Exploring the dynamic changes of steel from the ships is critical for developing sustainable strategies for waste management of shipping industry. However, the information of stocks and flows of ships and related steel is currently unavailable, hindering the sustainable development of shipping industry. By collecting dispersed information on production, use, material composition, and end-of-life management of five types ships, we first estimated the historical steel stocks and flows respect to global ships from 1980 to 2019, and further projected the amount of steel scraps from shipbreaking by 2050. The steel stocks of ships increased by 2.6 times from 208.4 Mt in 1980 to 542.9 Mt in 2019. The top 2 regional contributors, Asia and Latin America & the Caribbean, were together responsible for about half of the total increase. A transition from oil tankers to container ships and bulk carriers reduced the in-use steel stock due to the lower steel intensity of the latter. The rapid increase of ship stocks after year 1980 led to significant increase of steel scrap in the 2010 s, reaching 10.1 Mt/year in 2019. Our projections showed that the steel from scrapped ships worldwide will increase by around 4-fold to 40.4–47.3 Mt/year by 2050, which imposed a great challenge on coordination of recycling ship-related steel and require long-term planning on ship recycling facility development. By identifying the stocks and flows of ships and related steel, this study provides insights for the steel waste and recycling management of end-of-life ships worldwide.

探索船舶钢材的动态变化对于制定航运业废物管理的可持续战略至关重要。然而，目前船舶及相关钢材的库存和流量信息无法获取，阻碍了航运业的可持续发展。通过收集五种船舶的生产、使用、材料成分和报废管理的分散信息，我们首先估算了1980年至2019年全球船舶的历史钢材库存和流量，并进一步预测了废钢量到 2050 年，船舶钢材库存从 1980 年的 208.4 公吨增加到 2019 年的 542.9 公吨，增长了 2.6 倍。亚洲和拉丁美洲和加勒比地区的前两个地区贡献者合计占总增幅的一半左右。由于后者的钢材强度较低，从油轮到集装箱船和散货船的过渡减少了在用钢材库存。1980 年后船舶库存的快速增加导致 2010 年代废钢显着增加，2019 年达到 10.1 Mt/年。我们的预测显示，全球报废船舶的钢材将增加约 4 倍，达到 40.4-47.3到 2050 年吨/年，这对回收船舶相关钢材的协调提出了很大的挑战，需要对船舶回收设施的发展进行长期规划。通过确定船舶和相关钢材的库存和流量，本研究为全球报废船舶的钢材废物和回收管理提供了见解。1980 年后船舶库存的快速增加导致 2010 年代废钢显着增加，2019 年达到 10.1 Mt/年。我们的预测显示，全球报废船舶的钢材将增加约 4 倍，达到 40.4-47.3到 2050 年吨/年，这对回收船舶相关钢材的协调提出了很大的挑战，需要对船舶回收设施的发展进行长期规划。通过确定船舶和相关钢材的库存和流量，本研究为全球报废船舶的钢材废物和回收管理提供了见解。1980 年后船舶库存的快速增加导致 2010 年代废钢显着增加，2019 年达到 10.1 Mt/年。我们的预测显示，全球报废船舶的钢材将增加约 4 倍，达到 40.4-47.3到 2050 年吨/年，这对回收船舶相关钢材的协调提出了很大的挑战，需要对船舶回收设施的发展进行长期规划。通过确定船舶和相关钢材的库存和流量，本研究为全球报废船舶的钢材废物和回收管理提供了见解。这对回收船舶相关钢材的协调提出了很大的挑战，需要对船舶回收设施的发展进行长期规划。通过确定船舶和相关钢材的库存和流量，本研究为全球报废船舶的钢材废物和回收管理提供了见解。这对回收船舶相关钢材的协调提出了很大的挑战，需要对船舶回收设施的发展进行长期规划。通过确定船舶和相关钢材的库存和流量，本研究为全球报废船舶的钢材废物和回收管理提供了见解。