NSW Minerals Council suggested 12,000 jobs were at risk.

But of course, the opposite is true. Turnbull’s proposal to protect existing coal workers from competition from new mines would save jobs, not threaten them. He didn’t suggest coal mines be shut down tomorrow, or even early. And, given existing coal mines are running so far below capacity, his call has no potential to impact coal exports.




Read more:
Labor politicians need not fear: Queenslanders are no more attached to coal than the rest of Australia


Coal workers
Opening new coal mines won’t help save the jobs of existing coal workers.
Dan Himbrechts/AAP

Predictably, the Murdoch press ran a relentlessly misleading campaign in support of the coal industry and in opposition to their least favourite Liberal PM. But surprisingly, the NSW government rolled over in record time.

While the government might think appeasing the coal industry will play well among some older regional voters, they must know such kowtowing is a gift to independents such as Zali Steggall, and a fundamental threat to inner-city Liberals such as Dave Sharma, Jason Falinski and Trent Zimmerman.

The decision to dump Turnbull might have bought NSW Premier Gladys Berejiklian some respite from attacks from the Daily Telegraph. But such denial of economics and climate science will provide no respite for existing coal workers in shuttered coal mines or the agriculture and tourism industry that is looking to expand.

No doubt the National Party are pleased with their latest scalp. But it must be remembered this is the party that last year wanted to wage a war against koalas on behalf of property developers. Such political instincts might help the Nationals fend off the threat from One Nation in regional areas but it does nothing to retain votes in leafy Liberal strongholds that deliver most Liberal seats.




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Aren’t we in a drought? The Australian black coal industry uses enough water for over 5 million people


The Conversation


Richard Denniss, Adjunct Professor, Crawford School of Public Policy, Australian National University

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

Marine life is fleeing the equator to cooler waters. History tells us this could trigger a mass extinction event


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Anthony Richardson, The University of Queensland; Chhaya Chaudhary, University of Auckland; David Schoeman, University of the Sunshine Coast, and Mark John Costello, University of AucklandThe tropical water at the equator is renowned for having the richest diversity of marine life on Earth, with vibrant coral reefs and large aggregations of tunas, sea turtles, manta rays and whale sharks. The number of marine species naturally tapers off as you head towards the poles.

Ecologists have assumed this global pattern has remained stable over recent centuries — until now. Our recent study found the ocean around the equator has already become too hot for many species to survive, and that global warming is responsible.

In other words, the global pattern is rapidly changing. And as species flee to cooler water towards the poles, it’s likely to have profound implications for marine ecosystems and human livelihoods. When the same thing happened 252 million years ago, 90% of all marine species died.

The bell curve is warping dangerously

This global pattern — where the number of species starts lower at the poles and peaks at the equator — results in a bell-shaped gradient of species richness. We looked at distribution records for nearly 50,000 marine species collected since 1955 and found a growing dip over time in this bell shape.

A chart with three overlapping lines, each representing different decades. It shows that between 1955 and 1974, the bell curve is almost flat at the top. For the lines 1975-1994 and 1995-2015, the dip gets progressively deeper, with peaks either side of the centre.
If you look at each line in this chart, you can see a slight dip in total species richness between 1955 and 1974. This deepens substantially in the following decades.
Anthony Richardson, Author provided

So, as our oceans warm, species have tracked their preferred temperatures by moving towards the poles. Although the warming at the equator of 0.6℃ over the past 50 years is relatively modest compared with warming at higher latitudes, tropical species have to move further to remain in their thermal niche compared with species elsewhere.

As ocean warming has accelerated over recent decades due to climate change, the dip around at the equator has deepened.

We predicted such a change five years ago using a modelling approach, and now we have observational evidence.




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For each of the 10 major groups of species we studied (including pelagic fish, reef fish and molluscs) that live in the water or on the seafloor, their richness either plateaued or declined slightly at latitudes with mean annual sea-surface temperatures above 20℃.

Today, species richness is greatest in the northern hemisphere in latitudes around 30°N (off southern China and Mexico) and in the south around 20°S (off northern Australia and southern Brazil).

school of tuna fish
The tropical water at the equator is renowned for having the richest diversity of marine life, including large aggregations of tuna fish.
Shutterstock

This has happened before

We shouldn’t be surprised global biodiversity has responded so rapidly to global warming. This has happened before, and with dramatic consequences.

252 million years ago…

At the end of the Permian geological period about 252 million years ago, global temperatures warmed by 10℃ over 30,000-60,000 years as a result of greenhouse gas emissions from volcano eruptions in Siberia.

A 2020 study of the fossils from that time shows the pronounced peak in biodiversity at the equator flattened and spread. During this mammoth rearranging of global biodiversity, 90% of all marine species were killed.

125,000 years ago…

A 2012 study showed that more recently, during the rapid warming around 125,000 years ago, there was a similar swift movement of reef corals away from the tropics, as documented in the fossil record. The result was a pattern similar to the one we describe, although there was no associated mass extinction.

Authors of the study suggested their results might foreshadow the effects of our current global warming, ominously warning there could be mass extinctions in the near future as species move into the subtropics, where they might struggle to compete and adapt.

Today…

During the last ice age, which ended around 15,000 years ago, the richness of forams (a type of hard-shelled, single-celled plankton) peaked at the equator and has been dropping there ever since. This is significant as plankton is a keystone species in the foodweb.

Our study shows that decline has accelerated in recent decades due to human-driven climate change.

The profound implications

Losing species in tropical ecosystems means ecological resilience to environmental changes is reduced, potentially compromising ecosystem persistence.

In subtropical ecosystems, species richness is increasing. This means there’ll be species invaders, novel predator-prey interactions, and new competitive relationships. For example, tropical fish moving into Sydney Harbour compete with temperate species for food and habitat.

This could result in ecosystem collapse — as was seen at the boundary between the Permian and Triassic periods — in which species go extinct and ecosystem services (such as food supplies) are permanently altered.

The changes we describe will also have profound implications for human livelihoods. For example, many tropical island nations depend on the revenue from tuna fishing fleets through the selling of licenses in their territorial waters. Highly mobile tuna species are likely to move rapidly toward the subtropics, potentially beyond sovereign waters of island nations.




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Similarly, many reef species important for artisanal fishers — and highly mobile megafauna such as whale sharks, manta rays and sea turtles that support tourism — are also likely to move toward the subtropics.

The movement of commercial and artisanal fish and marine megafauna could compromise the ability of tropical nations to meet the Sustainable Development Goals concerning zero hunger and marine life.

Is there anything we can do?

One pathway is laid out in the Paris Climate Accords and involves aggressively reducing our emissions. Other opportunities are also emerging that could help safeguard biodiversity and hopefully minimise the worst impacts of it shifting away from the equator.

Currently 2.7% of the ocean is conserved in fully or highly protected reserves. This is well short of the 10% target by 2020 under the UN Convention on Biological Diversity.

Manta ray with other fish
Manta rays and other marine megafauna leaving the equator will have a huge impact on tourism.
Shutterstock

But a group of 41 nations is pushing to set a new target of protecting 30% of the ocean by 2030.

This “30 by 30” target could ban seafloor mining and remove fishing in reserves that can destroy habitats and release as much carbon dioxide as global aviation. These measures would remove pressures on biodiversity and promote ecological resilience.

Designing climate-smart reserves could further protect biodiversity from future changes. For example, reserves for marine life could be placed in refugia where the climate will be stable over the foreseeable future.

We now have evidence that climate change is impacting the best-known and strongest global pattern in ecology. We should not delay actions to try to mitigate this.

This story is part of Oceans 21

Our series on the global ocean opened with five in-depth profiles. Look out for new articles on the state of our oceans in the lead-up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.




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The Conversation


Anthony Richardson, Professor, The University of Queensland; Chhaya Chaudhary, , University of Auckland; David Schoeman, Professor of Global-Change Ecology, University of the Sunshine Coast, and Mark John Costello, Professor, University of Auckland

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

Climate explained: how particles ejected from the Sun affect Earth’s climate


Earth’s magnetic field protects us from the solar wind, guiding the solar particles to the polar regions.
SOHO (ESA & NASA)

Annika Seppälä


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


When the Sun ejects solar particles into space, how does this affect the Earth and climate? Are clouds affected by these particles?

When we consider the Sun’s influence on Earth and our climate, we tend to think about solar radiation. We are acutely aware of the skin-burning dangers of ultraviolet, or UV, radiation.

But the Sun is an active star. It also continuously releases what is known as “solar wind”, made up of charged particles, largely protons and electrons, that travel at speeds of hundreds of kilometres per hour.

Some of these particles that reach Earth are guided into the polar atmosphere by our magnetic field. As a result, we can see the southern lights, aurora australis, in the southern hemisphere, and the northern equivalent, aurora borealis.

Aurora Australis
Aurora australis observed above southern New Zealand.
Shutterstock/Fotos593

This visible manifestation of solar particles entering Earth’s atmosphere is a constant reminder there is more to the Sun than sunlight. But the particles have other effects as well.




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Solar particles and ozone

When solar particles enter the atmosphere, their high energies ionise neutral atmospheric nitrogen and oxygen molecules, which make up 99% of the atmosphere. This “energetic particle precipitation”, named because it’s like a rain of particles from space, is a major source of ionisation in the polar atmosphere above 30km altitude — and it sets off a chain of reactions that produces chemicals that facilitate the destruction of ozone.

The impact of solar particles on atmospheric ozone was first observed in 1969. Since the early 2000s, thanks to new kinds of satellite observations, we have seen growing evidence that solar particles play an important part in influencing polar ozone. During particularly active times, when the Sun releases large amounts of particles into space, up to 60% of ozone at altitudes above 50km can be depleted. The effect can last for weeks.

Lower down in the atmosphere, below 50km, solar particles are important contributors to the year-to-year variability in polar ozone levels, often through indirect pathways. Here, solar particles again contribute to ozone loss, but a recent discovery showed they also help curb some of the depletion in the Antarctic ozone hole.

How ozone affects the climate

Most of the ozone in the atmosphere resides in a thin layer at altitudes of 20-25km — the “ozone layer”.

But ozone is everywhere in the atmosphere, from the Earth’s surface to altitudes above 100km. It is a greenhouse gas and plays a key role in heating and cooling the atmosphere, which makes it critical for climate.

In the southern hemisphere, changes in polar ozone are known to influence regional climate conditions.

Satellite image of Earth's atmosphere
Solar particles ionise nitrogen and oxygen molecules in the atmosphere, which leads to other chemical reactions that contribute to ozone destruction.
Shutterstock/PunyaFamily

Its depletion above Antarctica had a cooling effect, which in turn pulled the westerly wind jet that circles the continent closer. As the Antarctic hole recovers, this wind belt can meander further north and affect rainfall patterns, sea-surface temperatures and ocean currents. The Southern Annular Mode describes this north-south movement of the wind belt that circles the southern polar region.

Ozone is important for future climate predictions, not only in the thin ozone layer, but throughout the atmosphere. It is crucial we understand the factors that influence ozone variability, be it man-made or natural like the Sun.

The Sun’s direct influence

The link between solar particles and ozone is reasonably well established, but what about any direct effects solar particles may have on the climate?

We have observational evidence that solar activity influences regional climate variability at both poles. Climate models also suggest such polar effects link to larger climate patterns (such as the Northern and Southern Annular Modes) and influence conditions in mid-latitudes.

The details are not yet well understood, but for the first time the influence of solar particles on the climate system will be included in climate simulations used for the upcoming Intergovernmental Panel on Climate Change (IPCC) assessment.




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Through solar radiation and particles, the Sun provides a key energy input to our climate system. While these do vary with the Sun’s 11-year cycle of magnetic activity, they can not explain the recent rapid increase in global temperatures due to climate change.

We know rising levels of greenhouse gases in the atmosphere are pushing up Earth’s surface temperature (the physics have been known since the 1800s). We also know human activities have greatly increased greenhouse gases in the atmosphere. Together these two factors explain the observed rise in global temperatures.

What about clouds?

Clouds are much lower in the atmosphere than where most solar particles penetrate. Particles know as galactic cosmic rays (coming from the centre of our galaxy rather than the Sun) may be linked to cloud formation.

It has been suggested cosmic rays could influence the formation of condensation nuclei, which act as “seeds” for clouds. But recent research at the CERN nuclear research facility suggests the effects are insignificant.

This doesn’t rule out some other mechanisms for cosmic rays to affect cloud formation, but thus far there is little supporting evidence.The Conversation

Annika Seppälä, Senior Lecturer in Geophysics

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

What is a 1 in 100 year weather event? And why do they keep happening so often?


Andy Pitman, UNSW; Anna Ukkola, UNSW, and Seth WestraPeople living on the east coast of Australia have been experiencing a rare meteorological event. Record-breaking rainfall in some regions, and very heavy and sustained rainfall in others, has led to significant flooding.

In different places, this has been described as a one in 30, one in 50 or one in 100 year event. So, what does this mean?

What is a 1 in 100 year event?

First, let’s clear up a common misunderstanding about what a one in 100 year event means. It does not mean the event will occur exactly once every 100 years, or that it will not happen again for another 100 years.

For meteorologists, the one in 100 year event is an event of a size that will be equalled or exceeded on average once every 100 years. This means that over a period of 1,000 years you would expect the one in 100 year event would be equalled or exceeded ten times. But several of those ten times might happen within a few years of each other, and then none for a long time afterwards.




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Ideally, we would avoid using the phrase “one in 100 year event” because of this common misunderstanding, but the term is so widespread now it is hard to change. Another way to think about what a one in 100 year event means is that there is a 1% chance of an event of at least that size in any given year. (This is known as an “annual exceedance probability”.)

How common are 1 in 100 year events?

Many people are surprised by the feeling that one in 100 year events seem to happen much more often than they might expect. Although a 1% probability might sound pretty rare and unlikely, it is actually more common than you might think. There are two reasons for this.

First, for a given location (such as where you live), a one in 100 year event would be expected to occur on average once in 100 years. However, across all of Australia you would expect the one in 100 year event to be exceeded somewhere far more often than once in a century!

In much the same way, you might have a one in a million chance of winning the lottery, but the chance someone wins the lottery is obviously much higher.

Second, while a one in 100 year flood event might have a 1% chance of occurring in a given year (hence it’s referred to as a “1% flood”), the chance is much higher when looking at longer time periods. For example, if you have a house designed to withstand a 1% flood, this means over the course of 70 years there’s a roughly 50% chance the house would be flooded at some point during this time! Not the best odds.

How well do we know how often flood events occur?

Incidents like these 1% annual exceedance probability events are often referred to as “flood planning levels” or “design events”, because they are commonly used for a range of urban planning and engineering design applications. Yet this presupposes we can work out exactly what the 1% event is, which sounds simpler than it is in practice.

First of all, we use historical data to estimate the one in 100 year event, but Australia has only about 100 years of reliable meteorological observations, and even shorter records of river flow in most locations. We know for sure this 100-year record does not contain the largest possible events that could occur in terms of rainfall, drought, flood and so on. We have data from indirect paleoclimate evidence pointing to much larger events in the past.




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So a 1% event is by no means a “worst case” scenario, and some of the evidence from paleoclimate data suggests the climate has been very different in the deep past.

Second, estimating the one in 100 year event using historical data assumes the underlying conditions are not changing. But in many parts of the world, we know rainfall and streamflow are changing, leading to a changing risk of flooding.

Moreover, even if there was no change in rainfall, changes to flood risk can occur due to a host of other factors. Increased flood risk can result from land clearing or other changes in the vegetation in a catchment, or changes in catchment management.

Increased occurrence of flooding can also be associated with poor planning decisions that locate settlements on floodplains. This means a one in 100 year event estimated from past observations could under- or indeed overestimate current flood risk.

A third culprit for influencing how often a flood occurs is climate change. Global warming is unquestionably heating the oceans and the atmosphere and intensifying the hydrological cycle. The atmosphere can hold more water in a warmer world, so we would expect to see rainfall intensities increasing.

Extreme rainfall events are becoming more extreme across parts of Australia. This is consistent with theory, which suggests we will see roughly a 7% increase in rainfall per degree of global warming.

Australia has warmed on average by almost 1.5℃, implying about 10% more intense rainfall. While 10% might not sound too dramatic, if a city or dam is designed to cope with 100mm of rain and it is hit with 110mm, it can be the difference between just lots of rain and a flooded house.

So what does this mean in practice?

Whether climate change “caused” the current extreme rainfall over coastal New South Wales is difficult to say. But it is clear that with temperatures and heavy rainfall events becoming more extreme with global warming, we are likely to experience one in 100 year events more often.

We should not assume the events currently unfolding will not happen again for another 100 years. It’s best to prepare for the possibility it will happen again very soon.




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The Conversation


Andy Pitman, Director of the ARC Centre of Excellence for Climate System Science, UNSW; Anna Ukkola, ARC DECRA Fellow, UNSW, and Seth Westra, Associate Professor, School of Civil, Environmental and Mining Engineering

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