To evaluate shipping's environmental impact, all types of impact from all ships operating in an area need to be included in the assessment.
Shipping gives rise to a number of different types of environmental impacts such as emissions to air and water from various on-board systems, exhaust gases from combustion engines, toxic substances from anti-fouling paints, and grey, black (sewage), ballast cooling, bilge and scrubber water, tank cleaning residues , propeller sleeve oil and solid waste such as food scraps. In addition to emissions, shipping also causes various types of energy pollution, such as underwater noise from engines and propellers, sonar, artificial light, and turbulent energy in the wake. Other types of direct and indirect environmental impacts linked to shipping include erosion from surge waves, physical disturbance of the seabed at anchorage, dredging and dumping of dredged masses from harbors and waterways, and the spread of alien species. In order to evaluate shipping's environmental impact, all types of impact from all ships operating in an area need to be included in the assessment.