Saturday, March 19, 2016

Population Growth - Holocene Extinction - The Sixth Extinction

Rainbow trout live in the coldest part of the river. As river levels drop the water heats and the trout have to go lower and lower looking for their ideal temperature of about 12 degrees Celsius.

Large trout, the older and wiser, push the young ones out of the cooler spot. There just isn't enough space for them all. The older trout are going to make sure they get to their 11-year lifetime.
Experts agree there are three things that we must do to fight climate change. The first is to use less fossil fuel. Second, we have to deal with the carbon we have. And we must slow global population growth. That's the tough one.

The older trout have the same issues that we have. The river is dividing into the haves and have-nots. There's not enough cool water for everybody, and whats left is running out.
Carrying capacity refers to the maximum abundance of a species that can be sustained within a given habitat. When an ideal population is at equilibrium with the carrying capacity of its environment, the birth and death rates are equal, and size of the population does not change. Populations larger than the carrying capacity are not sustainable, and will degrade their habitat.

Chart of extinction events that wiped out most life on Earth.
Humans have benefited greatly through active management of Earth's carrying capacity. An enormously greater number of Earth's species have not fared as well, having been made extinct as a consequence of ecological changes associated with the use and management of the environment by humans. In general, any increase in the carrying capacity of the environment for one species will negatively affect other species.

Symptoms of environmental deterioration include the extinction crisis, decreased soil fertility, desertification, deforestation, fishery declines, pollution, and increased competition among nations for scarce resources. Many scientists believe that the sustainable limits of Earth's carrying capacity for humanity has already been exceeded.

The Holocene Extinction, sometimes called the Sixth Extinction, is a name used to describe the currently ongoing extinction event of species during the present Holocene epoch (since around 10,000 BCE) mainly due to human activity. The large number of extinctions span numerous families of plants and animals including mammals, birds, amphibians, reptiles and arthropods. Although 875 extinctions occurring between 1500 and 2009 have been documented, the vast majority are undocumented.

World Population Density