IPCC’s 6th Assessment Report (2021–22) shifted to a new core set of future representative scenarios, based on Shared Socio-economic Pathways (SSPs). These comprise different socio-economic assumptions that drive future greenhouse gas emissions. The scenarios span a wide range of plausible societal and climatic futures, based on greenhouse gas emissions, that result in the stabilisation of global warming at 1.5°C to over 4°C warming by 2100. You can find out more about the SSPs here. 

Below are the scenarios we use in the graphs of our climate change driven projections of sea-level rise based on the latest information from the 6th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).

Projections to 2150 - Medium confidence (moderate polar ice sheet melt)

  • This is a world with extremely low emissions (1.5°C warmer world), which is not possible without major technological innovation. This is an aspirational scenario and not recommended for adaptation planning.

  • A world with low emissions (2°C warmer world). This is the ‘Paris Pathway’, which is only possible if COP26 pledges are delivered on.

  • This is a world with moderate emissions (+2.7°C warmer world). This is the path we are on, if we follow current policy settings.

  • A world with high emissions (3°C warmer world).

  • This is a worst-case scenario world with very high emissions (>4°C warmer world). It is unlikely.

Projections to 2300 - Low confidence (rapid polar ice sheet melt)

  • Low emissions (2°C warmer world).

  • Moderate emissions (2.7°C warmer world - current trajectory)

  • Very high emissions (>4°C warmer world).

 

As you can see in the text box above, there are two suites of sea-level rise scenarios (SSPs): 

  • “Medium Confidence” scenarios, where the processes used in polar ice sheet models are known with moderate confidence to the year 2150.

  • “Low Confidence” scenarios, where the processes used in polar ice sheet models (particularly the Antarctic Ice Sheet) result in much faster rates of melting. These are known with less confidence, due to the lack of maturity of scientific knowledge. The low confidence scenarios go out to the year 2300, because rapid Antarctic ice sheet melt, if it happens, will have its biggest impact at the end of the 21st century and beyond. 

These low confidence, high-impact projections are extreme, but plausible. They are important on intergenerational timescales. This is why the IPCC 6th Assessment Report Summary for Policymakers says “2 m of global mean sea-level rise by 2100 cannot be ruled out”. It also shows that by 2300 global mean sea-level could be up to 15 m higher than today.

The Climate Action Tracker Thermometer shows warming projections against targets and policies in more detail.

The change from the previous representative concentration pathways or RCPs to SSP scenarios is to recognise there are varying pathways to reaching global warming levels (as were defined in the RCPs). These include different trajectories of CO2 and non-CO2 greenhouse-gas emissions, aerosols, energy use, and land use from different socio-economic responses to ongoing climate change.