The environmental impact of laughing gas from waste treatment and agriculture should be taken seriously, an expert warned.
Nitrous oxide, also known as laughing gas, only makes up 9% of greenhouse gas emissions but has 300 times more global warming potential than carbon dioxide, said Professor David Richardson.
He added: "It can survive in the atmosphere for 150 years and it's recognised in the Kyoto protocol as one of the key gases we need to limit."
The gas is mainly produced by bacteria in municipal sewage treatment plants, landfill sites, and marshy areas polluted with agricultural fertiliser, said Prof Richardson, from the University of East Anglia in Norwich. Its release is increasing at the rate of 0.25% each year, he said.
"When faced with a shortage of oxygen, many species of bacteria can switch from using oxygen to using nitrates instead," said Prof Richardson.
"Nitrates can support their respiration, the equivalent of our breathing, and bacteria can get energy through processes called denitrification and ammonification. When they do this, nitrous oxide is released into the environment."
Nitrous oxide hotspots are places so teeming with bacteria that oxygen was in short supply, forcing the bugs to adopt their alternative method of respiration, Prof Richardson said.
He added: "We are finding new biological routes for nitrous oxide emission that no one ever suspected before. This could make a big impact on the environment.
"Global warming affects everyone, and understanding the biology of nitrous oxide emissions will be an important step in mitigating their impact. We urgently need to start developing better strategies to improve management of these emissions in the agricultural and waste treatment sectors."
Prof Richardson was speaking at the 162nd meeting of the Society for General Microbiology in Edinburgh.