Cartoons of the Week

 

David Pope

Glen Le Lievre

James Gillray

 

Matt Golding

Headline To Remember

 

The Guardian, 30 December 2023

CLIMATE CRISIS: I don't know how many times and in how many ways governments & big business will have to be told the world had run out of time before they accept the science. A moot point because it is already too late

It is hard reading the United Nations Conference of the Parties serving as the meeting of the Parties to the Paris Agreement (COP28) final document titled "Outcome of Global Stocktake" Revised Advance Version, 13 December 2023.

It announces itself pleased that the world is on track to limit global warming to "an increase in the range of 2.1–2.8 °C with the full implementation of the latest nationally determined contributions" by the 196 parties to the 2015 Paris Agreement (COP21).

The document posits that the world has until 2050 before it needs to have completed "transitioning away from fossil fuels in energy systems" by using, among other things, "renewables, nuclear, abatement and removal technologies such as carbon capture and utilization and storage, particularly in hard-to-abate sectors, and low-carbon hydrogen production". This tool kit is expected to keep the global surface temperature of the Earth at an average1.5°C with no or limited overshoot.

The Closing Plenary Remarks of COP28 President Dr. Sultan Al Jaber were just as unrealistic:

"Excellencies, colleagues and friends. First let me say As-Salamu Alaykum … and thank you…We have travelled a long road together… in a short amount of time. Over the last two weeks, we have worked very hard to secure a better future for our people and our planet. We should be proud of our historic achievement. And the United Arab

Emirates…my country… is rightly proud of its role in helping you to move this forward.

Ladies and gentlemen, the world needed to find a new way. By following our North Star, we have found that path. We have delivered a comprehensive response to the Global Stocktake and all the other mandates. Together, we have confronted realities and we have set the world in the right direction. We have given it a robust action plan to keep 1.5 within reach. It is a plan that is led by the science. It is a balanced plan, that tackles emissions, bridges the gap on adaptation, reimagines global finance, and delivers on loss and damage. It is built on common ground. It is strengthened by inclusivity. And it is reinforced by collaboration.

It is an enhanced, balanced, but… make no mistake… historic package to accelerate climate action. It is…the UAE Consensus".....

The situation we find ourselves in is very different from the unrealistic imagining of government and industry representatives in Dubai UAE over the fourteen conference days between 30 November to 13 December 2023.

Fig. 1. Global temperature relative to 1880-1920 based on the GISS analysis.[1],[2] 

Global Warming Acceleration: El Nino Measuring Stick Looks Good

14 November 2023

James Hansen, Makiko Sato, Reto Ruedy

Abstract. Global warming is accelerating because the drive for warming, Earth’s energy imbalance, has doubled in the past decade. Measurement of the acceleration is hampered by unforced tropical (El Nino/La Nina) variability, but a good measuring stick is provided by warming between successive large El Ninos. Strengthening of the current (2023-24) El Nino has raised it to a level similar to the 1997-98 and 2015-16 El Ninos. The first six months of the current El Nino are 0.39°C warmer than the same six months of the 2015-16 El Nino, a global warming rate of 0.49°C/decade, consistent with expectation of a large acceleration of global warming. We expect the 12-month mean temperature by May 2024 to eliminate any doubt about global warming acceleration. Subsequent decline of the 12-month temperature below 1.5°C will likely be limited, confirming that the 1.5°C limit has already been passed.

Global temperature has increased 0.18°C/decade since 1970 (Fig. 1). Temperature prior to the current El Nino was ~1.2°C above the preindustrial level (taken to be the 1880-1920 average, the earliest period with reasonable global coverage of instrumental measurements). The goal of the United Nations Framework Convention on Climate Change[3] and the Paris Agreement[4] is for the rate of warming to slow down so that global warming stabilizes at a level of 1.5°C or less. We find,[5] on the contrary, that global warming post-2010 must be in an accelerated warming phase, based on a large increase in Earth’s energy imbalance, which is the immediate drive for global temperature change. We project an acceleration of the post-2010 warming rate by 50-100 percent (yellow area in Fig. 1). Thus, global temperature is now accelerating past 1.5°C and it could reach 2°C in the 2030s, barring purposeful actions to reduce or reverse Earth’s energy imbalance.

Acceleration of global warming has been hidden so far by the large natural variability of global temperature, especially because of the unusual 3-year period of strong La Ninas that ended this year. If we wait long enough, say another decade, the changed trend will be obvious, but we need to understand the situation sooner. We will argue elsewhere[6] that actions to cool the planet should be taken within less than a decade if we are to have a good chance of avoiding polar climate change amplifications that would be difficult, if not impossible, to reverse.....

[my yellow highlighting]

Read the full paper at:

https://mailchi.mp/caa/global-warming-acceleration-el-nino-measuring-stick-looks-good?e=[UNIQID] 

CLIMATE CHANGE STATE OF PLAY 2023: the climate change microwave has been cooking Australia on "High"

 

It been easy in recent years to take our eyes off the ball when it came to the that important predictive climate change number, the Global Surface Temperature Anomaly which tracks the degree the Earth is warming over time. So many urgent distractions - global pandemic, wars and war crimes, the local effects of rolling unnatural disasters and rising cost of living.

This is where the world, Australia, Eastern Australia and New South Wales stand in 2023......

Commonwealth Science Industrial Research Organisation (CSIRO), Climate Change In Australia, YEARS AT THE +1.5 °C GLOBAL WARMING LEVEL, retrieved 25 November 2023:

Climate variability is greater at the national and state level than in the global average, so some places have already experienced a year consistent with the what is expected to be the ‘new normal’ (the long-term average) at a +1.5 °C global warming level. Have we already seen any such years in Australia?

The answer is now yes.

The globe has warmed by around +1.1 °C, Australia by around +1.6 °C, a ratio of around x1.4. This suggests that when the world is at +1.5 °C, Australia will be at around +2.1 °C since 1850–1900. The average temperature of the record year 2019 was at around this temperature – so is expected to be typical of an average year in Australia in a +1.5 °C world. [my yellow highlighting]

ABC News, 24 November 2023:

Last week, global temperatures appeared to momentarily breach a threshold set by world governments to try and avoid widespread climate devastation.

On November 17 and 18, the world was, on average, 2 degrees Celsius warmer than pre-industrial levels for the first time in modern recorded history.

The pre-industrial period was a time before widespread fossil fuel use....

Over the past 10 months, the average global temperature was more than 1.3C above pre-industrial levels.....

Current greenhouse gas levels and emissions puts the planet on a trajectory to exceed Paris Agreement targets....

BBC News, 7 October 2023:

...BBC analysis of data from the Copernicus Climate Change Service shows that, up to 2 October, around 86 days in 2023 have been over 1.5C warmer than the pre-industrial average. That beats the 2016 record well before the end of the year.

There is some uncertainty in the exact number of days that have breached the 1.5C threshold, because the numbers reflect a global average which can come with small data discrepancies. But the margin by which 2023 has already passed 2016 figures gives confidence the record has already been broken.

"The fact that we are reaching this 1.5C anomaly daily, and for a longer number of days, is concerning," said Dr Lazenby.

One important factor in driving up these temperature anomalies is the onset of El Niño conditions.

When it comes to tracking temperature anomalies across  relatively smaller areas over time, such as the eastern half of the Australian continent or the state of New South Wales, one has some indication as to why the CSIRO expects Australia to be so much hotter than the global temperature anomaly when 1.5°C is the 'normal' annual average. 

Monthly maximum temperature anomalies retrieved from Australian Bureau of Meteorology (BOM) 25.11.23.

NOTE:

 Anomalies denote the departure of an element from its long-period average value for the location concerned. For example, if the maximum temperature for June in Melbourne was 1 degree Celsius higher than the long-term average for this month, the anomaly would be +1 degrees Celsius. The current international standard is to use the 30 year average from 1961 to 1990 as the long-term average. (BOM, Climate Glossary 2023]

With regard to tracking climate change global surface temperature anomalies the baseline is pre-industrial temperature levels which is widely interpreted as those occurring before 1850 perhaps as early as before 1800. The United Nations IPCC uses as its reference period the years 1850–1900 to represent pre-industrial temperature. 

El Niño continues and its warming effect predicted to last though to the early months of the southern hemisphere Autumn

Bureau of Meteorology, 08.11.23

Bureau of Meteorology, Climate Diver Update Summary, by email, 8 November 2023:

El Niño and positive Indian Ocean Dipole continue

• El Niño continues in the tropical Pacific. Climate model forecasts indicate some further warming of the central to eastern Pacific is likely, with SSTs remaining above El Niño thresholds into the early southern hemisphere autumn 2024.

• The positive Indian Ocean Dipole (IOD) event persists. All models indicate that this positive IOD will likely continue into early December.

• The Southern Annular Mode (SAM) index is currently positive with forecasts indicating it will return to neutral in the coming days.

• The Madden–Julian Oscillation (MJO) is currently weak. Approximately half of international climate models suggest the MJO will strengthen and move eastwards across the western Pacific later this week. When the MJO is in the western Pacific, there is an increased chance of showers and rain over northern parts of the NT and Queensland.

• Global warming continues to influence Australian and global climate. Global sea surface temperatures (SSTs) were highest on record for their respective months during April to October.

Scientists call ‘Code Blue emergency’ for Australian oceans, as off-the-scale marine heat looms

 

OCEAN
IMAGE: AdobeStock_207088658

Climate Council, media release, 9 November 2023:

Scientists call ‘Code Blue emergency’ for Aussie oceans, as off-the-scale marine heat looms

AUSTRALIA’S OCEANS ARE in crisis, as extreme heat punishes marine life and raises the spectre of irreversible changes with profound consequences for all life on our planet, a new report has found.

The Climate Council’s CodeBlue: Oceans in Crisis report reveals the immense amount of climate-change induced heat currently being absorbed by the world’s oceans is equivalent to boiling the Sydney Harbour every eight minutes.

In addition, the Climate Council ran a highly targeted survey of 30 leading ocean scientists across five continents. All (100%) were ‘extremely’ or ‘very’ concerned about climate-driven changes to the world’s oceans. Half (53%) said these changes were outpacing scientific predictions.

Overwhelmingly, these scientists agreed ‘rapidly phasing out fossil fuels’ is the single most important action governments could take to address ocean warming.

Report author and the Climate Council’s Research Director Dr Simon Bradshaw said: "The science can’t be any clearer: our oceans are in deep trouble. Today the ocean is absorbing excess heat energy that’s equivalent to five Hiroshima bomb explosions every second, or enough to boil Sydney Harbour every eight minutes. [my yellow highlighting]

"As our climate changes, driven by rampant burning of coal, oil and gas, our seas are transforming before our eyes. More frequent and severe marine heatwaves are pushing coral reefs to the brink, ice sheets are melting at an alarming rate, ocean currents are slowing and seas are rising. The climate crisis is also an ocean crisis.

"In hospital emergency rooms, a code blue is called when a very serious life-threatening event is underway. We are calling a code blue for our oceans today, because this threatens all the species that inhabit them, the people who depend on them, as well as all life on land.

"Over the past few decades as the climate has warmed, the oceans have done an incredible job of protecting us by absorbing CO2 and an immense amount of heat, but there’s a limit to what they can take and we are close to crossing dangerous tipping points. We must scale up the use of clean energy like solar and wind, backed by storage, as quickly as we can so the use of coal, oil and gas is phased out. Every step that cuts pollution will help secure our future."

Ocean scientist Professor Gretta Pecl, Director for the Centre for Marine Socioecology at the University of Tasmania, author of the Australian ocean section of the latest IPCC report and report co-author added: “Make no mistake, ocean scientists around the world are growing increasingly concerned about rapid and intensifying changes to our oceans.

"While much of the worry for the brutal summer ahead is quite rightly about the impact on our iconic Great Barrier Reef, the scientific community is also extremely concerned about the Great Southern Reef. With forecasts of unprecedented and 'off the charts' marine heat this summer, these critical marine ecosystems face risk of utter devastation.

"We’re observing the transformation of the oceans in real time, as marine species move to survive. In Australia, at least 200 marine species have shifted since 2003, with the vast majority headed south. As waters warm further south, many will have nowhere left to go.

"While climate change has already caused extensive change to our oceans - and we’ll continue to see devastating impacts for decades - stronger action by governments to reign in fossil fuels right now can limit future harms and ensure more species and ecosystems are given a fighting chance. Scientists agree: the single most important action we can take now is to leave fossil fuels in the polluting past - and it has to happen this decade."

Pro-surfer Adrian ‘Ace’ Buchan, Surfing Australia Deputy Chairman, has joined the Climate Council’s call to declare a Code Blue emergency, adding: “Surfers have a deep and spiritual connection to the ocean and we are deeply concerned about the devastating impact the climate crisis is having on our big blue playground. Erosion is threatening our most iconic surfing spots. Our water is being polluted from flood runoff and dangerous jellyfish moving south. Loss of coral reefs and impacts on sandbars, is not just altering where and how waves break, but is also having devastating impacts on marine life.

"This is all terrible news for the millions of ocean loving Aussies - every one of whom should be concerned and take note. This is a call to action: we must work to draw attention to the ocean’s plight and push for decisive and rapid climate action now."

Tishiko King, a proud Kulkalaig woman from Masig in Zenadth Kes (Torres Strait Islands) marine scientist and co-author of the report said: “We know what is needed to protect our futures: leaving fossil fuels in the ground, having the resources to adapt to our changing climate and ocean, being able to access funds to address loss and damage.

"We have the opportunity to work together: First Nations, Pacific Island nations, non-Indigenous Australians. It starts by listening, and understanding what we all have in common. The ocean is what connects us all together."

ENDS

The Climate Council is Australia’s leading community-funded climate change communications organisation. It was founded through community donations in 2013, immediately after the then-Abbott Government dismantled the Climate Commission. We provide authoritative, expert and evidence-based advice on climate change to journalists, policymakers, and the wider Australian community. For further information, go to: climatecouncil.org.au Or follow us on social media: facebook.com/climatecouncil and twitter.com/climatecouncil

Full report can be found at:

https://www.climatecouncil.org.au/resources/code-blue-our-oceans-in-crisis/

Global ocean heat is intensifying and seas below the 30th Parallel South appear to have seen the largest increase in absorbed & accumulated heat

 

‘The world ocean, in 2023, is now the hottest ever recorded, and sea levels are rising because heat causes water to expand and ice to melt,’...‘Ecosystems are also experiencing unprecedented heat stress, and the frequency and intensity of extreme weather events are changing rapidly, and the costs are enormous.’ [Scientia Professor Matthew England, co-author of the study from the UNSW Centre for Marine Science and Innovation, in the Echo, 6 November 2023]

Over the years science has made the general public increasingly aware that anthropomorphic global warming and subsequent climate change has been heating the world's oceans beyond their normal temperature range.

What we aren't always aware of is exactly which oceans are exhibiting the most persistent warming and the fastest temperature rises.

This recent study below highlights those particular oceans.

It seems that ocean waters from the 30th Parallel south (latitude: -30° 00' 0.00" S longitude: 0° 00' 0.00") are experiencing the most rapid increase in temperatures.

To place that in perspective. From a line running through Australian waters from a point roughly halfway between Red Rock on the Clarence Coast and Corindi Beach on the Coffs Coast (NSW), right down to Tasmania and on towards Antarctica, seawater is heating and expanding until at latest measurement the reading over time now stands at 75.3 ± 4.

While from around Cape Leeuwin to Antarctica the reading is 43.2 ± 4.4.

On the Australian west coast the 30th Parallel can be thought of as running on a latitude approximately halfway between Leeman and Green Head (WA).

This study appears to indicate that, sooner rather than later, the considerable impacts of climate change will increase for the Australian population.

Nature Communications, Article number: 6888 (2023), 28 October 2023, excerpts:

Recentacceleration in global ocean heat accumulation by mode andintermediate waters

Authors: Zhi Li, Matthew H. England & Sjoerd Groeskamp

The ocean directly impacts the Earth’s climate by absorbing and redistributing large amounts of heat, freshwater, and carbon, and by exchanging these properties with the atmosphere1. About 91% of the excess heat trapped by greenhouse gases and 31% of human emissions of carbon dioxide2 are stored in the ocean, shielding humans from even more rapid changes in climate. However, warmer oceans result in sea-level rise, ice-shelf melt, intensified storms, tropical cyclones, and marine heatwaves, as well as more severe marine species and ecosystem damage. These effects depend on the pattern of ocean warming; it is thus critical to quantify the dynamics and distribution of ocean warming to better understand its consequences and predict its implications.

The observed distribution of ocean warming is not uniform. About 90% of total ocean warming is found in the upper 2000 m, with over two-thirds concentrated in the upper 700 since the 1950s, and an increase of warming rates at both intermediate depths of 700–2000 m, and in the deeper ocean below 2000 m. The Southern Ocean south of 30°S has been estimated to account for 35–43% of global ocean warming from 1970 to 2017, and an even greater proportion in recent years, while Northern Hemisphere ocean warming appears to be concentrated in the Atlantic Ocean. Due to the accumulated excess heat in ocean basins, an acceleration of total ocean warming has become more evident from recent observational-based studies. While much past work has focused on the distribution of ocean warming as a function of depth and basin, relatively little analysis has been undertaken of the distribution as a function of water-mass layers and within specific water masses. This is the focus of the present study......

When evaluating the ocean heat uptake for each decade (“Methods”), analysis of the past three decades reveals that the ocean heat uptake during 2010–2020 has increased more than 25% relative to 2000–2010 and has nearly doubled relative to the 1990’s WOCE era, as seen in Fig. 1b, where we highlight the decadal ocean heat uptake since the 1960s. Note that there has been both increased ocean sampling and a shift of the observational network from a ship-based system to the Argo network since the initiation of the global Argo array (2001–2003)34. This may impact the estimated increase in global ocean warming over the past three decades (Fig. 1). However, the rate of global mean sea-level rise has also been increasing since 1993 based on an independent estimate from satellite altimeter data1,35, providing confidence in our results given that half of the global sea surface height increase is due to thermal expansion of the ocean since altimeter measurements began. Significant ocean warming and accelerating OHC changes are also consistent with the increase in net radiative energy absorbed by Earth detected in satellite observations, something that is likely to continue throughout the 21st century in the absence of substantial greenhouse gas emissions reductions.

The increased ocean warming is non-uniformly distributed across ocean basins. Overall, in each ocean basin, an increase in OHC is observed (values indicated in Fig. 2a, b), with stronger warming in the mid-latitude Atlantic Ocean and the Southern Ocean compared with other basins. Total warming in the Southern Ocean is estimated to account for ~31% of the global upper 2000-m OHC increase from 1980–2000 to 2000–2010 (Fig. 2a), and almost half of the global OHC increase from 2000–2010 to 2010–2020 (values indicated in parentheses of Fig. 2b). Hence the Southern Ocean has seen the largest increase in heat storage over the past two decades, holding almost the same excess anthropogenic heat as the Atlantic, Pacific, and Indian Oceans north of 30°S combined (Fig. 2d). The most striking warming in the Southern Ocean is concentrated on the northern flank of the Antarctic Circumpolar Current, the location of deep mixed layers and subduction hotspots for Subantarctic Mode Water and Antarctic Intermediate Water, as well as the location of subtropical mode waters formation further equatorward (Fig. 3). The well-ventilated regions near western boundary current extensions in the North Atlantic and North Pacific also reveal large warming over the past two decades. These hotspots of ocean warming are likely linked to enhanced uptake, subduction, and lateral spreading of heat associated with mode and intermediate waters that warrant further investigation.

Fig. 2: Regional intensification in ocean warming over the past two decades, 0–2000 m. Click on image to enlarge

The ensemble mean of ocean heat content (OHC) changes averaged for years a 2000–2010 and b 2010–2020, relative to the 1980–2000 mean. Units of shadings in panels (a, b) are shown as 109 J m−2. The values over each basin indicate the OHC increase relative to the 1980–2000 mean over the Southern (S.O., south of 30°S, dark-red line), Atlantic (ATL), Pacific (PAC), and Indian (IND) Oceans, and are limited to 65°S–65°N. Units are shown as 1021. The values in parentheses in panel (b) indicate the basin-integrated OHC increase from 2000–2010 to 2010–2020. The basin mask used to distinguish ocean basins of the Southern, Atlantic, Pacific, and Indian Oceans is obtained from ref.  Superimposed gray contours represent the positions of wintertime isopycnals 25, 26.45, 27.05, and 27.5 kg m−3 at 10 m depth from SIO RG-Argo. c, d Zonally integrated OHC change (1021 per degree latitude) versus latitude for the period 2000–2010 (blue line), and 2010–2020 (red line), relative to the 1980–2000 mean. Lines in panels (c) and (d) represent the ensemble mean, and shadings indicate the ±2 ensemble standard deviation uncertainty range (±2σ) of OHC changes.

[my yellow highlighting in the excerpts]

The full study can be read and downloaded at:

https://www.nature.com/articles/s41467-023-42468-z#ref-CR13

Cartoons of the Week

 

Winner of the Climate Cartoon People’s Choice Award

 2023

Cathy Wilcox
1 November 2023



Runners Up

Andrew Weldon

Megan Herbert

Analysing large scale heat maps appearing on social media seeking small scale information - an example

 

This interesting temperature anomaly map appeared on social media on the evening of 25 October 2023:

It was accompanied by an observation that "Today 41.0C at Grafton NSW beats its October monthly temperature record"

Unfortunately this remark leads to some confusion as there are two official "real time" weather stations covering the wider Grafton district and none within the boundaries of Grafton City.  

On 25 October 2023 the Australian Bureau of Meteorology recorded maximum air temperature at Grafton NSW as:

Grafton Ag Research Station – 41.0°C

{Trenayr NSW weather station 058077 commenced 1917} 

Grafton Airport AWS – 39.7°C

{Glenugie NSW weather station 058161 commenced 1973}

 

The recorded maximum temperature at BOM’s research centre weather station on 25 October 2023 did exceed its previous highest recorded maximum temperature for the month of October which was 40.6°C in 2019. 

The recorded temperature at BOM’s airport weather station on the same day also exceeded the highest recorded maximum temperature in October for that site of 38.9°C in 2017 and, it is this weather station's real time recording which is the basis of daily temperature reporting for Grafton generally. 

The highest temperature recorded for what might be considered Grafton City itself was 39.3°C in October 1988, but as Station 058130 on corner of Oliver & Turf streets only operated between 1966 and 10 Jan 2015 this is of limited value for comparison with maximum temperature records over time.

As both BOM recording units are some distance from the city's main urban population, perhaps as a public service Clarence Valley Council might consider installing a real time recording unit in the park adjoining its Grafton council chambers or a digital temperature display below the Market Square clock.

Tweed Shire expects to start rolling out water restrictions within next few weeks and rest of the Northern Rivers region likely to be following its lead sooner rather than later

NSWDPI Combined Drought Indicator (CDI) mapping, 23 September 2023. CDI = Combined Drought Indicator. RI = Rainfall Index. SWI = Soil Water Index. PGI = Pasture Growth Index. DDI = Drought Direction Index

Click on map to enlarge

There are 19 large dams on NSW regional regulated rivers and hundreds of smaller dams, reservoirs & weirs associated with a mix of environmental use, off-farm agricultural and urban water storage on other rivers.

Across the seven local government areas in the Northern Rivers region water storage locations include:

Toonumbar Dam

Rocky Creek Dam

Clarrie Hall Dam

Emmigrant Creek Dam

Korrumbyn Creek Dam

Shannon Creek Dam

Bray Park weir

Tyalgum weir

Mullumbimby Power Station weir

Jambour weir

Kyogle weir

Nymboida weir

Rushforth Road 100ML Reservoir.

Tweed Shire Council is strongly alerting its residents and ratepayers as to the current situation and what may lie ahead.

The Echo, 27 September 2023:

Following the devastating floods of 2022 we are back to dry weather. The Bureau of Meteorology (BOM) has declared an El Nino weather pattern and it has predicted that there will be less-than-average rainfall in the Northern Rivers this year. Tweed Council is reminding residents and visitors that it is important to save water as we head into dry weather.

‘Without significant rain, the Tweed will head into water restrictions, with restrictions for Tyalgum looking likely in the next few weeks,’ said Tweed Shire Council’s (TSC) water and wastewater business and assets manager Michael Wraight.

‘We source our water from the Tweed River at Bray Park and Uki, plus the Oxley River at Tyalgum. The river flows are down and the weir pools at Bray Park and Tyalgum are drying up.

‘While Clarrie Hall Dam is currently sitting at 98 per cent capacity, it will now drop about 1 to 1.5 per cent, per week, as we start releasing water to supply the Bray Park Weir – the source of water for most of the Shire.

‘We will trigger level 1 water restrictions when the Clarrie Hall Dam level drops to 85 per cent.

‘Restrictions at Tyalgum will be introduced sooner. The flow of the Oxley River at Tyalgum is down to a trickle and the weir pool there is dropping fast.’

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

Click on image to enlarge

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.

Click on image to enlarge

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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