Factors Contributing to Climate Change
In this section, a selection of natural and anthropogenic factors that affect climate will be investigated in further detail.
Natural Factors that Affect Climate
Orbit and Axis of Earth
The orbit and axis of Earth both fluctuate on a regular basis through small, slow, but consistent cycles. These cycles are called Milankovich cycles, which affect the climate of Earth by changing the amount and intensity of solar radiation that affects Earth. The below are three of the Milankovich cycles, which are:
- eccentricity - orbital shape: the shape of Earth's orbit varies from nearly circular to slightly elliptical. Caused by the gravity of other planets in the solar system, and a cycle has a period of 100,000 years
- obliquity - axial tilt: the angle of Earth's tilt in relation to the plane of its orbit. This angle varies from 22.1°to 24.5°, and a cycle has a period 41,000 years.
- precession - axial precession: the direction of the "wobble" of Earth's axis. Caused by tidal forces caused by the Sun and the moon. Cycle has a period of 26,000 years.
Volcanic Activity
When volcanoes erupt, they throw large quantities of ash, dust, water vapour, carbon dioxide, and sulfur dioxide into the atmosphere. The sulfur dioxide molecules then react with water vapour in the atmosphere to create sulfuric acid, which is then transferred all over the world through prevailing winds. The sulfuric acid that is produced from the atmosphere can affect the climate of the land below by affecting the amount of solar radiation that hits the Earth's surface. The effects that occur depend on the size of the droplets of sulfuric acid. If the droplets are relatively large, then they will let solar radiation in but not let heat radiated off Earth out, assisting the greenhouse effect. However, if the droplets are smaller than two microns, the droplets will absorb some of the solar radiation that is coming towards Earth, which cools the surface of Earth, creating an effect reverse of the greenhouse effect. Also, the ash that volcanoes throw into the atmosphere contains high concentrations of bromine and chlorine, which react with ozone in the ozone layer, depleting it and lowering levels of ozone in the atmosphere.
An example of volcanic eruptions affecting the climate of the world is the eruption of Mount Pinatubo in the Philippines in 1991. It ejected 20,000,000 tonnes of sulfur dioxide into the atmosphere, and between 1991-93, global temperatures dropped by 0.5°
An example of volcanic eruptions affecting the climate of the world is the eruption of Mount Pinatubo in the Philippines in 1991. It ejected 20,000,000 tonnes of sulfur dioxide into the atmosphere, and between 1991-93, global temperatures dropped by 0.5°
Anthropogenic Factors that Affect Climate
Burning of Fossil Fuels
The burning of fossil fuels affects the climate by releasing carbon dioxide back into the atmosphere as a product of the combustion. During the history of Earth, atmospheric levels of CO2 have varied considerably, impacting the temperature of our globe. About 300-360 million years ago during the Carboniferous period, a large amount of carbon dioxide was sequestered (captured from the atmosphere) and turned into inert forms such as oil and coal. Since that major geological event, all ecosystems and organisms have adapted to survive with a lower level of atmospheric carbon dioxide. Burning fossil fuels intensifies the greenhouse effect, raising average global temperatures and sea levels.
Land Use
Changes in land use can affect the climate of the globe by impacting the carbon cycle. While some forms of agriculture can help in the sequestration of carbon dioxide, other forms of farming and deforestation can cause carbon dioxide to be released back into the atmosphere. Also, changing the use of land on Earth can cause changes to Earth's albedo, which increases or decreases depending on what the land is being used for. This can alter the amount of solar radiation that affects Earth and helps play part in the greenhouse effect.