An international team of astronomers has determined the extent to which astronomical facilities – that is, telescopes on Earth and in space that astronomers use to study the sky – are contributing to climate change. Report natural astronomythe team predicts that this trail outperforms all other research-related activities, a finding that has significant implications for the future of the field.
The researchers felt motivated to conduct research based on current events: “Humanity faces a climate emergency,” says team member Annie Hughes (Max Planck Institute for Astronomy, Germany). “The scientific evidence is beyond doubt that human activities are responsible for changing the climate. The scientific evidence is also clear that we will have to change our activities in the next decade.”
Astronomers, like everyone else, have carbon footprint. These terms used can have slightly different definitions; In this case, Jürgen Knodelsder (University of Toulouse, France) and colleagues defined it as the total greenhouse gas emissions from the facility over its life cycle. Emissions consist mainly of carbon dioxide and methane but also include a number of other heat-trapping 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 biggest source of the astronomical carbon footprint is the construction and operation of ever-larger telescopes.
Due to the lack of accurate data, often due to confidentiality concerns, the team came to this conclusion using a technique called Economic Inputs and Outputs Analysis. Carbon emissions are determined primarily by cost and/or weight. Knödlseder compares the process to refueling a car: filling the tank full, not half, will double its weight. Doubling the fuel will cost twice as much and double the emissions.
Using this input-output analysis, the team calculated that over their life cycle, current astronomical facilities produce the equivalent of 20 million tonnes of carbon dioxide equivalent, with annual emissions of more than one million tonnes of carbon dioxide equivalent.
“To give you some perspective,” notes Knudelsder, “these are the annual carbon footprints 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.
This is the beginning
Knodelsder says cost/weight data has the advantage of being publicly available, although sometimes hard to find. It literally allows all kinds of calculations. But Andrew Ross Wilson (University of Strathclyde, UK), who wrote the attached perspective article for natural astronomysaid this method is not commonly used in carbon accounting, especially for space activities.
“He found that the use of economic input-output methods … greatly overestimated the overall environmental impact.” The reasons are many: First, the aerospace industry, which is often state-funded, is not a truly free market. Also, often expensive Made-to-order materials are used in space missions 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 this gap and does not recommend applying economic input and output databases for space lifecycle assessments,” Wilson said.
The Nodelsider team acknowledges these caveats, but argues that providing this initial estimate is an important first step. The next step is for utilities to do their own more detailed analysis – and then take action.
Wilson agreed, saying, “I think Knodelsider’s assessment is a fairly accurate approximation of the first order due to the lack of data available to him and his team.” “This is definitely a good first step for a more detailed assessment.”
But he cautioned, “I do not believe that any practitioner in space lifecycle assessment would specifically use these findings to inform their own analysis. The ESA certainly won’t look twice at this forecast.”
However, Knodelsider’s team argues that even numerical estimates are the basis of the work: “The solution is in our hands, we just need to be able to accept it,” says team member Luigi Tibaldo (Institute for Research in Astrophysics and Planetary Science, France).
The first step is to convert existing facilities from fossil fuels to renewable energy sources, an effort already being made in many places. Telescopes in remote locations still struggle because they are usually not connected to the local power grid. The Atacama Large Millimeter/submillimeter range in Chile, for example, is powered by a diesel generator. It may be easier to incorporate other facilities into the ongoing methodology change.
The team says these steps will not be enough. Astronomers will also have to slow down the pace of construction of new facilities. The benefits go beyond reducing emissions, as “slow science” will give us more time to make full use of the data we already have. Of course, the entire PhD thesis is searched using only archived records.
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 many of the scientific papers published today are based on archival data such as from new observations,” he said. “This means well, a lot of data usage will be available for years to come.”
But many astronomers object to the slowdown. In fact, some members met resistance from peers even before the paper was published.
“Nobody’s saying astronomy can’t or won’t switch to renewable energy along with the rest of the economy,” said John Mather (NASA’s Goddard Space Flight Center), James Webb Space Telescope project scientist. “The calculated carbon footprint is not a constant of nature, it’s just an estimate of the part of the system governed by the feedback loop.”
Mather also puts forward a counter argument for slowing the pace of science: “Some types of astronomy have become difficult or impossible because of light pollution, radio interference, and satellite constellations,” he said. “It can be said that we must increase our efforts to learn all we can, as soon as possible, before we can.”
Nevertheless, the team remains steadfast in its position: “Fighting climate change is a shared challenge, and everyone, every sector of activity and every country, must contribute to meeting this challenge,” said Knudelsider. “In the fight against climate change, there are no priority solutions; we must activate all possibilities to reduce our emissions. Of course, some measures will be more efficient than others, but we need all of them to succeed.”