Subject: Natural Science
Chapter: Written Notes
Type: Free PDF Notes
Global Warming Causes and Impacts — Free written notes for Natural Science on EduFlame Pakistan.
Global warming refers to the long-term increase in Earth's average surface temperature due to the enhanced greenhouse effect caused by human activities, especially the excessive release of greenhouse gases into the atmosphere.
The Earth's average temperature has already risen by approximately 1.1°C above pre-industrial levels. Scientists project that without significant reductions in emissions, temperatures could rise by 2–4°C or more by the end of the 21st century.
Causes of Global Warming
Burning of Fossil Fuels:
The combustion of coal, oil, and natural gas in power plants, factories, and vehicles releases enormous amounts of CO₂ into the atmosphere. This is the largest single cause of global warming.
Deforestation:
Trees absorb CO₂ through photosynthesis. When forests are cleared for agriculture or urban development, this carbon sink is removed, and the carbon stored in trees is released into the atmosphere.
Agricultural Activities:
Livestock (especially cattle) produce large amounts of methane through digestion. Rice cultivation in flooded paddies also produces methane. Fertilizer use releases nitrous oxide.
Industrial Processes:
Cement manufacturing, steel production, and chemical industries release CO₂ and other greenhouse gases.
Waste Management:
Decomposing organic waste in landfills produces methane. Improper waste burning releases CO₂ and other pollutants.
Urbanization:
The expansion of cities, increased energy consumption, and land-use changes contribute to warming.
Impacts of Global Warming
Rising Sea Levels:
Melting glaciers and polar ice caps add water to oceans. Thermal expansion (water expanding when heated) also raises sea levels, threatening coastal areas.
Extreme Weather Events:
Heatwaves, hurricanes, floods, and droughts become more frequent and severe due to higher global temperatures.
Changes in Rainfall Patterns:
Some regions face heavy rainfall and flooding, while others experience droughts, affecting agriculture and water supply.
Loss of Biodiversity:
Many species cannot adapt quickly to climate change. Coral reefs are especially vulnerable to bleaching and death.
Food Security Threats:
Changing climate reduces crop yields and threatens global food supply.
Human Health Impacts:
Heatwaves increase deaths, and disease-carrying insects spread to new regions. Air quality also worsens.
Ocean Acidification:
Oceans absorb CO₂, forming carbonic acid. This harms marine life, especially shell-forming organisms like corals and oysters.
Ice Melt:
Arctic and Antarctic ice sheets are shrinking, disrupting ocean currents and global climate systems.
Population Displacement:
Rising seas, floods, and droughts may force millions of people to migrate, creating climate refugees.
Solutions to Global Warming