Queensland Climate Change: Ocean Warming and Sea Surface Temperature Impacts

Physical Climate Science Projections

Compiled: 10 March 2026

Executive Summary

The oceans surrounding Queensland are warming at rates that are transforming the state’s climate system. Sea surface temperatures around Australia have risen by over 1 degrees C since 1900, with the Coral Sea — Queensland’s primary moisture source — now at its warmest in at least 400 years. This warming drives a cascade of interconnected effects: more intense marine heatwaves, amplified cyclone fuel, greater moisture supply for rainfall events, accelerating coral bleaching, and rising sea levels that compound storm surge and coastal flooding risk.

Key findings:

  • Australian SSTs have warmed 1.08 degrees C since 1900, with 9 of 10 warmest years since 2010
  • The Tasman Sea is warming at twice the global average, driven by intensification of the East Australian Current
  • Marine heatwave frequency increased 34% and duration 17% globally since 1925, with a 54% increase in annual marine heatwave days
  • The Great Barrier Reef has experienced 6 mass bleaching events since 2016, with the 2024 event having the largest spatial footprint on record
  • Sea level rise has accelerated from 1.5 cm/decade (1901–2000) to 4 cm/decade (1993–2023), with rates north and southeast of Australia exceeding the global average
  • The East Australian Current is extending further south, redistributing tropical heat into temperate waters
  • Professor Matthew England’s research shows AMOC weakening could push Australia toward a persistent La Nina-like state with wetter summers

3. East Australian Current (EAC)

3.1 Observed Changes

The East Australian Current — the western boundary current of the South Pacific subtropical gyre — is undergoing significant changes:

  • The EAC now extends further south than historically observed
  • It is intensifying regional heat uptake, particularly in the Tasman Sea
  • The Tasman Sea warming rate is now twice the global average, making it one of the fastest-warming ocean regions globally
  • Species are migrating poleward along the EAC pathway, with tropical fish now regularly observed in Sydney waters

3.2 Implications for Queensland

The EAC strengthening has dual implications for Queensland:

Positive feedback for northern QLD weather: - The EAC transports warm tropical water southward along the QLD coast - Enhanced EAC flow maintains elevated SSTs along the entire east coast - This provides sustained moisture supply for weather systems affecting coastal QLD

Broader circulation effects: - EAC intensification is linked to changes in the South Pacific wind stress curl - This is part of a hemispheric-scale circulation adjustment driven by greenhouse warming - The changes are expected to continue and accelerate under all emission scenarios

Source: CSIRO — State of the Climate 2024: Oceans; UNSW — Australia’s ocean hottest on record 2024

4. Marine Heatwaves

4.1 Definition and Categories

Marine heatwaves (MHWs) are defined as prolonged discrete anomalously warm water events lasting 5 or more days, with temperatures warmer than the 90th percentile of the 30-year historical baseline (Hobday et al., 2016). They are categorised by intensity thresholds based on local SST percentiles (90th, 95th, 98th).

4.3 Australian and Queensland Marine Heatwaves

Australian waters are experiencing increasingly frequent and intense marine heatwaves:

  • Marine heatwaves persist longer than land-based heatwaves, sometimes lasting months or years
  • Impacts include: kelp forest depletion, seagrass loss, poleward species migration, disease proliferation
  • The GBR has experienced marine heatwave conditions during each of its mass bleaching events (2016, 2017, 2020, 2022, 2024, 2025)

4.4 Future Projections

Climate models project “more frequent, extensive, intense and longer-lasting marine heatwaves” under continued warming (CSIRO/BoM State of the Climate 2024). This has direct implications for:

  • Coral bleaching frequency (reducing recovery windows)
  • Fisheries and aquaculture
  • Cyclone intensification (sustained warm SSTs providing fuel)
  • Moisture availability for extreme rainfall events

Source: Nature Communications (2018) — Longer and more frequent marine heatwaves; Hobday et al. (2016) — Defining marine heatwaves; CSIRO — Marine heatwaves research

5. Great Barrier Reef — Ocean Heat Trajectory

5.1 Mass Bleaching Events

The Great Barrier Reef has experienced an unprecedented acceleration of mass coral bleaching:

Year Event Key Details
2016 1st mass bleaching Northern GBR devastated
2017 2nd mass bleaching Unprecedented back-to-back events
2020 3rd mass bleaching Most widespread to date at that time
2022 4th mass bleaching First during La Nina conditions
2024 5th mass bleaching Largest spatial footprint on record; high-to-extreme bleaching across all 3 regions
2025 6th mass bleaching Sixth event in 9 years

The 2022 event was particularly significant: it was the first mass bleaching during La Nina conditions, when cooler-than-average SSTs are typically expected. This suggests the background warming trend has pushed baseline temperatures so high that even relatively cool years can trigger bleaching.

5.2 GBRMPA Outlook Report 2024

The Great Barrier Reef Outlook Report 2024 — the statutory five-yearly assessment by the Great Barrier Reef Marine Park Authority — concluded:

  • The overall outlook for the GBR “remains one of future deterioration due largely to climate change”
  • Future warming already locked into the climate system means further degradation is inevitable
  • Climate change impacts will become “more frequent, severe, and widespread” and will amplify other threats
  • Recovery windows between bleaching events are narrowing critically
  • Since July 2024, SSTs around Australia have been the warmest or second-warmest on record
  • The Marine Park is expected to stay ~1 degrees C warmer than usual into the austral summer

5.3 Long-Term Modelling

The most sophisticated modelling to date (published November 2025) forecasts that under current global emissions pathways, the GBR could lose most of its coral by the end of the century. However, curbing climate change and strategic management could help maintain coral resilience.

5.4 Ocean Acidification

In addition to warming, the Coral Sea has experienced significant ocean acidification:

  • pH decreased 19% between 1982–2022
  • Acidification reduces coral’s ability to build calcium carbonate skeletons
  • Combined with thermal stress, this represents a compound threat to reef integrity

Source: GBRMPA — Outlook Report 2024; GBRMPA — Sea temperature; AIMS — Annual summary of coral reef condition 2024/25; Phys.org — New modelling shows difficult future for GBR

6. Sea Level Rise

6.2 Australian Regional Variation

“Rates of sea level rise to the north and south-east of Australia have been significantly higher than the global average” — CSIRO/BoM State of the Climate 2024.

This is particularly relevant for Queensland, which has: - Extensive low-lying coastal development (Gold Coast, Sunshine Coast, Cairns, Townsville) - Major tidal range amplification in the Torres Strait - Coral cay and island communities vulnerable to inundation

6.3 Compound Risk: Sea Level + Storm Surge + Cyclone Rainfall

Sea level rise does not act in isolation. The compound effect of: 1. Higher baseline sea level (4 cm/decade) 2. More intense tropical cyclone storm surge 3. Heavier cyclone rainfall

creates multiplicative flooding risk for coastal Queensland. A 20 cm sea level rise means that today’s 1-in-100-year coastal flood becomes far more frequent, and extreme events exceed any historical precedent.

Source: CSIRO — State of the Climate 2024: Oceans

7. Professor Matthew England’s Research

7.1 Southern Western Australia: Why It’s Drying

Professor England’s observation that Southern Western Australia is “noticeably drier” is connected to the same large-scale circulation changes affecting Queensland:

  • The Southern Annular Mode (SAM) has trended positive, pushing the westerly wind belt and its rain-bearing fronts further poleward
  • This is driven by both greenhouse warming and ozone depletion
  • SWA has experienced a ~20% decline in winter rainfall since the 1970s
  • The jet stream shifts documented in February 2026 research confirm this mechanism is intensifying

7.2 AMOC Weakening — Implications for Queensland

England’s research on the Atlantic Meridional Overturning Circulation (AMOC) has direct implications for Queensland:

  • Climate models project AMOC could weaken 30% by 2060
  • An AMOC collapse would cause excess tropical heat to accumulate south of the equator
  • This would intensify trade winds, pushing warm water toward the Indonesian maritime continent
  • The result: a persistent La Nina-like state for Australia
  • For Queensland, this means wetter summers with flooding rain — the worst impact under concurrent long-term warming
  • A warmer south equatorial Atlantic triggers atmospheric waves that lower air pressure over northern Australia, pulling in more moisture

7.3 Southern Ocean Overturning

England’s 2023 work on the Southern Hemisphere’s deep-water formation system shows it may also be failing:

  • Antarctic meltwater is disrupting formation of dense abyssal water
  • This could shift tropical rainfall systems
  • May make the Southern Hemisphere drier overall, Northern Hemisphere wetter
  • Could reduce storm tracks reaching southern Australia, creating drier winters

The net effect for Queensland is complex: potentially wetter summers (AMOC/La Nina) combined with drier winters (Southern Ocean circulation change) — amplifying the seasonal extremes and the drought-flood cycle.

Source: UNSW — Matthew England profile; The Conversation (2022) — AMOC collapse could make La Nina the norm; The Conversation (2025) — Weakening Atlantic currents and wetter northern Australia; Yale E360 — Ocean circulation collapse

8. Tropical Cyclone Intensification via Ocean Heat

8.1 The SST-Cyclone Connection

Ocean surface temperatures are the primary fuel for tropical cyclones. Key findings:

  • Oceans around Australia have warmed ~1.1 degrees C since 1900 (Climate Change Authority)
  • Warmer SSTs increase available energy for cyclone intensification
  • The proportion of Category 4-5 tropical cyclones is increasing (IPCC, medium confidence)
  • Rapid intensification events are becoming more frequent
  • Cyclone rainfall intensity is projected to increase by +14% median globally

8.2 Poleward Extension of Warm Waters

As warm surface waters extend further south: - The zone where cyclones can maintain or intensify expands poleward - Cyclones can sustain intensity further along their track - This extends the damage footprint further south toward populated southeastern Queensland - TC Alfred (2025) demonstrated this: forming in near-record Coral Sea warmth and maintaining intensity to Moreton Island

Source: Climate Change Authority — Tropical cyclones factsheet; GFDL — Global warming and hurricanes

9. Synthesis: Ocean Heat and Queensland’s Climate Future

The Ocean-Atmosphere-Land Cascade

Ocean warming drives a cascade of effects through Queensland’s climate system:

Ocean warming (+1°C since 1900)
  ├── More moisture available → heavier rainfall events
  ├── More energy for storms → more intense cyclones
  ├── Marine heatwaves → coral bleaching, ecosystem degradation
  ├── EAC intensification → warm water extending further south
  ├── Sea level rise → compound coastal flooding
  └── Circulation changes → altered drought/rainfall patterns
        ├── AMOC weakening → wetter QLD summers (La Nina-like)
        ├── SAM trend → drier QLD winters
        └── Jet stream shift → less winter rainfall in southern QLD

Implications for Queensland

Domain Direction Key Driver
Summer rainfall intensity Increasing Warmer Coral Sea, more moisture
Winter/dry season rainfall Decreasing SAM trend, jet stream shift
Cyclone intensity Increasing Warmer SSTs, more energy
Cyclone damage footprint Expanding south Poleward warm water extension
Marine heatwaves More frequent, longer Background SST rise
Coral bleaching Accelerating 6 events in 9 years; narrowing recovery
Sea level Rising, accelerating Thermal expansion, ice melt
Coastal flooding Increasing Compound: SLR + surge + rainfall
Seasonal contrast Widening Wetter summers, drier winters

Key Uncertainties

  • Rate and timing of AMOC weakening (30% by 2060 is a projection, not certain)
  • Whether the Southern Ocean overturning slowdown will offset or compound AMOC effects for Queensland
  • The interaction between background warming and natural variability (La Nina brought 2022 bleaching — at what point does “variability” no longer provide relief?)
  • Speed of EAC intensification and its effects on SEQ coastal climate
  • Whether marine ecosystem adaptation (coral, fisheries) can keep pace with warming rates

Key Sources

Government / Institutional

  1. CSIRO/BoM — State of the Climate 2024: Oceans
  2. BoM — State of the Climate: Oceans at a glance
  3. QLD State of Environment 2024 — Sea surface temperature
  4. QLD State of Environment 2024 — Climate change and the GBR
  5. GBRMPA — Great Barrier Reef Outlook Report 2024
  6. GBRMPA — Sea temperature
  7. GBRMPA — Reef health updates
  8. AIMS — Annual summary of coral reef condition 2024/25
  9. IMOS Ocean Report — Long-term SST around Australia
  10. Climate Change Authority — Tropical cyclones factsheet
  11. BoM — Sea temperatures knowledge centre
  12. AIMS — Sea temperatures

Peer-Reviewed Research

  1. Nature (2024) — 400-year GBR temperature record
  2. Nature Communications (2018) — Longer and more frequent marine heatwaves
  3. Hobday et al. (2016) — A hierarchical approach to defining marine heatwaves
  4. Phys.org (Nov 2025) — New modelling shows difficult future for GBR

Matthew England / Ocean Circulation

  1. UNSW — Matthew England profile
  2. UNSW — Australia’s ocean surface hottest on record in 2024
  3. The Conversation (2022) — AMOC collapse could make La Nina norm for Australia
  4. The Conversation (2025) — Weakening Atlantic currents and wetter northern Australia
  5. Yale E360 — Ocean circulation collapse and Antarctica

Additional

  1. CSIRO — Marine heatwaves research
  2. GFDL — Global warming and hurricanes
  3. Carbon Brief — IPCC report on extreme weather
  4. GBRMPA — Sea temperature threats