London: With space tourism being the latest fad, soot from commercial space flight will change global temperatures.
Researchers have estimated that climate change caused by black carbon, also known as soot, during a decade of commercial space flight would be comparable to that from current global aviation.
The findings suggest that emissions from 1,000 private rocket launches a year would persist high in the stratosphere, potentially altering global atmospheric circulation and distributions of ozone.
"There are fundamental limits to how much material human beings can put into orbit without having a significant impact," Nature quoted Martin Ross, an atmospheric scientist at the Aerospace Corporation in Los Angeles, as saying.
Commercial rockets burn a mixture of kerosene and liquid oxygen. But several private space-flight companies, such as Virgin Galactic, may soon use a more economical ``hybrid`` rocket engine that ignites synthetic hydrocarbon with nitrous oxide, said Ross.
These hybrid engines emit more black carbon than a kerosene and oxygen engine, he added.
"Rain and weather wash out these particles from the atmosphere near Earth`s surface, but in the stratosphere there isn`t any rain and they can remain for 3 to 10 years," said Michael Mills, an atmospheric chemist at the National Center for Atmospheric Research (NCAR) in Boulder.
The researchers ran global atmospheric models of an injection of about 600 tonnes of black carbon per year at a single location, Las Cruces.
The results showed a soot layer in the stratosphere that stays within 10° latitude of the launch site, says Ross. Furthermore, around 80 percent of the black carbon remained in the Northern Hemisphere, spreading out to between 25° and 45° northern latitude.
The black carbon layer caused the temperature to decrease about 0.4 °C in the tropics and subtropics, whereas the temperature at the poles increased by between 0.2 and 1 °C, he said, emphasizing that the exact details would have to be refined with further models.
The black carbon also caused ozone reductions of up to 1.7 percent in the tropics and subtropics, and increases of 5-6 percent in the polar regions.
The findings were reported in the Geophysical Research Letters1.