Regional but not global temperature variability underestimated by climate models at supradecadal timescales
New paper by Laepple T et al. in Nature Geoscience.
The article by Laepple T et al. discusses the importance of understanding natural climate variability for assessing future climate trajectories. It highlights the challenges in reliably detecting climate fluctuations on multidecadal to centennial timescales due to the limited observational record, which extends back only a few decades in most parts of the world. To address this limitation, researchers use proxy reconstructions (indirect measures of climate, such as tree rings or ice cores) and model simulations.
Some key points include:
Importance of Understanding Natural Climate Variability: Knowledge of natural climate variability is crucial for evaluating the range of plausible future climate scenarios over the coming decades to centuries.
Role of Proxy Reconstructions and Model Simulations: Proxy reconstructions and climate models are essential tools for studying climate variability on longer timescales, as the instrumental record is limited.
Contradictory Comparisons: There are discrepancies in comparisons between model-simulated and proxy-based inferences of natural variability. Locally, simulated temperature variability on multidecadal and longer timescales appears consistently smaller than indicated by proxy-based reconstructions.
Global vs. Local Agreement: While there is agreement between simulated and proxy-reconstructed temperature variations at the global scale, there are apparent discrepancies at the local level.
Identified Deficiencies: The paper suggests that there are systematic reconstruction deficiencies that may contribute to the differences in local and global model-proxy agreement. However, these deficiencies alone may not fully explain the discrepancies observed.
Persistence of Regional Climate Variations: The authors argue that regional climate variations may have persisted for longer timescales than what climate models are currently able to reproduce in their simulations of past climate states.
Implications for Climate Projections: The underestimation of regional variability on multidecadal and longer timescales could bias climate projections and attribution studies, highlighting the need for improved simulations of natural variability in climate models and refinements in proxy-based inferences.