Target Pillar: Earth Observation and Satellites
Last Updated: August 1, 2026 Author: Sarah Mitchell
Introduction
Ground stations can tell you the temperature in one place. Ice cores can tell you what the atmosphere looked like thousands of years ago at one location. Neither can tell you, on its own, what’s happening to the whole planet at once, continuously, in a way you can compare year over year with confidence. That’s the specific job satellites do that nothing else can: measure Earth as a single system, the same way, repeatedly, for decades.
NASA’s Earth Science Division currently operates more than 20 satellites dedicated to exactly this,[^1] and several of the climate record’s most important datasets now stretch back 30 years or more — long enough to separate a genuine trend from ordinary year-to-year noise.
Sea Level: The Clearest Long-Term Signal
Sea level rise is one of the best-documented climate indicators precisely because it’s been measured continuously by a single lineage of satellites since 1993 — TOPEX/Poseidon, followed by the Jason series, and now the Sentinel-6 missions.[^2] That continuity matters: switching instruments frequently would introduce calibration gaps, so this program has deliberately overlapped each new satellite with its predecessor to keep the record unbroken.
The result is one of the most solid numbers in climate science: global sea level has risen approximately 3.6 inches (91 millimeters) since 1993, according to NASA’s satellite altimetry record.[^3] Roughly two-thirds of that rise comes from melting land ice — glaciers and ice sheets — with the remaining third from thermal expansion, as ocean water physically expands when it warms.[^3]
The newest satellite in this lineage, Sentinel-6B, launched in late 2025 specifically to extend this record with even greater precision, continuing a partnership between NASA and European space agencies that’s now approaching its fourth decade.[^4]
Ice Sheets: Measuring Losses You Can’t See From the Ground
Antarctica and Greenland hold the vast majority of Earth’s fresh water, and tracking their mass loss from the ground is effectively impossible at the necessary scale — these are among the most remote, hostile environments on the planet. Satellites solve this with laser and radar altimetry, essentially measuring the changing height of the ice surface from orbit with enough precision to detect thinning over time.
NASA’s ICESat-2 mission, one of the primary tools for this work, uses exactly this approach — a satellite-based laser altimeter precise enough to track subtle elevation changes across ice sheets and even measure snow depth.[^1] This data feeds directly into the sea level rise figures above, since ice sheet melt is the single largest contributor to rising seas.
Carbon Dioxide: Watching the Greenhouse Effect in Real Time
The most direct link between satellite data and the mechanism of climate change itself is atmospheric CO2 monitoring. Ground-based measurement — most famously the continuous record from Mauna Loa Observatory in Hawaii, running since 1958 — established the baseline trend, but satellite instruments now extend that monitoring globally rather than from a single mountaintop.[^5]
Both measurement approaches agree on the scale of the change: atmospheric CO2 has increased by more than 50% since the start of the industrial era, a rise scientific consensus attributes primarily to fossil fuel combustion.[^5] Because CO2 is a greenhouse gas that traps outgoing heat, this increase is the physical mechanism, not just a correlated symptom, behind the broader warming trend — a connection scientists demonstrated in laboratory conditions as far back as the mid-19th century, long before satellites existed to confirm it globally.[^6]
Beyond the Headline Numbers: What Else Satellites Track
Sea level, ice, and CO2 get the most public attention, but NASA’s climate indicator datasets extend considerably further. Ocean surface current analyses track how quickly water moves through the oceans, which affects everything from regional weather to fishery health. Ecosystem CO2 exchange data measures how much carbon forests and other ecosystems absorb versus release, revealing changes in ecosystem health that ground surveys alone would take vastly longer to detect at a global scale.[^7] Permafrost monitoring tracks a genuine feedback-loop risk: as permafrost thaws, it releases stored carbon, which can accelerate the very warming that thawed it in the first place.[^7]
Satellite data also plays a direct role in tracking major ocean-atmosphere cycles like El Niño and La Niña. In 2026, satellite altimetry data has shown early signs consistent with a developing El Niño event — detected through characteristic waves of warmer water moving eastward across the Pacific months before the event fully emerges, a pattern satellites can spot well before it’s obvious from surface observations alone.[^4]
Why the Continuity Matters More Than Any Single Measurement
The scientific value of this record isn’t really any one satellite or any single year’s data point — it’s the unbroken continuity. A one-year spike or dip in sea level or CO2 tells you very little on its own; a consistent trend sustained across three decades of consecutive, calibrated satellite measurements is much harder to dismiss as noise, instrument error, or short-term natural variability. This is precisely why missions like Jason-CS/Sentinel-6 are explicitly designed as continuations of existing records rather than fresh, disconnected datasets — the goal is an unbroken 40-year measurement chain, not a series of separate snapshots.[^2]
Frequently Asked Questions
How is satellite data different from ground-based climate measurements?
Ground stations and instruments like tide gauges or the Mauna Loa CO2 record provide extremely precise measurements at fixed locations, built up over long histories. Satellites trade some of that local precision for global, consistent coverage — measuring the entire planet the same way at once, which is essential for confirming that a trend is truly global rather than a regional or local artifact.
Can satellites actually measure something as small as sea level rise in millimeters?
Yes — satellite altimeters bounce a radar or laser signal off the ocean surface and measure the return time with enough precision to detect sea surface height changes at the millimeter level, repeated over millions of measurements across the globe and averaged over time to produce the trend line.
Do satellites measure temperature directly?
Some do, using infrared sensors to measure radiated heat, but much of the climate satellite record focuses on indirect indicators — sea level, ice mass, CO2 concentration — that are easier to measure with high precision from orbit and that collectively provide a more complete picture than temperature alone.
Why does ice sheet melting matter so much for sea level?
Because ice sheets store enormous volumes of fresh water on land; when that ice melts and flows into the ocean, it directly adds volume to sea water. NASA’s data attributes roughly two-thirds of observed sea level rise to this land-ice contribution, more than the contribution from ocean thermal expansion alone.
How far back does reliable satellite climate data go?
It depends on the indicator — continuous satellite sea level measurements date to 1993, while other datasets have different start dates depending on when the relevant instruments launched. Thirty-plus years is now common for the core indicators, which is long enough to meaningfully separate genuine trends from short-term natural variability like El Niño and La Niña cycles.
Sources
- NASA Science — Climate Change (Earth Science Division overview)
- NASA JPL — Ocean Surface Topography from Space
- NASA Science — Sea Level Earth Indicator
- NASA JPL — Ocean Surface Topography from Space (2026 updates)
- NASA Science — Carbon Dioxide Earth Indicator
- NASA Science — Climate Change Evidence
- NASA Earthdata — Climate Indicators
Note on methodology: figures above are drawn directly from NASA’s published Earth science datasets and mission pages as of mid-2026. Climate indicator data updates continuously; for the latest figures, consult the linked NASA sources directly.
[^1]: NASA Science, Climate Change [^2]: NASA JPL, Ocean Surface Topography from Space [^3]: NASA Science, Sea Level Earth Indicator [^4]: NASA JPL, Ocean Surface Topography from Space, 2026 [^5]: NASA Science, Carbon Dioxide Earth Indicator [^6]: NASA Science, Climate Change Evidence [^7]: NASA Earthdata, Climate Indicators