Although the four systems have their individual identities, there is important interaction between them. Environmental scientists study the effects of events in one sphere on the other spheres. There are ten possible types of interactions that could occur within the earth system.
Four of these interactions are between the event and each of the earth’s spheres. The double-headed arrows indicate that the cause and effect relationships of these interactions go in both directions. For example, a volcanic eruption in the geosphere may cause profound direct and indirect effects on the hydrosphere, atmosphere and biosphere as follows.
Example: (Volcano) On May 18, 1980, Mount Saint Helens, in the state of Washington, erupted. This event altered the surrounding environment, and provided scientists with an opportunity to study the effects of volcanic eruptions on the lithosphere, hydrosphere, atmosphere and biosphere. Such studies are important because volcanic eruptions will continue to occur, and will have increasing impact on humans as people continue to settle lands closer to dormant volcanoes.
In addition to the above four event- sphere interactions, there are six interactions that occur among the spheres themselves. The ten types of interactions that can occur within the earth system often occur as a series of chain reactions. This means one interaction leads to another interaction, which leads to yet another interaction–it is a ripple effect through the earth’s spheres.