Issue Ammonia as a fuel could push nitrogen fixation to new highs

Summary

The nitrogen boundary currently covers only industrial fixation for fertilizer and intentional biological fixation by legumes, which together reach 165 Tg a year against a boundary of 62 Tg, deep in the high-risk zone. Human nitrogen inputs already exceed all natural sources on land and in the ocean combined, and the excess drives algal blooms, dead zones and air pollution that causes hundreds of thousands of avoidable deaths each year. The report says future assessments should also count reactive nitrogen from fossil fuel combustion and from the breakdown of long-accumulated soil stocks. It adds that the emerging use of ammonia as a fuel and long-distance energy carrier could push nitrogen fixation to unprecedented levels in the coming decades. Without effective regulation, the report warns, this shift would bring high pollution risks.