Complex sentence: The Emission reduction unit (ERU) is a trading unit under the Kyoto Protocol representing a reduction of greenhouse gases under the Joint Implementation mechanism, where it represents one tonne of equivalent reduced.
Split into simpler sentences: The Emission reduction unit (ERU) is an emissions unit issued under a Joint Implementation project in terms of the Kyoto Protocol. An ERU represents a reduction of greenhouse gases under the Joint Implementation mechanism, where it represents one tonne of equivalent reduced.