The question of how global warming is caused naturally is one that has been actively debated for more than a century. Though human activity is by far the leading cause of global warming, natural processes are becoming increasingly important to consider since they play an integral role in driving climate change. The increasing levels of greenhouse gases in the atmosphere, such as water vapor, carbon dioxide, and methane, are mostly caused by the burning of fossil fuels, but the reactions of the Earth’s natural systems are also important contributors.
The main source of natural global warming is the Sun. The Sun emits a certain amount of solar radiation and its luminosity has increased by approximately 6–7% over the last 100 million years. This means that the amount of solar radiation reaching the Earth’s surface has increased, resulting in higher temperatures across the globe. However, a decrease in cloud cover as well as an increase in aerosols, such as dust and particles, in the atmosphere has also been linked to a rise in global temperatures.
Changes in the Earth’s orbit around the Sun have also contributed to natural global warming. Stretching out the time it takes for the Earth to travel around the Sun from 199.9 days to 205.3 days has been known to increase average temperature level by 0.1 to 0.2 degrees Celsius. Another natural influence on global warming is due to natural cycles that occur in the atmosphere. The El Niño-Southern Oscillation is one such cycle, in which there is an increase of water vapor in the atmosphere, leading to higher temperatures worldwide.
The release of stored carbon from terrestrial sources, such as soil microbial activity, is another natural source of global warming. This process can be accelerated by the impacts of global warming, leading to what is known as “positive feedback,” a vicious cycle in which global warming increases the release of carbon and further intensifies global warming.
Volcanic eruptions are also known to release greenhouse gases into the atmosphere, although the exact effects on global warming remain uncertain. Early models indicated that the release of sulfates, carbon dioxide, and other aerosols from volcanoes to temporarily mask the effects of greenhouse gas concentrations over short term periods. However, recent studies have shown that the cooling effect could be reduced to a greater extent than expected in the future due to the gradual increase of greenhouse gases.
Finally, the changes in land use across the world, such as deforestation, agricultural activities, and other human developments, have been known to significantly influence global warming. These activities can both increase levels of greenhouse gases and alter the amount of reflectivity from surfaces, both of which can contribute to an increase in global temperatures.
In conclusion, global warming is caused by a combination of both natural and human processes. The Sun and various cycles in the Earth’s atmosphere are the primary sources of natural global warming, while human activities, such as burning fossil fuels, land use changes, and the release of stored carbon, are responsible for a majority of global warming. To combat the effects of global warming, it is essential to recognize the importance of both natural and human contributions and to create policies and solutions that account for these factors.