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Impacts, scale and risk of greenhouse gases

Chemistry of the atmosphere • Carbon dioxide and methane

Key concepts

What you'll likely be quizzed about

  • Global climate change refers to long-term changes in average temperature, precipitation, and weather patterns caused by an altered energy balance in the Earth system.
  • Increased atmospheric concentrations of CO2 and CH4 raise the greenhouse effect because both gases absorb outgoing infrared radiation.
  • Human activities, including burning fossil fuels, agriculture, and land-use changes, increase emissions of these gases.
  • Natural factors such as volcanic eruptions and solar variability create shorter-term variations but do not explain the current sustained warming trend.
  • Climate forcing measures the change in energy balance (watts per square meter) produced by a driver such as increased CO2.
  • Climate sensitivity quantifies the expected temperature change for a given forcing.
  • Both parameters limit precision in regional projections and contribute to uncertainty in timing and magnitude of impacts.

Flashcards

Test your knowledge with interactive flashcards

What causes global sea-level rise?

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Thermal expansion of seawater due to warming and melting of land-based ice, such as glaciers and ice sheets, are primary causes.

Key notes

Important points to keep in mind

Greenhouse gases increase radiative forcing, causing global temperature rise and widespread impacts.

Headline effects include sea-level rise, biodiversity loss, food/water security threats, and extreme weather.

Scale spans local to global and short-term to century-long changes.

Risk combines hazard, exposure, and vulnerability to determine actual impacts.

Positive feedback mechanisms like ice melt increase long-term risks.

Regional uncertainties arise from climate models, geography, and socioeconomic choices.

Mitigation lowers long-term risk; adaptation alleviates present-day vulnerability.

Ocean acidification connects CO2 chemistry to damage in marine ecosystems.

Tipping points may lead to irreversible shifts, enhancing systemic risk.

Accurate evaluation of impacts requires clear definitions of exposure and adaptive capacity.

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