Thomas Lamb  ·  June 11, 2026  ·  Part IX — The Bloom

The Bloom
The Algae-SST Feedback Loop
Nobody Is Modelling

Sources: Nature (2023) · Journal of Oceanology and Limnology (2024) · Nature Communications (2024)
Climate Dynamics · Science Advances (2025) · NOAA CoralTemp · Global Volcanism Program

The standard climate model has a clear causal chain: greenhouse gases trap heat, oceans warm, ecosystems respond. Algal blooms are a downstream consequence — a symptom of warming, not a cause of it. The data published between 2022 and 2026 tells a more complicated and more alarming story. Algae are not just responding to warming. They are actively amplifying it — and in the process generating the greenhouse gases that drive the next cycle of bloom.

This post documents the algae-SST feedback loop — what it is, what the peer-reviewed literature now confirms, how it connects to the submarine volcanic framework that seeded the original observation in 2004, and why it is not in a single operational climate model.

The Mechanism — How Algae Heat the Ocean

Phytoplankton contain chlorophyll — the same pigment that captures sunlight for photosynthesis. That pigment does not distinguish between the wavelengths useful for photosynthesis and those that become heat. When a bloom forms, it concentrates chlorophyll at the ocean surface. The surface layer becomes a solar collector — absorbing radiation that would otherwise penetrate to depth and warm a much larger volume of water. Instead it warms a thin surface layer very efficiently.

Global SST Rise from Phytoplankton

+0.5°C

Solar radiation absorbed by phytoplankton raises SST by ~0.5°C globally — confirmed by multi-century coupled climate model simulations. (Climate Dynamics, 2012)

Local SST Rise — Peak Events

+4.5°C

More localised observations show SST increases of up to 4.5°C over just 4 days due to presence of phytoplankton blooms. (Journal of Oceanology and Limnology, 2024)

Bloom Frequency Increase 2003–2020

+59%

Global bloom frequency increased 59.2% and spatial extent by 13.2% between 2003 and 2020. (Nature, 2023)

Atmospheric Humidity Increase

2–5%

Phytoplankton-driven SST rise increases evaporation, enhancing atmospheric humidity 2–5% — amplifying the greenhouse effect locally. (Climate Dynamics, 2012)

The Full Feedback Chain — From Mantle to Atmosphere

The Amplifying Loop — Each Step Peer-Reviewed

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Step 1 — Geothermal heat injection

Submarine volcanic and hydrothermal systems inject heat into the deep ocean from below. Geothermal forcing accounts for nearly 20% of global ocean warming over the past two decades. The Indonesian arc — most volcanically active seafloor on Earth — sits beneath the warmest ocean on Earth.

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Step 2 — Hydrothermal iron and nutrient flux

Hydrothermal vents inject iron, silica, phosphorus and other micronutrients directly into the water column. Hydrothermal systems contribute nearly 23% of the dissolved iron inventory in the entire oceanic water column. Iron is the limiting nutrient for Pseudo-nitzschia — the primary domoic acid producer.

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Step 3 — Warm water + iron triggers bloom

Warm surface water combined with nutrient loading triggers phytoplankton bloom. Bloom frequency has increased 59% globally since 2003, with strongest correlations between SST and bloom frequency in the Alaska Current (r=0.44) and Oyashio Current off Japan (r=0.48) — the Japan-to-Alaska corridor documented in Part VII.

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Step 4 — Bloom absorbs solar radiation as heat

Phytoplankton chlorophyll concentrates at the surface, absorbing solar radiation that would otherwise penetrate to depth. SST rises +0.5°C globally from phytoplankton solar absorption. Local peak events reach +4.5°C in 4 days. The surface layer becomes a heat collector.

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Step 5 — Warmer ocean releases more CO₂ and methane

Warmer surface water holds less dissolved gas. CO₂ and methane outgas into the atmosphere. When blooms die and decompose, they release CH₄, CO₂, and N₂O. A 2024 Nature Communications study confirmed phytoplankton proliferation intensifies climate warming through this GHG release pathway.

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Step 6 — Atmospheric humidity amplifies greenhouse effect

Phytoplankton-driven SST rise increases evaporation, enhancing atmospheric humidity by 2–5%. This amplifies the greenhouse effect and raises atmospheric temperature by up to 0.5°C locally. The Hadley Cell weakens and expands poleward — reducing cloudiness at subtropical latitudes and driving further warming.

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Step 7 — Higher atmospheric temperature drives more warming

Increased atmospheric temperature warms the ocean further. The ocean outgasses more CO₂. Permafrost thaws faster, releasing methane. The warm pool expands. The next bloom cycle is seeded. The loop continues — each cycle leaving a warmer baseline than the last.

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Return to Step 3 — Loop repeats, amplified

Each iteration of the loop begins from a warmer baseline. The staircase pattern visible in 146 years of global temperature data — the abrupt step changes of 1977, 1998, 2016 — may represent discrete amplification events in this loop rather than purely atmospheric forcing.

Case Study — South Australia 2025: 20,000 km² of Solar Collector

The South Australian Karenia bloom that ran from March 2025 to February 2026 covered approximately 20,000 km² — an area larger than the state of Kuwait. For nearly a full year, that patch of ocean was functioning as a concentrated solar heat absorber, trapping radiation in the surface layer rather than distributing it through the water column.

At peak in December 2025, 9,400 kilograms of dead marine life were washing ashore weekly — the visible consequence of oxygen depletion and toxin release as the bloom died and decomposed. Less visible was the CO₂ and methane being released into the atmosphere as that 20,000 km² of biomass decomposed. Less visible still was the heat being trapped in the surface layer by 20,000 km² of chlorophyll absorbing solar radiation every day for nine months.

None of this is in the GHG emissions inventories. None of it appears in the energy-related CO₂ charts that dominate the climate policy conversation. It is a natural amplifying loop — seeded by warming, amplifying warming, releasing GHGs, driving more warming — and it is entirely outside the standard attribution framework.

The 2006 Connection — What Was Said 20 Years Ago

Thomas Lamb — May 28, 2006 (Part I-B of this series)

"While greenhouse gases contribute to increases in global temperature, the reverse is also true — higher temperatures exacerbate the release of greenhouse gases."

That single observation — quoted from a European study in 2006 — is now documented across multiple peer-reviewed publications as a multi-stage amplifying feedback loop. What was a footnote in a personal blog post is now confirmed by Nature Communications, Climate Dynamics, and the Journal of Oceanology and Limnology. The mechanism is real. The scale is global. And it is still not in the models that drive climate policy.

Algae are not just a symptom of a warming ocean. They are one of its amplifiers — absorbing solar heat, releasing greenhouse gases, and seeding the conditions for the next bloom. A 59% increase in global bloom frequency since 2003 is not a footnote. It is a forcing.

What The GHG Acceleration Charts Miss

The Forster et al. April 2026 chart showing accelerating CO₂, CH₄ and N₂O concentrations since 2015 is being interpreted entirely through an energy-sector lens — fossil fuel emissions, land use change, agricultural methane. That interpretation is real and important. But the post-2015 acceleration in all three gases coincides precisely with:

The 2015–16 Convergence

▸  Strongest central Pacific El Niño on record — draining the western Pacific warm pool above the submarine volcanic arc

▸  Largest Pacific HAB in recorded history — domoic acid from California to Alaska, toxic decomposition releasing CO₂ and CH₄

▸  Axial Seamount eruption April 2015 — iron and heat pulse into the Pacific, feeding bloom initiation

▸  Blob marine heatwave — 4 million km² of anomalous warmth, expanding bloom conditions from California to Alaska

▸  Indonesian peat fires — triggered by El Niño drought over the country sitting above the volcanic arc, releasing massive CO₂ pulses

Every one of these events generates GHGs. None of them appear in energy-sector emissions inventories. All of them were amplified by or directly caused by the El Niño event that drained the western Pacific warm pool — which sits above the submarine volcanic system that seeded the original observation in 2004.

NASA's 0.2°C Gap — What May Be In It

In March 2024, NASA Goddard Institute director Gavin Schmidt published in Nature that 2023 warming exceeded all known forcing factors by 0.2°C — and that no combination of proposed mechanisms could reconcile models with observations. The proposed explanations included greenhouse gases, aerosol reductions, Hunga Tonga water vapor, and solar activity. Not one of them included:

Missing Factor 1

Phytoplankton solar heat absorption — global +0.5°C SST contribution from bloom-driven surface heating, now increasing 59% per decade in frequency

Missing Factor 2

Hydrothermal iron flux from submarine volcanic systems seeding bloom initiation — particularly in the western Pacific, Japan-Alaska corridor and Juan de Fuca Ridge

Missing Factor 3

Bloom decomposition GHG release — CO₂, CH₄ and N₂O from dying blooms not captured in energy-sector inventories but contributing to atmospheric GHG acceleration

Missing Factor 4

Submarine volcanic CO₂ and heat injection — directly into the ocean and rising to the atmosphere. "How much — that will have to be studied." (2004). Still not studied. Still not in the models.

The ocean is not a passive recipient of atmospheric warming. It is an active participant — generating, amplifying, and releasing the gases that drive the next cycle. The bloom is not a symptom. It is a gear in the engine.

On The Record — June 11, 2026

Today NOAA declared the strongest El Niño in a generation officially begun. The western Pacific warm pool — heated from below by the most volcanically active seafloor on Earth, seeding blooms through hydrothermal iron flux, those blooms trapping solar heat and releasing greenhouse gases — is now draining eastward. The next phase of the amplifying loop is beginning.

The instruments that would help us quantify this loop — the Ocean Observatories Initiative, the NOAA monitoring network, the satellite systems cancelled by the current administration — are being removed from service as the most critical observational window in a generation opens.

The question asked in 2004 was simple: is it a coincidence that the warmest ocean on Earth sits above the most volcanically active seafloor? The answer, assembled across twenty-two years of citizen observation and now confirmed by multiple independent lines of peer-reviewed evidence, is: no. And the bloom is one of the mechanisms that connects them.

The Convergence Series — Thomas Lamb

Part I: Climate Science Revisited (2004) →

Part I-B: The First Eruption (2006)

Part II: The Furnace Below

Part III: Indonesia SST Deep Dive

Part IV: Going Blind — Dismantling NOAA

Part V: It Has Begun — JMA Declaration

Part VI: Two Roads to the Same Fire

Part VII: The Corridor — Japan to Alaska

Part VIII: Icebreakers for a Melting Ocean

Part IX: The Bloom — The Algae-SST Feedback Loop (this post)

SOURCES:
Ma et al. "Mutual feedback between algal blooming and global warming." J. Ocean. Limnol. 42, 787–801 (2024)
Shi et al. "Global lake phytoplankton proliferation intensifies climate warming." Nature Communications 15 (2024)
Sonntag & Hense. "Global climate response to solar radiation absorbed by phytoplankton." Climate Dynamics (2012)
Xiao et al. "Coastal phytoplankton blooms expand and intensify in the 21st century." Nature (2023)
Guinaldo & Neukermans. "2023 North Atlantic coccolithophore bloom dynamics." Ocean Sciences 22:145 (2026)
NOAA CoralTemp / Coral Reef Watch · Global Volcanism Program · JMA Monitoring Report No. 405 (June 10, 2026)
Schmidt G.A. "Climate models can't explain 2023's huge heat anomaly." Nature 627:467 (2024)
Original framework: Thomas Lamb, Climate Science Revisited, March 2004
Research assistance: Claude, Anthropic · June 11, 2026