When 70 years of climate data hangs in the balance at Mauna Loa, science loses its north star.

More than 11,100 feet above sea level, surrounded by nothing but black rocks, white clouds and blue sky, the Mauna Loa Observatory is in a Goldilocks spot for studying the atmosphere.

The air that swirls around the isolated outpost located on a Hawaiian volcano is a mix from all over the Northern Hemisphere. That makes it one of the best places to measure greenhouse gases in the atmosphere. It is indispensable to scientists around the world.

The readings collected from Mauna Loa, starting in 1958, were used to create what is famously known as the Keeling curve. It’s an upward-swooping line that charts the steady rise of carbon dioxide over the past seven decades — the result of nations burning oil, gas and coal.

But President Trump’s proposed 2026 budget would put an end to Mauna Loa, along with three other key observatories and almost all the climate research being done by the National Oceanic and Atmospheric Administration.

“It’s frankly inconceivable,” said Lisa Graumlich, an emeritus climate scientist at the University of Washington and past president of the American Geophysical Union. People know and understand the “iconic” record, she said. “A lot of the science we do is incredibly complex, and this record is something that can be grasped.”

The observatory is part of a global network of stations that monitor the atmosphere. The research performed at these labs lets scientists assess changes over the long term, figure out what caused the changes and make better predictions for extreme events like heat waves, droughts and floods. And the stations can help scientists tell which climate policies are working, which are not, and if global warming is accelerating.

“Why, for relatively little cost, would we want to lose that ability?” Dr. Graumlich said.

Consistency in collecting these climate records is key. “It’s not unlike going to the doctor,” said Rick Spinrad, who was the administrator of NOAA during the Biden administration. “You go regularly, you get your blood work done, and if there are any changes, you can catch them early.”

The same is true for planetary checkups, he said, and that’s what Mauna Loa provides. The average concentration of carbon dioxide, one of the main causes of climate change, has risen rapidly, throwing the planet’s natural systems out of balance. Mauna Loa’s records show it has climbed from 316 parts per million to more than 430 parts per million.

Dr. Graumlich has studied climate change since the 1970s, when, she recalled, scientists questioned whether humans were really capable of changing Earth’s climate. The data from Mauna Loa answered that question.

“It became so clear that we were moving beyond natural variability, and that fossil fuel burning was causing it,” Dr. Graumlich said. “It took decades for us to realize that.”

As important as the Mauna Loa Observatory is, it doesn’t work in isolation. To have a reliable and global picture of greenhouse gases in the atmosphere, scientists need to collect samples from multiple places. NOAA operates three other monitoring stations — one in Alaska, one in American Samoa and one at the geographic South Pole — to compile its global average carbon dioxide trend.

The president’s budget would close all four stations, eliminating the United States’ pole-to-pole view of greenhouse gases. They cannot easily be replaced.

“We’d lose large areas of observation and make it harder to understand where greenhouse gases are coming from, and where they’re going,” Dr. Spinrad said.

NOAA declined a request to comment for this article, saying that the agency does not comment on the budget.

But the cuts are in line with the Trump administration’s dismissal of the risks of global warming and end federal efforts to reduce the emissions that are heating the planet.

NOAA also runs a “flask network” that collects air samples from all around the world, including remote places that lack the infrastructure to take measurements. These are processed at NOAA’s Global Monitoring Lab in Boulder, Colo., which would also fall under the budget ax. Other such networks of air sampling exist, but they lack the coverage that NOAA’s provides, said Ralph Keeling, a professor of climate science at the Scripps Institution of Oceanography and the son of Charles Keeling, who started the Mauna Loa carbon dioxide curve.

“We would lose any understanding of how climate is changing, at what pace, and where,” Dr. Spinrad said. Identifying what places are most vulnerable to climate change would be more difficult, as would pinpointing promising spots for carbon dioxide removal efforts and assessing those efforts, he said.

Although other countries and scientific organizations are measuring greenhouse gases and the atmosphere, both through air sampling networks and dedicated measurement labs, NOAA’s observatories and programs are internationally invaluable.

Scientists at Mauna Loa and other observatories also track methane, a greenhouse gas that’s much more potent in the short term than carbon dioxide, as well as nitrous oxide, aerosols and ozone-depleting substances. They monitor for soot and other particulate pollution in the air and observe changes in solar radiation, weather and wind patterns.

Failing to track those metrics could have broad implications.

“It’s not just the climate mission that gets compromised,” Dr. Spinrad said. “It’s the ability to protect people and property for things like wildfire. So much is lost with the elimination and termination of these labs.”

Abandoning Mauna Loa would be yet another clear signal to the world that the United States is no longer serious about climate change, scientists said.

“The NOAA effort is really the backbone of the global effort to track greenhouse gases,” Dr. Keeling said. Scientists building other long-term records rely on the Keeling curve to interpret their own. “We need to do everything we can do make sure these stations don’t close.”

https://www.nytimes.com/2025/07/17/climate/budget-cuts-climate-observatories.html