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Human Activity and Its Impact on Climate Change

Apr 7, 2025

Climate Change Lecture: Human Activity as a Major Cause of Global Warming

Background and Context

  • The IPCC has addressed the role of human activity in climate change since its first report in 1990.
  • Consistent findings in subsequent reports, including the 2016 AR-5, affirm human activity as a major factor in global warming.

Key Concepts

Radiative Forcing

  • Measured relative to 1750, indicating warming (right of zero) and cooling (left of zero).
  • Greenhouse Gases: Main contributors to warming, especially CO2.
    • Other gases include carbon monoxide and nitrogen oxides.

Natural Contributors

  • Solar Irradiance: Energy from the sun; is a natural warming factor but contributes less significantly than human activity.
  • Cooling Factors: Clouds and particulate matter.

Human Impact on Warming

  • Anthropogenic Factors: Human-caused, with significant increase post-1950s.
  • Solar Irradiance vs. Temperature: From the mid-1970s, no correlation between solar irradiance and temperature.
    • Denies natural cycles as sole explanation for recent warming.

Data Analysis

Measured vs. Modeled Temperature

  • Black Line: Measured temperature.
  • Purple Region: Temperature from natural forcings.
  • Light Pink Region: Temperature from both natural and human factors.
    • Correlation with actual measurements only occurs when including human factors.

Greenhouse Gas Correlations

  • Ice Core Data: Shows correlation between CO2 levels and temperature.
  • Recent increases in greenhouse gases (CO2, methane, nitrous oxide) coincide with human activity.
    • Notable increase since the 1800s with fossil fuel burning.

Conclusions

  • Human activity is the main factor in global warming due to:
    • Correlation of greenhouse gases with temperature changes.
    • Recent, significant increases in greenhouse gases parallel human industrial activity.
    • Data confirms these changes align with the beginning of large-scale fossil fuel use.

The evidence strongly supports that human activity, particularly through the emission of greenhouse gases from fossil fuel burning, is the primary driver of recent global warming trends.

Full transcript