When we talk about climate change, we talk about the future. But, how can we have an idea of that given the uncertainties that possess both the physical process and social dynamics? Here is where the concepts of plausible and possible can be helpful.
Possible futures encompass all conceivable scenarios that could occur given any imaginable set of circumstances, either due to technological advancement, policy changes, social developments, and economic shifts. For instance, we could imagine a future were based in technology and keeping business as usual, climate change was reversed by 2050, with minimal alteration to global economies and lifestyles. This scenario although possible, given the actual science progress, is not plausible.
On the other hand, we have plausible futures. Engels at al. (2023) mentions that having established models of social dynamics and physical processes, we use the current evidence to see “whether the world is moving toward or away from a predefined climate future”. Therefore, we pass the possible for the reality filter to obtain plausible futures. As example, consider the SSP2, where some efforts are made to limit emissions, but with moderate success. Based on existing GHG trajectories, it is plausible an outcome where global temperatures rise by approximately 2°C by the year 2100.
Although make this difference can be seen as pessimistic, it helps in focusing resources and efforts toward those scenarios that are not only conceivable but also plausible. For that we need an Integrated Earth Systems Science and Socio-Economic and Technological Analysis, that enhances the effectiveness of policy interventions and strategies in addressing climate change.
References:
Engels, A., & Marotzke, J. (2023). Assessing the plausibility of climate futures. Environmental Research Letters, 18.