It’s strange when you think about it.
We constantly hear that accurately measuring CO₂ sources and sinks (what’s really being emitted versus absorbed by forests, oceans, cities, etc.) is essential for climate policy, carbon markets, and effective emission reductions.
Yet for years, our main satellite tools for measuring CO₂ had a big limitation: they only worked well during the daytime.
The difference is night and day (literally)
Most CO₂ satellites (like NASA’s OCO-2 or others) rely on sunlight. They measure how sunlight passes through the atmosphere and reflects back from Earth. This gives good data on the total amount of CO₂ in the air – but only when the sun is up. At night, in heavy clouds, or during polar winters, they can’t collect reliable data.
China’s breakthrough: In 2022, they launched DQ-1 (AEMS) with a special laser-based instrument. Instead of waiting for sunlight, it shoots its own laser pulses down to Earth and measures the signal that comes back. This lets it measure CO₂ day and night, in many cloudy conditions, and in places where other satellites struggle.
And just last month (April 2026), China launched DQ-2, the second satellite in this series.
These satellites still measure the overall CO₂ levels in the full air column (not direct emissions at the surface). But having data around the clock helps scientists see daily changes and fill big gaps.
On the ground we still need high-precision measurements.
Satellites give us broad global coverage, but for true accuracy they depend on a relatively small network of ground-based stations (TCCON). These high-precision stations are ultimately tied to real air samples through infrequent aircraft calibration campaigns. That’s exactly what we do: we combine advanced satellite data with our high-precision ground observations to deliver a reliable, real-time picture of the net CO₂ situation, with strong sensitivity to the lower atmosphere and planetary boundary layer.
If we’re serious about verifying real emission cuts, supporting carbon trading, and understanding nature’s role as CO2 absorbers – we need robust monitoring both from space and on the ground.
Importance
China now has two of these advanced satellites in orbit. It shows impressive innovation – and how surprisingly limited and emergent our global CO2 observation system still is.
We talk a lot about climate urgency. Maybe we should talk more about measurement urgency too. Which, of course, is straight up our alley. 😊
What do you think – should stronger international collaboration on round-the-clock CO₂ monitoring be a higher priority?
Photo credits: Robèrt Kroonen
