Ammonia is being considered as a potential near-zero-emission fuel to assist the shipping sector in transitioning away from fossil fuels. Recent studies highlight the need for a deeper understanding and effective management of ammonia's complex lifecycle emissions to realize genuine climate benefits while safeguarding the environment. The International Maritime Organization is set to adopt a new global fuel standard that considers greenhouse gas emissions across the full lifecycle of fuels, aiming to help the shipping industry in decarbonization efforts. Different methods of ammonia production, such as blue ammonia and e-ammonia, offer ways to reduce emissions, with e-ammonia showing potential for near-zero emissions when powered by renewables. However, ammonia combustion results in reactive nitrogen emissions, including powerful greenhouse gas nitrous oxide, necessitating a comprehensive assessment of its suitability as a marine fuel. A recent lifecycle assessment study compared e-ammonia and blue ammonia with conventional ship fuel and found significant emissions reductions when using environmentally friendly ammonia production methods. Despite its potential to cut emissions, ammonia's impact goes beyond direct emissions, with concerns about its effects on ecosystems and air quality. Indirect N2O emissions across the value chain are often overlooked but play a crucial role in assessing ammonia's overall climate impact, highlighting the need for a holistic approach to managing ammonia as a sustainable marine fuel.