Net zero refers to a state in which the volume of greenhouse gas emissions from human activities does not exceed the amount that can be captured and stored in nature. This is achieved by reducing emissions and at the same time utilising carbon sinks such as forests, oceans and technologies to absorb excess carbon. Net zero may refer only to carbon emissions (carbon neutral) or also take account of other greenhouse gases such as methane (CH4) (greenhouse gas neutral). Climate neutral also takes account of the grey emissions caused abroad and the climate impact of international air travel.