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

During the winter of 2013-2014, a shift in the jet stream’s strong winds pushed north, leading to the spread of a warm water mass called “the blob” across over 1,500 kilometers of the north Pacific Ocean.

Floating instruments anchored off the coasts of Alaska, Washington, and Oregon notified scientists and the fishing industry about this water, which was up to 4°C warmer than usual.

These instruments were part of the Ocean Observatories Initiative (OOI), comprising five mooring arrays situated off the US west and east coasts and Greenland. In 2023, the US National Science Foundation (NSF) announced $220 million in funding for the program, emphasizing the OOI’s role in monitoring the Earth’s “critical organs.” However, last month, the NSF declared these arrays would be mostly withdrawn due to funding reductions by the administration of US President Donald Trump.

As the El Niño climate phase heated the waters further in 2015-16, sensors along the OOI mooring wires showed that the blob was expanding into the deep sea below 250 meters. The data demonstrated that this phenomenon, which reoccurred in 2019 and may become more frequent with climate change, led to toxic algal blooms that forced the closure of California’s $60 million Dungeness crab fishery for the season.

Removing the majority of OOI moorings will reduce the precision of weather forecasts, affecting precipitation patterns that contribute to the record drought in the western US. This will also impede the monitoring of a potential decline in the Atlantic Meridional Overturning Circulation (AMOC), which maintains Europe’s temperate climate, and the impacts of an impending El Niño.

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

Though operating the OOI costs $56 million annually, the US commercial fishing industry, which partially depends on OOI data, generates billions of dollars each year. In 2024, weather and climate disasters caused $183 billion in damages. (The US government discontinued tracking this figure in 2025.)

Without the OOI, fishing fleets will lack information about which areas might be less affected by the next El Niño, which some models predict could be the strongest recorded, explains Jack Barth at Oregon State University. Oyster, clam, and shellfish farms will struggle to prepare for the warming and nutrient reduction that El Niño might bring, and scientists will lose insight into marine ecosystem damages. Historically, the OOI has also alerted researchers to low-oxygen “dead zones” forming on the seafloor.

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

Since satellites cannot penetrate below the ocean’s surface, measurements by underwater floats, gliders, and moorings are essential for understanding the conditions in the 70 percent of the planet covered by ocean.

While these instruments primarily measure temperature, salinity, and flow rate, the OOI moorings also have sensors for pH, oxygen, and CO2, providing insights into the ocean’s biology and chemistry. They are particularly valuable in remote, under-monitored locations where water mass movements influence the climate.

The absence of these sensors will have global repercussions, particularly by decreasing observations of the AMOC. The OOI array in the Irminger Sea, east of Greenland, is part of OSNAP, a network of moorings, gliders, and floats extending from Canada to Greenland to Scotland. This system monitors warm, salty water traveling from the tropics to the North Atlantic, where it cools and sinks, driving the AMOC. A disruption in this system could subject Europe to “ice age” winters and disturb monsoon rains crucial 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,” notes Femke de Jong at the Royal Netherlands Institute for Sea Research.

According to Palevsky, eliminating the OOI will create a data void that will impede understanding of the AMOC, even if the system is eventually reinstated.

Scientists worry that dismantling the OOI marks the beginning of a substantial reduction in US ocean research funding, which might lead to the termination of OSNAP. There is also concern that it could undermine Argo, a crucial network of nearly 4,000 instrument floats throughout the global ocean, half of which are supplied by the US.

In a statement to New Scientist, the NSF explained that the OOI removal was intended to “prioritise support for evolving scientific priorities.” However, this decision coincides with what Gretchen Goldman at the Union of Concerned Scientists describes as an “attack on science” by the Trump administration, which has canceled or suspended thousands of research grants and proposed a 55 percent cut to the NSF’s budget by 2027.

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

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

A study published last month found that dismantling even one-fifth of the Global Ocean Observing System, a network that includes the OOI arrays and Argo floats, would increase errors in the annual rate of ocean heating by 33 percent. This is comparable to predicting an unemployment rate of 3 percent this year but only being able to provide a range of 2 to 4 percent, according to Abraham, who contributed to the research.

He describes the OOI dismantling as an intentional effort to “remove our eyes and ears in the ocean,” adding, “Because if we don’t measure something, how do we know we have a problem?”