The mechanisms of change in state were largely based on the International Union for the Conservation of Nature’s threat classification (more information here).
Definitions for the mechanisms of change in state are as follows:
Change in species composition
Changes in species composition of communities over time and space.
Change in species population size
Changes in species populations over time and space.
Changes in Ocean current and circulation
Large scale movement of waters in the ocean basins.
Diseases
Harmful pathogens and microbes that are originally found within the ecosystem(s) in question, but have become 'out-of-balance' or 'released' directly or indirectly due to human activities.
Droughts
Periods in which rainfall falls below the normal range of variation.
Earthquakes
Earthquakes manifest themselves by shaking and displacing or disrupting the ground. They may also cause associated events such as tsunamis, landslides, or even volcanic activity.
Fires
Suppression or increase in fire frequency and/or intensity outside of its natural range of variation.
Flooding
Extreme precipitation events leading to the submergence of dry land.
Land /freshwater/ seabed area modification
Major changes in habitat composition and location, for example deforestation.
Landslides
Landslide events leading to geological changes.
Ocean acidification
Changes to the ocean chemistry which occurs when carbon dioxide is absorbed from the atmosphere and reacts with seawater to produce acid.
Pests
Harmful plants or animals that are originally found within the ecosystem(s) in question, but have become 'out-of-balance' or 'released' directly or indirectly due to human activities.
Pollutants concentration change
Threats arising from the introduction of contaminants into the natural environment.
Sea level rise
Increase in global mean sea level as a result of an increase in the volume of water in the world's oceans or heat dilation.
Sea surface temperature
Periods in which sea surface temperatures exceed or go below the normal range of variation.
Storms
Extreme precipitation and/or wind events.
Volcanoes
Volcanic events which may lead to changes in ecosystem components.
Weather conditions
Weather conditions outside of the natural range of variation.