The importance of climate change projections and modelling

Climate change projections rely on a deep understanding of the causes and evidence of climate change, using data to make informed predictions.

Key aspects of climate change modelling

• Physical processes - Processes like atmospheric circulation and volcanic effects on climate are simulated using advanced computer models.
• Human activity - Factors such as industrial expansion and the development of clean energy sources are incorporated into models by analysing greenhouse gas emissions data.
• Scenario analysis - Climate models are used to explore various future scenarios, such as the consequences of a significant methane release from thawing permafrost while greenhouse gas emissions remain high.

The role of the IPCC and RCPs

The Intergovernmental Panel on Climate Change (IPCC) is a global body of scientists dedicated to assessing and predicting climate change.

Functions and contributions of the IPCC

• Global collaboration - The IPCC brings together experts worldwide to evaluate climate data and develop projections.
• Representative concentration pathways (RCPs) - These are scenarios developed by the IPCC to represent a range of possible future outcomes for greenhouse gas concentrations, from the most optimistic to the most severe.

Different climate change scenarios and their predicted outcomes

The IPCC's RCPs outline various scenarios for greenhouse gas emissions, each leading to different climate outcomes by the year 2100. These are often visualised on graphs showing projected changes in temperature and sea level, with best and worst-case scenarios defining the range of possibilities.

The scenarios outlined by the RCPs are:

• Scenario 1 (minimum emissions) - Best-case scenario with significant emission reductions where levels peak early then decline sharply, leading to the least severe climate impacts.
• Scenarios 2 & 3 (stabilising) - Moderate scenarios with delayed emission reductions where levels rise but eventually stabilise, resulting in moderate temperature and sea level rise.
• Scenario 4 (maximum emissions) - Worst-case scenario with unchecked emissions growth where levels continue to increase dramatically, causing severe climate change with major impacts.

Graphs plotting these scenarios typically show lines for the best and worst outcomes, with other possibilities falling in between.

Uncertainties and challenges in climate change predictions

Predicting future climate change is inherently complex and involves significant uncertainties. While models provide valuable insights, they cannot offer exact predictions due to the intricate nature of climate systems and human behaviour.

Sources of uncertainty in climate projections

• Emissions uncertainty - It is challenging to predict how greenhouse gas emissions will change over time and which scenario will most closely match reality.
• Influencing factors - Predictions must consider variables such as population growth and economic development, both of which can significantly alter emission levels and climate outcomes.
• Complexity of climate systems - The precise effects of each scenario on climate are not fully understood, as natural processes can have unpredictable impacts.
• Management uncertainty - The effectiveness of strategies to control greenhouse gas levels in the atmosphere remains uncertain.

Climate change forecasting is not an exact science, as it involves numerous variables and unknowns.