Climate change projections and timelines
Pro Research Analysisby 
Searched over 200M research papers
Long-Term Climate Change Projections and Timelines
Climate change projections typically focus on the end of the 21st century (around 2100) and beyond, with scenarios showing that the forced climate signal—driven by greenhouse gas emissions—will be much larger than the natural variability of the climate system by that time. These projections are usually referenced against a baseline period of 1986–2005, and they indicate significant changes in global temperature and climate patterns depending on the emissions scenario followed .
However, research highlights that limiting projections to 2100 is short-sighted. Climate impacts, such as threats to food production and increased human migration due to heat stress, are expected to intensify well before 2100, and the consequences of current emissions will persist for centuries beyond this benchmark. Modeling studies extending to 2500 show that without rapid mitigation, global climate impacts will continue to increase significantly after 2100, affecting human well-being and the habitability of some regions Lyon2020Carvalho2022.
Near-Term Climate Change Projections (2016–2035 and 2041–2060)
For the near-term, projections generally cover the period from the present through mid-century (2016–2035), compared to the 1986–2005 baseline. These projections are important for understanding immediate risks and planning adaptation strategies. Studies show that while climate models can reliably guide broad mitigation and adaptation strategies, their precision at local scales and for short-term practical actions is limited. This is due to the models' inability to represent future conditions with high spatial and temporal detail, which can give a false sense of certainty Kirtman2014Fernández2019.
For Europe, projections for 2041–2060 under high-emission scenarios (like RCP8.5) show that different methods for constraining model outputs generally agree on median changes in temperature and precipitation, but there is more disagreement in the uncertainty ranges. The choice of method and the region of interest can significantly affect the assessed uncertainty, especially for risk-averse stakeholders .
Model Performance and Uncertainty in Climate Projections
Comparisons of past climate model projections (CMIP3, CMIP5, CMIP6) with observed warming trends reveal that models have slightly underestimated recent global warming, with observed temperatures closer to the upper end of projected ranges. This suggests that higher-emission scenarios may be more realistic, and that models may have a slight cold bias in their projections up to 2100. However, due to the short periods analyzed, it is difficult to confidently project warming trends for longer timescales Liang2020Brunner2020.
Uncertainty in climate projections arises from several sources, including the choice of global and regional climate models, emission scenarios, and internal climate variability. For near-future changes, the driving global climate model is the main contributor to uncertainty, while the emission scenario plays a lesser role. Increasing the spatial resolution of models does not necessarily lead to significant changes in mean seasonal projections .
Upper Atmosphere and Extended Projections
Projections for the upper atmosphere (up to 500 km altitude) indicate that global mean cooling and a decline in thermosphere density are expected to be stronger in the coming decades (2015–2070) than in the past, mainly due to the rapid increase in CO2 concentrations. These changes will also affect ionospheric parameters, with the largest impacts expected in specific geographic regions .
The Need for Long-Term and Decision-Relevant Projections
There is a growing consensus that climate change research and policy must look beyond 2100, as the effects of greenhouse gas emissions will persist for centuries. Projections should be framed with longer timelines to better inform governance, adaptation, and mitigation strategies. At the same time, climate information should be tailored to decision-relevant timescales, integrating climate variability and expert judgment to support practical actions, especially in international development contexts Lyon2020Carvalho2022Fernández2019.
Conclusion
Climate change projections show significant warming and associated impacts by the end of the 21st century and well beyond, with the severity depending on future emissions. While models have been slightly conservative in their past projections, the need for both near-term and long-term planning is clear. Reliable projections require careful consideration of model uncertainties, appropriate timescales, and the integration of expert judgment to support effective policy and adaptation strategies.
Sources and full results
Most relevant research papers on this topic