Climate Change Science Basics

Climate Change Science Basics - Earth's Warm Hug

• Greenhouse Effect: Natural process warming Earth's surface. Atmosphere traps solar energy.
  • Sunlight (shortwave radiation) reaches Earth.
  • Earth absorbs and re-radiates heat (longwave infrared radiation).
• Greenhouse Gases (GHGs): Absorb and re-emit this infrared radiation, trapping heat.
  • Key GHGs: Carbon Dioxide ($CO_2$), Methane ($CH_4$), Nitrous Oxide ($N_2O$), Water Vapour ($H_2O$).
  • 📌 Mnemonic: "Can Monkeys Nibble Watermelons?" ($CO_2$, $CH_4$, $N_2O$, $H_2O$)

⭐ $CO_2$ is the primary anthropogenic GHG, contributing most to current warming. Its atmospheric lifetime is centuries.

Climate Change Science Basics - The Heat Trappers

• Greenhouse gases (GHGs) trap atmospheric heat, warming Earth (Greenhouse Effect).
• Enhanced effect from ↑ human activities (e.g., burning fossil fuels) causes global warming.
• Key GHGs and their characteristics:

Climate Change Science Basics - Planet's Vital Signs

• Global Temperature Rise:
  • Atmosphere & oceans warming significantly.
  • Global average temperature ↑ by ~1.1-1.2°C above pre-industrial levels (1850-1900).
  • Due to ↑ anthropogenic greenhouse gases (GHGs).
• Sea Level Rise:
  • Global average sea level ↑ by ~20 cm (0.2m) since 1900.
  • Causes: Thermal expansion of water, melting glaciers & ice sheets.
• Ocean Acidification:
  • Oceans absorb ~25-30% of anthropogenic $CO_2$ emissions.
  • Leads to ↓ pH (increased acidity), harming marine ecosystems.
• Extreme Weather Events:
  • ↑ Frequency & intensity of heatwaves, droughts, heavy rainfall, and tropical cyclones.
• Melting Ice & Snow (Cryosphere Changes):
  • Widespread glacier retreat, shrinking ice sheets (Greenland, Antarctica), ↓ Arctic sea ice extent.

⭐ Atmospheric $CO_2$ levels now exceed 410 ppm, the highest in at least 800,000 years an crucial indicator of climate change.

Climate Change Science Basics - Who's Pushing Buttons?

• Primary Drivers of Climate Change:
  • Anthropogenic (Human-Caused): The dominant influence.
    • Fossil Fuel Combustion: Releases Greenhouse Gases (GHGs): $CO_2$, $CH_4$, $N_2O$.
    • Deforestation & Land Use Change: Reduces $CO_2$ sinks.
    • Industrial Processes: GHG & aerosol emissions.
    • Agriculture: Livestock ($CH_4$), rice ($CH_4$), fertilizers ($N_2O$).
  • Natural Factors: Minor role in current warming.
    • Solar Activity Variations.
    • Volcanic Eruptions: Aerosols cause short-term cooling.
    • Earth's Orbital Cycles (Milankovitch): Long-term climate influence.

⭐ IPCC: Unequivocal that human influence has warmed atmosphere, ocean, land.

• Greenhouse gases (GHGs) like CO2, CH4, N2O trap heat, causing global warming.
• Global Warming Potential (GWP) measures a GHG's heat-trapping ability relative to CO2.
• The IPCC is the primary international body for climate change assessment.
• The Paris Agreement aims to limit warming well below 2°C, pursuing efforts for 1.5°C.
• Key anthropogenic sources: fossil fuel burning, deforestation, and agriculture.
• Major consequences include ↑ sea levels, extreme weather events, and vector-borne disease spread.