Black Carbon (BC) is the product of incomplete combustion of fossil fuels, biofuels and biomass, and is co-emitted with other aerosols, such as organic carbon and sulphates. Black carbon and co-emitted aerosols make up the majority of PM2.5 air pollution, and is the leading environmental cause of poor health and premature death. Black Carbon also impacts climate by exerting a direct net positive radiative forcing at the top-of-the atmosphere equivalent to ~40% of the current radiative forcing due to the CO2 greenhouse effect. In addition, BC influences cloud formation and properties, and impacts regional circulation and rainfall patterns. Finally, when deposited on ice and snow causes positive climate forcing by reducing the albedo of the cryosphere, hence increasing its melting rate. Owing to its impacts on climate and health, BC is receiving growing attention. However, there are still large uncertainties related to the magnitude of the impact of atmospheric BC due to difficulties to obtain accurate emission inventories. As a result, current global climate models systematically underestimate the BC direct radiative forcing relative to observations, which is often attributed to the underestimation of BC emissions. Another impact of BC, much less known than its direct impacts on health and climate, is related to its introduction in the ocean. The atmospheric lifetime of BC ranges from a few days to a few weeks, and BC eventually deposits on the surface of lands and oceans. In addition to the direct deposition on the surface of the ocean, significant amounts of BC deposited on lands are washed out by rainfall and transported by rivers, hence ultimately ending up in the ocean. The estimated total flux of BC to the ocean via direct atmospheric deposition and fluvial transport is on the order of 20 Tg/year. Since estimates of the flux of BC to the ocean are derived from estimates of BC emissions, they may be underestimated as well. Finally, at the global scale, emissions of BC are expected to increase in the coming decades (up to 40% more BC emitted by 2060) due to growing energy demand; this global increase masking wide regional differences, as it will be mostly localized in Asia. Considering that most of the BC ends up in the ocean, it is important to understand how this material impacts marine systems. Because BC are highly porous and surface-active particles, with a high density, they can ad/absorb dissolved compounds, increase aggregation processes and ballast sinking particulate organic matter. Because they bring nutrients and contaminants to the surface ocean, and modify the structuring of the environment at the microscale, BC may alter phytoplankton and microbial community composition and activity. As a result, BC may alter the efficiency of the Biological Carbon Pump, and hence could lead to either positive or negative feedbacks on the atmospheric concentration of CO2. Owing to its short residence time in the atmosphere, atmospheric-BC is considered as a short-lived climate forcer, which mitigation has been suggested to have a direct and rapid effect on climate change. Considering the long residence time of BC in ocean (i.e., >2400 years), and its potential impacts on marine processes responsible for the production of biogenic carbon, for the transfer of organic carbon from the dissolved to the particulate phase, for the formation and characteristics of sinking marine aggregates, and subsequent feedback on climate, marine-BC may act as a long-lived climate forcer.