Causes of global warming

Causes of Global Warming

Global warming, also known as the Greenhouse Effect, is defined as the phenomenon where Earth’s atmosphere retains some of the energy received from the sun in the form of heat. This phenomenon occurs on Earth’s surface and in the troposphere—the lowest layer of the atmosphere—due to increased concentrations of certain gases such as carbon dioxide (CO₂), water vapor, methane (CH₄), and others. Among these gases, water vapor has the most significant impact on this phenomenon. These gases are characterized by their transparency to most wavelengths of solar radiation, allowing sunlight to reach Earth’s surface. However, they are relatively opaque to infrared radiation and thermal emissions, absorbing them within the atmosphere and Earth’s surface. These gases then convert this energy into heat, making it difficult for the heat to escape back into outer space.

To learn more about greenhouse gases, you can read the article What Are Greenhouse Gases?

Causes of Greenhouse Gas Emissions

Greenhouse gases or “greenhouse effect gases” accumulate in the atmosphere, including carbon dioxide (CO₂), nitrous oxide (N₂O), methane (CH₄), and fluorinated gases, such as chlorofluorocarbons (CFCs). While these gases naturally occur in the atmosphere, human activities have significantly increased their concentrations, contributing to global warming. Below is an explanation of these causes:

Human Causes

1. Burning Fossil Fuels
   The Industrial Revolution, which began in the mid-18th century, significantly increased atmospheric CO₂ levels from 280 parts per million (ppm) to 387 ppm due to heightened use and combustion of fossil fuels. CO₂ concentration in the atmosphere continues to rise by approximately 2–3 ppm annually. By the end of the 21st century, CO₂ levels are expected to reach 535–983 ppm, causing global temperatures to rise between 1.4°C and 5.6°C.
2. Deforestation
   Land-use patterns have dramatically shifted, with forests, particularly in tropical regions, being cleared for other purposes. This practice contributes one-third of the total CO₂ emissions, significantly exacerbating global warming.
3. Agricultural Activities
   Farming practices, including fertilizer use, rice cultivation, irrigation methods, and others, increase atmospheric methane levels. Overuse of fertilizers also raises nitrous oxide (N₂O) levels. Removing vegetation changes Earth’s albedo (reflectivity), affecting the balance of absorbed and reflected solar radiation.
4. Livestock Farming
   Livestock farming contributes 18% of global greenhouse gas emissions, according to the UN. Activities like deforestation for grazing land, as seen in the Amazon (where 70% of deforestation is due to cattle ranching), and methane emissions from livestock digestion, compound the greenhouse effect.
5. Cement Production
   The cement manufacturing process emits CO₂ during the heating of calcium carbonate, producing both CO₂ and lime. Additionally, burning fossil fuels to provide heat increases emissions. Cement production alone accounts for 5% of human-caused CO₂ emissions, releasing about 900 kg of CO₂ per 1,000 kg of cement produced.
6. Industrial Waste and Landfills
   Factories and industrial processes release harmful gases into the atmosphere, contributing to global warming. Additionally, landfills emit significant amounts of methane and CO₂, further intensifying the greenhouse effect.
7. Population Growth
   Rising global populations increase demand for food, housing, clothing, and industrial goods, leading to more factories and industrial processes. This raises emissions of harmful gases. Population growth also drives increased fossil fuel use, which significantly worsens global warming.

Natural Causes

Several natural factors contribute to increased greenhouse gas levels in the atmosphere. While natural processes previously maintained a balance for thousands of years, these factors have changed over time. Examples include:

1. Termites
   Termites emit methane during digestion.
2. Wild Herbivores and Grazing Animals
   These animals release methane during their natural digestion processes.
3. Forest Fires
   Wildfires release carbon monoxide (CO), methane (CH₄), carbon dioxide (CO₂), nitrous oxide (N₂O), and other nitrogen oxides into the atmosphere.
4. Wetland Ecosystems
   Wetlands release significant amounts of methane.
5. Grasslands, Forests, and Savannahs
   These ecosystems contribute to nitrous oxide (N₂O) emissions.
6. Freshwater Ecosystems
   Lakes, rivers, streams, and wetlands emit greenhouse gases such as methane, nitrous oxide, and carbon dioxide.
7. Volcanic Activity
   Volcanic eruptions release greenhouse gases.
8. Decomposition of Organic Matter
   Natural decomposition of plants and animals contributes to emissions.
9. Melting Ice Caps
   Melting polar ice caps release previously trapped greenhouse gases.