So how would the proud new homeowners in Clarence Property Corporation Limited’s Wallum ‘Enviro Development’ residential estate feel if before the house mortgage is even paid off the ground is turning to swamp beneath their feet?

 

Lot 13 DP 1251383 15 Torakina Road and environs, Brunswick Heads NSW. IMAGE: Clarence Property Corporation Limited

Readers will catch a glimpse through dense tree cover of Simpsons Creek, which connects with the Brunswick River not far from the river's mouth.

On this mapping presented to Byron Shire Council on 8 February 2024, the reader can see that coastal wetlands and Simpons Creek adjoin the approximately 30.5ha development site and at times the creek comes within est. 200 meters of the proposed residential lot grid.

Wallum Estate, Torakina Road, Brunswick HeadsLot 13 DP 1251383, Revised Wallum Froglet Management Plan

Vegetation mapping with residential lot grid 

In August this year the NSW Government agency AdaptNSW released the NSW and Australian Regional Climate Modelling (NARCliM 2.0) which contain regional snapshots outlining climate projections for different NSW regions. These provide a summary of plausible future climate change in NSW relative to a baseline of average climate from 1990–2009. The projections for 2050 represent averaged data for 2040–2059 and projections for 2090 represent averaged data for 2080–2099.

The North Coast Climate Change Snapshot at

https://www.climatechange.environment.nsw.gov.au/sites/default/files/2024-08/NARCliM2-Snapshot-NorthCoast.pdf

clearly states volume ranges for sea level rise across the next 26 years (2024-2050) and across the following 40 years (2051-2090). The report expects seawater inundation heights of between 0.23m (2050) and 0.59m (2090) above the current mean sea level.

Climate Central, Coastal Risk Screening Tool, Simpsons Creek at a 0.5m sea level rise

In this mapping the projected sea level rise has already brought the ocean nearer the development site and the Simpson's Creek overflow to an est. 230m of the northern boundary of the residential lot grid by 2050. While saline creek water has entered the full length of the development site between 2051-2090 and is within less than est. 200m of the lower eastern boundary of the residential lot grid.

It doesn't take much imagination to realise that high rainfall events and storm surges will in future have a greater impact on Wallum ‘EnviroDevelopment’ Estate and with land, incapable of natural drainage likely to continue with poor drainage issues with or without climate change impacts, also likely to have the natural water table raised by persistent saltwater incursion into the Wallum wetlands, the outlook is not the rosy, bright 'sea change' life many prospective Wallum land purchasers believe they are buying.

Echo, 2 October 2024:

What’s under the hood of the environmental certification that the Wallum Brunswick Heads greenfield development relies on for its environmental credentials?

Like many developments across the nation, developer Clarence Property’s Wallum urban estate has been certified as an ‘EnviroDevelopment’.

It is clearly marked on www.wallumbrunswick.com.au, and it has been awarded accreditation across all six of its categories – water, energy, waste, materials, community and ecosystems.

A leaf is awarded for each category that has passed the technical standards.

Paid-for accreditation

This paid-for accreditation is awarded by the Sustainability and Research division of the Urban Development Institute of Australia (UDIA), based in Queensland.

UDIA describes EnviroDevelopment certification (www.envirodevelopment.com.au) as ‘a scientifically-based branding system designed to make it easier for purchasers to recognise and, thereby, select more environmentally sustainable homes and lifestyles’.

To be accredited with an EnviroDevelopment certification, developers need to, ‘demonstrate that an ecological net gain will be achieved for the project in relation to local native vegetation communities and fauna habitat resources.’

Yet throughout the Save Wallum campaign, ecologists, councillors, MPs and residents have raised issue with the claims that the development will produce an ecological net gain, and say instead that threatened ecological communities (TEC) are in danger.

Frog habitat claims. According to www.envirodevelopment.com.au/projects/wallum, ‘2.6ha of high-quality endangered wallum froglet habitat will be created as part of the early site works, which is monitored and protected during subdivision construction works to ensure success’.

Yet ecologist and Save Wallum campaigner, James Barrie, says, ‘The expectation that the threatened species of “Wallum” tolerate the contentious offset arrangements such as the machine-dug ponds (that are well known to fail for these rare acid frogs), poses a very real risk of local extinction of these species’.

‘There has been considerable outcry from several notable ecologists since, with detailed reports about why this is misleading, and does not constitute a ‘ecological net gain’ in practice by any standards.’

Stormwater design

The EnviroDevelopment website also claims of Wallum: ‘The site is also subject to an innovative stormwater design outcome which utilises the drainage characteristics of the existing sandy material on the site to treat stormwater without the need for extensive networks of underground concrete pipes and pits.’

Former Byron Shire Councillor, Duncan Dey, who is also a civil engineer specialising in flood hydrology and stormwater design told The Echo, ‘Clarence Property are relying on an “innovative” concept of recharge (my term for it). This is usually just to save money, but in this case, it is because the site is too flat to drain’.

‘The lack of hydraulic gradient is bizarrely even noted in the DA Consent Conditions of May 2023, just beneath Condition 11b).

‘The site simply doesn’t offer sufficient fall to drain correctly. Hydraulic gradients of less of one per cent are generally unacceptable. This project proposes a channel way flatter than that.

‘Several eminent local ecologists have developed outstanding knowledge of the Wallum site over recent decades’, says Mr Dey.

‘They have watched this development progress down the conveyor belt of NSW Planning, and found issues with most of the ecological reports.

‘The developer’s consultants omitted entire species, as well as coming up with proposals to recreate unique habitat to replace that which will be destroyed.

The Echo asked NSW Fair Trading if they ‘had any interest in ensuring the EnviroDevelopment certification is fit-for-purpose, or if not, can you please direct The Echo to who can?’

A NSW Fair Trading spokesperson replied, ‘Unfortunately, I haven’t been able to track down and confirm a NSW agency who may be able to provide you with commentary on your request’.

ACF comment

When presented with the draft story, Australian Conservation Foundation (ACF) investigator, Martine Lappan, told The Echo, ‘It is difficult to assess the integrity of an accreditation system when the application documents property developers submit are not made publicly available’.

‘A grand claim about protecting the environment may serve as a marketing tool, but that doesn’t make it scientifically accurate or even something that can be held to account under the law’, Ms Lappan added.

CP replies

Clarence Property was offered an opportunity to comment on this story.

Its CEO, Simon Kennedy, replied, ‘there are numerous factual errors in the story provided, and we dispute the ecological assessments made by Save Wallum Inc through its ecological interpreter both publicly, and those recently made under oath at the NSW parliamentary inquiry into the environment’.

‘We have followed all required environmental and bio-diversity requirements under the statutory approvals given to us to proceed with this project that will provide much needed housing for the Byron Shire’.

This story was provided to UDIA in draft form for comment numerous times, but no comment was forthcoming. [my yellow highlighting throughout this news article]

On 27 August 2024 the World Meteorological Organisation released its "State of the Climate in the South-West Pacific 2023": in meteorological terms the far northern section and much of eastern Australia along with its islands are situated in the this region

 

In meteorological terms the far northern section and much of eastern Australia along with its islands are situated in the South-West Pacific.

Along with the Maritime Continent (the region between the Indian and Pacific Oceans including the archipelagos of Indonesia, Borneo, New Guinea, the Philippine Islands, the Malay Peninsula, and the surrounding seas), Solomon Islands, New Caledonia, Fiji, Tuvalu, Nauru, Samoa, Micronesia, Kiribati and New Zealand.

On 27 August 2024 the World Meteorological Organisation released its "State of the Climate in the South-West Pacific 2023".

By way a brief look at some of the key issues in the report it is worth noting that:

> Atmospheric concentrations of the three major greenhouse gases reached new record observed highs in 2022, the latest year for which consolidated global figures are available. Real-time data from specific locations, including Mauna Loa (Hawaii, United States of America) and Kennaook/Cape Grim (Tasmania, Australia) indicate that levels of CO2 (carbon dioxide), CH4 (methane) and N2O (nitrous oxide) continued to increase in 2023;

> Over the past two decades, the ocean warming rate has increased; the ocean heat content in 2023 was the highest on record;

> Temperatures in 2023 were higher than normal in many areas of the region. The most significant warmth was over an area extending from south-east Australia to east of New Zealand. The most prominent and persistent marine heatwave in 2023 occurred in a large area around New Zealand. This heatwave was categorized as extreme and lasted approximately six months;

> Ocean warming and accelerated loss of ice mass from the ice sheets contributed to the rise of the global mean sea level by 4.77 mm per year between 2014 and 2023, reaching a new record high in 2023.

> In 2023, the sea level continued to rise globally and regionally as shown by high precision satellite altimetry measurements. The average global mean sea level rise (GMSL) was 3.4 mm +/- 0.3 mm/year over the January 1993 to May 2023 period. Sea levels continued to rise at rates higher than the global mean in several parts of the South West Pacific;

Click on image to enlarge

Figure 7 shows the sea-level trend over the January 1993–May 2023 period as measured by satellite altimeters. In the South-West Pacific region, the sea-level rise of the last three decades exceeds the global mean sea-level rise. Altimetry-based sea-level time series from January 1993 to May 2023 have been averaged over two areas within the region (Figure 7, bottom left and bottom right). The mean rate of sea-level rise in both areas is significantly higher than the global mean (4.52 mm +/-0.25 mm/year in area 1 and 4.13 mm +/-0.08 mm/year in area 2). The sea-level time series in area 1 (Figure 7,bottom left) displays strong inter-annual variability, mostly driven by ENSO (see the strong sea-level drops in 1997/1998 and 2015/2016). Sea-level rise is more regular in area 2 except for a steep increase around 1998.

NOTE: Regional sea-level trends are based on gridded C3S altimetry data, averaged from 50 km

offshore to the coast, by the Laboratory of Space Geophysical and Oceanographic Studies (LEGOS);

> The South-West Pacific region is extremely prone to disasters associated with hydrometeorological hazards, especially storms and floods. In 2023, a total of 34 hydrometeorological hazard events were reported in the region according to the International Disaster Database (EM-DAT), of which over 90% were flood and storm events. These reported hydrometeorological hazard events resulted in over 200 fatalities, most of which were associated with floods, storms, and landslides.

Over 25 million people were directly affected by these hazards, and they caused total economic damage of close to US$ 4.4 billion. Floods were the leading cause of death, whereas drought was the natural hazard type that affected the greatest number of people.

Storms were the hazard type that caused the greatest economic damage, followed by floods.

Click on image to enlarge

In March, a landslide triggered by flooding in north-western Indonesia resulted in 54 fatalities, more than 2,800 displaced people and 27 buried houses. This disaster event caused the greatest number of fatalities in the South-West Pacific in 2023, highlighting the importance of understanding the multiple and cascading impacts of natural hazard events;

> Precipitation is a key climate parameter, closely related to indispensable resources for human activities such as water for drinking and domestic purposes, agriculture, and hydropower. It also drives major climatic events such as droughts and floods.

In 2023, the largest precipitation deficits (measured as a percentage of the average) were observed in the Hawaiian Islands and south-western Australia. Other areas with below-average rainfall amounts were New Caledonia, Tuvalu, parts of Fiji, Tonga and the Cook Islands, parts of northern Australia, Tasmania, the southern South Island of New Zealand, some areas in the Greater Sunda Islands (Indonesia) and parts of Luzon (Philippines). Based on time series analyses (not shown), it was unusually dry (below the 10th percentile) in southern Borneo, south-west and East Australia (around Brisbane) and some central Pacific islands.

Above-normal precipitation amounts were recorded around the Solomon Sea, the Solomon Islands, Vanuatu, Samoa, Niue, the Line Islands, the southern Philippines, northern Borneo, the Malay Peninsula, Sumatra, large parts of New Zealand, and northern Central Australia.

Download full report at:

https://library.wmo.int/records/item/68995-state-of-the-climate-in-south-west-pacific-2023

SEA LEVEL RISE 2024 : It's later than you think

Most of what we the general public think we know about sea level rise calculations by inundation height and rate is derived from models which did not anticipate global land and sea surface temperatures accelerating as sharply as they have in the last two years nor thought that an average annual global temperature anomaly of 1.5°C above pre-industrial levels was quite literally just around the corner.

So it is highly possible that what is quoted below by way of text and maps is an underestimation of what the Australian East Coast will begin to experience between now and 2030. While it is also likely that the most common established timelines of climate change milestones which run out to 2100 will be truncated to a marked degree.

UN Intergovernmental Panel on Climate Change (IPCC), AR6 Synthesis Report (2020-23), Headline Statements, excerpt:

Continued greenhouse gas emissions will lead to increasing global warming, with the best estimate of reaching 1.5°C in the near term in considered scenarios and modelled pathways. Every increment of global warming will intensify multiple and concurrent hazards (high confidence).

AdaptNSW, excerpt, retrieved 15 January 2024:

IPCC modelling suggests slightly higher sea level rise to the north of the state and slightly lower to the south. These projections do not include processes associated with the melting of ice sheets which for NSW could result in sea level rise of up to 2.3m by 2100 and 5.5m by 2150.

In the longer term, the IPCC show sea level is committed to rise for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and will remain elevated for thousands of years.

• If warming is limited to 1.5°C, global mean sea level will rise by about 2 to 3m.

• for 2°C, 2 to 6m is expected, and

• for 5° 19 to 22m is expected. [my yellow highlighting]

National Oceanography Centre, Clarence Coast Mean Sea Level 1986 – 2022

YAMBA

NASA, Projected Sea Level Rise Under Different SSP Scenarios, Yamba:

Clarence Valley Sea Level Rise 2030 onwards based on Climate Central Interactive Mapping

Extent of inundation at 2 metre rise

Extent of inundation at 3 metre rise

Rise by 2030 - six years time

Rise by 2040 - sixteen years time

This next Southern Hemisphere Summer may bring more unwelcome news for Australia's coastal zone

 

“Climate breakdown has begun”

[U.N. Secretary-General Antonio Guterres, 6 September 2023]

NOAA Research, Global ocean roiled by marine heatwaves, with more on the way, 28 June 2023, excerpts:

This map depicts predicted marine heatwave conditions in September 2023 as generated by the Physical Sciences Laboratory’s experimental forecast model.

Credit: NOAA Physical Sciences Laboratory. *Click on image to enlarge*

The experimental forecast, which tracks the NOAA Climate Prediction Center’s official outlook, is based on a large ensemble of climate model predictions spanning June 2023 through May 2024….

A marine heatwave is defined as a monthly regional sea surface temperature anomaly that ranks in the top 10% of warmest months compared with the 1991–2020 average. Long-term ocean warming trends also contribute to unusually high ocean temperatures, but even with the effects of long-term warming removed, models predict 25% of the global ocean will experience sharp upward departures from more recent conditions by September…..

In this scenario it appears that the Southern Ocean waters are within a probability range of between 60-80 per cent for the occurrence of marine heatwave which might have also lead to a rise in Antarctic sea surface temperatures.

Which begs the questions:

How will the over 60km long Halloween Crack in west Antarctica react to any additional stressors on the Brunt Ice Shelf?

Will the East Coast Ice Sheet which is said to contain four fifths of the world’s ice again lose ice shelf through iceberg calving as it did with C-37 (144 sq.km) & C-38 (415 sq. km) in March 2022?

Just how big are these Anthropocene Age icebergs going to grow – given many are the size of cities already? and

How long does the Southern Hemisphere have before sea level rise beyond the Antarctic Circle increases exponentially past millimetres into metres?

BACKGROUND

NASA Earth Observatory, retrieved from website 7 September 2023:

Antarctica’sBrunt Ice Shelf Finally Breaks

January 24, 2023

In February 2019, a rift spanning most of the Brunt Ice Shelf in Antarctica appeared ready to spawn an iceberg about twice the size of New York City. The question among scientists was not if the growing rift would finish traversing the shelf and break, but when? Now, nearly four years later, it has done just that.

According to the British Antarctic Survey (BAS), the break occurred late on January 22, 2023, and produced a new iceberg with an area of 1550 square kilometers (about 600 square miles). The U.S. National Ice Center has named it Iceberg A-81. The berg is visible in this image, acquired on January 24, 2023, with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.

The glacial ice in the shelf flows away from the interior of Antarctica and floats on the eastern Weddell Sea. (For reference, the Antarctic Peninsula and its ice shelves are located on the opposite side of the Weddell.) The shelf has long been home to the British Antarctic Survey’s Halley Research Station, where scientists study Earth, atmospheric, and space weather processes. BAS reported that the station, which was relocated farther inland in 2016 as the chasm widened, was unaffected by the recent break.

January 12, 2021

The break occurred along a rift known as Chasm 1. This chasm started growing in the 1970s, followed by a period of dormancy, and then resumed growth in 2012. It continued to lengthen for almost a decade, extending by as much as 4 kilometers (2.5 miles) per year in early 2019. But even this growth spurt slowed. That is, until the 2022–2023 Antarctic summer when the chasm sped up and ultimately broke past the McDonald Ice Rumples—a submerged knob of bedrock that served as a pinning point for this part of the shelf. Several factors may have contributed to the completion of the break, including a lack of sea ice to help resist, or “push back,” against the stresses on the shelf ice in 2023.

The second image, acquired with the Operational Land Imager (OLI) on Landsat 8, shows the extent of Chasm 1 on January 12, 2021, about two years prior to the break. Notice several other cracks across the northeast part of the shelf. The “new crack” in that image ultimately separated in February 2021 and formed Iceberg A-74.

“The rapid formation of subsequent rifts—to long-standing Chasm 1 and 2—and recent calving to the northeast makes it clear that these shelf areas are dynamic with poorly understood stresses,” said Christopher Shuman, a University of Maryland, Baltimore County, glaciologist based at NASA’s Goddard Space Flight Center.

The breaking (calving) of icebergs from ice shelves is part of a natural, cyclical process of growth and decay at the limits of Earth’s ice sheets. As glacial ice flows from land and spreads out over the sea, shelf areas farthest from shore grow thinner. These areas are stressed by storms and tides and thin as they are melted from above or below, ultimately making them more prone to forming rifts and breaking away.

As for the “new” Brunt, it remains to be seen how the complex floating glacial ice responds to the most recent calving event. According to Shuman: “We have no solid idea what ‘normal’ really is for this unusual ice shelf.”

NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview and Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen.

~~~~~~~~~~~~~~~~~

Other large iceberg calvings

NASA Earth Observatory

Early on July 12, 2017, satellites captured imagery of the new, massive iceberg that broke away from Larsen C—an ice shelf on the east side of the Antarctic Peninsula…..On July 13, the U.S. National Ice Center issued a press release confirming the new iceberg and officially naming it A-68.

February 22 - March 21, 2022

Collapse of the ice shelf in front of both the Glenzer Glacier (C-37) and Conger Glacier (C.38)commencing around 12 March 2022.

In 2023 Science has the tools to refine its climate change predictive scenarios, never-the-less the Earth's land masses & oceans continue to heat up because neither world leaders, governments nor industry will accept what is now the increasingly urgent evidence of their own eyes

 

“Warming oceans cause sea levels to rise, both directly via heat expansion, and indirectly through melting of ice shelves. Warming oceans also affect marine ecosystems, for example through coral bleaching, and play a role in weather events such as the formation of tropical cyclones” [The Conversation, 14 September 2021, reporting on research by Kewei Lyu, Xuebin Zhang & John A. Church]

This is a Australian Bureau Of Meteorology visualisation of sea surface temperatures around the Australian coastline on 4 August 2023 as El Niño conditions continue to be expected to arrive within weeks.

On 1 August BOM stated:

The Bureau's El Niño Alert continues, with El Niño development considered likely in the coming weeks, despite the current lack of atmospheric response. When El Niño Alert criteria have been met in the past, an El Niño event has developed around 70% of the time.

Sea surface temperatures (SSTs) in the tropical Pacific are exceeding El Niño thresholds, with climate models indicating this is likely to continue at least through to the end of the year. In the atmosphere, however, wind, cloud and broad-scale pressure patterns mostly continue to reflect neutral ENSO conditions. This means the Pacific Ocean and atmosphere have yet to become fully coupled, as occurs during El Niño events. El Niño typically suppresses winter–spring rainfall in eastern Australia.

And this is what is being discussed by climate scientists in our region.

Asia Oceania Geosciences Society, 20^th Annual Conference, Axford Medal Lecture given by UNSW Emeritus Professor John Church, 2 August 2023:

What do we really know about 20th and 21st Century Sea-Level Change?

Abstract: Accelerating sea-level rise in much of the world will result in growing impacts through the 21st century and beyond. Despite the clear identification of an accelerating rise, many uncertainties remain. Understanding historical sea-level change is a prerequisite for building confidence in useful and accurate predictions of future changes.

For many decades, our limited knowledge of the contributions to sea-level change could not explain the rise measured by coastal tide gauges – the sea level enigma. New and improved in situ and satellite observations of the ocean, improved understanding of the “solid Earth”, and better understanding and improved modelling of the climate system have helped resolve this enigma. A number of recent studies have argued that the sum of contributions from both observations and model estimates to sea-level change over the satellite era, the last half century and since 1900 adequately explains the observed sea-level rise, which means the sea-level budget is closed. The major contributions are from ocean thermal expansion and contributions from glaciers, with an accelerating ice sheet contributions over the recent decades.

Our recent work has explored the sensitivity of global and regional sea-level reconstructions to poorly known land motions and the factors causing temporal and regional variations in the rate of rise. With this knowledge, existing reconstructions of global mean sea level are mostly not significantly different to each other from 1900 to the present, both in the time-averaged rate and the temporal variability. However, while the average rate over 1900 to present is similar to that from the sum of contributions, the rate of reconstructed GMSL rise is significantly smaller/larger than the sum of contributions prior to 1940/after 1970. Why is this? What do we really know? What are potential explanations for this continuing enigma?

And what can we project about future sea level, both for the 21st century and beyond. And can we constrain projections for the 21st century and beyond?

One of the notable take-aways from this lecture appears to be:

..that one of the main impacts of sea level on society will be how we adapt.

“We will have to adapt to that sea level rise we can no longer prevent. Of particular concern is very significantly increased rates of coastal flooding events and eventually inundation of some coastal areas,” Prof. Church said.

“We are already experiencing more severe and more frequent coastal flooding events impacting an increasing number of people.

“This century, we could expect up to about a metre of sea level rise with unmitigated emissions. This could rise to several metres over coming centuries. Today, an estimated 200 million people live within one metre of current high tide level, and by mid-century over a billion people are likely to live in the low elevation coastal zone, which is within 10 metres of current sea level.” [UNSW Newsroom, “'Urgent action is required’: UNSW climate expert on what’s to come as sea levels rise”, 2 August 2023]

A reminder that much of the NSW Northern Rivers coastal region is predicted to experience significant levels of inundation at an average global surface temperature rise of 1.5°C.

Climate Central, north-east NSW (Northern Rivers) mapping, 2021. Click on image to enlarge

BACKGROUND

John Church is an Emeritus Professor in the Climate Change Research Centre, University of New South Wales. He has published across a broad range of topics in oceanography.

His area of expertise is the role of the ocean in climate, particularly anthropogenic climate change, and in understanding global and regional sea-level rise. He is the author of over 180 refereed publications, over 110 other reports and co-edited three books. He was co-convening lead author for the Chapter on Sea Level in the IPCC Third and Fifth Assessment Reports. He was awarded the 2006 Roger Revelle Medal by the Intergovernmental Oceanographic Commission, a CSIRO Medal for Research Achievement in 2006, the 2007 Eureka Prize for Scientific Research, the 2008 AMOS

R.H. Clarke Lecture, the AMOS Morton Medal in 2017, a joint winner of the BBVA Frontiers of Knowledge Climate Change Category Prize in 2019, the AAS Jaeger Medal in 2021 and the Royal Society of NSW James Cook Medal in 2022. He is an Officer of the Order of Australia, a Fellow of the Australian Academy of Science, the Australian Academy of Technology and Engineering, the American Geophysical Union, the American Meteorological Society and the Australian Meteorological and Oceanographic Society.

CSIRO: new research shows that stronger El Niño may speed up warming of deep waters in the Antarctic shelf, making ice shelves and ice sheets melt faster

 

CSIRO News, 21 February 2023:

Stronger El Niño could cause irreversible melting of Antarctica

Totten Glacier. Photo: Esmee Van Wijk

New research led by scientists at CSIRO, Australia’s national science agency, has shown that future increases in the strength of El Niño may accelerate the irreversible melting of ice shelves and ice sheets in Antarctica.

The results, published in Nature Climate Change, used climate models to show how an increase in the variability of El Niño Southern Oscillation (ENSO) leads to reduced warming near the surface, but accelerated warming of deeper ocean waters.

ENSO is a key driver of climate variability, as both its warm phase, El Niño, and its colder phase, La Niña, influence weather conditions around the world, including in Australia.

Wenju Cai, lead author of this study and global expert on the relationship between climate change and ENSO, said the research was a critical step in further understanding how Antarctica will be affected by climate change.

“Climate change is expected to increase the magnitude of ENSO, making both El Niño and La Niña stronger,” Dr Cai said.

“This new research shows that stronger El Niño may speed up warming of deep waters in the Antarctic shelf, making ice shelves and ice sheets melt faster.

“Our modelling also revealed that warming around the edges of floating sea ice is slowed during this process, slowing down the melting of sea ice near the surface.

“Models with increased ENSO variability show a reduced upwelling of deeper, warmer waters, leading to slower warming of the ocean surface,” he said.

The associated winds around Antarctica are the mechanism driving this result.

When ENSO variability increases, it slows the intensifying westerly winds along the shelf. As a result, the upwelling of warm water around Antarctica is not able to increase as much.

The research team examined 31 climate models that participated in Phase 6 of the Coupled Model Intercomparison Project (CMIP6) under historical forcings and a high-emissions scenario.

Co-author Ariaan Purich from Securing Antarctica’s Environmental Future at Monash University said the effects of increasing ENSO variability go beyond extreme weather risks, and affect changes in Antarctic sea ice and ice shelves and sheets.

“This could have broad implications for the global climate system, so continuing to understand how ENSO will respond to climate change is a critical area of climate research,” Dr Purich said.

“There is still a lot more we need to understand about processes influencing shelf temperatures, and the finding is an important piece of the puzzle," she said.