Carbon dioxide (CO₂) is one of the most significant anthropogenic greenhouse gases, and its concentration is closely linked to global climate change. Since the industrial revolution, the extensive combustion of fossil fuels and changes in land use have led to a continuous rise in atmospheric CO₂ levels, triggering a series of environmental issues such as global warming, increased frequency of extreme weather events, glacier retreat, and sea-level rise. CO₂ plays a critical role in radiative forcing within the climate system and profoundly influences the balance of the carbon cycle, ecosystem stability, and the sustainable development of human society. Therefore, comprehensive research on the observation, simulation, and underlying mechanisms of CO₂ dynamics is a central component of global climate change studies. With the global push for carbon peaking and carbon neutrality, there is an urgent demand from both the scientific community and policymakers for high-precision, high-resolution CO₂ observations to evaluate carbon source-sink patterns, verify emission reduction outcomes, and improve climate models. Therefore, achieving high-precision CO₂ observations has become particularly important.

The integral path differential absorption (IPDA) lidar technology has unique advantages in global CO₂ monitoring, making it an important tool in climate change research. Unlike passive remote sensing technologies that rely on sunlight, IPDA lidar uses its own laser pulses as the light source, enabling high-precision observations in all weather conditions and at any time, making it particularly suitable for nighttime and high-latitude gas monitoring. This allows IPDA technology to overcome limitations of passive remote sensing in these conditions. Furthermore, IPDA is less affected by cloud cover and aerosols, showing strong resistance to interference, and can still provide reliable measurement data under complex meteorological conditions.

The principle of IPDA is based on measuring the absorption characteristics of gas molecules to laser signals, allowing precise inversion of gas concentrations by analyzing the attenuation of the laser signal as it passes through the atmosphere. This technology offers high spatial resolution and large coverage, making it particularly suitable for satellite platforms, enabling global CO₂ monitoring. IPDA also has a high signal-to-noise ratio, allowing it to maintain high precision in long-range detection, significantly improving measurement accuracy.

China has made significant progress in this field, successfully developing lidar systems based on IPDA technology. In 2022, China successfully launched the atmospheric environment monitoring satellite (DQ-1), marking an important step for China in global CO₂ monitoring technology.

The DQ-1 satellite offers significant promise for enhancing global CO₂ monitoring capabilities. Trends indicate the integration of artificial intelligence with satellite data to improve carbon flux detection. Ongoing advancements in active remote sensing technology, along with improvements in data processing and fusion techniques, will enhance the accuracy and spatial resolution of CO₂ observations. These developments will drive progress in global carbon monitoring, enabling more precise tracking of emissions and supporting efforts to mitigate climate change.