ESO adopts new measures to improve its environmental sustainability

12 November 2021

As one of the world’s leading astronomy organisations, the European Southern Observatory (ESO) is fully committed to fighting climate change by reducing the environmental impact of its activities. The ESO Directors Team has now approved a new set of measures to gradually decrease the organisation’s carbon footprint over the coming years. The measures are inspired by the United Nations guidelines and build upon the actions ESO had already adopted in the past.

ESO carries out the design, construction and operation of powerful ground-based observing facilities, providing astronomers worldwide with some of the best tools for their research and discoveries. This work leads to invaluable scientific and technological progress and other societal benefits, but also unavoidably places demands on resources, energy and the environment. In a carbon audit conducted in 2019, ESO’s 2018 footprint budget was estimated to be around 28 000 tonnes of CO2 equivalent per year (tCO2e/yr) [1], with energy consumption, purchases (including maintenance and equipment), and transporting of people and goods representing the largest sources of emissions.

In a key step towards sustainability, ESO has now committed to new measures addressing a range of environmental issues, such as saving energy and water, reducing waste and cutting greenhouse gas emissions. These include:

  • Implementing a large 9 MW solar array serving the future Integrated Paranal Observatory in Chile, which will host the upcoming ESO’s Extremely Large Telescope (ELT, on the nearby Cerro Armazones) and the ESO-operated Cherenkov Telescope Array Observatory South, in addition to the already existing facilities. This could save up to 1700tCO2e/yr.
  • Wherever operationally feasible, preferring sea freight over air freight for shipments of materials from Europe to Chile. This could save up to 1400 tCO2e/yr.
  • Reducing business travels, especially flights, opting for virtual meetings over physical meetings whenever possible, for a potential saving of up to 800 tCO2e/yr.
  • Optimising the electricity consumption at ESO’s Headquarters in Garching, Germany by regularly investigating and addressing sources of energy consumption, for a carbon footprint reduction up to 250 tCO2e/yr.
  • Finalising the ongoing transition to renewable energy of ESO’s offices in Vitacura, Chile. The corresponding saving may reach up to 200 tCO2e/yr when completed in four years.
  • Extending the lifetime of IT equipment and exploring ways to repair broken devices, only resorting to new purchases where necessary. These actions may save up to two tCO2e/yr.
  • Move progressively towards taking sustainability into account during the design phase of new projects and procurement, working with contractors who share ESO’s concerns on sustainability and acting together to minimise CO2 emissions.
  • Continuing to increase the share of electric vehicles at ESO sites.
  • Monitoring ESO’s emission sources on a periodic basis in the coming years and producing regularly updated roadmaps for the reduction of the organisation’s carbon footprint.

Identifying the specific activities that result in the highest emissions is a complex process in an organisation like ESO that works with multiple companies and institutes. The measures now announced focus on the areas ESO has identified thus far where it is possible to achieve emission reductions in the immediate future. In addition, ESO is carrying out more analysis and has begun to elaborate a detailed action plan to systematically address environmental sustainability in the long term. 

“ESO’s current and planned environmental sustainability actions represent a starting point. ESO is committed to regularly analysing its sources of emissions and to continue to take steps to reduce its carbon footprint,” says Claudia Burger, ESO’s Director of Administration and Chair of ESO's Environment Committee. 

These measures are in line with sustainability actions taken by ESO Member States, which have committed to reducing carbon emissions under the Paris Climate Agreement. Developed by ESO’s Environment Committee, the measures follow the reports of the Intergovernmental Panel on Climate Change (IPCC) — the United Nations’ body responsible for deepening our understanding of climate change, how it affects our planet and what emission reductions are needed to limit it.

The new measures build on ESO’s previous and ongoing environmental sustainability actions. These include the use of geothermal heating as a sustainable energy source at ESO’s Headquarters in Garching, and rainwater use for watering the park at ESO’s offices in Vitacura. In addition, at ESO’s observing sites in Chile, significant steps towards economic and environmental sustainability were taken with the connection of ESO’s Paranal Observatory to the Chilean national grid in 2017. Grid electricity is produced with a lower percentage of fossil primary energy, reducing the observatory’s carbon footprint. Further sustainability improvements have been made at ESO’s La Silla Observatory, with the installation of a 1.7 MW solar farm, which covers an area of over 100 000 square metres providing clean energy to the site, and saving more than 400 tCO2e/yr.

More generally, ESO is also looking into ways to address sustainability in a broader sense, in line with the United Nations’ Sustainable Development Goals, by also promoting social and economic sustainability. “We are proud of taking the first steps in charting a more sustainable future,” says ESO Director General Xavier Barcons. “Addressing our environmental impact is a key aspect of this, but we are also working on devising the long-term financial sustainability of our research infrastructures, while ensuring our activities remain harmonised with and supportive of the social environment in our member states and partners.


[1] CO2 equivalent is a metric converting a given quantity of a greenhouse gas to the CO2 amount with the same global-warming potential. ESO’s 2018 carbon footprint was estimated through an external audit from the consulting firm Carbone 4. It does not include activities related with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is partner, nor construction activities related to ESO’s upcoming Extremely Large Telescope (ELT), which is not yet in operation.


Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670

About the Announcement



The solar power plant at ESO’s La Silla Observatory
The solar power plant at ESO’s La Silla Observatory