Eyes in the Sky: How Satellites Track Earth’s Changing Climate

In Part One of this series, we learned how scientists measure climate change right here on Earth’s surface—using weather stations, ocean tools, and field surveys. In Part Two, we zoom out to space.

Satellites help scientists see the whole planet. Together with ground measurements, they let scientists spot small changes up close and big patterns around the world.

Think of satellites and aircraft as super-smart Earth cameras, orbiting the planet 24/7 and checking Earth’s vital signs.

Here’s how they do it.

They Measure Earth’s Temperature

Satellites also measure temperature—but not with thermometers. Instead, they measure the energy (brightness) coming from Earth’s surface and atmosphere. Scientists use computer models to turn that energy into temperature readings.

Because satellites cover the whole globe, they can measure temperatures in places that are hard to reach, like oceans, deserts, and the poles.

Ground measurements are more accurate and need fewer adjustments, but together with satellites, they make a great team.

They Watch the Ocean Rise and Fall

Scientists measure sea level in two main ways.

On land, they use tide gauges. These tools measure how sea level changes compared to the land nearby. They are very accurate, but they only work in one place at a time.

From space, satellites measure sea level across the entire planet—including faraway oceans where no one lives. NASA and its partners have done this for over 30 years using satellites starting with starting with the U.S.-French TOPEX/Poseidon mission, which launched in 1992. That was followed by the Jason series (Jason-1, -2, -3) an now followed by Sentinel-6 Michael Freilich and Sentinel-6B.

Special radar satellites send signals down to the ocean and time how long it takes for the signal to bounce back.

• Shorter time = higher sea level
• Longer time = lower sea level

This is how scientists know global sea level is rising as ice melts and the ocean warms.

Satellites Track Ice Loss

Gravity Satellites: Ice as Weight

Some satellites, like GRACE and GRACE-FO are like giant scales in the sky! Here’s the idea: big ice sheets are very heavy, and their weight slightly pulls on nearby satellites. When ice melts and flows into the ocean, the ice sheet gets lighter, and the pull of gravity becomes weaker. By tracking these tiny gravity changes, scientists can tell how much ice has been lost or gained, even if the ice is hidden under snow or clouds.

Altimetry: Measuring Ice Height

Other satellites, such as ICESat-2, use a method called altimetry.

They send laser or radar pulses down to Earth and measure how long it takes for the signal to bounce back. This tells scientists how high the ice surface is.

If the surface gets lower over time, it usually means ice is melting or flowing away.
Think of this as using a huge ruler from space to see if glaciers and ice sheets are shrinking.

However, altimetry alone can’t tell the difference.

To figure out how much ice is really disappearing, scientists combine altimetry data with information about ice and snow density. They use field measurements, weather data, and models to estimate how much of the Here’s the tricky part: height alone doesn’t tell the full story.

Ice sheets aren’t solid ice from top to bottom. Near the surface, they often contain snow and packed snow called firn, which is much lighter than solid ice.

That means:

• The surface can sink because fluffy snow is slowly getting packed tighter
• Or it can sink because solid ice is actually being lost

Satellites Measure So Much More

Satellites can measure deforestation, greenhouse gases, lightning, cloud cover, air quality, ocean color, geomagnetic storms (DSCOVR), ozone levels, how plants use water, and drought. They can also track disasters, monitor ecosystems and crops, and understand how Earth’s surface moves and changes. 

Satellites Aren’t Working Alone

Satellites don’t just watch ice and oceans. They also track:

• Greenhouse gases
• Deforestation
• Air quality
• Cloud cover
• Lightning
• Ocean color
• Drought
• Ozone
• How plants use water
• Earth’s magnetic storms (like those measured by DSCOVR)

They also help monitor disasters, crops, ecosystems, and changes in Earth’s surface.

There are even more “eyes in the sky.”

Instruments like ECOSTRESS, EMIT, and OCO-3 operate from the International Space Station (ISS).

Aircraft also play a key role. They:

• Study methane leaks, earthquakes, landslides, permafrost, and more
• Test instruments before satellites launch
• Zoom in on local areas

Why Satellites Matter

Satellites can observe every part of Earth, all the time—even remote places like the open ocean or Antarctica.

Ground measurements are often more precise in one spot. Satellites show the big picture.
Together, they are best buddies.

Up Next: Part Three

In Part Three, we’ll look back in time and explore paleoclimate data—clues from ice cores, tree rings, and ancient records that show how Earth’s climate has changed long before satellites existed.

If you want to do a little more digging, you might enjoy this website:

NASA Sea Level Change Portal