Another kind of factor is an internal factor.
An example of this is volcanic activity. Volcanic eruptions release large amounts of sulphur dioxide into the atmosphere. These act as a ‘cloak’ and reduce the amount of solar radiation reaching the earth’s surface. An example of this is the Laki eruption of 1783. Millions of tonnes of poisonous gas and particles were sprayed out over Iceland over 8 months. Lava erupted from vents in the mountain, killing off vegetation and in turn animals died from starvation - a third of the islands population died from famine. On a global level the particles released into the atmosphere blocked solar radiation and global temperatures also fell. Crops failed in Europe and starvation followed.
A second factor is surface reflection. During cooler periods when there is a larger amount of snow and ice on earth, global temperature will drop due to the snow and ice reflecting sunlight back into space. This is called the albedo effect. If the planet warms up then the amount of snow and ice will decline, causing less reflection of heat and more absorption which leads in turn to heating of the earth.
A very significant factor is changes in atmospheric gas. There have been many strong links established between levels of CO2 in the atmosphere and climate change. This is because CO2 is a contributing factor to the greenhouse effect. The greenhouse effect keeps heat within the Earth’s atmosphere by absorbing long wave radiation. Without the greenhouse effect the average global temperature of the earth would be -18°C rather than the present 15°.
The current climate change has numerous different causes, including the burning of fossil fuels and the increase in methane in the atmosphere.
Burning fossil fuels releases gases such as carbon dioxide. Extra carbon dioxide from factories, power stations and vehicle exhausts is emitted into the atmosphere. This then absorbs both incoming and reflected radiation, heating the atmosphere. The generation of power contributes to 25% of global carbon dioxide emissions, which in turn exaggerates global warming. The key to solving this is by using more sustainable energy sources.
Methane is a second greenhouse gas which can trap heat within the atmosphere the same way as carbon dioxide. Methane makes up 20% of all the greenhouse gases in the atmosphere and is 20 times more potent than carbon dioxide.
Methane comes from organisms which were alive many years ago, recently dead rotting organisms and those alive today. Fossil methane provides approx 30% of methane released into the atmosphere and was formed underground many years ago. It comes to the surface when fossil fuels are mined.
Modern sources of methane include wetlands/swamps, paddy fields growing rice, landfills which contain rotting vegetable matter and the bowels of animals.
The levels of methane in the atmosphere have been rising by 1.5% a year for the past decade. This is due to an increase in the mining of fossil fuels, rising temperatures leading to increased bacteria emissions from wetlands, increased rice production due to population growth in rice producing countries and increased cattle and sheep for meat due to increase in western style diets.