The Temperature of La Palma's Highest Point Has Risen Beyond Climate Predictions

The meteorological data recorded over the past two decades by sensors of the Roque de los Muchachos astronomical observatory facilities point to a rise of 1.1 ºC in the average temperature. The analysis, led by UAB researchers, shows more than double the increase predicted by climate models for the same area, and even more than expected for the next 20 years.

Researchers from the Department of Physics of the Universitat Autònoma de Barcelona led a long-term study of climatic conditions at one of the main astronomical observation sites in the northern hemisphere: the Roque de los Muchachos Observatory, on the island of La Palma. In an area located 200 metres below the ridge on which most of the optical telescopes such as the Gran Telescopio Canarias are located, are the MAGIC Telescopes, built to detect very high energy gamma-ray sources by a collaboration in which UAB researchers were also involved. It is also the site of the construction of the northern hemisphere’s Cherenkov Telescope Array Observatory (CTAO).

UAB researchers Markus Gaug and Lluís Font analysed a unique series of meteorological data from the area recorded over a period of 20 years by the meteorological instruments installed on the roof of the MAGIC telescope control building. The weather station has sent data on temperature, relative humidity, atmospheric pressure and wind speed and direction every two seconds during all this time.

“The station was built with the intention to have some guidance for telescope operations, not to characterise local weather professionally, let alone the effects of climate change on the measured parameters,” explains Markus Gaug. But “the fact that they were relatively low-cost devices has been an advantage, since they had to be changed and recalibrated every two years or so, which has favoured the reliability of the data and greatly limited the effects of long-term sensor drifts, which are difficult to detect,” he adds.

The Spanish meteorological service, AEMET, did not install a professional station at Roque de los Muchachos until 2022. However, thanks to data from 36 other AEMET weather stations spread across the island of Tenerife, it has been possible to carry out studies of temperature variation in the Canary Islands for many years. Some studies show an increase of 0.3 ºC per decade between 1970 and 2010. Other more recent studies had obtained an increase per decade of up to 0.25 ºC in the same area with historical data up to 2014, and the models predicted between 2015 and 2050 a temperature increase of 0.3 to 0.5 ºC per decade.