Greenhouse Gas Emissions Scenarios (HL) (DP IB Environmental Systems & Societies (ESS))

Greenhouse Gas Emissions Scenarios

• Purpose of scenarios:

  • Greenhouse gas (GHG) emissions scenarios help predict future climate outcomes

  • They help to define clear targets to reduce the risk of catastrophic climate change

  • Different scenarios are based on different levels of human actions and policies

• Developed by IPCC:

  • The Intergovernmental Panel on Climate Change (IPCC) creates these scenarios

• Uncertainty and variability:

  • Scenarios can vary greatly due to uncertainties about:

    • Future actions

    • Technological development (e.g. green energy technologies, carbon capture)

    • Policy changes

IPCC emissions scenarios (SSPs)

• The IPCC has also developed five Shared Socioeconomic Pathways (SSPs) to model different future GHG emissions scenarios

• These scenarios combine potential emissions changes with a range of socio-economic factors to give slightly different potential pathways

  • E,g. global cooperation

  • Economic policies

  • Population growth

  • Technological development

• The SSPs reflect how choices in economic growth, energy use, and societal trends could shape GHG levels and climate change impacts by the end of the century

SSP1: Sustainability ('Taking the Green Road')

• Description: A sustainable, environmentally-focused future

• Features:

  • Strong global cooperation and reduced inequalities

  • Investments in green technologies and low-carbon energy sources

• Climate Impact: Lower GHG emissions, likely to limit global warming to around 1.5–2°C

SSP2: 'Middle of the Road'

• Description: A continuation of current global trends without significant changes (i.e. 'business-as-usual')

• Features:

  • Moderate economic growth with limited inequality reduction

  • Balanced investments in both traditional and renewable energy

• Climate Impact: Moderate GHG emissions, leading to moderate levels of warming

SSP3: Regional Rivalry ('A Rocky Road')

• Description: A fragmented world with regional conflicts and minimal cooperation

• Features:

  • Limited technology sharing, economic growth focused within regions

  • High reliance on fossil fuels, with few environmental protections

• Climate Impact: High GHG emissions and a substantial risk of severe climate impacts

SSP4: Inequality ('A Road Divided')

• Description: A world with significant social and economic inequality

• Features:

  • High disparities between rich and poor countries and within societies

  • Wealthy nations adapt well, while poorer regions struggle with climate impacts

• Climate Impact: Moderate to high GHG emissions with variable adaptation and mitigation success

SSP5: Fossil-fuelled Development ('Taking the Highway')

• Description: high fossil fuel use and technological advancement are driving rapid economic growth

• Features:

  • High energy consumption, widespread reliance on fossil fuels

  • Innovation and economic growth prioritised over environmental protection

• Climate Impact: Very high GHG emissions, leading to significant warming

Awaiting image: IPCC SSPs

Image caption: Predicted atmospheric CO₂ concentrations for different Shared Socioeconomic Pathways (SSPs) across the 21st century (Wikimedia Commons, CC BY-SA 4.0)

IPCC Shared Socioeconomic Pathways (SSPs)

The names of these scenarios consist of the SSP on which they are based (SSP1-SSP5), combined with the expected level of radiative forcing in the year 2100 (1.9 to 8.5 W m^-2). SSP4 has not been included.