How many space launches does it take to have a serious climate impact?

A new satellite launch site is being planned for Unst, a windswept UK island that was once part of a ring of radar stations used to detect incoming V-2 rockets – the German “wonder weapons” that spawned a government-led space race more than a half-century ago.

Launches at the Unst facility, which will cater to commercial clients, should generate an estimated 764 tonnes of carbon dioxide equivalent every year. That's a negligible fraction of the country’s total annual emissions. But the site is just one of seven planned for the UK alone, as a second, largely profit-driven space race heats up.

Space launches haven’t raised much climate concern to date. That may change, as the private sector books an increasing number of flights for space tourists, and potentially starts ferrying miners and factory workers beyond Earth’s atmosphere (two successful commercial voyages to space this month both inspired would-be explorers and prompted some pundits to calculate their carbon footprint).

Alongside space tourism, the growing use of satellites will also likely ramp up launch activity; a record 1,283 satellites were launched last year, according to the UN, and by April of this year nearly 850 more had been sent into space.

In addition to coughing up not-inconsiderable amounts of CO2, rockets can spew exhaust that depletes the ozone layer through chemical reactions. And if the black carbon “soot” particles they leave in the atmosphere reach high enough concentrations, it could impact surface and atmospheric temperatures, according to a NASA assessment.

One study estimated that 1,000 space launches per year could create a layer of black carbon particles capable of causing the loss of 5% or more of Antarctic sea ice.

As private commercial interest in space increases, a wider variety of governments are also likely to initiate launches. More than a dozen countries now have the ability to send objects into orbit, and related costs have generally declined since 2005.

Nations submitting information to the UN on their first satellites in 2019 included Bhutan and Kenya; Indonesia, Lithuania, and Egypt were among the other countries registering functional space objects that year.

China now has a space station where it can send additional astronauts and supplies, and the United Arab Emirates plans to follow its successful launch of a Mars orbiter with a satellite-manufacturing complex and a settlement on the Red Planet by 2117.

Not long before the private-sector launches this month stirred excitement about new possibilities for spaceflight, an extreme heatwave linked to climate change had blanketed the region from Texas north to Canada – killing hundreds of people, cooking millions of sea creatures, and hinting that an environmental catastrophe may be closer at hand than anticipated.

Some argue greater access to space means we could send the most climate-unfriendly aspects of the global economy there. Others say we must find better ways to deal with the problem right here on Earth.

A number of efforts are underway to blunt the climate impact of rockets – similar to the anticipated shift among aviation companies to more sustainable fuels.

A company in Europe is working on carbon-neutral rockets that run on hydrogen produced from biomass, for example, and another says it's been developing a rocket that doesn't emit black carbon.

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