Climate change is revving up the jet stream, the river of air which meanders around the North Pole. It is quickening, propelling planes across the north Atlantic at record speed. On 8 February 2020 British Airlines Flight 112 rocketed from New York to London in 4 hours 56 minutes, at one point traveling faster than 1328 km per hour.
Writing on SpaceWeather.com, Dr Tony Philips asks the question “Why do we care?” We do, because airplanes surfing the jet stream absorb significantly less cosmic radiation. Researchers have long known that air travellers are exposed to cosmic rays. At typical cruising altitudes, passengers absorb 50 to 100 times more radiation than they would at sea level. This has led the International Commission on Radiological Protection (ICRP) to classify pilots and flight attendants as occupational radiation workers.
By shortening flights, the jet stream can reduce radiation exposure. Passengers onboard the record-setting British Airways flight spent an hour less at cruising altitude and, according to the models, absorbed about 30% less radiation. Two Virgin Atlantic flights following close on the heels of the British Airways Dreamliner had similar results.
These conclusions are based on E-RAD, an empirical model for aviation radiation. Since 2015, Spaceweather.com and the students of Earth to Sky Calculus have been collecting X-ray, gamma-ray, and neutron radiation data onboard airplanes. The current database contains more than 25,000 radiation measurements gathered while flying over 27 countries, 5 continents, and 2 oceans. E-RAD uses these measurements to predict dose rates on any flight.
Dr Philips applied E-RAD to British Airways Flight 112 on several dates in February, comparing dosages on 8 February when the plane surfed the jet stream, to nearby dates when it didn’t. Surfing the jet stream shaved as much as 10 uSv of radiation off the total dose, a reduction equivalent to almost 1 dental X-ray.
Gain one loose one
An active fast-moving jet stream is often filled with turbulence, making flights miserable for passengers. Planes dodging the rough air can increase their flight times, boosting cosmic ray exposure instead of reducing it. Passengers returning to New York from London must cross the Atlantic against the jet stream. Their flights will be slower, increasing exposure-time to cosmic rays.
If you are a frequent flyer maybe you should consider investing in a spacesuit!