Scientists warn of 'abrupt changes' taking place in Antarctica
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ABC News
4 hours ago
- ABC News
Dramatic rebound for southern right whale numbers along Great Australian Bight
Researchers say it has been one of the best years in recent history for southern right whale numbers in the Great Australian Bight (GAB). An annual count of the species on Australia's southern coast has found the mammals' numbers are the strongest they have been in almost a decade, despite historical declines. Researchers counted 140 whales — mostly mothers and their calves — at Head of Bight, the northernmost point of the GAB and the area endangered southern right whales visit every year to give birth. A further 18 were found in nearby Fowlers Bay, in the far west of South Australia, and another eight at Encounter Bay on the Fleurieu Peninsula, south of Adelaide. Last year, there were 114 whales at Head of Bight. Researchers said this year's results were a relief because there had been signs of declines in births in recent years, after decades of improvement. Australian Right Whale Research Program chief scientist Claire Charlton said it was a relief for the population that it was a good year. While a toxic algal bloom is having a devastating effect on marine life in some areas of South Australia's coast, it has not yet been detected in the far west of the state where most whales congregate. The official advice is that the bloom, Karenia mikimotoi, is not toxic to mammals. However, dead sea mammals have been found washed up along some parts of the coast, including dolphins and sea lions. This year marks 30 years since the establishment of the Great Australian Bight Marine Reserve — a vast protected ocean area which stretches across South Australia and Western Australia's coastlines that was created in 1995 largely to foster research on southern right whales. Dr Charlton said she had seen a change in whale numbers and how they were counted in the 18 years she had been part of the conservation effort. "It certainly has progressed now to operating Starlink, flying drones, using photogrammetry. She said there were years in the early 90s when conservationists had counted 18 mums and calves. "This year we've recorded 70 mums and calves," she said. "It really is a world-class example of how science-based research and good marine park management, plus geographical isolation and low population, can add up into a real success story. "We need to keep conserving the oceans and protect them while they are in our backyard … and protect them when they're outside of our backyard through management of krill fisheries and climate." Counting of the southern right whales pre-dates the GAB Marine Reserve. A whale named Topsy is currently at the Head of Bight, having first been spotted with a calf in 1984. Taking into account the average age of sexual maturation, Topsy would likely be in her 50s. Another female has returned to the Bight for the 12th time to give birth. Southern right whales are identified by callosities on their heads, where they have unique patterns somewhat similar to fingerprints. A publicly available national southern right whale photo identification catalogue now has over 2,500 known individuals. Counting the whales and the subsequent conservation work is part of a joint project from Curtin University, Flinders University and the Minderoo Foundation. Two studies published in recent weeks detailed the success of conservation at the GAB Marine Reserve, but also concerns for the years ahead. "Our data shows rapid recolonisation at Fowlers Bay — one of the fastest growth rates for southern right whales anywhere in the world," said co-author Bridgette O'Shannessy in one of the studies. "This demonstrates the power of marine protected areas, but also the need for ongoing threat mitigation for the Australian population. The recently slowed population growth is likely linked to climate change, with researchers believing a decline in reproductive cycles is due to a lack of available prey. The bumper birthing year comes as South Australia's Department for Environment and Water (DEW) prepares to introduce whale nursery protection areas at Fowlers Bay and Sleaford Bay, near Port Lincoln. Rod Keogh has run whale tours at Fowlers Bay for 17 years, and is required to stay a minimum of 100 metres from whales. The whale nursery protection areas come into effect from September 1, and mean tourist boats will need to stay at least 300m from whales. Dr Charlton said she believed losing Mr Keogh's tours would have a negative impact on the protection of the whales. "If the tourist operations here at Fowlers Bay weren't to continue, that would be a real loss for the protection and the advocacy of southern right whales here," she said. "EP Cruises are best practice operators; they're extremely conscientious around the whales. "The success of a long-term research program such as this really relies on community — citizen scientists, the Yalata Anangu people who we work really closely with, the funders, the researchers and tourists."
ABC News
16 hours ago
- ABC News
Scientists warn of 'abrupt changes' taking place in Antarctica
A new report warns it may be too late to prevent some changes due to human-caused climate change.
News.com.au
a day ago
- News.com.au
Antarctic climate shifts threaten 'catastrophic' impacts globally
Abrupt and potentially irreversible changes in Antarctica driven by climate change could lift global oceans by metres and lead to "catastrophic consequences for generations", scientists warned Wednesday. More broadly, a state-of-knowledge review by a score of top experts revealed accelerating shifts across the region that are often both cause and effect of global warming, according to a study published in Nature. "Antarctica is showing worrying signs of rapid change across its ice, ocean and ecosystems," lead author and Australian National University professor Nerilie Abram told AFP. "Some of these abrupt changes will be difficult to stop." Shifts in different facets of Antarctica's climate system amplify each other and have accelerated the pace of warming globally as well, she said. The study looked at evidence of abrupt change -- or "regime shifts" -- in sea ice, regional ocean currents, the continent's ice sheet and ice shelves, and marine life. It also examined how they interact. Floating sea ice does not add to sea level when it melts. But its retreat does replace white surfaces that reflect almost all of the Sun's energy back into space with deep blue water, which absorbs the same amount instead. Ninety percent of the heat generated by manmade global warming is soaked up by oceans. - Retreating sea ice - After increasing slightly during the first 35 years that satellite data was available, Antarctic sea ice cover plunged dramatically over the last decade. Since 2014, sea ice has retreated on average 120 kilometres (75 miles) from the continent's shoreline. That contraction has happened about three times faster in 10 years than the decline in Arctic sea ice over nearly 50. The "overwhelming evidence of a regime shift in sea ice" means that, on current trends, Antarctica could essentially become ice free in summer sooner than the Arctic, the study found. This will speed up warming in the region and beyond, and could push some marine species toward extinction. Over the last two years, for example, helpless emperor penguin chicks perished at multiple breeding grounds, drowning or freezing to death when sea ice gave way earlier than usual under their tiny feet. Of five sites monitored in the Bellingshausen Sea region in 2023, all but one experienced a 100 percent loss of chicks, earlier research reported. Unlike sea ice, ice sheets and the ice shelves to which they are connected are on -- or supported by -- land. The world would need to heat up by five degrees Celsius compared with pre-industrial levels to melt the entire Antarctic ice sheet, which would lift global oceans an almost unimaginable 58 metres (nearly 200 feet). - Point of no return - But global warming to date -- on average about 1.3C -- is fast approaching a threshold that would cause part of the ice sheet to generate at least three metres of sea level rise, flooding coastal areas inhabited today by hundreds of millions, the study said. "Unstoppable collapse of the West Antarctic Ice Sheet is one of the most concerning global tipping points," said Abram. "The evidence points to this being triggered at global warming well below 2C." Another potential risk is the collapse of the Antarctic Overturning Circulation, a system of ocean currents that distribute heat and nutrients within the the region and globally. A "rapid and substantial slowdown" of the currents has already begun, and evidence from the previous interglacial period -- between two ice ages -- before our own, 125,000 years ago, points to an abrupt stagnation of the system under conditions similar to those seen today. "This would lead to widespread climate and ecosystem impacts," ranging from an intensification of global warming to a decrease in the ocean's capacity to absorb CO2, the study reported. Ultimately, the only way to slow down the interlocking changes is to stop adding more planet-warming gases into the atmosphere. "The greenhouse gas emission decisions that we make over the coming decade or two will lock in how much ice we will lose and how quickly it will be lost," Abram said. mh/jxb
