Climate projections are scientific predictions about how Earth's climate might change in the future. These predictions are based on different scenarios each involving differing levels of greenhouse gas emissions and human activities. They can help us to understand and predict potential changes in temperature, rainfall patterns, sea levels, and extreme weather. Projections help guide governments, businesses, communities, and organizations, in planning, preparing, and mitigating climate impacts.
Shared socioeconomic pathways (SSPs) are a newer more complex approach to climate modelling used in the latest IPCC report. They illustrate five different pathways of how the world will develop over time in the absence of any climate policies. These scenarios are as follows:
This is considered the best case scenario for future climate projections. The world moves towards a more sustainable future, focusing on more inclusive development, human well being such as education and healthcare, and reducing inequality both within and between nations. Consumption would be oriented towards low material growth, with lower resource and energy intensity.
This is considered to be the business as usual scenario. This scenario would see limited shifts from historical social, economic, and technological trends. Development would remain uneven between countries, environmental degradation would continue despite a decline in resource and energy use. Population growth will eventually stabilize, and challenges regarding inequality and social and environmental vulnerability will persist.
This scenario is characterized by growing nationalism, competition, security security, and regional conflicts, leading to an increased focus on domestic issues and goals at the expense of global development. Investment in education and technology declines, economic growth will slow down, and inequalities may increase. Industrialized nations will see low population growth, whilst developing countries will grow rapidly. Environmental issues are deprioritized globally, resulting in severe degradation in some regions.
In this scenario, growing inequality and uneven investment in education and opportunities lead to a divided world. Wealthy, connected communities will advance in high-tech industries, while poorer regions will remain in low-wage, low-tech economies. Social unrest grows, and the energy sector expands with both fossil fuel development and clean alternatives. Environmental efforts will focus mainly on local issues in wealthier areas.
This is the worst case scenario for future climate projections. It involves reliance on markets and innovation to drive fast technological progress and human development. Global markets will grow to be more connected, with strong investments in health, education, and institutions. Economic growth would be rapid, but would depend very heavily on fossil fuels and resource intensive lifestyles.
Source: Government of Canada (2023), https://climate-scenarios.canada.ca/?page=cmip6-overview-notes
Climate projections are valuable tools, but they do come with limitations. They are based on models that simplify and make assumptions about complex natural systems. Calculations are done based on the area within a grid, thus limiting the representation of small scale processes and micro climates. There are also limitations in the data available to calibrate these models. Gaps in the historical record or limitations in which variables have been measured affect the ability to validate the model performance.
A lack of knowledge or understanding can also be a limitation to climate data projections. For example it has long been assumed that relative humidity would increase with climate change. This assumption was based on the fact that warmer air can hold more water. However, recent studies have found that this is not the case. Many areas specifically arid or semi arid climates have actually seen a decrease in relative humidity with the progression of climate change.
https://climate-scenarios.canada.ca/?page=cmip6-overview-notes
https://climatedata.ca/resource/understanding-shared-socio-economic-pathways-ssps/
https://climate.sustainability-directory.com/question/what-are-the-limits-of-climate-prediction/
https://climatedata.ca/resource/uncertainty-in-climate-projections/