Changes in the Earth’s climate can be attributed to the following factors: ocean currents, solar variations, volcanic eruptions, orbital changes of the earth and man-made activities.
The oceans are a significant part of Earth’s climate system. Interactions between the atmosphere and the oceans lead to the El Niño phenomenon which happens every two to six years. Also, changes in the circulation of the ocean could affect the climate by the movement of carbon dioxide out or into the atmosphere.
In a volcanic eruption, large amounts of gases (sulfur dioxide, dust, water vapour and ash released into the atmosphere could influence patterns in the climate for years. Volcanoes also produce aerosols that cause a cooling effect on Earth. Carbon dioxide, a greenhouse gas, is also produced by volcanoes. However, the amount of this gas produced by volcanoes is relatively insignificant when compared to the carbon dioxide that is produced by man.
The Earth is tilted at 23.5 degrees at right angles with its orbital path. Any change in the tilt angle, however small it may be, can cause changes in the climate pattern of the Earth. A large tilt results to colder winters and warmer summers. A small tilt results to milder winters and cooler summers.
Prolonged small changes in the sun’s output of energy can lead to climate changes. Scientific studies have shown that solar variations were responsible for the climatic changes in the previous years.
However, much of the cause of the Earth’s climate change in recent years can be attributed to man-made activities that create or generate greenhouse gasses, and not because of solar variations. Human activities such as fossil fuel combustion, deforestation and agriculture all release greenhouse gases that contribute to changes in the Earth’s climate.