A woman cleared algae in Qingdao, China, a buildup caused by too much nitrogen in the Yellow Sea, resulting in a “dead zone.”

By RICHARD MORGAN

TOOLIK FIELD STATION, Alaska - Public discussion of climate change is largely reduced to carbon: carbon emissions, carbon footprints, carbon trading. But other chemicals play large roles in the planet’s health, and one that a growing number of scientists are investigating is nitrogen.
One of those researchers is Anne Giblin, a senior scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts, who was working this summer at an Arctic science outpost here.
“Mud is a great storyteller,” she said, as she lugged 1.
2-meter tubes of Arctic lakebed mud from her inflatable raft to her nearby lab to measure its nitrogen content.
In addition to its role in climate change, nitrogen has a huge, probably more important biological impact through its presence in fertilizer.
Peter Vitousek, an ecologist at Stanford University in California, wrote an essay in 1994 that first raised environmental awareness of nitrogen. This summer he was co-author of a study in the journal Nature that put greater attention on the nitrogen cycle and warned against ignoring it in favor of carbon.
For example, he said in an interview, “There’s a great danger in doing something like overfertilizing a cornfield to boost biofuel consumption, where the carbon benefits are far outweighed by the nitrogen damage.”
Soon after his report, the journal Geophysical Research Letters branded as a “missing greenhouse gas” nitrogen trifluoride, which is used in production of semiconductors .
According to the report, it contributes more to global warming than carbon dioxide emissions from any one of the largest coal-fired power plants. Nitrogen trifluoride, which is not one of the six gases covered by the Kyoto Protocol, the international global warming accord, is about 17,000 times more potent than carbon dioxide.
“The nitrogen dilemma,” Dr. Vitousek added, “is not just thinking that carbon is all that matters. But also thinking that global warming is the only environmental issue. The weakening of biodiversity, the pollution of rivers, these are local issues that need local attention. Smog. Acid rain. Coasts. Forests. It’s all nitrogen.”
Environmentalists worry that after the hard-fought campaign spotlighting carbon, turning to focus on nitrogen could upset that momentum.
The tension can plague even the most informed and articulate campaigners , including Al Gore, the former vice president who won a Nobel Peace Prize for his environmental work.
“Look, I can start a talk by saying, ‘There are 14 global warming pollutants, and we have a different solution for addressing each of them.’ And it’s true,” Mr. Gore said. “But you start to lose people.”