Assessment of anticipated changes in extreme temperature and precipitation under 1.5 °C and 2.0 °C warming over the Mississippi River Basin

Authors: DOMMO, ATANAS - University Of Missouri; LEASOR, ZAHARY - University Of Missouri; LUPO, ANTHONY - University Of Missouri; Hunt, Sherry; ALOYSIUS, NOEL - University Of Missouri

Submitted to: International Journal of Climatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2025
Publication Date: 10/2/2025
Citation: Dommo, A., Leasor, Z., Lupo, A., Hunt, S., Aloysius, N. 2025. Assessment of anticipated changes in extreme temperature and precipitation under 1.5 °C and 2.0 °C warming over the Mississippi River Basin. International Journal of Climatology. 45(15).Article e70135. https://doi.org/10.1002/joc.70135.
DOI: https://doi.org/10.1002/joc.70135

Interpretive Summary: High resolution climate models are critical for designing regional and local adaptation strategies and mitigation planning in the context of changing weather patterns causing disasters such as severe storms, flooding or severe droughts. In this study, a statistical technique was used to reduce bias in extreme precipitation and temperature indices over the Mississippi River Basin (MRB) using ensemble mean from multiple models. Changing of extreme precipitation and temperature related indices are examined at two global warming temperatures, 1.5°Celsius and 2°Celsius. Findings showed a strong occurrence of heavy rainfall along the overall increased extremes precipitation and temperatures over the MRB at both warming targets. Many areas over the MRB will experience reduction in cumulative wet days at both temperatures. With an additional 0.5°C (from 1.5°C to 2°C), warm days and warm spell duration index are expected to increase significantly over most parts of the MRB, with consequence on water availability, crop yields, and ecosystems. The uncertainties estimate exhibits 75% contribution of internal variability and marginal contribution of climate scenario to total variance. The uncertainties dominate the signal of change pointing to the necessity to reduce internal variability in future generations of climate models, and to prioritize large set of climate models rather than climate scenarios in such studies. This research is anticipated to inform researchers, emergency managers, farmers, dam operators, insurance agents, lenders, and policy makers about creating strategies and mitigation plans to address the impacts of changing weather patterns have on disaster recovery, conservation practices, farming operations, residential and commercial development, and regulations like zoning laws.USDA is an equal opportunity provider and employer.

Technical Abstract: Extreme precipitation and temperature have large socioeconomic and human health impacts. This study aims to analyze the changes, compared to baseline period 1971-2000, of extreme precipitation and temperature indices at 1.5°Celsius and 1.5°Celsius over the Mississippi River Basin (MRB) under Shared Socio-economic pathways (SSP) 2-4.5 and SSP5-8.5. We used a technique named bias correction constructed analogues with quantiles mapping reordering (BCCAQ) to downscale daily precipitation, minimum and maximum temperature from a set 12 Coupled Models Intercomparison Project phase 6 (CMIP6) over the MRB. The BCCAQ is able to reproduce the spatial pattern and reduce the bias in precipitation and temperature indices. The changes in precipitation and temperature indices are sensitive to warming targets and emission scenario. Results indicate that both warming targets are expected to exacerbate the very heavy precipitation (R95p) while intensifying increased extreme precipitation and temperature at whole except cumulative wet days (CWD)(many parts of MRB are experiencing reduced CWD at both 1.5°C and 2°C under both scenario). An additional 0.5°C global warming is expected to increase warm days (TX90p) and warm spell duration by 50% under SSP2-4.5 and nearly 100% under SSP5-8.5 over much of the MRB subregions. The additional warming 0.5°C (from 1.5°C to 2°C) will reduces extreme precipitation in the center MRB, except CWD which exhibits reduction almost everywhere in the MRB. This impact of additional 0.5°C will be enhanced under SSP5-8.5 compared to SSP2-4.5. Our uncertainty analysis indicates that internal variability contributes to more than 75% to total variance followed by uncertainty from climate models and marginal contribution from climate scenarios. Overall, uncertainty dominates the magnitude of changes probably due to large inter-models’ variability. However, global warming will pose serious challenges to water availability over the MRB, with consequences on agriculture, crops yield and ecosystems.