After delays, cancellations and far too much talk about poo, the River Seine was finally given its chance to shine, highlighting an important issue about the health of our major rivers.
Paris made the Seine central to the opening ceremony at the 2024 Olympic Games, and now Brisbane’s past and present leaders weigh in on whether the city could replicate the experience in 2032.
The Southern Ocean is wild and dynamic. It experiences Earth’s strongest winds and largest waves. It is home to city-sized icebergs and the biggest ocean current on the globe, as well as tiny turbulent flows that fit inside a teacup.
The Southern Ocean is also crucial to Earth’s natural systems. It forms the dense water that fills the world’s deep oceans. It stores heat and carbon resulting from human-caused global warming, and controls the flux of heat to the huge ice sheet of Antarctica – the greatest threat to runaway global sea-level rise.
The scale and complexity of the Southern Ocean can be hard to comprehend. But our new paper may help. It summarises the present state of understanding of the Southern Ocean, how it is changing, and where the knowledge gaps lie.
Scientists and others regularly voyage to the Southern Ocean’s furthermost icy reaches – but more research is needed. The scientific and broader community must join together to advance Southern Ocean science and protect this vital natural asset.
The Antarctic Ice Sheet is the largest ice mass on Earth, equivalent to 58 metres of the global sea level.
The ice sheet flows onto the Southern Ocean surface in the form of giant ice shelves. Many of these ice shelves are being eaten away from below by a warmer ocean, or crumbling and becoming icebergs at a faster rate than before.
Beyond the ice shelves, millions of square kilometres of the Southern Ocean surface is frozen into a layer of sea ice. This acts as a giant solar reflector and shields ice shelves from powerful Southern Ocean waves.
After decades of seemingly defying warming temperatures, the Southern Ocean’s sea ice has dramatically declined in recent years. This puts ice shelves and the ice sheet under even greater stress.
Much of the sea ice is produced in small regions of open water, called “polynyas”, formed by strong and cold winds blowing off Antarctica. These winds cool the ocean surface below the freezing point, causing ice to form.
As the ice forms it ejects salt into the ocean surface. This extra salt, in addition to cooling effects from the atmosphere, makes the surface seawater heavier, or more “dense”.
The dense water sinks in turbulent plumes (imagine an upside-down volcano) and cascades through underwater canyons into the deep ocean, while mixing with overlying waters.
The resulting dense water mass, produced in only a few relatively small regions of Antarctica, accounts for an extraordinary 40% of the global ocean volume. It is ultimately lifted back to the ocean surface by centimetre-scale turbulent eddies – of the type you see when mixing milk into your tea.
In the deep ocean, this mixing is largely driven by ocean tides that slosh over the rough seafloor and produce internal waves.
It takes many hundreds of years for the ocean water to cycle from the surface Southern Ocean to the deep and back. Water returning to the surface today is like a time capsule, reflecting the cooler, pre-industrial climate when it first sank to the ocean depths.
The water that sinks today has absorbed more carbon to store in the deep ocean, helping to limit global warming.
However, models and observations suggest reductions in sea ice and ice shelves are weakening this crucial climate system. They are making the water warmer, less salty and more buoyant, so less prone to sinking. This means less carbon storage and a warmer atmosphere in the years ahead.
Making measurements in the Southern Ocean is immensely challenging due to its remote location and hostile conditions. This means in many cases data is sparse, and so scientists don’t know exactly how quickly changes are occurring.
Our review identified several areas as a key priority for future Southern Ocean research. They include observations of ocean temperatures and melting beneath ice shelves, as well as long term measurements of dense water formation.
More data is needed to monitor changes and provide early warning of significant climate events, such as ice sheet collapse. Crucially, more data is also needed to inform and assess the computer models on which government, industry and society rely to predict future climate.
Unfortunately, ocean observations are expensive. For example, Australia’s premier research vessel, the RV Investigator, costs more than A$100,000 a day to run. And the new SWOT satellite – a joint project of the European Union and United States to measure the ocean surface at unprecedented resolution – cost more than US$1 billion.
These costs also highlight the need for enhanced national and international collaboration. This would make the best use of available resources, and promote technological innovation to develop more cost-effective observing systems such as drones and drifting robotic instruments.
The federal government’s scientific priorities and funding decisions should reflect the crucial importance of Southern Ocean science.
We are currently in the UN Decade of Ocean Science, which aims to improve predictions of ocean and climate change. Improved understanding of the Southern Ocean is vital to this effort.
Luke Bennetts receives funding from the Australian Research Council.
Callum Shakespeare receives funding from the Australian Research Council
Catherine Vreugdenhil receives funding from the Australian Research Council.
The new budget comes after the previous government failed to award a single new offshore wind contract in 2023
The Labour government will make record amounts of funding available to clean energy developers after it increased the value of its summer subsidy auction by 50%, to £1.5bn.
The addition, compared with figures previously announced, means the total budget is seven times the amount available at last year’s auction, the government said.
One of the most significant achievements of the 26th United Nations climate conference in Glasgow (COP26) three years ago was the launch of the Global Methane Pledge. The goal is to reduce global methane emissions at least 30% by 2030.
Methane (CH?) is the second most significant climate pollutant after carbon dioxide (CO?). In the words of one of the architects of the pledge, then US Special Presidential Envoy for Climate, John Kerry, “tackling methane is the fastest, most effective way to reduce near-term warming and keep 1.5°C within reach”.
Australia signed up to the methane pledge in October 2022. It was a good start, but a promise is not a plan. To date, Australia has no official methane reduction targets, nor an agreed strategy to deal with this dangerous pollutant.
The Climate Council’s report, released today, sets out actions Australia can take right now to cut methane emissions. We need to get on with it.
Methane in the atmosphere is rising at a record rate: up about 260% since preindustrial times to a high not seen for at least 800,000 years.
Research just released shows if we don’t act, the problem will only worsen. It suggests increases in atmospheric methane are outpacing projected growth rates – threatening the global goal of reaching net-zero emissions by 2050.
The gas is likely responsible for at least 25 to 30% of warming Earth has experienced since the Industrial Revolution.
Methane is a “live fast, die young” gas, persisting in the atmosphere for a relatively short amount of time. But while it’s there, it punches above its weight in warming. Over 20 years, methane is about 85 times more effective at trapping heat than the equivalent amount of carbon dioxide.
After 100 years, it’s still about 28 times more effective at trapping heat.
This means methane has an outsized impact on warming in the short term, turbocharging unnatural disasters such as floods, bushfires and heatwaves.
Roughly half of global methane pollution comes from human activities. The rest comes from natural sources such as wetlands and soils.
Australia produces more than its fair share of methane because we have such large fossil fuel and agriculture industries. We are the world’s 12th largest methane polluter, producing four to five times as much methane as would be expected based on population alone.
In the year to December 2023, Australia produced nearly four million tonnes of methane. The main sources from human activity were agriculture (52%), fossil fuel mining (25%) and waste (11%). The good news is there are plenty of ways to reduce emissions in each sector that we can and should implement right now.
The largest source of methane emissions in agriculture is the burps of ruminant animals – mainly cows and sheep.
Promising research suggests each animal’s methane production can be cut by as much as 90% using daily feed supplements. These include supplements from the red seaweed Asparagopsis, and the chemical marketed as 3-NOP.
Other approaches to reducing methane emissions from animals also show promise. They include vaccines that target methane-producing microbes in their guts, methane-reducing pasture species, and selective breeding.
These solutions should be scaled up and farmers encouraged to use them – for instance, by being eligible for carbon credits under the Emissions Reduction Fund.
Providing consumers with point-of-sale information about the climate impacts of their food choices could also serve to reduce the nation’s methane emissions. And the market can be encouraged to develop clear regulatory pathways for securing approval of animal-free protein and other lower-impact foods.
More than 90% of our food waste ends up in landfill where it produces methane when it rots. Composting is much better for the environment. Investing in organic collection services for food and garden waste, and tightening regulations to capture gas at landfill sites, can address much methane pollution from the waste sector.
We can’t control what we don’t measure. Currently, methane emissions are largely reported to the Clean Energy Regulator using indirect and outdated methods. The International Energy Agency estimates Australia could be under-reporting methane emissions from the coal and gas sector by up to 60%.
Fortunately, new global satellite capacity and, in Australia, the Open Methane visualisation tool, mean we can measure methane at its source far more accurately than before.
The federal government should make all coal and gas corporations directly measure and report their methane emissions from existing mines, in line with international best practice.
Every coal mine and gas plant produces methane during mining and processing. While we work towards phasing out fossil fuel mining, a few practical actions can reduce methane pollution:
Without concerted action, global methane pollution from human activities is expected to rise 15% this decade. On the other hand, meeting the commitments of the Global Methane Pledge can reduce warming in the next few decades.
If the goals of the pledge are met, we could shave about 0.25°C off the global average temperature by mid-century, and more than 0.5°C by 2100.
The federal government should establish a national methane reduction target and a dedicated action plan. This should be part of our updated national emissions reduction target, due to be set in 2025.
We can’t take our foot off the pedal in cutting carbon dioxide. But at the same time, in the words of United Nations head Antonio Guterres, we have to do “everything, everywhere, all at once”.
Lesley Hughes is a Director and Councillor with the Climate Council of Australia. She has previously received funding from the Australian Research Council. She is a member of the Wentworth Group of Concerned Scientists, a Director of the Environmental Defenders Office and a member of the Climate Change Authority