Climate Modeling, Predictions and Projections

CNR-ISAC is among the leading institutes in Italy for the study of climate, providing outstanding contributions in the field of climate prediction and projections. With its modeling chain (https://webtest.isac.cnr.it/modelli/), CNR-ISAC carries out a variety of activities encompassing numerous spatio-temporal scales, and is an active part of several important national and international projects (https://webtest.isac.cnr.it/en/progetti/), as well as task-oriented and permanent structures.

A non-exhaustive list of outstanding activities is provided below.

Contribution to CMIP6

CNR-ISAC took part in the Coupled Model Intercomparison Project, Phase 6 initiative contributing to the EC-Earth Consortium effort by running an ensemble member for historical plus five different scenarios. This has been done for both the EC-Earth3 configuration and the EC-Earth3-Veg, which includes dynamical vegetation, for a total of approximately 1250 model years. Data is currently hosted on a specific data node ESGF at CINECA.

Contributions to NaHosMIP and SOFIA 

CNR-ISAC conducted simulations using the EC-Earth3 climate model as part of the North Atlantic Hosing Model Intercomparison Project (NAHosMIP; Jackson et al., 2023a). NAHosMIP aims to investigate the processes and feedbacks that govern the response of the Atlantic Meridional Overturning Circulation (AMOC) in current-generation global climate models (GCMs). The experiments involved introducing additional freshwater (“hosing”) into the North Atlantic for a fixed period to assess the rate and mechanisms of AMOC weakening, as well as the potential for AMOC recovery once the hosing ceases. Selected NAHosMIP data are available on Zenodo (Jackson et al., 2023b)

CNR-ISAC also performed EC-Earth3 simulations as part of the Southern Ocean Freshwater Input from Antarctica (SOFIA) Initiative (SOFIA; Swart et al., 2023). These experiments involve hosing in the Southern Ocean, which is intended to mimic the meltwater from the Antarctic Ice Sheet. The impact of freshwater forcing on large-scale ocean circulations in the Southern Ocean was studied in idealized preIndustrial simulations, as well as historical and future scenario simulations.

QUECLIM (Quasi-equilibrium climates at fixed external forcing)

The long-term commitment of climate change has been explored with the EC-Earth3 model under the QUECLIM project, featuring a set of 1000-year-long stabilization simulations under different levels of forcing, consistent with the LongRunMIP protocol (Rugenstein et al., 2019). Each simulation follows a sudden stabilization of the external forcing at the level specified by CMIP6 for historical (1990) or SSP5-8.5 scenario (2025, 2050, 2065, 2080, 2100) conditions, with a final temperature increase ranging between 1.4 and 9.6 K with respect to the preindustrial baseline. Remarkably, the simulation stabilized at a greenhouse gas (GHG) level close to the present day (2025) exceeds the Paris Agreement goals of 1.5 and 2° warming above pre-industrial in the long term, and only the 1990 simulation leads to a stabilized climate below 1.5° warming. Fabiano et al. (2024) presents the simulations and the main results of the analysis, regarding the climate response and the deep ocean heat uptake.

OPTIMESM (Optimal High Resolution Earth System Models for Exploring Future Climate Change)

CNR-ISAC is a partner of the Horizon Europe project OptimESM to develop the novel generation of Earth system models to deliver cutting-edge and policy-relevant knowledge around the consequences of global warming. Using EC-Earth3-ESM-1 and EC-Earth4 historical and future climate scenarios simulations are planned as contributions to the upcoming CMIP7 Fast Track.

Decadal Predictions

CNR-ISAC carried out simulations with EC-Earth3, following the CMIP6 Decadal Climate Prediction Project (DCPP) tier-1 (Component A1, Boer et al, 2016). These simulations feature improved vegetation variability representation based on new satellite data and enhanced parameterisation (Van Oorschot et al., 2023). Prescribed observed LAI and land cover were used to evaluate potential climate predictability. Results were compared with CMIP6 simulations by the EC-Earth consortium using vegetation data from the LPJ-Guess dynamic model.

Regional Climate Modeling 

CNR-ISAC is part of a scientific collaboration agreement with ICTP-ESP aimed at the development, evaluation, and application of the regional climate model RegCM5 (F. Giorgi et al 2023). This partnership focuses on advancing regional climate modeling capabilities and supporting high-resolution climate studies and projections over the Euro-Mediterranean region, with particular attention to extreme weather events, atmospheric dynamics, and long-term climate change impacts. CNR-ISAC is running RegCM5-CLM4.5 EuroCordex Historical and SSP1 2.6 scenario simulations under Land Use & Climate Across Scales (LUCAS) protocols, a Flagship Pilot Study for Europe, as a EURO-CORDEX & LUCID initiative supported by WCRP CORDEX and the GEWEX-GLASS international program. 

Low-probability, high-impact occurrences with rare event algorithms 

CNR-ISAC is conducting simulations using rare-event algorithms to explore the likelihood of low-probability, high-impact climate events. This approach is gaining increasing attention due to its potential to assess so-called climate tipping points—abrupt and potentially irreversible shifts in the climate system that are difficult to predict using traditional methods. At ISAC, in particular, we are currently carrying out simulations to estimate the probability of a collapse of the Atlantic Meridional Overturning Circulation (AMOC) in response to anthropogenic climate change (Cini et al., 2024). 

An atmosphere-ocean coupled version of the GLOBO model (GLOBONE) 

Recently, CNR-ISAC started an effort to develop a coupled climate model by integrating GLOBO (the institute’s atmospheric model) with NEMO (a European oceanic model) using the OASIS-MCT coupler. GLOBO, previously used for sub-seasonal forecasting, is being adapted for longer climate timescales including seasonal, decadal prediction and climate projections. The coupling implementation allows GLOBO to run in three configurations: legacy atmosphere-only, AMIP with prescribed sea surface temperatures, and the new atmosphere-ocean-sea ice coupled configuration with NEMO. This development aims to expand climate modeling capabilities while strengthening the overall model development process. The model code is publicly available here. 

WCRP and related activities 

CNR-ISAC is active in several of the official initiatives taking place in the context of the World Climate Research Project (WCRP) as part of the United Nations Framework Convention on Climate Change (UNFCCC). We can mention the Joint Scientific Committee (JSC), Lighthouse activities (LHA) like the Global Precipitation Experiment (GPEX) and Explaining and Predicting Earth System Change (EPESC), the CLIVAR/GEWEX Monsoon Panel, the Model Benchmarking Task Team, the Fresh Eyes on CMIP Task Team, and Consistency between Paleo and Modern Forcing Team in preparation of the Coupled Model Intercomparison Project Phase 7 (CMIP7). Furthermore, CNR-ISAC has contributed and will actively contribute with lead authors, authors and reviewers for the redaction of the Assessment Reports (AR) and Special Reports (SR) coordinated by the Intergovernmental Panel for Climate Change (IPCC).  

Other activities/projects

In the PRIMAVERA project (Horizon 2020, 2015-2020) CNR-ISAC contributed realising high-resolution simulations with the EC-Earth model and focused on the development of process-based metrics tailored for different regions and seasons, assessing Pacific variability and its teleconnection to Europe, measuring climate variability and predictability in the Extra-Tropics. 

In the CRESCENDO project (Horizon 2020, 2015-2020) CNR-ISAC contributed to the realisation of ESM scenario simulations with EC-Earth and implemented new metrics to assess the capability of ESMs with dynamic natural vegetation in representing the main vegetation-precipitation-fire relationships and savanna, grassland, forest distribution and transitions. 

In the TIPES project (Horizon 2020, 2019-2024) CNR-ISAC investigated climate response in scenario simulations, the role of stochastic parameterizations and understanding multicentennial AMOC variability in a climate model of intermediate complexity.

In the C3S 34a Lot2 contract  (2016-2019) CNR-ISAC developed several climate model diagnostics, included in the ESMValTOOL software,  including atmospheric blocking, teleconnections, weather regimes, climate extreme event indices, hydroclimatic intensity and stratosphere- troposphere coupling.

In the MEDSCOPE Era4CS project (2017-2021)   CNR-ISAC has given a consistent contribution to the development of a software toolbox for assessing and improving the quality of climate forecasts for seasonal to multi–annual scales and to the development of an impact chain in the water sector.

References

Boer, G. J., Smith, D. M., Cassou, C., Doblas-Reyes, F., Danabasoglu, G., Kirtman, B., Kushnir, Y., Kimoto, M., Meehl, G. A., Msadek, R., Mueller, W. A., Taylor, K. E., Zwiers, F., Rixen, M., Ruprich-Robert, Y., and Eade, R.: The Decadal Climate Prediction Project (DCPP) contribution to CMIP6, Geosci. Model Dev., 9, 3751-3777, https://doi.org/10.5194/gmd-9-3751-2016, 2016

Cini, M., Zappa, G., Ragone, F. et al. Simulating AMOC tipping driven by internal climate variability with a rare event algorithm. npj Clim Atmos Sci 7, 31, https://doi.org/10.1038/s41612-024-00568-7, 2024

Fabiano, F., Davini, P., Meccia, V. L., Zappa, G., Bellucci, A., Lembo, V., Bellomo, K., and Corti, S.: Multi-centennial evolution of the climate response and deep-ocean heat uptake in a set of abrupt stabilization scenarios with EC-Earth3, Earth Syst. Dynam., 15, 527–546, https://doi.org/10.5194/esd-15-527-2024, 2024

Giorgi, F., Coppola, E., Giuliani, G., Ciarlo`, J. M., Pichelli, E., Nogherotto, R., Raffaele, F., Malguzzi, P., Davolio, S., Stocchi, P., and Drofa, O.: The fifth generation regional climate modeling system, RegCM5: Description and illustrative examples at parameterized convection and convection-permitting resolutions. Journal of Geophysical Research: Atmospheres, 128(6). https://doi.org/10.1029/2022JD038199, 2023

Jackson, L.C., E. Alastrué de Asenjo, K. Bellomo, G. Danabasoglu, H. Haak, A. Hu, J. Jungclaus, W, Lee, V.L. Meccia, O. Saenko, A. Shao and Swingedouw, D.: Understanding AMOC stability: the North Atlantic Hosing Model Intercomparison Project. Geoscientific Model Development. https://doi.org/10.5194/gmd-2022-277, 2023a

Jackson, L., Alastue de Asenjo, E., Bellomo, K., Danabasoglu, G., Hu, A., Jungclaus, J., Lee, W., Meccia, V., Saenko, O., Shao, A., and Swingedouw, D.: NAHosMIP data (published) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.7643437, 2023b

Swart, N. C., Martin, T., Beadling, R., Chen, J.-J., Danek, C., England, M. H., Farneti, R., Griffies, S. M., Hattermann, T., Hauck, J., Haumann, F. A., Jüling, A., Li, Q., Marshall, J., Muilwijk, M., Pauling, A. G., Purich, A., Smith, I. J., and Thomas, M.: The Southern Ocean Freshwater Input from Antarctica (SOFIA) Initiative: scientific objectives and experimental design, Geosci. Model Dev., 16, 7289–7309, https://doi.org/10.5194/gmd-16-7289-2023, 2023van Oorschot, F., van der Ent, R. J., Hrachowitz, M., Di Carlo, E., Catalano, F., Boussetta, S., Balsamo, G., and Alessandri, A.: Interannual land cover and vegetation variability based on remote sensing data in the HTESSEL land surface model: implementation and effects on simulated water dynamics, Earth Syst. Dynam., 14, 1239–1259, https://doi.org/10.5194/esd-14-1239-2023, 2023