When it comes to the consequences of climate change, one thinks more of extreme weather events, strong winds or floods than of observing space. But now astrophysicists are complaining that the changing climatic conditions are even affecting researchers' view of the cosmos. In the journal Astronomy
Stargazing is obviously better in a clear atmosphere than in a cloudy one. Clouds and higher humidity in general also have a negative effect on the quality of the observations. And the higher the temperatures in the atmosphere that the light from space has to pass through on its way to a terrestrial telescope, the higher the probability that air turbulence will disturb the straight path of the light rays.
It is no coincidence that optical telescopes are often located in a desert or on a mountain, so that the air is as dry and clear as possible and the path through the atmosphere is as short as possible. And the shimmering of the warm air has been compensated for years by so-called adaptive optics in particularly powerful telescopes. An artificial guide star is conjured up in the sky with a laser beam and the wavefront disturbances caused by air turbulence are registered.
These disturbances are then actively compensated for by moving or deforming the telescope mirrors, thus improving the quality of the image. But every technology has its limits - and if the mean air temperatures tend to rise, this worsens the image quality. However, higher temperatures also mean that the air can hold more moisture. This also interferes with the observation of distant celestial objects.
In their study, the researchers from the University of Bern, ETH Zurich, the European Southern Observatory ESO and the University of Reading come to the conclusion that climate change around the world will lead to a deterioration in the observation conditions for telescopes. Major astronomical observatories from Hawaii to the Canary Islands, Chile, Mexico, South Africa and Australia will be affected by higher air temperatures and greater atmospheric water content.
There are no simple solutions to ensure the quality of the measurements carried out with the telescopes. Since climate change will have different effects in different regions of the world - and this can be predicted with the help of climate models - the researchers suggest that the expected climatic changes should be taken into account at least when new telescopes are built.
“Although telescopes usually have a lifespan of several decades, the atmospheric conditions are only taken into account when choosing a location for a short period of time. Usually this is the last five years - too short to capture long-term trends, let alone to map future changes due to global warming," says the lead author of the study, Caroline Haslebacher from the University of Bern.
But it's not just climate change that worries astronomers. The increasing number of low-flying satellites in Earth orbit is also disrupting the view of the night sky and the exploration of the universe. The US company SpaceX alone wants to put more than 30,000 small satellites into orbit. Each of them can reflect light – and thus generate interference signals. Since the satellites exchange data with ground stations via radio waves, radio astronomers are particularly affected by the mini-satellite boom.
Astronomers have been calling for international agreements to protect the night sky as a human cultural asset and research object for years. They don't get a lot of attention with that. And the astro researchers will certainly not be able to stop climate change.