Marine Heatwaves
Duration & Intensity · Coral Bleaching · Coastal Economics
MICRO-NODE 01
Defining MHWs
- SST exceeds 90th percentile of historic baseline
- Must persist for at least 5 consecutive days
- Can last for months or even years
- The "wildfires" of the global ocean
MICRO-NODE 02
Atmospheric Blocking
- High-pressure domes stall over the ocean
- Suppresses wind and cloud formation
- Maximum solar radiation enters the water
- Prevents surface mixing and cooling
MICRO-NODE 03
Ocean Current Anomalies
- Warm boundary currents shift poleward
- Injects tropical heat into temperate zones
- Suppression of cold, deep-water upwelling
- Creates stationary pools of super-heated water
MICRO-NODE 04
The Baseline Shift
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- Anthropogenic warming raises the baseline SST
- Makes extreme thresholds easier to cross
- Frequency increased by 50% over past century
- Events are now longer, hotter, and larger
MICRO-NODE 05
Coral Bleaching
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- Heat stress forces corals to expel zooxanthellae
- Corals lose primary food source and color
- Mass mortality if heat persists over weeks
- Destroys foundational reef architecture
MICRO-NODE 06
Kelp Forest Collapse
- Temperate habitats devastated by heat
- Kelp fronds disintegrate and die off
- Replaced by barren "urchin barrens"
- Total loss of complex 3D coastal habitats
MICRO-NODE 07
Harmful Algal Blooms
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- Warm water turbocharges toxic algae growth
- "Red Tides" produce severe neurotoxins
- Poisons shellfish, mammals, and birds
- Creates massive deoxygenated dead zones
MICRO-NODE 08
Species Migration
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- Mobile species flee poleward seeking cooler water
- Tropical species invade temperate zones
- Causes sudden local extinction of endemic species
- Permanently alters local food web dynamics
MICRO-NODE 09
Wild Fisheries
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- Target species migrate out of legal fishing zones
- Spawning cycles disrupted by thermal shock
- Sudden, unpredictable catch failures
- E.g., "The Blob" devastated Pacific cod
MICRO-NODE 10
Aquaculture Devastation
- Farmed fish cannot migrate away from heat
- High temperatures decrease dissolved oxygen
- Massive die-offs in salmon/shellfish farms
- Multi-million dollar overnight losses
MICRO-NODE 11
Trophic Cascade
- Phytoplankton decline starves forage fish
- Top predators (birds, sea lions, whales) starve
- Mass beachings and breeding failures
- Entire ecosystem collapses from the bottom up
MICRO-NODE 12
Coastal Economies
- Loss of commercial fishing revenue
- Decimation of dive/reef tourism industries
- Toxic blooms shut down local beaches
- Severe socioeconomic shock to coastal towns