Fourth IMO GHG Study 2020
Faber, J., Hanayama, S., Zhang, S., Pereda, P. Comer, B., Hauerhof, E., Schim van der Loeff, W., Smith, T., Zhang, Y., Kosaka, H., Adachi, M., Bonello, J., Galbraith, C., Gong, Z., Hirata, K., Hummels, D., Kleijn, A., Lee, D.S., Liu, Y., Lucchesi, A., Mao, X., Muraoka, E., Osipova, L., Qian, H., Rutherford, D., Suárez de la Fuente, S., Yuan, H., Perico, C.V., Wu, L., Sun, D., Yoo, D., Xing, H. Fourth IMO GHG Study 2020. International Maritime Organization. Available here.
The Fourth IMO Greenhouse Gas Study 2020 reports a 9.6% increase in total shipping greenhouse gas (GHG) emissions, including CO2, methane, and nitrous oxide (expressed in CO2e), from 977 million tonnes in 2012 to 1,076 million tonnes in 2018. CO2 emissions alone rose 9.3% to 1,056 million tonnes, with shipping’s share in global anthropogenic emissions increasing from 2.76% to 2.89%. International shipping CO2 emissions grew 5.6% (voyage-based) or 8.4% (vessel-based) over the same period, maintaining a stable ~2% of global CO2 emissions. Carbon intensity improved by 21–29% voyage-based and 22–32% vessel-based from 2008 to 2018, though the pace of reduction slowed post-2015. Emissions are projected to rise to 90–130% of 2008 levels by 2050, influenced by economic and energy scenarios. COVID-19 may slightly lower near-term emissions, but long-term projections remain uncertain, aligning with global decarbonization challenges.