Cuts to US ocean programme will hinder monitoring of El Niño and AMOC

In the winter of 2013-2014, the strong winds of the jet stream shifted north, allowing a mass of warm water dubbed “the blob” to swell across more than 1500 kilometres of the north Pacific Ocean.

Floating instruments moored to the seabed off Alaska, Washington and Oregon alerted scientists and the fishing industry to the arrival of this water, which was up to 4°C hotter than normal.

They were part of the Ocean Observatories Initiative (OOI), five mooring arrays off the US west and east coasts and Greenland. Announcing $220 million in funding for the programme in 2023, the US National Science Foundation (NSF) said the OOI was needed to monitor “critical organs of the Earth”. But last month the NSF announced that these arrays would be largely removed from the water following funding cuts by the administration of US President Donald Trump.

As a planet-warming El Niño climate phase warmed the water further in 2015-2016, sensors running up and down OOI mooring wires revealed the blob was expanding into the deep sea below 250 metres. The mooring data helped show the blob, which repeated in 2019 and may be happening more frequently due to climate change, spurred toxic algal blooms that closed California’s $60 million Dungeness crab fishery for the season.

The removal of most OOI moorings will diminish the accuracy of weather forecasting, including precipitation patterns influencing the record drought in the western US. It will also hinder efforts to monitor a possible weakening in the Atlantic Meridional Overturning Circulation (AMOC) that keeps Europe temperate, as well as the effects of an imminent El Niño.

“We’re flying blind, and it will end up costing us more,” says John Abraham at the University of St. Thomas in Minnesota.

While the OOI costs $56 million a year to run, the US commercial fishing industry, which relies in part on OOI data, generates billions of dollars each year. Weather and climate disasters did $183 billion of damage in 2024. (The US government discontinued this tally in 2025.)

Without the OOI, fleets won’t know which fishing areas might be less impacted by the coming El Niño, which some models say could be the strongest on record, says Jack Barth at Oregon State University. Oyster, clam and shellfish farms won’t be able to prepare for heating and reduced nutrients the El Niño could bring, and scientists will lose their view of harms to marine ecosystems. In the past, the OOI has also alerted scientists to the formation of low-oxygen “dead zones” on the seafloor.

“That is going to be lost at exactly the worst time,” says Hilary Palevsky at Boston College in Massachussetts.

Because satellites can’t see beneath the surface of the sea, measurements by underwater floats, gliders and moorings are crucial to understand what’s happening in the 70 per cent of the planet covered by ocean.

While these mostly measure temperature, salinity and flow rate, the OOI moorings also have sensors for parameters like pH, oxygen and CO2 for understanding the biology and chemistry of the ocean. And they do so in remote, little-monitored places where the movement of water masses affects the climate.

The loss of these sensors will impact the rest of the world, especially by reducing observations of the AMOC. The OOI array in the Irminger Sea, east of Greenland, is part of OSNAP, a line of moorings, gliders and floats stretching from Canada to Greenland to Scotland. It monitors warm, salty water flowing from the tropics to the north Atlantic, where it cools and sinks, driving the AMOC. A collapse in this system could plunge Europe into “ice age” winters and disrupt monsoon rains critical for agriculture in Africa and Asia.

“OSNAP has taught us that most of the actual overturning takes place east of Greenland and that the Irminger Sea is key in understanding the overturning variability,” says Femke de Jong at the Royal Netherlands Institute for Sea Research.

Removing OOI will create a data gap that will limit understanding of the AMOC, even if it’s someday replaced, Palevsky adds.

Scientists fear the dismantling of OOI is the start of a massive rollback of US ocean research funding that could see the discontinuation of OSNAP. Some worry it could even undercut Argo, a vital network of almost 4000 descending instrument floats across the global ocean, half of which are provided by the US.

In a statement to New Scientist, the NSF said the OOI removal was to “prioritise support for evolving scientific priorities”. But it comes as the Trump administration wages what Gretchen Goldman at the Union of Concerned Scientists calls an “attack on science”. The administration has cancelled or suspended thousands of research grants, and it has proposed slashing the NSF’s budget by 55 per cent in 2027.

This week, the administration proposed a rule that would cancel peer review of research grant applications, allowing political appointees rather than independent experts to decide the fate of federally funded research. It would also ban international collaborations and research on gender and diversity.

Edward Dever at the Oregon State University, who manages the OOI array off the coast of Washington and Oregon, says the dismantling of OOI and the proposed grant rule are both part of sweeping changes that would “weaken peer review and politicise NSF-funded science”.

A study last month found that dismantling even one-fifth of the Global Ocean Observing System, a network of instruments that includes the OOI arrays and the Argo floats, would increase the error in the annual rate of ocean heating by 33 per cent. That would be like going from predicting an unemployment rate of 3 per cent this year to only being able to give a range of 2 to 4 per cent, says Abraham, who was part of the team behind the research.

“This is purposeful to try and remove our eyes and ears in the ocean,” he says of the OOI dismantling. “Because if we don’t measure something, how do we know we have a problem?”