The other shoe has finally dropped - El Niño has been declared by Australian Bureau of Meteorology

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Central and eastern Pacific sea surface temperatures (SSTs) currently exceed El Niño thresholds. International climate models suggest some further warming of the central and eastern tropical Pacific Ocean is likely. All surveyed models indicate SSTs will remain above El Niño thresholds until at least the end of the 2023–24 southern hemisphere summer.

Bureau long-range forecasts are for SSTs up to 2.5 °C warmer than average off eastern Tasmania and in the eastern Tasman Sea from October to the end of 2023.

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Australian Bureau of Meteorology, 19 September 2023:

ElNiño and positive Indian Ocean Dipole underway

An El Niño and a positive IOD are underway.

The declaration of these events, and their concurrence over spring, reinforces the Bureau's long-range rainfall and temperature forecasts, which continue to predict warmer and drier conditions for much of Australia over the next three months. The confirmation of an established El Niño increases the likelihood that the event will be sustained through the summer period.

Oceanic indicators firmly exhibit an El Niño state. Central and eastern Pacific sea surface temperatures (SSTs) continue to exceed El Niño thresholds. Models indicate further warming of the central to eastern Pacific is likely.

Broadscale pressure patterns over the tropical Pacific reflect El Niño, with the 90-day Southern Oscillation Index (SOI) at −7.7. Recent trade wind strength has been generally close to average, but was slightly weaker than average across the tropical Pacific in August 2023 for the first time since January 2020.

Overall, there are signs that the atmosphere is responding to the pattern of SSTs in the tropical Pacific and coupling of the ocean and atmosphere has started to occur. This coupling is a characteristic of an El Niño event and is what strengthens and sustains an event for an extended period. Climate models indicate this El Niño is likely to persist until at least the end of February. El Niño typically leads to reduced spring and early summer rainfall for eastern Australia, and warmer days for the southern two-thirds of the country.

A positive Indian Ocean Dipole is underway. The Indian Ocean Dipole (IOD) index is +1.25 °C for week ending 17 September. This is its fifth week above the positive IOD threshold (+0.40 °C). The longevity of this trend, combined with the strength of the dipole being observed and forecast, indicate a positive IOD event is underway. All models predict this positive IOD will persist to at least the end of spring. A positive IOD typically leads to reduced spring rainfall for central and south-east Australia.

When a positive IOD and El Niño occur together, their drying effect is typically stronger and more widespread across Australia.

The Madden–Julian Oscillation (MJO) is currently weak and is forecast to remain weak over the coming week.

The Southern Annular Mode (SAM) index is currently negative and is expected to remain negative for at least the coming week, before a possible return to neutral late in September. During spring, a negative SAM is associated with decreased rainfall across parts of the east in both NSW and Victoria, and increased rainfall over western Tasmania.

The long-rangeforecast for Australia indicates warmer and drier than average conditions are likely across most of southern and eastern Australia from October to December. The Bureau's climate model takes into account all influences from the oceans and atmosphere when generating its long-range forecasts.

Global warming

Global warming continues to influence Australian and global climate. Global sea surface temperatures (SSTs) were warmest on record for their respective months during April to August 2023. August 2023 SSTs were also the warmest globally for any month since observational records began in 1850. July and August 2023 were also respectively the hottest and second-hottest months globally in terms of 2-metre air temperature.

Australia’s climate has warmed by an average of 1.48 ± 0.23 °C since national records began in 1910. There has also been a trend towards a greater proportion of rainfall from high intensity, short duration rainfall events, especially across northern Australia. Southern Australia has seen a reduction, by 10 to 20%, in cool season (April to October) rainfall in recent decades. This is due to a combination of natural variability on decadal timescales and changes in large-scale circulation caused by an increase in greenhouse gas emissions.

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The north-east NSW coastal fringe started the week with reasonable land & sea temperatures and only 6 bush & grass fires at advice level

Australian Bureau of Meteorology (BOM), 18 September 2023: 

Air-Surface Temperature 4pm Monday 18 September 2023
MAP: BOM

Between 6am to 4pm Monday 18 September 2023 temperatures along the coastal fringe of north-east NSW ranged from 5.5°C to 26.7°C as the day progressed.

Sea Surface Temperatures & Current Direction 

4pm Monday 18 September 2023

MAP: BOM

The East Australian Current was still bringing waters close to shore which were a comfortable 20-21°C at 4pm Monday 18 September 2023.

This may not last long.....

Australian Bureau of Meteorology

Warmer than median October to December days and nights for almost all of Australia

Issued: 14 September 2023

For October to December, above median maximum temperatures are very likely (greater than 80% chance) for almost all of Australia.

For October to December, most of Australia is at least 3 times likely to experience unusually high maximum temperatures, with chances increasing to more than 4 times likely for most of western and central WA, and parts of central and south-eastern Australia. Unusually high maximum temperatures equate to the warmest 20% of October to December periods from 1981 to 2018.

For October to December, minimum temperatures are very likely (greater than 80% chance) for almost all of Australia apart from a small area of Queensland's North Tropical Coast.

For October to December, broad areas of Australia are at least 2.5 times likely to experience unusually high minimum temperatures, with chances increasing to more than four times likely for parts of central WA, southern Queensland, and north-east NSW. Unusually high minimum temperatures equate to the warmest 20% of October to December periods from 1981 to 2018.

Past accuracy of the October to December long-range forecast for chance of above median maximum temperatures has been high to very high across all of Australia. For minimum temperatures, accuracy is high to very high for most of Australia, dropping to low to moderate for parts of north-western Australia.

NASA-National Snow and Data Center reports extensive melting in West Antarctica and the Peninsula

 

“The Antarctica Ice Sheet contains approximately 30 million cubic kilometres of ice, which is around 1,779,359 times the volume of Sydney Harbour. We’ll just let that sink in for a little bit…

It’s the largest single mass of ice on earth, and most of that ice is sitting on land – which means it has the potential to contribute to sea level rise if melted.”

[Climate Council, News/The Facts, ANTARCTIC ICE MELT UNSTOPPABLE WITHOUT STRONG CLIMATE ACTION, 16 October 2015]

For all of us in Australia who trust the scientific method but whose understanding is limited by lack of training in the appropriate fields, watching Antarctica for the last seven years is like waiting for the other climate change shoe to drop.

This is the latest information I have read......

National Snow and Ice Data Center, 12 January 2023:

Extensive melting in West Antarctica and the Peninsula

As the peak of Antarctica’s melt season approaches, surface snow melting has been widespread over coastal West Antarctica, with much of the low-lying areas of the Peninsula and northern West Antarctic coastline showing 5 to 10 days more melting than average. However, much of the East Antarctic coast is near average. Snowfall in Antarctica for the past year has been exceptionally high as a result of an above average warm and wet winter and spring.

Overview of conditions

Figure 1a. The upper maps of the Antarctic Ice Sheet (left) and the Antarctic Peninsula (right) show the total melt days for the areas from November 1, 2022 to January 10, 2023. The graph on the bottom shows daily melt extent for the Antarctic Ice Sheet as a percentage of ice sheet area for the same time period in red and the 1990 to 2020 average in blue. The interquartile and interdecile ranges appear in grey bands.

Credit: E. Cassano and M. MacFerrin, CIRES and T. Mote, University of Georgia

Antarctic surface snow melting through January 10 is above average and reached near-record extent in late December. A significant melt event spread over the Peninsula and across much of the West Antarctic Ice Sheet northern coast and into the Ross Ice Shelf area (Figure 1a). Melting has been moderately above average for the Peninsula areas, but unusually high in the Getz Ice Shelf area, where melting is less frequent. The Larsen Ice Shelf area has seen up to 25 days of melting, about 5 more than average, and the Wilkins region up to 30 days, again about 5 more than average (Figure 1b). The Getz and Sulzberger Ice Shelves (to the lower left of the Antarctic maps) have seen 10 melt days this season, about double the average for this time of year. East Antarctic Ice Shelves—Fimbul, Roi Baudouin, and Amery—have had near-average to slightly above-average melting of 5 to 10 days each.

Conditions in context

Figure 2. These plots show weather conditions as a difference from average relative to the 1991 to 2020 reference period for Antarctica and the surrounding coastal areas. The top plot shows air temperature at the 925 millibar level, in degrees Celsius, for December 1, 2022 to January 10, 2023. Yellows and reds indicate higher-than-average temperatures; blues and purples indicate lower-than-average temperatures. The bottom plot shows sea level pressure for the same period. Yellows and reds indicate higher-than-average air pressure; blues and purples indicate lower-than-average pressure.

Credit: National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research

Snow globe Antarctica

Snowfall over Antarctica has been significantly above average over these last weeks, continuing a trend that began in November 2021. Several recent hydrological years (March 1 to February 28) for Antarctica have had up to 200 billion tons more snow than average, but the 2022 to 2023 year has reached nearly 300 billion tons as of January 10, 2023. This is in line with some future projections that suggest larger accumulation with a warmer climate until warming reaches above 7.5 degrees Celsius (13.5 degrees Fahrenheit). This very high deviation from average snow input suggests that the Antarctic Ice Sheet could gain mass this year. Snowfall amounts have been especially high along the western edge of the Peninsula and the Bellingshausen coast, where persistent southeastward-flowing winds push marine air against a series of mountain ranges and the ice ridge along the spine of the Peninsula. However, the biggest contribution to the above average total snow input occurs in East Antarctica, and specifically Wilkes Land and the interior of Antarctica. Overall, high snowfall in Antarctica may completely offset recent net ice losses from faster ice flow off the ice sheet for this assessment period. Most of the past decade has seen annual net losses of 50 to 150 billion tons.

Melt ponds and glacier retreat in the Peninsula

Figure 4. This true color image shows several melt ponds on the northern part of the Antarctic Peninsula (see inset map) on January 10, 2023. The image is from the Moderate-resolution Imaging Spectroradiometer (MODIS) sensor aboard the NASA Aqua satellite. For reference, North is towards the upper right, and the image is 312.5 by 187.5 kilometers in size (about 180 x 120 miles).

Credit: NASA Worldview

Above average surface melting over the northern Peninsula is evident in the accumulation of surface meltwater in several areas of the eastern side of the Peninsula. The Larsen C Ice Shelf, and the SCAR Inlet Ice Shelf, a remnant of the former Larsen B shelf, are all showing significant areas of accumulated meltwater on their surfaces. Meltwater on ice shelves can pose a threat to ice shelf stability through a process called hydrofracture, where water fills pre-existing cracks in the shelf and forces the crack to open further as water pressure increases inside the crack.

The warm conditions have also triggered several rapid tidewater-style retreats in the area this season, most noticeably for Hektoria/Green/Evans glacier system in the northwestern Larsen B embayment. The glacial ice front of Hektoria has retreated roughly 5 kilometers (3 miles) in the past two months. A similar outflow can be seen in the Moderate Resolution Imaging Spectroradiometer (MODIS) data to the north near the Sobral Peninsula from the Bombadier/Edgeworth/Dinsmore glacier system (not shown). The Seal Nunataks Ice Shelf remnant, which is between the Larsen A and Larsen B Ice Shelves, is also degrading since the sea ice minimum of early 2022.