Shared Socioeconomic Pathways (SSPs) /(RCPs)

Why in News ? A recent study by ETH Zurich researchers, published on May 22, 2025, indicates that cyclones will become more destructive under the SSP5-8.5 climate scenario, which assumes high greenhouse gas emissions and rapid fossil fuel use.

Relevance : UPSC Pre & Mains

Prelims: SSPs/RCPs

Mains :  GS 1 /Geography/ GS 3 ( Science & Tech>)

About Shared Socioeconomic Pathways (SSPs):

SSPs describe five plausible socioeconomic futures based on global trends in population, economic growth, technology, governance, and environmental policies. They provide the “human context” for climate scenarios, focusing on how societies might evolve. The five SSPs are:

1. SSP1 (Sustainability – Taking the Green Road): A world with strong global cooperation, sustainable development, and rapid shifts to renewable energy. Low population growth, high education, and effective climate policies.
2. SSP2 (Middle of the Road): A continuation of current trends, with moderate economic growth, uneven climate action, and medium population growth. Progress is made, but challenges persist.
3. SSP3 (Regional Rivalry – A Rocky Road): Fragmented global cooperation, with high population growth in developing regions, slow economic growth, and weak climate policies.
4. SSP4 (Inequality – A Road Divided): High inequality within and across countries, with elites driving technological progress but limited benefits for poorer regions. Weak global climate action.
5. SSP5 (Fossil-fueled Development – Taking the Highway): Rapid economic growth, high energy demand, and reliance on fossil fuels. Strong technological progress but minimal climate mitigation.

 About Representative Concentration Pathways (RCPs):

RCPs quantify greenhouse gas emissions and their impact on radiative forcing (the extra energy trapped in the Earth’s atmosphere, measured in watts per square meter, W/m²) by 2100. They focus on the physical climate system. The main RCPs are:

1. RCP2.6: Very low emissions, requiring aggressive mitigation to limit warming to ~1.5–2°C above pre-industrial levels. Strong global climate action.
2. RCP4.5: Moderate emissions with stabilization efforts, leading to ~2–3°C warming by 2100. Intermediate mitigation policies.
3. RCP6.0: Higher emissions with some mitigation, resulting in ~3–4°C warming.
4. RCP8.5: High emissions with little to no mitigation, leading to ~4.4°C (range: 3.3–5.7°C) warming by 2100. Often considered a “worst-case” scenario.

Combining SSPs and RCPs:

SSPs and RCPs are paired to create integrated scenarios that link societal choices with climate outcomes. For example:

• SSP5-8.5: Combines SSP5 (fossil-fueled, high-growth society) with RCP8.5 (high emissions). This is the scenario referenced in the ETH Zurich cyclone study, where minimal climate action leads to intensified cyclones due to warmer oceans and higher atmospheric moisture.
• SSP1-2.6: Combines SSP1 (sustainable development) with RCP2.6 (low emissions), projecting a world with strong climate mitigation and limited warming.
• Not all combinations are plausible (e.g., SSP1 is unlikely to pair with RCP8.5 due to its focus on sustainability).