Worried about Earth’s future? Well, the outlook is worse than even scientists can grasp



Daniel Mariuz/AAP

Corey J. A. Bradshaw, Flinders University; Daniel T. Blumstein, University of California, Los Angeles, and Paul Ehrlich, Stanford University

Anyone with even a passing interest in the global environment knows all is not well. But just how bad is the situation? Our new paper shows the outlook for life on Earth is more dire than is generally understood.

The research published today reviews more than 150 studies to produce a stark summary of the state of the natural world. We outline the likely future trends in biodiversity decline, mass extinction, climate disruption and planetary toxification. We clarify the gravity of the human predicament and provide a timely snapshot of the crises that must be addressed now.

The problems, all tied to human consumption and population growth, will almost certainly worsen over coming decades. The damage will be felt for centuries and threatens the survival of all species, including our own.

Our paper was authored by 17 leading scientists, including those from Flinders University, Stanford University and the University of California, Los Angeles. Our message might not be popular, and indeed is frightening. But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face.

Girl in breathing mask attached ot plant in container
Humanity must come to terms with the future we and future generations face.
Shutterstock

Getting to grips with the problem

First, we reviewed the extent to which experts grasp the scale of the threats to the biosphere and its lifeforms, including humanity. Alarmingly, the research shows future environmental conditions will be far more dangerous than experts currently believe.

This is largely because academics tend to specialise in one discipline, which means they’re in many cases unfamiliar with the complex system in which planetary-scale problems — and their potential solutions — exist.

What’s more, positive change can be impeded by governments rejecting or ignoring scientific advice, and ignorance of human behaviour by both technical experts and policymakers.

More broadly, the human optimism bias – thinking bad things are more likely to befall others than yourself – means many people underestimate the environmental crisis.

Numbers don’t lie

Our research also reviewed the current state of the global environment. While the problems are too numerous to cover in full here, they include:

  • a halving of vegetation biomass since the agricultural revolution around 11,000 years ago. Overall, humans have altered almost two-thirds of Earth’s land surface

  • About 1,300 documented species extinctions over the past 500 years, with many more unrecorded. More broadly, population sizes of animal species have declined by more than two-thirds over the last 50 years, suggesting more extinctions are imminent




Read more:
What is a ‘mass extinction’ and are we in one now?


  • about one million plant and animal species globally threatened with extinction. The combined mass of wild mammals today is less than one-quarter the mass before humans started colonising the planet. Insects are also disappearing rapidly in many regions

  • 85% of the global wetland area lost in 300 years, and more than 65% of the oceans compromised to some extent by humans

  • a halving of live coral cover on reefs in less than 200 years and a decrease in seagrass extent by 10% per decade over the last century. About 40% of kelp forests have declined in abundance, and the number of large predatory fishes is fewer than 30% of that a century ago.

State of the Earth's environment
Major environmental-change categories expressed as a percentage relative to intact baseline. Red indicates percentage of category damaged, lost or otherwise affected; blue indicates percentage intact, remaining or unaffected.
Frontiers in Conservation Science

A bad situation only getting worse

The human population has reached 7.8 billion – double what it was in 1970 – and is set to reach about 10 billion by 2050. More people equals more food insecurity, soil degradation, plastic pollution and biodiversity loss.

High population densities make pandemics more likely. They also drive overcrowding, unemployment, housing shortages and deteriorating infrastructure, and can spark conflicts leading to insurrections, terrorism, and war.




Read more:
Climate explained: why we need to focus on increased consumption as much as population growth


Essentially, humans have created an ecological Ponzi scheme. Consumption, as a percentage of Earth’s capacity to regenerate itself, has grown from 73% in 1960 to more than 170% today.

High-consuming countries like Australia, Canada and the US use multiple units of fossil-fuel energy to produce one energy unit of food. Energy consumption will therefore increase in the near future, especially as the global middle class grows.

Then there’s climate change. Humanity has already exceeded global warming of 1°C this century, and will almost assuredly exceed 1.5 °C between 2030 and 2052. Even if all nations party to the Paris Agreement ratify their commitments, warming would still reach between 2.6°C and 3.1°C by 2100.

people walking on a crowded street
The human population is set to reach 10 billion by 2050.
Shutterstock

The danger of political impotence

Our paper found global policymaking falls far short of addressing these existential threats. Securing Earth’s future requires prudent, long-term decisions. However this is impeded by short-term interests, and an economic system that concentrates wealth among a few individuals.

Right-wing populist leaders with anti-environment agendas are on the rise, and in many countries, environmental protest groups have been labelled “terrorists”. Environmentalism has become weaponised as a political ideology, rather than properly viewed as a universal mode of self-preservation.

Financed disinformation campaigns against climate action and forest protection, for example, protect short-term profits and claim meaningful environmental action is too costly – while ignoring the broader cost of not acting. By and large, it appears unlikely business investments will shift at sufficient scale to avoid environmental catastrophe.

Changing course

Fundamental change is required to avoid this ghastly future. Specifically, we and many others suggest:

  • abolishing the goal of perpetual economic growth

  • revealing the true cost of products and activities by forcing those who damage the environment to pay for its restoration, such as through carbon pricing

  • rapidly eliminating fossil fuels

  • regulating markets by curtailing monopolisation and limiting undue corporate influence on policy

  • reigning in corporate lobbying of political representatives

  • educating and empowering women across the globe, including giving them control over family planning.

A coal plant
The true cost of environmental damage should be borne by those responsible.
Shutterstock

Don’t look away

Many organisations and individuals are devoted to achieving these aims. However their messages have not sufficiently penetrated the policy, economic, political and academic realms to make much difference.

Failing to acknowledge the magnitude and gravity of problems facing humanity is not just naïve, it’s dangerous. And science has a big role to play here.

Scientists must not sugarcoat the overwhelming challenges ahead. Instead, they should tell it like it is. Anything else is at best misleading, and at worst potentially lethal for the human enterprise.




Read more:
Mass extinctions and climate change: why the speed of rising greenhouse gases matters


The Conversation


Corey J. A. Bradshaw, Matthew Flinders Professor of Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University; Daniel T. Blumstein, Professor in the Department of Ecology and Evolutionary Biology and the Institute of the Environment and Sustainability, University of California, Los Angeles, and Paul Ehrlich, President, Center for Conservation Biology, Bing Professor of Population Studies, Stanford University

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

Gene editing is revealing how corals respond to warming waters. It could transform how we manage our reefs



Mikaela Nordborg/Australian Institute of Marine Science, Author provided

Dimitri Perrin, Queensland University of Technology; Jacob Bradford, Queensland University of Technology; Line K Bay, Australian Institute of Marine Science, and Phillip Cleves, Carnegie Institution for Science

Genetic engineering has already cemented itself as an invaluable tool for studying gene functions in organisms.

Our new study, published in the Proceedings of the National Academy of Sciences, now demonstrates how gene editing can be used to pinpoint genes involved in corals’ ability to withstand heat stress.

A better understanding of such genes will lay the groundwork for experts to predict the natural response of coral populations to climate change. And this could guide efforts to improve coral adaptation, through the selective breeding of naturally heat-tolerant corals.

A threatened national treasure

The Great Barrier Reef is among the world’s most awe-inspiring, unique and economically valuable ecosystems. It spans more than 2,000 kilometres, has more than 600 types of coral, 1,600 types of fish and is of immense cultural significance — especially for Traditional Owners.

But warming ocean waters caused by climate change are leading to the mass bleaching and mortality of corals on the reef, threatening the reef’s long-term survival.




Read more:
The first step to conserving the Great Barrier Reef is understanding what lives there


Many research efforts are focused on how we can prevent the reef’s deterioration by helping it adapt to and recover from the conditions causing it stress.

Understanding the genes and molecular pathways that protect corals from heat stress will be key to achieving these goals.

While hypotheses exist about the roles of particular genes and pathways, rigorous testings of these have been difficult — largely due to a lack of tools to determine gene function in corals.

But over the past decade or so, CRISPR/Cas9 gene editing has emerged as a powerful tool to study gene function in non-model organisms.

CRISPR: a technological marvel

Scientists can use CRISPR to make precise changes to the DNA of a living organisms, by “cutting” its DNA and editing the sequence. This can involve inactivating a specific gene, introducing a new piece of DNA or replacing a piece.

In our 2018 research, we showed it is possible to make precise mutations in the coral genome using CRISPR technology. However, we were unable to determine the functions of our specific target genes.

For our latest research, we used an updated CRISPR method to sufficiently disrupt the Heat Shock Transcription Factor 1, or HSF1, in coral larvae.

Based on this protein-coding gene’s role in model organisms, including closely related sea anemones, we hypothesised it would play an important role in the heat response of corals.

Injection going into coral egg.
We injected CRISPR components into the fertilised eggs of the coral species Acropora millepora to inactivate the HSF1 gene.
Phillip Cleves/Carnegie Institute for Science, CC BY-NC-ND

Past research had also demonstrated HSF1 can influence a large number of heat response genes, acting as a kind of “master switch” to turn them on.

By inactivating this master switch, we expected to see significant changes in the corals’ heat tolerance. Our prediction proved accurate.




Read more:
What is CRISPR, the gene editing technology that won the Chemistry Nobel prize?


What we discovered by injecting coral eggs

We spawned corals at the Australian Institute of Marine Science during the annual mass spawning event in November, 2018.

We then injected CRISPR/Cas9 components into fertilised coral eggs to target the HSF1 gene in the common and widespread staghorn coral Acropora millepora.

_Acropora millepora_ coral colony during a mass spawning event.
Acropora millepora colonies can be found widely on the Great Barrier Reef. They reproduce sexually in ‘mass spawning’ events.
Mikaela Nordborg/Australian Institute of Marine Science, Author provided

We were able to demonstrate a strong effect of HSF1 on corals’ heat tolerance. Specifically, when this gene was mutated using CRISPR (and no longer functional) the corals were more vulnerable to heat stress.

Larvae with knocked-out copies of HSF1 died under heat stress when the water temperature was increased from 27℃ to 34℃. In contrast, larvae with the functional gene survived well in the warmer water.

Let’s understand what we already have

It may be tempting now to focus on using gene-editing tools to engineer heat-resistant strains of corals, to fast-track the Great Barrier Reef’s adaptation to warming waters.

However, genetic engineering should first and foremost be used to increase our knowledge of the fundamental biology of corals and other reef organisms, including their response to heat stress.

Not only will this help us more accurately predict the natural response of coral reefs to a changing climate, it will also shed light on the risks and benefits of new management tools for corals, such as selective breeding.

It is our hope these genetic insights will provide a solid foundation for future reef conservation and management efforts.The Conversation

During mass spawning events, corals release little balls that float to the ocean’s surface in a spectacle resembling an upside-down snowstorm.

Dimitri Perrin, Senior Lecturer, Queensland University of Technology; Jacob Bradford, , Queensland University of Technology; Line K Bay, Principal Research Scientist and Team Leader, Australian Institute of Marine Science, and Phillip Cleves, Principal Investigator, Carnegie Institution for Science

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

Photos from the field: these magnificent whales are adapting to warming water, but how much can they take?



Olaf Meynecke, Author provided

Olaf Meynecke, Griffith University

Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.


The start of November marks the end of the whale season in the Southern Hemisphere. As summer approaches, whales that were breeding along the east and west coasts of Australia, Africa and South America will now swim further south to feed around Antarctica.

This annual cycle of whales coming and going has taken place for at least 10,000 years. But rising ocean temperatures from climate change are challenging this process, and my colleagues and I have already seen signs that humpback whales are changing their feeding, migration and breeding patterns to adapt.




Read more:
Genome and satellite technology reveal recovery rates and impacts of climate change on southern right whales


As krill stocks decline and ocean circulation is set to change more drastically, climate change remains an unprecedented threat to whales. The challenge now is to forecast what will happen next to better protect them.

Losing krill is the biggest threat

I’m part of an international team of researchers trying to learn what the next 100 years might look like for humpback whales in the Southern Hemisphere, and how they’ll adapt to changing ocean conditions.

Whales depend on recurring environmental conditions and oceanographic features, such as temperature, circulation, changing seasons and biogeochemical (nutrient) cycles. In particular, these features influence the availability of krill in the Southern Ocean, their biggest food source.

Whales are particularly sensitive to this because they need enormous amounts of food to develop sufficient fat reserves to migrate, give birth and nurse a calf, as they don’t eat during this time.

In fact, models predict declines in krill from climate change could lead to local extinctions of whales by 2100. This includes Pacific populations of blue, fin and southern right whales, as well as fin and humpback whales in the Atlantic and Indian oceans.




Read more:
Climate change threatens Antarctic krill and the sea life that depends on it


Still, when it comes to their migration and breeding cycles, recent studies have shown humpback whales can adapt with changes in ocean temperature and circulation at a remarkable level.

Whales can adapt to warming water, but at what cost?

In a long term study from the Northern Hemisphere, scientists found the arrival of humpback whales in some feeding grounds shifted by one day per year over a 27-year period in response to small fluctuations in ocean temperatures.

This led to a one-month shift in arrival time, but a big concern is whether they can continue to time their arrival with their prey in the future when the water gets warmer still.

Likewise, in breeding grounds near Hawaii, the number of mother and calf humpback whale sightings dropped by more than 75% between 2013 and 2018. This coincided with persistent warming in the Alaskan feeding grounds these whales had migrated from.

Collecting humpback whale exhale (“whale snot”)

But humpback whales shifting their distribution and behaviour can cause unexpected human encounters, and cause new challenges that weren’t an issue previously.

Research from earlier this year found humpback whales switched to fish as their main prey when the sea surface temperature in the California current system increased in a heatwave. This has been leading to record numbers of entanglements with gear from coastal fisheries.




Read more:
I measure whales with drones to find out if they’re fat enough to breed


And between 2013 and 2016, we documented hundreds of newborn humpback whales in subtropical and temperate shallow bays on the east coast of Australia, 1,000 kilometres further south from their traditional breeding areas off the Great Barrier Reef.

However, since these aren’t designated calving areas, the newborns aren’t well protected from getting tangled in shark nets or colliding with jet skis or cruise ships.

Protecting whales

The Whales and Climate Program is the largest project of its kind, combining hundreds of thousands of humpback whale sightings and advanced modelling techniques. Our aim is to advance whale conservation in response to climate change, and learn how it threatens their recovery after decades of over-exploitation by the whaling industry.

Each whale season between June and October, I sail out to the open ocean. This means I have unique opportunities to see and engage with whales, especially during the breeding season. The following photos show some of our breathtaking encounters, and can remind us of our marine ecosystem’s fragile beauty.

A humpback whale fin

Olaf Meynecke, Author provided
Breaching humpback whale in front of buildings

Olaf Meynecke, Author provided

During one of our boat-based surveys on the Gold Coast, we encountered this acrobatic humpback whale calf, shown in the photos above. We counted 254 breaches in two hours, making it the record holder of most breaches in our 10 years of observation.

To check on whales’ health, we collect and study the air they exhale through their blow hole (“whale snot”), and measure their size at different times of the year. The photo above shows me tagging a whale with CATs suction cup tags, to collect data on short term changes in their movement patterns.

Close up of a humpback whale's mouth

Olaf Meynecke, Author provided

In regions where the whales adapt to ocean changes and, as such, move closer to shore for feeding and shift their breeding grounds, there’s a higher risk of entanglements and other human encounters. This is particularly concerning when they travel outside protected areas.

A newborn humpback whale resting on its mum's head

Olaf Meynecke, Author provided

Look closely and you can see a newborn humpback, just one to three days old, resting on its mother’s head.

In the first days of life, baby humpback whales sink easily and aren’t able to stay on the water surface for long. They need their mothers’ support to stay on the surface to breathe.

Once they’ve gained enough fat from the mothers milk they become positively buoyant (meaning they can float), making it easier for them to breathe.

Photo of a whale underwater

Olaf Meynecke, Author provided

A final note — during one of our land-based whale surveys this year, a keen whale watcher approached us, and we helped him find the whales with our binoculars. I will never forget the joy in his face when he spotted them.

It’s a joy I hope many future generations can experience. To ensure this, we need to understand how we can best protect whales in a changing climate.




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Photos from the field: capturing the grandeur and heartbreak of Tasmania’s giant trees


The Conversation


Olaf Meynecke, Research Fellow in Marine Science, Griffith University

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

Earth may temporarily pass dangerous 1.5℃ warming limit by 2024, major new report says


Pep Canadell, CSIRO and Rob Jackson, Stanford University

The Paris climate agreement seeks to limit global warming to 1.5℃ this century. A new report by the World Meteorological Organisation warns this limit may be exceeded by 2024 – and the risk is growing.

This first overshoot beyond 1.5℃ would be temporary, likely aided by a major climate anomaly such as an El Niño weather pattern. However, it casts new doubt on whether Earth’s climate can be permanently stabilised at 1.5℃ warming.

This finding is among those just published in a report titled United in Science. We contributed to the report, which was prepared by six leading science agencies, including the Global Carbon Project.

The report also found while greenhouse gas emissions declined slightly in 2020 due to the COVID-19 pandemic, they remained very high – which meant atmospheric carbon dioxide concentrations have continued to rise.

Woman holds a sign at a climate protest
The world may exceed the 1.5℃ warming threshold sooner than we expected.
Erik Anderson/AAP

Greenhouse gases rise as CO₂ emissions slow

Concentrations of the three main greenhouse gases – carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), have all increased over the past decade. Current concentrations in the atmosphere are, respectively, 147%, 259% and 123% of those present before the industrial era began in 1750.

Concentrations measured at Hawaii’s Mauna Loa Observatory and at Australia’s Cape Grim station in Tasmania show concentrations continued to increase in 2019 and 2020. In particular, CO₂ concentrations reached 414.38 and 410.04 parts per million in July this year, respectively, at each station.

Atmospheric concentrations of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂0) from WMO Global Atmosphere Watch.

Growth in CO₂ emissions from fossil fuel use slowed to around 1% per year in the past decade, down from 3% during the 2000s. An unprecedented decline is expected in 2020, due to the COVID-19 economic slowdown. Daily CO₂ fossil fuel emissions declined by 17% in early April at the peak of global confinement policies, compared with the previous year. But by early June they had recovered to a 5% decline.

We estimate a decline for 2020 of about 4-7% compared to 2019 levels, depending on how the pandemic plays out.

Although emissions will fall slightly, atmospheric CO₂ concentrations will still reach another record high this year. This is because we’re still adding large amounts of CO₂ to the atmosphere.

Global daily fossil CO₂ emissions to June 2020. Updated from Le Quéré et al. 2020, Nature Climate Change.

Warmest five years on record

The global average surface temperature from 2016 to 2020 will be among the warmest of any equivalent period on record, and about 0.24℃ warmer than the previous five years.

This five-year period is on the way to creating a new temperature record across much of the world, including Australia, southern Africa, much of Europe, the Middle East and northern Asia, areas of South America and parts of the United States.




Read more:
The world endured 2 extra heatwave days per decade since 1950 – but the worst is yet to come


Sea levels rose by 3.2 millimetres per year on average over the past 27 years. The growth is accelerating – sea level rose 4.8 millimetres annually over the past five years, compared to 4.1 millimetres annually for the five years before that.

The past five years have also seen many extreme events. These include record-breaking heatwaves in Europe, Cyclone Idai in Mozambique, major bushfires in Australia and elsewhere, prolonged drought in southern Africa and three North Atlantic hurricanes in 2017.

Left: Global average temperature anomalies (relative to pre-industrial) from 1854 to 2020 for five data sets. UK-MetOffice. Right: Average sea level for the period from 1993 to July 16, 2020. European Space Agency and Copernicus Marine Service.

1 in 4 chance of exceeding 1.5°C warming

Our report predicts a continuing warming trend. There is a high probability that, everywhere on the planet, average temperatures in the next five years will be above the 1981-2010 average. Arctic warming is expected to be more than twice that the global average.

There’s a one-in-four chance the global annual average temperature will exceed 1.5℃ above pre-industrial levels for at least one year over the next five years. The chance is relatively small, but still significant and growing. If a major climate anomaly, such as a strong El Niño, occurs in that period, the 1.5℃ threshold is more likely to be crossed. El Niño events generally bring warmer global temperatures.

Under the Paris Agreement, crossing the 1.5℃ threshold is measured over a 30-year average, not just one year. But every year above 1.5℃ warming would take us closer to exceeding the limit.

Global average model prediction of near surface air temperature relative to 1981–2010. Black line = observations, green = modelled, blue = forecast. Probability of global temperature exceeding 1.5℃ for a single month or year shown in brown insert and right axis. UK Met Office.

Arctic Ocean sea-ice disappearing

Satellite records between 1979 and 2019 show sea ice in the Arctic summer declined at about 13% per decade, and this year reached its lowest July levels on record.

In Antarctica, summer sea ice reached its lowest and second-lowest extent in 2017 and 2018, respectively, and 2018 was also the second-lowest winter extent.

Most simulations show that by 2050, the Arctic Ocean will practically be free of sea ice for the first time. The fate of Antarctic sea ice is less certain.

A polar bear on an ice floe
Summer sea ice in the Arctic is expected to virtually disappear by 2050.
Zaruba Ondrej/AP

Urgent action can change trends

Human activities emitted 42 billion tonnes of CO₂ in 2019 alone. Under the Paris Agreement, nations committed to reducing emissions by 2030.

But our report shows a shortfall of about 15 billion tonnes of CO₂ between these commitments, and pathways consistent with limiting warming to well below 2℃ (the less ambitious end of the Paris target). The gap increases to 32 billion tonnes for the more ambitious 1.5℃ goal.

Our report models a range of climate outcomes based on various socioeconomic and policy scenarios. It shows if emission reductions are large and sustained, we can still meet the Paris goals and avoid the most severe damage to the natural world, the economy and people. But worryingly, we also have time to make it far worse.




Read more:
Coronavirus is a ‘sliding doors’ moment. What we do now could change Earth’s trajectory


The Conversation


Pep Canadell, Chief research scientist, Climate Science Centre, CSIRO Oceans and Atmosphere; and Executive Director, Global Carbon Project, CSIRO and Rob Jackson, Chair, Department of Earth System Science, and Chair of the Global Carbon Project, Stanford University

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

Ocean warming threatens coral reefs and soon could make it harder to restore them



Climate-driven ocean warming threatens healthy coral reefs, like this one in Hawaii.
Shawna Foo, CC BY-ND

Shawna Foo, Arizona State University

Graphic stating that at 86.9 degrees Fahrenheit, the chance of transplanted corals surviving falls below 50%

CC BY-ND

Anyone who’s tending a garden right now knows what extreme heat can do to plants. Heat is also a concern for an important form of underwater gardening: growing corals and “outplanting,” or transplanting them to restore damaged reefs.

The goal of outplanting is to aid coral reefs’ natural recovery process by growing new corals and moving them to the damaged areas. It’s the same idea as replanting forests that have been heavily logged, or depleted farm fields that once were prairie grasslands.

I have studied how global stressors such as ocean warming and acidification affect marine invertebrates for more than a decade. In a recently published study, I worked with Gregory Asner to analyze the impacts of temperature on coral reef restoration projects. Our results showed that climate change has raised sea surface temperatures close to a point that will make it very hard for outplanted corals to survive.

Coral gardening

Coral reefs support over 25% of marine life by providing food, shelter and a place for fish and other organisms to reproduce and raise young. Today, ocean warming driven by climate change is stressing reefs worldwide.

Rising ocean temperatures cause bleaching events – episodes in which corals expel the algae that live inside them and provide the corals with most of their food, as well as their vibrant colors. When corals lose their algae, they become less resistant to stressors such as disease and eventually may die.

Hundreds of organizations worldwide are working to restore damaged coral reefs by growing thousands of small coral fragments in nurseries, which may be onshore in laboratories or in the ocean near degraded reefs. Then scuba divers physically plant them at restoration sites.

Outplanting is the process of transplanting nursery-grown corals onto reefs.

Outplanting coral is expensive: According to one recent study, the median cost is about US$160,000 per acre, or $400,000 per hectare. It also is time-consuming, with scuba divers placing each outplanted coral by hand. So it’s important to maximize coral survival by choosing the best locations.

We used data from the National Oceanic and Atmosphere Administration’s Coral Reef Watch program, which collects daily satellite-derived measurements of sea surface temperature. We paired this information with survival rates from hundreds of coral outplanting projects worldwide.

We found that coral survival was likely to drop below 50% if the maximum temperature experienced at the restoration site exceeded 86.9 degrees Fahrenheit (30.5 degrees Celsius). This temperature threshold mirrors the tolerance of natural coral reefs.

Globally, coral reefs experience an annual maximum temperature today of 84.9˚F (29.4˚C). This means they already are living close to their upper thermal limit.

When reefs experience temperatures only a few degrees above long-term averages for a few weeks, the stress can cause coral bleaching and mortality. Increases of just a few degrees above normal caused three mass bleaching events since 2016 that have devastated Australia’s Great Barrier Reef.

Map of global sea surface temperatures, color coded to show bleaching risks.
Sea surface temperatures on Aug. 3, 2020, measured from satellites. Warning = possible bleaching; Alert Level 1 = significant bleaching likely; Alert Level 2 = severe bleaching and significant mortality likely.
NOAA Coral Reef Watch

Warmer oceans

Climate scientists project that the oceans will warm up to 3˚C by the year 2100. Scientists are working to create coral outplants that can better survive increases in temperature, which could help to increase restoration success in the future.

When coral restoration experts choose where to outplant, they typically consider what’s on the seafloor, algae that could smother coral, predators that eat coral and the presence of fish. Our study shows that using temperature data and other information collected remotely from airplanes and satellites could help to optimize this process. Remote sensing, which scientists have used to study coral reefs for almost 40 years, can provide information on much larger scales than water surveys.

Coral reefs face an uncertain future and may not recover naturally from human-caused climate change. Conserving them will require reducing greenhouse gas emissions, protecting key habitats and actively restoring reefs. I hope that our research on temperature will help increase coral outplant survival and restoration success.

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

Shawna Foo, Postdoctoral Research Scholar, Arizona State University

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

Ocean warming has fisheries on the move, helping some but hurting more



An Atlantic cod on ice. Cod fisheries in the North Sea and Irish Sea are declining due to overfishing and climate change.
Robert F. Bukaty/AP

Chris Free, University of California, Santa Barbara

Climate change has been steadily warming the ocean, which absorbs most of the heat trapped by greenhouse gases in the atmosphere, for 100 years. This warming is altering marine ecosystems and having a direct impact on fish populations. About half of the world’s population relies on fish as a vital source of protein, and the fishing industry employs more the 56 million people worldwide.

My recent study with colleagues from Rutgers University and the U.S. National Oceanic and Atmospheric Administration found that ocean warming has already impacted global fish populations. We found that some populations benefited from warming, but more of them suffered.

Overall, ocean warming reduced catch potential – the greatest amount of fish that can be caught year after year – by a net 4% over the past 80 years. In some regions, the effects of warming have been much larger. The North Sea, which has large commercial fisheries, and the seas of East Asia, which support some of the fastest-growing human populations, experienced losses of 15% to 35%.

The reddish and brown circles represent fish populations whose maximum sustainable yields have dropped as the ocean has warmed. The darkest tones represent extremes of 35 percent. Blueish colors represent fish yields that increased in warmer waters.
Chris Free, CC BY-ND

Although ocean warming has already challenged the ability of ocean fisheries to provide food and income, swift reductions in greenhouse gas emissions and reforms to fisheries management could lessen many of the negative impacts of continued warming.

How and why does ocean warming affect fish?

My collaborators and I like to say that fish are like Goldilocks: They don’t want their water too hot or too cold, but just right.

Put another way, most fish species have evolved narrow temperature tolerances. Supporting the cellular machinery necessary to tolerate wider temperatures demands a lot of energy. This evolutionary strategy saves energy when temperatures are “just right,” but it becomes a problem when fish find themselves in warming water. As their bodies begin to fail, they must divert energy from searching for food or avoiding predators to maintaining basic bodily functions and searching for cooler waters.

Thus, as the oceans warm, fish move to track their preferred temperatures. Most fish are moving poleward or into deeper waters. For some species, warming expands their ranges. In other cases it contracts their ranges by reducing the amount of ocean they can thermally tolerate. These shifts change where fish go, their abundance and their catch potential.

Warming can also modify the availability of key prey species. For example, if warming causes zooplankton – small invertebrates at the bottom of the ocean food web – to bloom early, they may not be available when juvenile fish need them most. Alternatively, warming can sometimes enhance the strength of zooplankton blooms, thereby increasing the productivity of juvenile fish.

Understanding how the complex impacts of warming on fish populations balance out is crucial for projecting how climate change could affect the ocean’s potential to provide food and income for people.

Warming is affecting virtually all regions of the ocean.

Impacts of historical warming on marine fisheries

Sustainable fisheries are like healthy bank accounts. If people live off the interest and don’t overly deplete the principal, both people and the bank thrive. If a fish population is overfished, the population’s “principal” shrinks too much to generate high long-term yields.

Similarly, stresses on fish populations from environmental change can reduce population growth rates, much as an interest rate reduction reduces the growth rate of savings in a bank account.

In our study we combined maps of historical ocean temperatures with estimates of historical fish abundance and exploitation. This allowed us to assess how warming has affected those interest rates and returns from the global fisheries bank account.

Losers outweigh winners

We found that warming has damaged some fisheries and benefited others. The losers outweighed the winners, resulting in a net 4% decline in sustainable catch potential over the last 80 years. This represents a cumulative loss of 1.4 million metric tons previously available for food and income.

Some regions have been hit especially hard. The North Sea, with large commercial fisheries for species like Atlantic cod, haddock and herring, has experienced a 35% loss in sustainable catch potential since 1930. The waters of East Asia, neighbored by some of the fastest-growing human populations in the world, saw losses of 8% to 35% across three seas.

Other species and regions benefited from warming. Black sea bass, a popular species among recreational anglers on the U.S. East Coast, expanded its range and catch potential as waters previously too cool for it warmed. In the Baltic Sea, juvenile herring and sprat – another small herring-like fish – have more food available to them in warm years than in cool years, and have also benefited from warming. However, these climate winners can tolerate only so much warming, and may see declines as temperatures continue to rise.

Shucking scallops in Maine, where fishery management has kept scallop numbers sustainable.
Robert F. Bukaty/AP

Management boosts fishes’ resilience

Our work suggests three encouraging pieces of news for fish populations.

First, well-managed fisheries, such as Atlantic scallops on the U.S. East Coast, were among the most resilient to warming. Others with a history of overfishing, such as Atlantic cod in the Irish and North seas, were among the most vulnerable. These findings suggest that preventing overfishing and rebuilding overfished populations will enhance resilience and maximize long-term food and income potential.

Second, new research suggests that swift climate-adaptive management reforms can make it possible for fish to feed humans and generate income into the future. This will require scientific agencies to work with the fishing industry on new methods for assessing fish populations’ health, set catch limits that account for the effects of climate change and establish new international institutions to ensure that management remains strong as fish migrate poleward from one nation’s waters into another’s. These agencies would be similar to multinational organizations that manage tuna, swordfish and marlin today.

Finally, nations will have to aggressively curb greenhouse gas emissions. Even the best fishery management reforms will be unable to compensate for the 4 degree Celsius ocean temperature increase that scientists project will occur by the end of this century if greenhouse gas emissions are not reduced.

[ Like what you’ve read? Want more? Sign up for The Conversation’s daily newsletter. ]The Conversation

Chris Free, Postdoctoral Scholar, University of California, Santa Barbara

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

A landmark report confirms Australia is girt by hotter, higher seas. But there’s still time to act



Aerial imagery revealing the extent of storm damage in Dee Why on Sydney’s Northern Beaches in 2016 following wild weather.
NEARMAP/AAP

Jess Melbourne-Thomas, CSIRO; Kathleen McInnes, CSIRO; Nathan Bindoff, University of Tasmania, and Nerilie Abram, Australian National University

A landmark scientific report has confirmed that climate change is altering the world’s seas and ice at an unprecedented rate. Australia depends on the ocean that surrounds us for our health and prosperity. So what does this mean for us, and life on Earth?

The Intergovernmental Panel on Climate Change (IPCC) findings were launched in Monaco on Wednesday night. They provide the most definitive scientific evidence yet of warmer, more acidic and less productive seas. Glaciers and ice sheets are melting, causing sea level to rise at an accelerating rate.

The implications for Australia are serious. Extreme sea level events that used to hit once a century will occur once a year in many of the world’s coastal places by 2050. This situation is inevitable, even if greenhouse gas emissions are dramatically curbed.

The findings, titled the Special Report on the Ocean and Cryosphere in a Changing Climate, strengthen the already compelling case for countries to meet their emission reduction goals under the 2015 Paris agreement.

Beachgoers cool off in the water at Bondi Beach in Sydney, February 2019. Australia’s coast dwellers must adapt to the inevitable effects of climate change.
Joel Carrett/AAP



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A rapid and dramatic cut in greenhouse gas emissions would prevent the most catastrophic damage to the ocean and cryosphere (frozen polar and mountain regions). This would help protect the ecosystems and people that rely on them.

The report entailed two years of work by 104 authors and review editors from 36 countries, who assessed nearly 7,000 scientific papers and responded to more than 30,000 review comments.

The picture is worse than we thought

Mountain glaciers and polar ice sheets are shrinking and, together with expansion of the warming ocean, are contributing to an increasing rate of sea level rise.

During the last century, global sea levels rose about 15cm. Seas are now rising more than twice as fast – 3.6mm per year – and accelerating, the report shows.

The IPCC’s projections are more dire than in its 2014 oceans report. It has revised upwards by 10% the effect of the melting Antarctic ice sheet on sea level rise by 2100. Antarctica appears to be changing more rapidly than was thought possible even five years ago, and further work is needed to understand just how quickly ice will be lost from Antarctica in future.

Key components and changes of the ocean and cryosphere, and their linkages in the Earth system.
IPCC, 2019

If you live near the Australian coast, change is coming

By 2050, more than one billion of the world’s people will live on coastal land less than 10 metres above sea level. They will be exposed to combinations of sea level rise, extreme winds, waves, storm surges and flooding from intensified storms and tropical cyclones.

Many of Australia’s coastal cities and communities can expect to experience what was previously a once-in-a-century extreme coastal flooding event at least once every year by the middle of this century.

Our island neighbours in Indonesia and the Pacific will also be hit hard. The report warns that some island nations are likely to become uninhabitable – although the extent of this is hard to assess accurately.

Some change is inevitable and we will have to adapt. But the report also delivered a strong message about the choices that still remain. In the case of extreme sea level events around Australia, we believe a marked global reduction in greenhouse as emissions would buy us more than 10 years of extra time, in some places, to protect our coastal communities and infrastructure from the rising ocean.

Indonesian residents wade through flood water in Jakarta. The northwestern part of Jakarta is rapidly sinking.
MAST IRHAM/EPA

More frequent extreme events are often occurring at the same time or in quick succession. Tasmania’s summer of 2015-16 is a good example. The state experienced record-breaking drought which worsened the fire threat in the highlands. An unprecedented marine heatwave along the east coast damaged kelp forests and caused disease and death of shellfish, and the state’s northeast suffered severe flooding.

This string of events stretched emergency services, energy supplies and the aquaculture and manufacturing industries. The total economic cost to the state government was an estimated A$445 million. The impacts on the food, energy and manufacturing sectors cut Tasmania’s anticipated economic growth by about half.

Reefs and fish stocks are suffering

The ocean has taken a huge hit from climate change – taking up heat, absorbing carbon dioxide that makes the water more acidic, and losing oxygen. It will bring ocean conditions unlike anything we have seen before.

Marine ecosystems and fisheries around the world are under pressure from this barrage of stressors. Overall, the fisheries potential around Australia’s coasts is expected to decline during this century.

Heat build-up in the surface ocean has already triggered a marked rise in the intensity, frequency and duration of marine heatwaves. Ocean heatwaves are expected to become between four and ten times more common this century, depending on how rapidly global warming continues.

The report said coral reefs, including the Great Barrier Reef, are already at very high risk from climate change and are expected to suffer significant losses and local extinctions. This would occur even if global warming is limited to 1.5℃ – a threshold the world is set to overshoot by a wide margin.




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Extreme weather caused by climate change has damaged 45% of Australia’s coastal habitat


Our choices now are critical for the future

This report reinforces the findings of earlier reports on the importance of limiting global warming warming to 1.5℃ if we are to avoid major impacts on the land, the ocean and frozen areas.

Even if we act now to drastically reduce greenhouse gas emissions, some damage is already locked in and our ocean and frozen regions will continue to change for decades to centuries to come.

Mertz Glacier in east Antarctica. IPCC scientists say the expected effect of melting Antarctic ice on sea level rise is worse than projected five years ago.
Australian Antarctic Division

In Australia, we will need to adapt our coastal cities and communities to unavoidable sea level rise. There are a range of possible options, from building barriers to planned relocation, to protecting the coral reefs and mangroves that provide natural coastal defences.

But if we want to give adaptation the best chance of working, the clear message of this new report is that we need to reduce greenhouse gas emissions as quickly as possible.The Conversation

Jess Melbourne-Thomas, Transdisciplinary Researcher & Knowledge Broker, CSIRO; Kathleen McInnes, Senior research scientist, CSIRO; Nathan Bindoff, Professor of Physical Oceanography, Institute for Marine and Antarctic Studies, University of Tasmania, and Nerilie Abram, ARC Future Fellow, Research School of Earth Sciences; Chief Investigator for the ARC Centre of Excellence for Climate Extremes, Australian National University

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

The air above Antarctica is suddenly getting warmer – here’s what it means for Australia



Antarctic winds have a huge effect on weather in other places.
NASA Goddard Space Flight Center/Flickr, CC BY-SA

Harry Hendon, Australian Bureau of Meteorology; Andrew B. Watkins, Australian Bureau of Meteorology; Eun-Pa Lim, Australian Bureau of Meteorology, and Griffith Young, Australian Bureau of Meteorology

Record warm temperatures above Antarctica over the coming weeks are likely to bring above-average spring temperatures and below-average rainfall across large parts of New South Wales and southern Queensland.

The warming began in the last week of August, when temperatures in the stratosphere high above the South Pole began rapidly heating in a phenomenon called “sudden stratospheric warming”.




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In the coming weeks the warming is forecast to intensify, and its effects will extend downward to Earth’s surface, affecting much of eastern Australia over the coming months.

The Bureau of Meteorology is predicting the strongest Antarctic warming on record, likely to exceed the previous record of September 2002.

(Left) Observation of September 2002 stratospheric warming compared to (right) 2019 forecast for September.
The forecast for 2019 was provided by the Australian Bureau of Meteorology and was initialised on August 30, 2019.

What’s going on?

Every winter, westerly winds – often up to 200km per hour – develop in the stratosphere high above the South Pole and circle the polar region. The winds develop as a result of the difference in temperature over the pole (where there is no sunlight) and the Southern Ocean (where the sun still shines).

As the sun shifts southward during spring, the polar region starts to warm. This warming causes the stratospheric vortex and associated westerly winds to gradually weaken over the period of a few months.

However, in some years this breakdown can happen faster than usual. Waves of air from the lower atmosphere (from large weather systems or flow over mountains) warm the stratosphere above the South Pole, and weaken or “mix” the high-speed westerly winds.

Very rarely, if the waves are strong enough they can rapidly break down the polar vortex, actually reversing the direction of the winds so they become easterly. This is the technical definition of “sudden stratospheric warming.”

Although we have seen plenty of weak or moderate variations in the polar vortex over the past 60 years, the only other true sudden stratospheric warming event in the Southern Hemisphere was in September 2002.

In contrast, their northern counterpart occurs every other year or so during late winter of the Northern Hemisphere because of stronger and more variable tropospheric wave activity.

What can Australia expect?

Impacts from this stratospheric warming are likely to reach Earth’s surface in the next month and possibly extend through to January.

Apart from warming the Antarctic region, the most notable effect will be a shift of the Southern Ocean westerly winds towards the Equator.

For regions directly in the path of the strongest westerlies, which includes western Tasmania, New Zealand’s South Island, and Patagonia in South America, this generally results in more storminess and rainfall, and colder temperatures.

But for subtropical Australia, which largely sits north of the main belt of westerlies, the shift results in reduced rainfall, clearer skies, and warmer temperatures.

Past stratospheric warming events and associated wind changes have had their strongest effects in NSW and southern Queensland, where springtime temperatures increased, rainfall decreased and heatwaves and fire risk rose.

The influence of the stratospheric warming has been captured by the Bureau’s climate outlooks, along with the influence of other major climate drivers such as the current positive Indian Ocean Dipole, leading to a hot and dry outlook for spring.

Anomalous Australian climate conditions during the nine most significant polar vortex weakening years (1979, 1988, 2000, 2002, 2004, 2005, 2012, 2013, 2016) on both maximum and minimum temperatures, and rainfall for October-November, as compared to all other years between 1979-2016.
Bureau of Meteorology

Effects on the ozone hole and Antarctic sea ice

One positive note of sudden stratospheric warming is the reduction – or even absence altogether – of the spring Antarctic ozone hole. This is for two reasons.

First, the rapid rise of temperatures in the upper atmosphere means the super cold polar stratospheric ice clouds, which are vital for the chemical process that destroys ozone, may not even form.

Secondly, the disrupted winds carry more ozone-rich air from the tropics to the polar region, helping repair the ozone hole.

We also expect an enhanced decline in Antarctic sea ice between October and January, particularly in the eastern Ross Sea and western Amundsen Sea, as more warm water moves towards the poles due to the weaker westerly winds.




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Thanks to improvements in modelling and the Bureau’s new supercomputer, these types of events can be forecast better than ever before. Compared to 2002, when we didn’t know much about the event until after it had happened, this time we’ve had almost three weeks’ notice that a very strong warming event was coming. We also know much more about the process that has been set in train, that will affect our weather over the next one to four months.The Conversation

Harry Hendon, Senior Principal Research Scientist, Australian Bureau of Meteorology; Andrew B. Watkins, Manager of Long-range Forecast Services, Australian Bureau of Meteorology; Eun-Pa Lim, Senior research scientist, Australian Bureau of Meteorology, and Griffith Young, Senior IT Officer, Australian Bureau of Meteorology

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

New research shows that Antarctica’s largest floating ice shelf is highly sensitive to warming of the ocean



Since the last ice age, the ice sheet retreated over a thousand kilometres in the Ross Sea region, more than any other region on the continent.
Rich Jones, CC BY-ND

Dan Lowry, Victoria University of Wellington

Scientists have long been concerned about the potential collapse of the West Antarctic Ice Sheet and its contribution to global sea level rise. Much of West Antarctica’s ice lies below sea level, and warming ocean temperatures may lead to runaway ice sheet retreat.

This process, called marine ice sheet instability, has already been observed along parts of the Amundsen Sea region, where warming of the ocean has led to melting underneath the floating ice shelves that fringe the continent. As these ice shelves thin, the ice grounded on land flows more rapidly into the ocean and raises the sea level.

Although the Amundsen Sea region has shown the most rapid changes to date, more ice actually drains from West Antarctica via the Ross Ice Shelf than any other area. How this ice sheet responds to climate change in the Ross Sea region is therefore a key factor in Antarctica’s contribution to global sea level rise in the future.

Periods of past ice sheet retreat can give us insights into how sensitive the Ross Sea region is to changes in ocean and air temperatures. Our research, published today, argues that ocean warming was a key driver of glacial retreat since the last ice age in the Ross Sea. This suggests that the Ross Ice Shelf is highly sensitive to changes in the ocean.




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History of the Ross Sea

Since the last ice age, the ice sheet retreated more than 1,000km in the Ross Sea region – more than any other region on the continent. But there is little consensus among the scientific community about how much climate and the ocean have contributed to this retreat.

Much of what we know about the past ice sheet retreat in the Ross Sea comes from rock samples found in the Transantarctic Mountains. Dating techniques allow scientists to determine when these rocks were exposed to the surface as the ice around them retreated. These rock samples, which were collected far from where the initial ice retreat took place, have generally led to interpretations in which the ice sheet retreat happened much later than, and independently of, the rise in air and ocean temperatures following the last ice age.

But radiocarbon ages from sediments in the Ross Sea suggest an earlier retreat, more in line with when climate began to warm from the last ice age.

An iceberg floating in the Ross Sea – an area that is sensitive to warming in the ocean.
Rich Jones, CC BY-ND

Using models to understand the past

To investigate how sensitive this region was to past changes, we developed a regional model of the Antarctic ice sheet. The model works by simulating the physics of the ice sheet and its response to changes in ocean and air temperatures. The simulations are then compared to geological records to check accuracy.

Our main findings are that warming of the ocean and atmosphere were the main causes of the major glacial retreat that took place in the Ross Sea region since the last ice age. But the dominance of these two controls in influencing the ice sheet evolved through time. Although air temperatures influenced the timing of the initial ice sheet retreat, ocean warming became the main driver due to melting of the Ross Ice Shelf from below, similar to what is currently observed in the Amundsen Sea.

The model also identifies key areas of uncertainty of past ice sheet behaviour. Obtaining sediment and rock samples and oceanographic data would help to improve modelling capabilities. The Siple Coast region of the Ross Ice Shelf is especially sensitive to changes in melt rates at the base of the ice shelf, and is therefore a critical region to sample.




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Implications for the future

Understanding processes that were important in the past allows us to improve and validate our model, which in turn gives us confidence in our future projections. Through its history, the ice sheet in the Ross Sea has been sensitive to changes in ocean and air temperatures. Currently, ocean warming underneath the Ross Ice Shelf is the main concern, given its potential to cause melting from below.

Challenges remain in determining exactly how ocean temperatures will change underneath the Ross Ice Shelf in the coming decades. This will depend on changes to patterns of ocean circulation, with complex interactions and feedback between sea ice, surface winds and melt water from the ice sheet.

Given the sensitivity of ice shelves to ocean warming, we need an integrated modelling approach that can accurately reproduce both the ocean circulation and dynamics of the ice sheet. But the computational cost is high.

Ultimately, these integrated projections of the Southern Ocean and Antarctic ice sheet will help policymakers and communities to develop meaningful adaptation strategies for cities and coastal infrastructure exposed to the risk of rising seas.The Conversation

Dan Lowry, PhD candidate, Victoria University of Wellington

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

Warming oceans are changing Australia’s fishing industry



File 20180710 122253 9yj55v.jpg?ixlib=rb 1.1
Ocean fish are changing where they live due to climate change.
Annie spratt/Unsplash, CC BY-SA

Alistair Hobday, CSIRO; Beth Fulton, CSIRO, and Gretta Pecl, University of Tasmania

A new United Nations report on fisheries and climate change shows that Australian marine systems are undergoing rapid environmental change, with some of the largest climate-driven changes in the Southern Hemisphere.

Reports from around the world have found that many fish species are changing their distribution. This movement threatens to disrupt fishing as we know it.

While rapid change is predicted to continue, researchers and managers are working with fishers to ensure a sustainable industry.




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Lessons from across the world

Large climate-driven changes in species distribution and abundance are evident around the world. While some species will increase, global models project declining seafood stocks in tropical regions, where people can least afford alternative foods.

The global concern for seafood changes led the UN Food and Agriculture Organisation (FAO) to commission a new report on the impacts of climate change on fisheries and aquaculture. More than 90 experts from some 20 countries contributed, including us.

The report describes many examples of climate-related change. For instance, the northern movement of European mackerel into Icelandic waters has led to conflict with more southerly fishing states, and apparently contributed to Iceland’s exit from negotiations over its prospective European Union membership.




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Changes in fish abundance and behaviour can lead to conflicts in harvesting, as occurred in the Maine lobster fishery. Indirect effects of climate change, such as disease outbreaks and algal blooms, have already temporarily closed fisheries in several countries, including the United States and Australia.

All these changes in turn impact the people who depend on fish for food and livelihoods.

Climate change and fisheries in Australia

The Australian chapter summarises the rapid ocean change in our region. Waters off southeastern and southwestern Australia are particular warming hotspots. Even our tropical oceans are warming almost twice as fast as the global average.




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More than 100 Australian marine species have already begun to shift their distributions southwards. Marine heatwaves and other extreme events have harmed Australia’s seagrass, kelp forests, mangroves and coral reefs. Australia’s marine ecosystems and commercial fisheries are clearly already being affected by climate change.

Summary of recent climate-related marine impacts in Australia. Warming on both coasts is also moving species southwards.
Author provided

In the Australian FAO chapter, we present information from climate sensitivity analysis and ecosystem models to help managers and fishers prepare for change.

We need to preparing climate-ready fisheries, to minimise negative impacts and to make the most of new opportunities that arise.

Experts from around Australia have rated the sensitivity of more than 100 fished species to climate change, based on their life-history traits. They found that 70% of assessed species have moderate to high sensitivity. As a group, invertebrates are the most sensitive, and pelagic fishes (that live in the open ocean sea) the least.

A range of ecosystem models have also been used to explore how future climate change will impact Australia’s fisheries over the next 40 years. While results varied around Australia, a common projection was that ecosystem production will become more variable.

As fish abundance and distribution changes, predation and competition within food webs will be affected. New food webs may form, changing ecosystems in unexpected ways. In some regions (such as southeastern Australia) the ecosystem may eventually shift into a new state that is quite different to today.

How can Australian fisheries respond?

Our ecosystem models indicate that sustainable fisheries are possible, if we’re prepared to make some changes. This finding builds on Australia’s strong record in fisheries management, supported by robust science, which positions it well to cope with the impacts of climate change. Fortunately, less than 15% of Australia’s assessed fisheries are overfished, with an improving trend.

We have identified several actions that can help fisheries adapt to climate change:

  • Management plans need to prioritise the most sensitive species and fisheries, and take the easiest actions first, such as changing the timing or location of operations to match changing conditions.



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  • As ecosystem changes span state and national boundaries, greater coordination is needed across all Australian jurisdictions, and between all the users of the marine environment. For example, policy must be developed to deal with fixed fishing zones when species distribution changes.

  • Fisheries policy, management and assessment methods need to prepare for both long-term changes and extreme events. Australian fisheries have already shifted to more conservative targets which have provided for increased ecological resilience. Additional quota changes may be needed if stock productivity changes.

  • In areas where climate is changing rapidly, agile management responses will be required so that action can be taken quickly and adjusted when new information becomes available.

  • Ultimately, we may need to target new species. This means that Australians will have to adapt to buying (and cooking) new types of fish.




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The ConversationResearchers from a range of organisations and agencies around Australia are now tackling these issues, in partnership with the fishing industry, to ensure that coastal towns with vibrant commercial fishing and aquaculture businesses continue to provide sustainable seafood.

Alistair Hobday, Senior Principal Research Scientist – Oceans and Atmosphere, CSIRO; Beth Fulton, CSIRO Research Group Leader Ecosystem Modelling and Risk Assessment, CSIRO, and Gretta Pecl, Professor, ARC Future Fellow & Editor in Chief (Reviews in Fish Biology & Fisheries), University of Tasmania

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