How global warming affects astronomical observations

The guiding star of the VLT laser: A laser beam launched by the VLT’s 8.2-meter Yepun telescope crosses the majestic southern sky and creates an artificial star 90 km above the earth’s high mesosphere. The Laser Guide Star (LGS) is part of the adaptive optics system of the VLT and is used as a reference for correcting images with a blurred effect of the atmosphere. Credit: ESO / G. Hüdepohl (

The quality of ground-based astronomical observations delicately depends on the clarity of the atmosphere above the location from which they are made. The sites for the telescopes are therefore carefully selected. They are often high above sea level, so that less atmosphere gets between them and their targets. Many telescopes are also built in deserts, as clouds and even water vapor obstruct a clear view of the night sky.

A team of researchers led by the University of Bern and the National Center for Research Competence (NCCR) PlanetS shows in a study, published in the journal Astronomy and astrophysics and presented at the Europlanet Science Congress 2022 in Granada, as one of the main challenges of our time, anthropogenic climate change, now also affects our view of the cosmos.

A blind spot in the selection process

“Although telescopes usually have a lifespan of several decades, site selection processes consider atmospheric conditions only in a short amount of time. Usually in the last five years, too short to capture long-term trends, to not to mention the future changes caused by global warming, Caroline Haslebacher, lead author of the study and a researcher at the NCCR PlanetS of the University of Bern, points out.

The team of researchers from the University of Bern and NCCR PlanetS, ETH Zurich, European Southern Observatory (ESO) and the University of Reading in the UK therefore set out to show the long-term perspective.

Worsening conditions around the world

Their analysis of future climate trends, based on high-resolution global climate models, shows that major astronomical observatories from Hawaii to the Canary Islands, Chile, Mexico, South Africa and Australia are likely to experience an increase in atmospheric temperature and water content by the 2050. This, in turn, could mean a waste of observation time as well as a loss of quality in observations.

“Today, astronomical observatories are designed to operate in the current site conditions and have only few possibilities for adaptation. The potential consequences of climatic conditions for telescopes therefore include an increased risk of condensation due to an increase in dew point or malfunctions. cooling systems, which can lead to increased air turbulence in the telescope dome, “says Haslebacher.

The fact that the effects of climate change on observers were not taken into account before was not an oversight, as study co-author Marie-Estelle Demory says, but more due to modeling limitations. “This is the first time that such a study has been possible. Thanks to the increased resolution of global climate models developed through the Horizon 2020 SPRING project, we have been able to examine conditions in various locations around the globe with great fidelity, something that we have not been able to do with conventional models. These models are valuable tools for the work we do at the Wyss Academy, “says the senior scientist from the University of Bern and member of the Wyss Academy for Nature.

“This now allows us to say with certainty that anthropogenic climate change must be taken into account in site selection for next-generation telescopes and in the construction and maintenance of astronomical facilities,” says Haslebacher.

Long-term liquid water even on non-Earth-like planets?

More information:
C. Haslebacher et al, Impact of Climate Change on Site Features of Eight Major Astronomical Observatories Using High Resolution Global Climate Projections Up to 2050. Predicted Rise in Temperature and Humidity Leads to Poorer Astronomical Observation Conditions, Astronomy and astrophysics (2022). DOI: 10.1051 / 0004-6361 / 202142493

Provided by the University of Bern

Citation: How global warming affects astronomical observations (2022, 22 September) retrieved on 23 September 2022 from

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