Is ‘slow science’ the answer to astronomy’s carbon footprint? sky and telescope

An international team of astronomers has determined the extent to which astronomical facilities — the telescopes on Earth and in space that astronomers use to study the sky — contribute to climate change. Reports natural astronomyThe team estimates that this fingerprint dwarfs all other research-related activities, a finding that has major implications for the future of the field.

The motivation for the researchers’ study was current events: “Humanity is facing a climate emergency,” says team member Annie Hughes (Max Planck Institute for Astronomy, Germany). “The scientific evidence is unequivocal that human activity is responsible for modifying the climate. The scientific evidence is also clear that we must change our activities in the next decade.”

Astronomers, like everyone else, have carbon footprints. This term used may have subtly different definitions; In this case, Jürgen Nodelsder (University of Toulouse, France) and colleagues define it as the total greenhouse gas emissions of a facility over its life cycle. Emissions consist primarily of carbon dioxide and methane, but also include a number of other heat capture gases.

The general lack of data makes it difficult to determine how much astronomers contribute to greenhouse gas emissions. Previous studies have focused on research-related activities, such as traveling to conferences and using supercomputers. But the new study finds that the largest source of astronomy’s carbon footprint is the construction and operation of much larger telescopes.

Due to a lack of accurate data, often for reasons of confidentiality, the team came to this conclusion using a technique called Economic entry and exit analyze. Carbon emissions are determined primarily by cost and/or weight. Knödlseder likens this process to filling a car: Filling the tank full instead of halfway through will double its weight. Doubling the fuel would cost twice that and produce twice the emissions.

Using this input-output analysis, the team calculated that over their life cycles, current astronomical facilities produce the equivalent of 20 million tons of carbon dioxide equivalent, with annual emissions in excess of one million tons of carbon dioxide equivalent.

“To give you some perspective,” Knodelsdr notes, “this is the annual carbon footprint of countries like Estonia, Croatia or Bulgaria.” Another perspective: In 2019, the United States contributed more than 6.5 one billion tons of carbon dioxide.

It’s a start

Knodelsder says cost/weight data has the advantage of being publicly available, although it can sometimes be hard to find. This makes any kind of calculation possible. But Andrew Ross Wilson (University of Strathclyde, UK), who wrote the perspective article accompanying the natural astronomyHe says the method is not commonly used in carbon accounting, especially for space activities.

“It was found that the use of cost-effective input-output methods … overestimated the overall environmental impacts.” The reasons are many: first, the airline industry, which is often state-funded, is not really a free market. The cost of custom-made materials used in space missions is often more due to research and development than manufacturing.

“As such, the European Space Agency (and others) have created a new process database to more accurately fill in these gaps and do not recommend the application of economic input and output databases for space life-cycle assessment,” Wilson says.

The Nodelsider team acknowledges these caveats, but argues that providing these initial estimates is a critical first step. The next step is for utilities to do a more detailed analysis – and then take action.

Wilson agrees, saying, “I think Knodelsider’s rating is a very appropriate approximation of the first order due to the lack of data available to him and his team.” “It’s definitely a good first step towards more detailed reviews.”

But he warns: “I am not convinced that any practitioner in space life-cycle assessment would specifically use this finding to guide their own analyzes. The ESA would certainly not look twice at this estimate.”

slow flag

However, Knodelsider’s team argues that even approximate numbers are the basis of the work: “The solutions are in our hands, we just need to be able to accept them,” says Luigi Tibaldo (Institute for Research in Astrophysics and Planetary Sciences, France).

The first step is to convert existing facilities from fossil fuels to renewable energy sources, an effort already underway in many places. There are still difficulties with telescopes in remote locations because they are often not connected to the local power grid. The Atacama Large Millimeter / submillimeter group in Chile, for example, is powered by diesel generators. It may be easier to incorporate other facilities into the ongoing methodological changes.

The team says these measures will not be enough. Astronomers are also expected to slow the pace of building new facilities. The benefits go beyond reducing emissions, because “slow science” will give us more time to make full use of the data we already have. Certainly, all PhD theses were searched using only archived notes.

Jennifer Wiseman, chief scientist for the Hubble Space Telescope project, agrees with the value of the archival data. “We’ve made the Hubble data archive so powerful that at least as many scientific papers are published today based on the archival data as the new observations are,” she says. “This means good, multiple uses of data that will be available for many years to come.”

But many astronomers oppose this slowdown. In fact, some members encountered resistance from colleagues even before the paper was published.

“There is no telling that astronomy cannot or will not transition to renewable energy along with the rest of the economy,” says John Mather (NASA’s Goddard Space Flight Center), James Webb Space Telescope project scientist. “The carbon footprints that were computed are not constants of nature, they are just estimates of a part of a system governed by feedback loops.”

Mather also makes a counter-argument for slowing the pace of science: “Some types of astronomy are already made difficult or impossible due to light pollution, radio interference, and satellite constellations,” he says. “It could be argued that we must increase our efforts to learn as much as possible, as quickly as possible, before we can do that.”

However, the team remains firm in its position: “Fighting climate change is a collective challenge and everyone, every industry and every country must contribute to meeting this challenge,” says Knodelsider. “In the fight against climate change, there are no priority solutions, we have to activate all possible levers to reduce our emissions. Of course, some actions will be more efficient than others, but we need all of them to be successful.”

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