Overview
This lecture explains the differences between global warming and climate change, describes how greenhouse gases cause warming, and discusses the consequences for the planet and living organisms.
Global Warming vs. Climate Change
- Global warming is the increase in Earth's average temperature caused by more greenhouse gases in the atmosphere.
- Climate change refers to all the effects of global warming on long-term weather patterns worldwide.
The Greenhouse Effect
- The atmosphere acts like a greenhouse, trapping some of the Sun’s heat and keeping the planet warm.
- Sunlight (short wavelength radiation) passes through the atmosphere and is absorbed by the Earth's surface.
- The surface re-emits energy as long wavelength radiation, some of which is trapped by greenhouse gases.
- Greenhouse gases absorb and re-emit this energy, keeping heat near the Earth's surface.
- Major greenhouse gases include carbon dioxide (CO₂), methane (CH₄), and water vapor.
Causes of Increased Greenhouse Gases
- Burning fossil fuels releases stored carbon as CO₂, increasing atmospheric levels.
- Deforestation reduces photosynthesis, so less CO₂ is removed from the air.
- Farm animals produce methane during digestion, which is released into the air.
- Decomposition of waste by microorganisms also produces methane.
Consequences of Global Warming and Climate Change
- Global temperatures are rising, as shown by long-term records.
- Climate change includes extreme events like more frequent droughts, hurricanes, and floods.
- Sea levels are rising due to melting ice and expansion of warmer water.
- Rising sea levels cause flooding and may submerge islands and coastal towns.
- Changing temperature and rainfall patterns threaten species that can't adapt or migrate quickly, leading to decreased biodiversity.
Key Terms & Definitions
- Global Warming — the rise in average global temperatures due to increased greenhouse gases.
- Climate Change — long-term alteration in global or regional climate patterns resulting from global warming.
- Greenhouse Effect — warming caused by gases trapping heat in the Earth's atmosphere.
- Greenhouse Gases — atmospheric gases (CO₂, CH₄, water vapor) that absorb and re-emit heat, contributing to the greenhouse effect.
- Deforestation — the removal of forests, reducing CO₂ absorption by plants.
- Biodiversity — the variety of living species in an area.
Action Items / Next Steps
- Review and understand the differences between global warming and climate change.
- Study how greenhouse gases are produced and their impact on climate.
- Prepare for questions on consequences, such as sea level rise and effects on biodiversity.