The Pacific Ocean is in the middle of a La Niña event, experiencing active volcanic eruptions along the Ring of Fire, ongoing coral bleaching in its western reaches, and a gray whale population that has dropped to near-historic lows. Here’s a breakdown of the major events and trends shaping the world’s largest ocean right now.
La Niña Is Cooling the Central Pacific
The Pacific is currently in an active La Niña phase, with below-average sea surface temperatures across the east-central equatorial region. La Niña is the cool counterpart to El Niño, and it shifts weather patterns worldwide: drier conditions across the southern United States, heavier monsoon rains in Southeast Asia and Australia, and a more active Atlantic hurricane season.
NOAA’s Climate Prediction Center gives a 60% chance that La Niña will transition to neutral conditions between February and April 2026, with neutral conditions likely persisting through the Northern Hemisphere summer. That means these shifted weather patterns should gradually ease in the coming months, though the effects on ocean temperatures and marine ecosystems will linger longer. There are currently no tropical cyclones active in the Pacific, which is expected since hurricane season doesn’t begin until May in the eastern Pacific and June in the central Pacific.
Volcanoes Are Erupting Across the Ring of Fire
As of late 2025, 45 volcanoes worldwide were in continuing eruption status, and several of the most notable sit in the Pacific basin. Home Reef in Tonga has been erupting since December 2025, building a new island roughly 70 meters high and more than a kilometer wide, with white-to-gray emissions rising from the main vent and visibly discolored seawater spreading offshore. Ambae in Vanuatu has been escalating since November 2025, with periodic ash emissions intensifying significantly in February 2026.
Ahyi Seamount, an underwater volcano in U.S. territory in the Mariana Islands, showed signs of unrest starting in October 2025 but has since quieted. No activity had been detected for weeks by late February, and its alert level was downgraded. Meanwhile, Hunga Tonga-Hunga Ha’apai, the Tongan volcano that produced a massive eruption in 2022 powerful enough to send shockwaves around the globe, showed no visible signs of activity during a February overflight.
Sea Levels Are Rising Faster Here Than the Global Average
Low-lying Pacific island nations face some of the most aggressive sea level rise on Earth. Between 1993 and 2023, the ocean around the Maritime Continent (the region including Indonesia, Papua New Guinea, and the Philippines) rose at about 4.5 millimeters per year, while waters around New Zealand climbed at roughly 4.1 millimeters per year. Both rates outpace the global average of about 3.4 millimeters per year during the same period.
Those numbers may sound small, but they compound. A rate of 4.5 millimeters per year translates to nearly 5 centimeters per decade, and for atolls that sit only a meter or two above high tide, that trajectory threatens freshwater supplies, agriculture, and habitability well before the land itself goes underwater. Saltwater intrusion into groundwater is already a reality for communities in Tuvalu, Kiribati, and the Marshall Islands.
Coral Bleaching Hit Record Scale
The western Pacific and its connected reef systems have been hammered by back-to-back mass bleaching events. The 2024 bleaching event on the Great Barrier Reef had the largest spatial footprint ever recorded there, with high to extreme bleaching observed across all three major regions of the reef. Fast-growing corals that had driven a notable recovery between 2017 and 2024 were among the hardest hit, raising concerns about how quickly the reef can bounce back this time.
Then it happened again. Above-average water temperatures returned during the 2025 austral summer, with sea surface temperatures running 1°C to 2.5°C above normal and peaking in March. This triggered the reef’s sixth mass bleaching event since 2016, primarily concentrated across the Northern Great Barrier Reef and northwestern Australia. Aerial surveys of 162 inshore and mid-shelf reefs found 41% had medium to high bleaching. Offshore reefs fared better, with 99% of northern offshore reefs showing low to no bleaching.
The underlying driver is ocean temperature. The Pacific has been running warmer than historical averages across broad swaths, and while La Niña typically cools the central and eastern equatorial Pacific, it can actually push warmer water westward toward reef systems in Australia and Southeast Asia.
The Ocean Is Becoming More Acidic
Beyond warming, the Pacific is absorbing carbon dioxide from the atmosphere, which lowers the pH of seawater. Ocean acidity has increased roughly 30% since the pre-industrial era. Global surface seawater pH has dropped from 8.11 in 1985 to 8.04 in 2024, a shift that sounds minor but represents a significant chemical change on a logarithmic scale.
This matters because lower pH reduces the availability of calcium carbonate, the mineral that corals, oysters, mussels, and certain types of plankton use to build their shells and skeletons. In more acidic water, these organisms spend more energy maintaining their structures and less energy growing and reproducing. For Pacific coral reefs already stressed by bleaching, acidification adds a compounding threat that slows recovery even when temperatures return to normal.
Gray Whale Numbers Have Dropped Sharply
The eastern North Pacific gray whale population, which migrates annually from Arctic feeding grounds to breeding lagoons in Mexico, is at one of its lowest points in decades. The 2024/2025 population estimate came in between 11,700 and 14,450 whales, the third lowest count since surveys began in the late 1960s.
This decline follows an Unusual Mortality Event that began in December 2018, when large numbers of gray whales started washing up dead along the west coast. The event lasted through November 2023 and drove the population down from its recent highs to roughly 13,200 to 15,960 whales by the 2022/2023 survey. A brief uptick in the 2023/2024 count offered some hope, but the latest estimate suggests the recovery stalled. NOAA conducts shore-based surveys from a field station south of Monterey, California, counting southbound whales from December through February as they pass on their migration. Researchers are closely monitoring calf production and body condition for signs of whether the population is stabilizing.
The Great Pacific Garbage Patch Keeps Growing
The North Pacific Garbage Patch, a massive accumulation zone of plastic debris caught in rotating ocean currents between roughly Hawaii and California, continues to expand. Modeling estimates for 2022 put the concentration of larger plastic debris at around 72 to 83 kilograms per square kilometer, with a net growth rate of 1% to 3% per year as new plastic enters faster than existing debris degrades.
The microplastic situation is even more staggering. The same region contains an estimated 1 million or more tiny plastic fragments per square kilometer, particles between 0.5 and 5 millimeters that are nearly impossible to filter out without capturing marine life along with them. Around 90% of the species living in the patch’s deep-sea sediments haven’t even been formally described by science yet, which complicates cleanup efforts: it’s difficult to assess ecological harm when you don’t fully know what lives there.
Deep-Sea Mining Trials Are Raising Alarms
The Clarion-Clipperton Zone, a vast stretch of Pacific seafloor between Hawaii and Mexico, is rich in potato-sized mineral nodules containing metals used in batteries and electronics. In October 2022, a company backed by the Pacific island nation of Nauru conducted the first large-scale trial of a prototype nodule collection vehicle in this zone.
The results, published in Nature, were sobering. In areas where the collector drove, the density of seafloor animals dropped by 37% and species richness fell by 32%. Even in nearby areas not directly mined but affected by sediment plumes kicked up by the vehicle, the balance of species shifted in ways that reduced overall biodiversity. The Clarion-Clipperton Zone hosts unusually high biodiversity for the deep sea, with more species diversity than comparable deep-ocean habitats elsewhere. The International Seabed Authority is still developing regulations for commercial mining, and these early trial results are feeding directly into that debate.