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Limited Skill of Projected Land Precipitation by IPCC Models During 2002−2020[2023-01-31]
The most convincing way of validating the credibility of climate projections is to quantify the extent to which past projections agree with subsequent observations. More than thirty years have passed since the First Assessment Report (FAR) was published in 1990 (IPCC, 1990). This length of the period is sufficient to conduct a retroactive analysis and answer a key question: are the projections of future climate changes credible in the series of IPCC assessment reports? Based on those observations, several studies have analyzed the credibility of models projected changes of temperature, CO2, and sea level. As the core component of the hydrological cycle, precipitation is most important for agricultural production, social economy, natural ecology, and human life. However, little attention has been given to whether precipitation projections over the past more than ten years agree with subsequent observations to date.
In this study, we retroactively investigate the skill of the IPCC TAR, AR4, and AR5 models for near-term precipitation projections over global land under 13 emissions scenarios by comparing them with the CRU dataset during 2002−2020. Results show that models show robust skills in projecting the subsequent climatological changes in global mean land precipitation from several to ten years ahead. Relative to global scale land, the models are less skillful in projecting the subsequent changes in precipitation at regional scale, although they exhibit some skills in northern mid- to high-latitudes, which is likely to be at least partly explained by the lower signal-to-noise ratio. Besides the climatological changes, we also analyze the projection skills of IPCC models for the precipitation trends both at global and regional scales. Since the signal-to-noise ratio for the trends is much lower than that for the climatological mean changes, especially on relatively short (multiannual to decadal) time scales and small spatial scales, the multimodel medians show much lower skills in projecting the precipitation trends both at global and regional scales compared to the climatological changes.
Hu, D., Tian, Z., Lang, X., & Jiang, D. (2023). Limited skill of projected land precipitation by IPCC models during 2002−2020. Journal of Geophysical Research: Atmospheres, 128, e2022JD037851. https://doi.org/10.1029/2022JD037851.