More businesses in Japan are using aircraft to measure the amount of carbon dioxide absorbed by forests. The aim is to lower the cost of emissions trading.

Major papermaker Nippon Paper used the aerial method to obtain government certification last month for its roughly 100-hectare forest in central Japan.

The research determined that the area can absorb 6,800 tons of CO2 over eight years.

Emissions trading allows companies to sell credits if they manage to cut their CO2 output. Buyers include businesses trying to meet their targets for carbon-footprint reduction.

On-site inspections of forests have been the common method. But that is expensive and raises the cost of exchanging carbon credits.

The Japanese government approved the use of airplanes and drones last year.

Suzuki Yoshiyuki, a Nippon Paper official, says, "We hope to accelerate our efforts so we can be a model case leading the trend."

Major trading firm Mitsui & Co. is using aircraft for its forest in Japan's northern prefecture of Hokkaido.