The theory of plate tectonics describes the movement of the Earth’s crust and mantle. In plate tectonics, water moves through the Earth’s mantle and returns to the surface by volcanoes.

The water cycle requires energy to drive the phase changes that defines different stages of the cycle. The sun in the form of solar energy provides the majority of the energy needed for this cycle.

Ice sheets are large areas of ice, including glaciers and ice caps. These represent large reserves of sequestered water that remain on the Earth’s surface for a very long time (i.e. those located in Antarctica). While ice sheets represent sequestered water, they are only a part of the water cycle due to the constantly changing climactic conditions of Earth.

The relationship between water evaporation and temperature is called “evaporative cooling.” Evaporative cooling is the principle that states that the release of water vapor into the air decreases the environment's temperature (i.e. sweating in mammals).

Human activity has a large impact on eco-chemical cycles, including the water cycle. Human activities that impact the cycle include agriculture, industry, and deforestation.

Acid precipitation is a type of precipitation that is acidic, meaning that it has a pH of less that 7. Acid precipitation is caused by the reaction of sulfur dioxide and nitrogen oxide with water in the atmosphere, which produces acids. The production of sulfur dioxide and nitrogen oxide is directly linked with human industrialization.

Atmospheric , fossil fuels (including coal), peat, and organic material in a durable form (such as the cellulose of trees) are the reservoirs of the carbon cycle. Glaciers, on the other hand, are primarily water and are one of the reservoirs of the hydrologic (water) cycle.

Genetic drift occurs as a result of chance events causing changes in the allele frequency of a population. It doesn't favor the most fit individuals, but occurs at random.

Mutations can contribute to genetic drift, however, genetic drift is a more specific answer and more relevant to the question at hand.

Genetic drift is the random process of alleles being passed from parents to offspring. Increasing genetic diversity in a population requires introducing a greater number of alleles, which can only occur through mutations or addition of unrelated members to the population. Genetic drift only affects how already-existing alleles are passed down.

If an allele has a high frequency at baseline, the chance of it being passed down to subsequent generations is higher than alleles of a lower frequency. Through random chance, a high-frequency allele can eventually have a frequency of 100%, becoming fixed in the population. Conversely, a low-frequency allele can eventually disappear from the population if none of the few parents who possess that allele happen to pass it onto their offspring.

Genetic drift describes the random selection of alleles that are passed from one generation to the next due to independent assortment in gametogenesis. Genetic drift cannot create new alleles, so it cannot increase genetic diversity (the number of alleles in a population). It can, however, decrease genetic diversity if an allele of a low frequency is not passed down to subsequent generations due to pure chance.

There is no hard and fast rule for whether genetic drift or natural selection have had a greater effect on shaping populations. Both have greatly shaped the populations present on Earth today, but their relative importance varies between species and has also varied over time. The conditions of Hardy-Weinberg equilibrium require that both natural selection and genetic drift be negligible. If genetic drift is occurring, then the population cannot be in Hardy-Weinberg equilibrium.