This chapter examines the temporal fluctuations in marine biodiversity different spectral bands ranging from millions of years to single-day events. It focuses on the natural temporal variability in biodiversity on timescales ranging from intraseasonal to million years. Although interpretation of this temporal variability is complex that many external forcings influence long-term variability in the marine environment. The chapter shows that climate tends to be an important parameter controlling biodiversity changes, even if it is not always the primary cause. The authors also discovered some relationships with CO2 concentration, suggesting that greenhouse gases might play an important role. The runaway model is important because it suggests that current global warming may lead to the breakdown of negative feedback mechanisms and the establishment of positive feedbacks that may trigger a runaway greenhouse. The chapter explains the sequence of events involved in the mass extinction because some processes may also be implicated in the current climatic crisis.