A cap on emissions is an integral part of the scheme and applies to total CO2 emissions subject to the regime. Achievement of the cap is the key objective of the scheme. This cap is not further divided into individual country obligations, or caps.
The volume of projected emissions above the agreed cap together with the prevailing market carbon price dictates the level of the levy (emission charge). Collected at this level, the levy would generate enough money to offset the emissions above the cap.
Emission reductions are therefore guaranteed, albeit not necessarily in the shipping sector. The collected money is spent on reducing emissions elsewhere. These reductions are most likely to be outside the shipping sector due to lower abatement costs in the power generation sector, and similar. If a deficit appeared in a given year for whatever reason, the levy is adjusted upwards the following year to cover it.