One of Heather Welch’s jobs — before she was fired via an email giving her just 90 minutes to pack up and leave — was to prevent collisions between the ships and whales navigating the water along the US West Coast.

Welch, who was an ecologist at the National Oceanic and Atmospheric Administration for nearly a decade, specialized in mapping the movement of marine animals. This information helped ships map their routes, and fisheries improve their catch, while avoiding accidentally scooping up and killing sea lions or turtles.

Welch is just one of more than 1,000 people who in the past few weeks have been laid off from NOAA, the nation’s top weather and climate agency. It was already understaffed before President Donald Trump’s cuts, and there are more to come. The team Welch worked with, which provided crucial climate data to fisheries, was hit hard. Much of its work “will have to be scaled back, if not stopped entirely,” she told CNN.

NOAA’s remit is wide, but one of its most critical roles is to observe the oceans. Multiple scientists told CNN the layoffs are taking experteyes off the oceans at the worst possible time: as the oceans undergo extreme change — some of which remains largely unexplained — with deep impacts for humans, wildlife and economies.

Global ocean temperatures shattered heat records for 450 straight days in 2023 and 2024, fueling more intense hurricanes, driving unexpectedly high sea level rise, killing marine life and causing catastrophic coral reef bleaching. A key system of ocean currents is showing signs of instability, and researchers are scrambling to understand if and when it could collapse, a potentially catastrophic event that would change weather in the Northern Hemisphere.

It’s hard to overstate the role NOAA plays in ocean science.

“If you’ve been to the ocean, or if you have experienced weather, you’ve been impacted by NOAA in some way,” said Tom Di Liberto, a climate scientist and former public affairs specialist at NOAA, who was also laid off in February.

Data from the agency’s vast ocean monitoring networks, including ships, satellites and fleets of robotic buoys, feeds into near-term forecasts for weather and helps predict waves and tides. It gives a long-term picture, too, including projecting changes to reservoir water levels, snowpack and hurricane frequency.

This information, provided publicly and for free, is leveraged by businesses. Fewer experts could reduce the quality of those much-used products.

NOAA’s rich trove of data feeds climate models that allow scientists to look into the future and answer questions like “what is sea level rise going to look like in 50 years? What is weather going to look like in 50 years? How will agriculture change?” said Sarah Purkey, an assistant professor at the Scripps Institution of Oceanography.

“Scattershot” firings have now “created holes all over NOAA” and the risks could be severe, Cooley said.

A White House official told CNN “an extensive process was conducted to ensure that mission critical functions to fulfill the NOAA’s statutory responsibilities weren’t compromised.”

NOAA’s science has implications for human lives. Hotter oceans fuel stronger storms and without accurate forecasts of their severity and where they will make landfall, “we’re going to have more people in harm’s way,” Cooley said.

Climate change is also increasing the frequency of vibrio blooms, a flesh-eating bacteria found in seawater thatinfects people through cuts or by eating raw shellfish. Without the ability to identify conditions that could lead to a vibrio bloom, people in coastal regions and those who rely on shellfish “are in the crosshairs for an awful public health outcome,” Cooley said.

“What we’re talking about here is a wholesale decrease in NOAA’s ability to support communities,” she added.

Another big concern is how layoffs might affect NOAA’s work predicting and understanding El Niño and La Niña events, natural climate fluctuations which start in the Pacific Ocean and have huge impacts on global weather patterns.

Agencies in other countries also monitor these patterns, including Peru and Japan, but the US plays a leading role. NOAA’s forecasts “can literally move global markets,” Di Liberto said.

He worries the layoffs might affect international efforts to understand whether climate change affects the frequency and strength of El Niño and La Niña. The answer could mean “massive impacts in seasonal conditions across a huge portion of the globe,” he said.

NOAA’s work also benefits industries.

US fisheries are “among the best-managed in the world” because of NOAA, Cooley said. The agency provides information aimed at helping the industry maximize its harvest and keep fishing decades into the future without collapsing fish stocks.

It’s too soon to understand the full impacts of the mass layoffs, but the first real test may come during a disaster like a hurricane. “When you stress a system during extremes, that’s when things can break,” Di Liberto said.

One thing scientists are sure about is there will be more climate change-driven disasters affecting the oceans and US coastlines over the next four years.

A more long-term consequence is the number of early career scientists who were laid off. People like Allison Cluett, who was a research physical scientist at NOAA and part of a team studying changes in the Pacific Ocean to help fisheries make long-term decisions. It’s “heart breaking,” she told CNN, “the next generation of federal workers was just erased.”

Firing young ocean scientists is a huge missed opportunity not least given the economic opportunities in the ocean economy, from food to clean energy, said Douglas McCauley, a professor of ocean science at the University of California Santa Barbara.

Many could have been making vast amounts of money in the private sector but chose NOAA because they love the ocean, he told CNN. “By treating these scientist as if they are deadbeats … we will be lucky to ever successfully compete for the trillions in ocean wealth and be an ocean superpower,’ he said.

Other countries may step into the gap. China is increasing its investment into ocean science, McCauley said. “Data is power, and that’s the same in the ocean as it is in any other domain,” he added, “with these cuts and this downsizing, we’re ceding that power.”