Scheme to track greenhouse gases takes to the air

Commercial aircraft is fitted with carbon dioxide detector.

Tokyo

Passenger planes in Japan are being pressed into service to monitor greenhouse-gas levels in the atmosphere. On 5 November, Japan Airlines flew its first plane equipped with a device that continuously measures atmospheric carbon dioxide.

Plane sailing: Japan Airlines plans to provide continuous data on CO₂ levels.

Targeting flight paths from Tokyo to southeast and east Asia and to Europe, researchers say that the measurements collected by the project will provide much-needed information about CO₂ emissions over Asia. Eventually five planes will carry the equipment on routine flights, measuring CO₂ from the moment they take off to when they land. As they criss-cross the region, they will build up a fuller three-dimensional picture of CO₂ than can be obtained by ground-based or satellite observations, researchers say.

“We were looking for a way to observe carbon dioxide continuously, in broad areas and at a low cost,” says Toshinobu Machida, an atmospheric researcher at the National Institute for Environmental Studies in Tsukuba, Japan. To get the project up and running the Japanese government has provided ¥80 million (US$670,000) per year since 2003. Running costs from next year are expected to be half that.

The latest project follows on from a similar idea in the 1990s. In 1993, two planes run by Japan Airlines began carrying simple equipment to collect air samples for analysis in the laboratory. But samples were taken only twice a month on flights between Tokyo and Australia.

When the planes came up for retirement, scientists began to develop a device that could offer continuous monitoring. The equipment samples air from the front of the plane's engines and so does not pick up the aircraft's own emissions, says Yukio Nakagawa, manager at the engineering department of Japan Airlines. The hardest task, he notes, was creating a device with the appropriate specifications given the limited time and cost.

Inside the plane's cargo compartment, air flows through spectrometers that continuously measure the CO₂ concentration. Associated equipment detects other greenhouse gases, such as sulphur hexafluoride.

Although the equipment has so far flown on just one plane, the company plans to add devices to four more of its Boeings by the end of next year.

Toshihiro Ogawa, a retired atmospheric chemist formerly at the University of Tokyo, says the project should help researchers to quantify carbon dioxide emissions and so make it easier for countries to conform to the Kyoto Protocol on climate change. “Figuring out the real carbon dioxide emissions per country is our big homework,” he says.