Private space travel may appear to be a step forward, but experts say there are still concerns about how it will affect our future climate.

Companies such as Blue Origin, SpaceX, and Virgin Galactic are attempting to make space travel more affordable for those who can afford it by sending paying customers into space instead of government-trained astronauts.

That “space tourism” could add hundreds more rocket launches each year, as companies like Virgin Galactic say they intend to increase flights to hundreds per year, and experts say those launches could generate more greenhouse gases in the fight against global warming.

According to one model published in the American Geophysical Union magazine, 400 space flights per year over a 40-year period would generate enough greenhouse gas emissions to cause up to 1°C more warming in the Arctic than is currently predicted.

“When you get to that kind of change, those are the kinds of changes that we worry about when it comes to the impacts of climate change in general from other human emissions at the surface like CO2,” said Darin Toohey, an atmospheric science professor at the University of Colorado-Boulder and one of the study’s authors.

There hasn’t been much research into the environmental impact of space tourism, but Toohey says experts can make some educated guesses based on the type of fuel used in rockets and what happens when that fuel is burned.

Toohey is particularly concerned about carbon-based fuels, such as those used by SpaceX and Virgin Galactic, because they emit soot or “black carbon” when burned.

According to Toohey, black carbon has the potential to be extremely problematic because it reflects sunlight and may amplify warming in the upper levels of the atmosphere.

According to Blue Origin, the rocket carrying the New Shepard capsule into space is powered by liquid oxygen and hydrogen. According to the company, the only byproduct of New Shepard’s engine combustion during flight is water vapor, with no carbon emissions.

Water vapor, according to Eloise Marais, a geography professor at University College London, can still contribute to warming the atmosphere.

“It isn’t doing anything up there.” [Water vapor] can also contribute to the formation of clouds in the upper atmosphere, where clouds are uncommon, and clouds, unfortunately, have climate consequences. “They change how much sun is reflected or reaches the earth’s surface,” she explained.

“So there are all these complexities to consider in something as seemingly innocuous as water vapor.”

Michael Strahan, co-anchor of “Good Morning America,” is expected to take part in Saturday’s Blue Origin launch. Marais went on to say that all types of space travel will emit nitrogen oxides, or NOx, due to the high temperatures required to re-enter the atmosphere. According to the EPA, NOx is 300 times more potent than carbon dioxide in warming the atmosphere.

While researchers have begun to investigate the effects of private rocket launches, it is difficult to estimate the impact on the climate without knowing how many flights will take place. Virgin Galactic has stated that it hopes to launch 400 flights per year. Blue Origin and SpaceX have not stated how many launches they intend to carry out.

However, even though the industry is much smaller than commercial air travel, there is a significant difference in that rockets fly at a higher altitude and emit pollution directly into multiple layers of the atmosphere.

“I think the huge difference that we have to take into account is the direct injection of these pollutants into multiple layers in the atmosphere and the impact that that has,” she said. “I think the huge difference that we have to take into account is the direct injection of these pollutants into multiple layers in the atmosphere and the impact that that has is completely different to aircraft, which tend to fly, roughly, 10 to 12 kilometers depending on what kind of flight you’re taking, and that’s really what separates them substantially.”

More research, according to Marais and Toohey, is needed to understand the effects of space tourism.

“I think the potential impacts are too uncertain and potentially hazardous to be able to gamble with this unregulated industry,” Marais said.

It will be difficult to advise policymakers on the best way to regulate space travel and its impact on the climate until data is available, they said.