Carbon footprint of huge astronomy observatories raises climate change concerns

According to a study, astronomers of the future may not be able to build large, complex and energy-intensive observatories if they want to reduce their carbon footprint in line with greenhouse gas emissions requirements.

Powerful ground and space telescopes, such as the recently launched James Webb Space Telescope or the Square Kilometer Array Observatory (SKAO) currently under construction in Australia and South Africa, come with large lifetime carbon footprints that augment the entire astronomy greenhouse gas emissions.

In a new study, a team of researchers from the Institute for Research in Astrophysics and Planetology (IRAP) in Toulouse, France, found that all combined, the world’s leading astronomical observatories generate over their lifetime about 22 million tons. [20 million metric tonnes] of carbon dioxide equivalent. This value is equivalent to the annual carbon emissions of some small European countries, such as Estonia, Croatia or Bulgaria, the authors said at a press conference on March 17.

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This value includes carbon emissions generated during the construction and manufacturing phase as well as greenhouse gases produced as a result of observatory operations. In the case of space telescopes, such as Webb and the The Hubble Space Telescopethe researchers also included the carbon footprint of delivering the telescopes to space.

Each year, the world’s astronomical research facilities emit 1.2 million tonnes of carbon dioxide, about five times more than the annual flight-related carbon footprint of the world’s astronomers, the study researchers said.

“No study has ever attempted to calculate the carbon emissions from the construction and operation of all the telescopes and space missions that astronomers use to make observations,” said Annie Hughes, astronomer at IRAP and l one of the authors of the article. the press conference. “Thus, the results of our paper constitute the first quantitative estimate of the carbon footprint associated with these infrastructures. Their footprint is significant, far greater than all other sources of our occupational carbon emissions combined.”

For example, Webb and SKAO mentioned above will each generate an equivalent of at least 330,000 tonnes [300,000 metric tonnes] of carbon dioxide over their lifetime, which is the largest carbon footprint of all the telescopes and observatories included in the study, the researchers said in the paper.

To estimate the carbon footprint, the astronomer used a method called economic input-output (EIO) analysis, which they admitted only gives a very rough idea of ​​the emissions generated by these facilities. “The method we used assumes that greenhouse gas emissions from astronomical research infrastructure are proportional to their costs or weight,” said Jürgen Knödlseder, also an IRAP astronomer and lead author of the study, during the press conference. “To understand this, just think about what happens when you double the amount of fuel you put in your car’s gas tank. It will cost you twice as much, you will double the weight of your gas tank. door, and when you dry your empty gas tank, you will emit twice as much greenhouse gases into the atmosphere.”

This cost-based estimate, however, is only accurate within an order of magnitude, with a whopping 80% uncertainty, the researchers admitted. A more accurate method of estimating the carbon footprint of astronomy research facilities would be the life cycle analysis, which would however require detailed data on each of the projects. These data, however, are generally not available for industrial confidentiality reasons, the researchers said.

Regardless of the accuracy of the estimate, the scientists said the astronomical community will need to reduce the carbon footprint of its research facilities by up to a factor of 20 if it is to meet global emission reduction targets.

“We have an overall reduction target for humanity and that is that the greenhouse gas emissions must decrease about half of 2010 levels by 2030, reaching net zero around 2050,” said co-author and IRAP astronomer Luigi Tibaldo at the press conference. is a necessary condition to keep the average global temperature increase below 1.5 degrees Celsius [2.7 degrees Fahrenheit] which has been identified as a goal to keep our planet habitable. This will require a sharp reduction for all business sectors, including research and astronomy.”

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Bigger observatories may not be better (for climate)

Achieving these goals will not be possible with the current pace of building larger and more complex new facilities, the researchers said.

“We believe that the only way we have to achieve faster adoption [of the emission reduction goals] short term is to reduce the pace at which we build new infrastructure,” Tibaldo said. “Not necessarily stop building new infrastructure, but do it more slowly. This has many advantages, in addition to reducing emissions, for example, we will have more time to carry out a more complete exploitation of the data of the existing infrastructures.

The researchers admitted that they had not taken into account the different proportions of renewable energy in the energy mix used by individual observatories or the facilities involved in development and manufacturing. Instead, they based their calculations on a current global average energy mix.

Many astronomical observatories, including SKAO and the European Southern Observatory (ESO) in Chile, however, have committed in recent years to improving their carbon footprint by investing in solar power generation and focusing on reducing energy consumption.

SKAO, for example, wants to meet at least 45% of its electricity needs from renewable resources, but hopes to eventually increase that proportion to 90%, observatory representatives told in a previous interview.

ESO, which operates state-of-the-art observatories in Chile’s Atacama Desert, including the very large telescopehas also embarked on a major greening program, which includes replacing gas turbine power generation with solar power plants at its remote facilities, which are not connected to the power grid.

The study was published Monday, March 21 in the journal Nature Astronomy.

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