By John Ian Lau

Marine heatwaves are no longer an occasional anomaly — they are becoming a planning variable for fisheries, shipping, tourism, and coastal protection. A new analysis from NOAA’s Physical Sciences Laboratory (PSL) argues that the biggest challenge for decision-makers is not only the heat itself, but how differently these events behave depending on when they begin. That seasonal nuance matters for early warning, because a heatwave that starts in summer may peak sharply and then collapse, while a winter-starting event can persist and reshape ecosystems and economies for far longer.

In a July 28 update tied to new research on the Northeast Pacific, Tongtong Xu of NOAA PSL explained how springtime patterns can set the stage for winter outcomes: “This spring we watched a North Pacific meridional mode-like pattern unfold, with ocean warming extending from California toward the central tropics and reaching marine heatwave conditions. Historically, this is a classic early-warning signal for El Niño development.” Xu added that NOAA’s data-driven model points toward El Niño development in winter 2026/27, and noted that if it resembles a Central Pacific event, “we might expect some warming in the Gulf of Alaska.”

The core takeaway from the PSL summary is that two driver sets can combine — large-scale tropical dynamics such as ENSO, and local processes such as subsurface heat storage and reemergence (often described as an “ocean memory”). In the Northeast Pacific, the researchers report that marine heatwaves that start in winter tend to last longer because ENSO impacts can reinforce reemergence, giving warm anomalies staying power. Summer-starting heatwaves, by contrast, can become more intense but usually end faster.

For OceanVines readers, the practical implication is straightforward: the same sea-surface-temperature maps can represent very different risk trajectories depending on the season and the subsurface state. Xu underscored that nuance by warning that without enough heat stored below the surface, the surface warming “may not be too extreme.” And in an alternative scenario — if an Eastern Pacific El Niño develops — she wrote that “we might not see open ocean heatwaves in the broader Northeast Pacific at all.”

That kind of conditional outlook also highlights a second challenge: the ocean is still under-instrumented, and observation gaps limit the confidence and usefulness of seasonal forecasts. This is where ocean mapping and autonomous monitoring are moving from long-term aspiration to near-term operational necessity — a shift illustrated by a July 27 announcement from the Nippon Foundation–GEBCO Seabed 2030 Project, which is formally linked to the Intergovernmental Oceanographic Commission (IOC) of UNESCO through GEBCO’s joint-programme governance.

Seabed 2030 said it is partnering with Ulysses, a company developing autonomous surface and underwater vehicles, to expand the collection of bathymetric data in places that are difficult and expensive to survey. In announcing the collaboration, Seabed 2030 Director Jamie McMichael-Phillips emphasized that coverage is still incomplete: “Much of the ocean remains unmapped, and accelerating progress will require new approaches to how bathymetric data is collected.” He argued that autonomous technologies could make data gathering “more scalable and efficient,” especially in challenging regions.

The connection between a marine heatwave forecast and a seabed-mapping partnership may not be obvious at first glance. But the link is the same: predictive ocean management depends on high-quality, high-frequency, and widely shared measurements. For marine heatwaves, that means observing not just surface conditions, but the subsurface heat content that can reemerge months later. For coastal resilience and habitat restoration, it means understanding how currents, seafloor features, and nearshore bathymetry steer heat, nutrients, larvae, and sediment transport.

As NOAA’s PSL notes, improved models and tools can give communities and industries more time to prepare for extreme events, potentially reducing harm. Yet those tools need real-world data to stay honest — and the world’s mapping and monitoring efforts are still catching up with the pace of change. For OceanVines, the mission is constant: to illuminate the inner sparks of every life we touch through our efforts in ocean conservation and education. When forecasts become more conditional and the ocean becomes more volatile, the value of sustained observation — and the partnerships that scale it — only increases.

Together, we celebrate The Greatest Good.

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