Scientists track 'global warming' and 'climate change' separately, even though they are deeply connected

NASA and NOAA keep separate definitions for global warming and climate change. One is a temperature number. The other covers much more.

People often use "global warming" and "climate change" as if they were interchangeable. NASA and NOAA do not. Both agencies keep separate definitions. The gap between the two phrases is much wider than it may seem.

Global warming is a temperature number. Climate change is a longer list. It includes the temperature number and more. At least one major process on that list would happen even if the planet didn't warm at all.

What global warming actually measures

NASA defines global warming as the long-term rise in Earth's average surface temperature, and nothing else. The agency's Goddard Institute for Space Studies in New York produces the number every January. Inputs include more than 25,000 weather stations, plus ship and buoy readings of sea surface temperature.

For 2025, that number was 2.14°F (1.19°C) above the 1951 to 1980 average. The result meant 2025 is statistically tied with 2023 for second place, while 2024 remains the hottest year since record-keeping began in 1880.

The ten most recent years are the ten warmest in the agency's 146-year record.

NOAA narrowly uses the phrase "global warming" as a replacement for the term "warming caused by people." The cause is carbon dioxide and other heat-trapping gases from coal, oil, and gas. The phrase has carried that meaning since the 1970s for NOAA.

Climate change is the wider category

NOAA defines climate change as any significant, sustained shift in climate measures over decades or longer. Rainfall, snowpack, wind patterns, and seasonal timing all count. Temperature is also on the list.

NASA groups a set of physical changes under the term and attributes them to warming. The agency's list includes rising seas, shrinking mountain glaciers, faster ice loss in Greenland and Antarctica, and earlier spring blooms. Warming is one symptom of climate change among several.

NOAA's definition also covers natural causes, and the agency says so on its own page: climate change results from both human activities and natural causes. The record backs that up.

Mount Tambora erupted in Indonesia in 1815 and threw enough ash into the atmosphere to cool the Northern Hemisphere. New England saw summer frosts and crop failures in 1816, a year NOAA records still call the year without a summer.

On a far longer timescale, NASA attributes the ice ages of the past few million years to slow, repeating changes in Earth's orbit and tilt, known as Milankovitch cycles.

Global warming, in the modern sense, does not stretch that far. It refers to one cause, heat-trapping gases from fossil fuels, and one trend, the rise in average surface temperature that NASA has measured since 1880.

Some of what NOAA measures under climate change has little to do with heat.

Ocean acidification is the clearest example

Seawater absorbs a large share of the carbon dioxide people release each year. The dissolved gas forms carbonic acid, and the chemistry changes whether or not the water warms.

Surface ocean water pH has fallen by about 0.1 units since the start of the Industrial Revolution, according to NOAA's Pacific Marine Environmental Laboratory. Because pH runs on a logarithmic scale, 0.1 units means roughly 30 percent more acidity. Oysters struggle to build shells in that water. So do pteropods, the tiny swimming snails that salmon eat.

Acidification comes from the same gas that drives warming. It is a different reaction with a different set of victims, and cooling the planet would not reverse it.

Sea level shows the connection

Sea level is at the other end of the spectrum. Almost all of the rise since the early 1990s traces back to warming, through two routes. One, warm water takes up more room than cold water, and two, warm air melts land ice that drains into the ocean.

NASA's Jet Propulsion Laboratory has maintained the satellite record since 1992, starting with the U.S.-French TOPEX/Poseidon mission. The ocean has risen about 4 inches (10 centimeters) over that span, and JPL says the yearly rate has more than doubled.

The year-to-year numbers are unsteady JPL measured a rise of 0.23 inches (0.59 centimeters) in 2024, compared with a long-term expected rate of 0.17 inches (0.44 centimeters). Almost two-thirds of that year's rise came from thermal expansion rather than from melt.

Then 2025 came in at 0.03 inches (0.08 centimeters). JPL attributes this to a La Niña pattern that dropped unusual amounts of rain on the Amazon basin. The basin then held on to the water longer than expected.

Josh Willis, a sea-level researcher at JPL, expects the faster rate to return as that water drains back to sea.

The phrase came out of Columbia

The first use of "global warming" in a scientific paper dates to August 1975. Wallace Broecker, a geochemist at Columbia University, published an article in the journal Science with the phrase in its title. Broecker argued that a natural cooling spell underway would soon give way to carbon dioxide-driven warming.

Broecker spent the next four decades at Columbia's Lamont-Doherty Earth Observatory. He disliked being called the father of global warming.

At one point, he offered $200 to anyone who could find the phrase in print before his paper. Lamont-Doherty announced his death in February 2019, after 67 years at the lab.

"Climate change" is the older of the two terms in the research literature and has always been more common. The Intergovernmental Panel on Climate Change included it in its name in 1988. Researchers have used both phrases side by side ever since.

The words change what people hear

In January 2014, the Yale Program on Climate Change Communication ran an experimental survey on a nationally representative sample of Americans.

George Mason University's Center for Climate Change Communication partnered on the study. Half of the subjects heard questions phrased with "global warming", and the other half heard "climate change."

"Global warming" scored higher on nearly every measure tracked. Measures tracked included the certainty that it is happening, understanding that humans are the main cause, emotional engagement, and support for personal and national action. The effect was largest among political Independents.

Scientists prefer "climate change" because it covers more of what they measure. The 2014 data suggest the American public took "global warming" more seriously that year. No one has repeated the study on the same scale since, so whether that gap still holds is an open question.

The temperature record, the sea level record and the ocean chemistry record all keep moving, and a different U.S. lab tracks each one.

The 1975 paper that put "global warming" into the scientific literature, "Climatic Change: Are We on the Brink of a Pronounced Global Warming?," was published in the journal Science.

How to get involved

Report rainfall, hail and snow through CoCoRaHS, the Community Collaborative Rain, Hail and Snow Network run out of Colorado State University. The National Weather Service pulls readings from its volunteer gauges into NOAA's precipitation records.

Log cloud cover, tree height, and mosquito habitat with NASA GLOBE Observer if you want to use your phone photos to help verify satellite data from the ground.

Track when plants leaf out, and animals migrate through Nature's Notebook, the USA National Phenology Network's program based at the University of Arizona. Shifting seasonal timing is one of the clearest signals of climate change beyond temperature.

Compare your county's attitudes with the rest of the country using the Yale Climate Opinion Maps. They draw on the same survey program that tested the two terms in 2014.

Use Earth Science Week https://www.earthsciweek.org/, held each October by the American Geosciences Institute, as a hook to share NASA and NOAA data with a classroom or community group.

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