Astronomers from the University of Warwick, in collaboration with institutions in Spain, have developed an innovative method to measure greenhouse gases (GHGs) using tools typically employed for studying stars. This new approach leverages astronomy technology to monitor changes in Earth’s atmosphere, providing vital data in the fight against global warming.
Light from distant stars undergoes alterations as it traverses through gas and dust, particularly when it passes through Earth’s atmosphere. These changes create unique absorption lines, known as telluric lines, which can be harnessed to track atmospheric gases. A new algorithm called Astroclimes aims to utilize these lines to quantify GHGs, such as carbon dioxide (CO2), methane (CH4), and water vapor (H2O), even at night.
Marcelo Aron Fetzner Keniger, a Ph.D. student at the University of Warwick and the developer of the Astroclimes algorithm, highlighted the importance of monitoring GHG levels. He stated, “Tracking the abundance of GHGs is necessary to quantify their impact on global warming and climate change.” Traditional methods have relied on solar spectra, which limits measurements to daytime observations. Astroclimes seeks to fill this gap by enabling nighttime assessments.
Innovative Observation Campaign
In July 2025, an observation campaign was conducted at the Calar Alto Astronomical Observatory in Almería, Spain. This initiative involved collaboration between the University of Warwick, the University of Almería, and the Spanish State Meteorological Agency (AEMET). The campaign aimed to demonstrate the effectiveness of combining solar and stellar measurements to enhance understanding of the carbon cycle and the role of GHGs in climate change.
Daytime measurements were obtained using a portable FTIR spectrometer (EM27/SUN) from the COCCON-Spain network, which was temporarily installed at the observatory. At night, starlight was analyzed with the Astroclimes algorithm, utilizing data from the CARMENES spectrograph on the observatory’s 3.5-meter telescope. The COCCON instrument provides calibrated atmospheric concentrations of GHGs, which serve as a benchmark for Astroclimes measurements.
“If we can successfully calibrate Astroclimes with the help of COCCON measurements, it could provide a new network for measuring GHG abundances,” added Keniger. This new system could significantly enhance nighttime observations, complementing existing daytime networks.
Addressing GHG Observation Gaps
The campaign’s daytime observations at approximately 2,100 meters were supplemented by additional measurements taken at sea level at the University of Almería. Joaquín Alonso Montesinos, a university professor and representative of the COCCON-Spain project, expressed gratitude to AEMET for their support, emphasizing the project’s potential impact on energy transition efforts.
Omaira García-Rodríguez, coordinator of the COCCON-Spain network, remarked, “The national network aims to address the latent lack of atmospheric GHG observations in Spain.” The initiative intends to improve knowledge of GHG sources and sinks, thereby aiding the development of effective climate change mitigation and adaptation strategies.
Jesús Aceituno, director of the Calar Alto Observatory, concluded, “Calar Alto, with its photovoltaic plant and biomass boiler, aims at reaching energy sustainability.” The greenhouse gas detections made through CARMENES illustrate how an astronomical observatory can contribute to monitoring the planet’s climate.
This pioneering work by the University of Warwick and its partners signifies a significant advancement in utilizing astronomical tools for environmental monitoring, highlighting the intersection of science and climate action.
