This guest post was written by Isobel Romero-Shaw. Isobel is a PhD student at Monash University in Melbourne, Australia. She tries to figure out how black holes and neutron stars meet up and crash together by studying the vibrations that these collisions send rippling through space-time. This sounds thrilling, but on a day-to-day basis it mainly involves debugging code. When shes done debugging, Isobel likes to spend time reading, drawing, and exploring.

Although the carbon footprint of the average astronomer might lead you to believe were all wearing clown shoes, the situation we find ourselves in is no joke.

The average human being is responsible for the release of about 7 tonnes of CO2 into the atmosphere every year roughly equivalent to the heft of one fully-grown male elephant. This in itself is a problem; we must reduce our net carbon emissions to zero before 2050 in order to maintain a habitable planet. Nonetheless, the carbon emissions of astronomers put the global average in the shade. In their recent study on the carbon emissions of Australian astronomers, Dr. Adam Stevens et al. found that the average astronomer could be sending more than 37 tonnes of CO2 thats five CO2 elephants spiralling into the sky every year.

Carbon dioxide (CO2) is a greenhouse gas: when it gets into the atmosphere it traps the Suns heat and warms the planet, like a greenhouse. For most of Earths history, atmospheric CO2 levels have been balanced by natural absorption of CO2 by plants and oceans. However, since humans came along, we have been pumping carbon into the atmosphere faster than it can be absorbed.

Human-induced global warming has catastrophic repercussions. In this Canadian White Paper, astronomer Professor Christopher Matzner et al. outline a number of these:

Awareness of the severity of global warming has grown rapidly in recent years, in part due to movements like the School Strikes for Climate led by renowned teen activist Greta Thunberg and Extinction Rebellion. In January 2020, over 12500 scientists from 153 countries signed the World Scientists Warning of a Climate Emergency. As of February 2020, 197 countries have signed the Paris Agreement, which aims to limit global warming to less than 2C above pre-industrial temperatures before the year 2100. But just being aware of the issue is not enough. We have a lot of work to do before our emissions hit the Paris targets especially in astronomy.

Observing facilities take partial blame for the comparatively high emission levels of astronomers. According to the Australian study, about 13% of total astro emissions one small elephants worth comes from the operation of observatories, while only 10% comes from powering our office buildings.

More concerning, though, is how much carbon we emit through work-related travel. Our flying habits make up a large fraction of our total emissions, especially in large countries like Australia, Canada and the United States, where we often fly interstate as well as overseas. In Australia, flights make up 17% of our work-related emissions. This is somewhat due to the remote location of Australia using Qantass carbon emissions calculator, Stevens found that a single round trip from Australia to the US or Europe can easily exceed 3 tonnes of CO2 per passenger. Even for astronomers living in less remote countries like Canada, Matzner points out that a typical transatlantic flight uses seven months worth of the annual per-capita emissions needed to reach the Paris targets.

Shockingly, the carbon cost of air travel is small change in comparison to the big bucks splashed on high performance computing. As a theoretical astronomer, you might think that your stellar simulations have no real ties to the material world. Yet the Australian study found that 60% of astro emissions come from supercomputer usage alone. More than three times the amount generated through our air travel, the CO2 generated just by powering and cooling computer clusters equates to three carbon elephants per astronomer.

While climate change impacts all of us as inhabitants of planet Earth, its vital to remember that it also threatens astronomical study. As explained in this American White Paper led by Dr. Kathryn Williamson, many of our activities depend on relatively stable weather conditions: extreme weather events leave ground-based telescopes and observatories out-of-action.

If we fail to combat climate change, then we depend on proposed mitigation strategies to keep our planet habitable. Some of these, like injecting aerosols into the stratosphere to reduce solar flux, will also render our ground-based telescopes close to useless. According to one recent study, such an aerosol injection would increase the night sky brightness by 25%, in addition to doubling the level of starlight scattering in the atmosphere. The profession of astronomy is jeopardy unless we seriously change our behaviour, and we must do it now.

We exist at a moment of balance an unstable solution where small actions that we take now could tip us into one of two very different futures. Here are just a few measures suggested by the papers referenced in this post that might tilt the balance in favour not only of astronomy, but of humanity.

If you are an astronomer, consider signing up with the grass-roots movement Astronomers for Planet Earth.

See the rest here:

The CO2 Elephant in the Room: Curbing the Carbon Footprint of Astronomy - Astrobites