Alteration in nitrogen cycle and its contribution to climate change: a review

Human activities have disrupted the global nitrogen cycle, fundamentally altered Earth's biogeochemical processes and accelerated climate change. Reactive nitrogen in the environment has increased 400% since pre-industrial times. In contrast, nitrous oxide (N2O), a greenhouse gas 265 times more potent than CO2, has risen 20% in atmospheric concentrations due to agriculture and fossil fuel use. This comprehensive review analyses natural and anthropogenic nitrogen sources, showing how synthetic fertilizers, livestock operations, and industrial emissions create cascading environmental impacts across terrestrial, aquatic, and atmospheric systems. Nitrogen pollution triggers water body eutrophication, soil acidification, biodiversity loss, and disrupted carbon sequestration. Complex feedback loops between nitrogen and carbon cycles amplify climate impacts, while agricultural runoff creates hypoxic dead zones threatening ecosystem stability. Evidence-based mitigation strategies include precision agriculture, enhanced fertilizer management, emission controls, and policy interventions, emphasizing urgent need for integrated approaches to restore nitrogen cycle balance.