In addition to these probabilistic factors, there are what people term deterministic factors, which are due primarily to humans, such as habitat destruction, direct over-killing of species, and fragmentation of habitat. These also contribute to extinction, but all these factors are interrelated. The current extinction episode in some ways, besides being deterministic to some point, also falls into the category of a catastrophic event. In other words, the human population explosion is a catastrophe to many other species. But it's a catastrophe that we can understand to some degree, and we may be able to control or at least try to reduce its affects.
Indirectly, human population growth affects Environmental Stochasticity by changing the climate and it affects Genetic and Demographic Stochasticity by reducing populations of other species down to a size where they're small enough that they can be impacted by those stochastic factors. One of the ways we may be able to reduce the magnitude of extinction is to provide refugia where species are buffered from the factors that cause extinctions, including the impact of human beings. This is becoming the unstated goal of nature reserves today: to provide areas which are refuges from extinction for as many species as possible.