Climate change is an undeniable reality that is transforming our planet’s atmosphere and impacting ecosystems, economies and societies across the world. Global warming is the main factor underlying these changes and the scientific community agrees that its primary cause is an increase in carbon dioxide and other greenhouse gases in the Earth’s atmosphere. Therefore, understanding why and how these gases are released is key to understanding the changes that affect us now, and will be increasingly felt in the future.
The emissions of greenhouse gases are multifaceted and their main sources can essentially be broken down into three of the most significant sources: human-made processes, natural processes, and the feedback loop between them.
The most widely accepted human-based culprit behind global warming are industrial activities such as burning fossil fuels. On a global scale, the burning of fossil fuels has increased dramatically since the industrial revolution and is still rising. The by-products of this burning process are carbon dioxide, nitrous oxide and methane, which are all extremely potent and long-lasting greenhouse gases. Additionally, agriculture and land use also play an important role in warming the planet, as deforestation releases large quantities of carbon into the atmosphere and the lack of vegetation negatively affects the land’s ability to absorb carbon. These human activities together contribute to a large percentage of the total emissions of greenhouse gases.
Apart from anthropogenic emissions, natural processes are also a significant source of greenhouse gas production. Volcanic activity produces a large amount of carbon dioxide and water vapor, whilst terrestrial and marine biotic processes, such as the decay of vegetation and animal matter, lead to the formation of methane. Additionally, compared to carbon dioxide, methane has more than 80 times more potency as a greenhouse gas and is thus a major contributor to global warming. Furthermore, changes in the Earth’s orbit and orientation towards the sun, Milankovitch cycles, or natural periodicities, are thought to play an important role in the past climate variations, including those related to global warming.
The feedback loops between human-made and natural processes also deserve attention. For example, higher global temperatures are linked to an increase in wildfires that produce large amounts of greenhouse gases, whilst soil organic matter is also affected, releasing more carbon than it is capable of absorbing. Warming oceans have detrimental consequences in many organisms, reducing their natural sinks of carbon and leading to ocean acidification and, ultimately, an increase in CO2 concentrations. Finally, the increase in surface temperatures associated with global warming, can cause further warming as it affects the albedo of the Earth surface, which is the capacity of Earth’s surface to reflect sunlight.
To conclude, empirical evidence unequivocally states that we are in the midst of global warming and its effects will continue to become more apparent if unchecked. It is clear that human- and natural-based processes are the two main sources of greenhouse gases in the atmosphere, whilst feedback loops between them are important determinants. Understanding the direct and indirect causes of global warming is essential if we are to eventually reverse its trends, develop adaptation measures, and ultimately protect future generations from the perils of climate change.
