The four spheres are closely connected in many ways. For example, many birds (biosphere) fly through the air (atmosphere), while water (hydrosphere) often flows through the soil (lithosphere). In fact, the spheres are so closely connected that a change in one sphere often results in a change in one or more of the other spheres.
Warm water from the ocean (hydrosphere) evaporates until the atmosphere above can hold no more. The wind (atmosphere) moves the moisture (water vapour in the atmosphere) over a colder mountainous area (lithosphere). The atmosphere above it becomes colder and the water vapour condenses and changes to rain. The rain (atmosphere) falls on the land (lithosphere) and returns to the oceans (hydrosphere).
An ‘event’ may be climate change. For example the burning of trees (biosphere) will release carbon dioxide (into the atmosphere) which traps heat and changes climate patterns (atmosphere) that lead to melting of ice sheets and cause sea levels to rise (hydrosphere). This reduces the land (lithosphere) available for human occupation.