If you have ever looked up at the night sky, you know that atmospheric conditions greatly affect astronomical observation . It’s not just that if it’s cloudy it’s impossible to see anything. The humidity or composition of the atmosphere also affects our measurements, especially when they require a high degree of precision , as occurs in professional astronomical observations. A new study led by the University of Bern in Switzerland predicts that global warming and consequent climate change will worsen astronomical observations throughout the world.
These observations depend on the clarity of the sky above the telescope. who is conducting the observation. This is why the locations of the observatories are chosen carefully , to guarantee the best possible sky. They are usually located far from large cities and urban agglomerations, since light pollution from these makes it difficult to observe the faintest objects. They are also usually built high above sea level , to reduce the amount of atmosphere that the light of the stars to be observed must pass through before reaching the telescope. Finally, for the most cutting-edge projects, they try to choose locations in deserts or especially arid areas , since the presence of a small amount of water vapor can considerably affect the quality of the observation.
Poor viewing conditions can cause the image obtained from a distant star to be blurred, distorted or its light to flicker . This can completely screw up the most sensitive observations. If, for example, we try to discern an exoplanet orbiting around its star , the blurring or distortion of the image may prevent us from detecting it. If we want to measure the variation in brightness of objects as fast as pulsars or from fleeting explosions, such as supernovae or gamma-ray bursts , that flicker can mess up the measurement. This is why the location of an observatory is chosen following the above considerations and this is why, in part, we need to send telescopes into space . Not only does the absence of atmosphere allow us to observe at wavelengths that would be absorbed by air, such as infrared, but we can also eliminate all these optical defects that arise from passing through a certain amount of atmosphere.
Today there are many computer techniques whose objective is to reduce all this distortion and generally improve the quality of the images obtained in astronomy. Adaptive optics , for example, is used in astronomy and telecommunications to compensate, through the deformation of the mirror or antenna, for disturbances introduced by the air. However, these solutions are not magic and it is usually a better option to reduce the disturbances in the first place.
When carrying out the feasibility study of a specific location for the construction of an astronomical observatory, only a short period of time is taken into account in terms of atmospheric conditions. This is usually limited to a period of a few years, so it is difficult to perceive longer-term trends and of course future conditions created by global warming, but also by urban development.
Their analysis, based on high-resolution global climate models, predicts that conditions at the world’s main astronomical observatories, such as those located in Hawaii, the Canary Islands, the Atacama desert in Chile , or those in Mexico, South Africa and Australia, will see an increase in air temperature and in the amount of water vapor between now and 2050 . Both of these will lead to a decrease in the available observing time and in the quality of those observations. Modern astronomical observatories are engineering works at the forefront of technology and have been designed for the conditions present when they were created. However, an astronomical observatory usually has, at a minimum, decades of operational life . If the conditions change enough, the observatory will not be able to adapt to them and the quality of its observations will decrease. It’s not just the air that will get worse . Higher temperature and humidity can also lead to condensation on the mirrors that make up the telescope or to overheating of key parts of its hardware.
Studies like this are scarce in the scientific literature not because they have been overlooked by the different research teams, but because until now they were not possible . Thanks to the climate models developed during the Horizon 2020 SPRING project, which have a higher resolution, the conditions in different locations throughout the world could be studied in great detail and with greater fidelity. This was unfeasible with the previous, cruder and more general models.
Therefore, the team concludes that the climate change we are experiencing, of clear anthropogenic origin, must be taken into account when deciding where and how the next generation of super telescopes will be built and also when keeping current telescopes in operation. .
C. Haslebacher et al, 2022, Impact of climate change on site characteristics of eight major astronomical observatories using high-resolution global climate projections until 2050. Astronomy & Astrophysics , DOI: 10.1051/0004-6361/202142493