Climate Variability and Change in Southeast U.S. River Basins

The river basins of the southeastern United States, draining to both the Atlantic and Gulf coasts, exhibit pronounced variability in temperature, precipitation and streamflow over seasonal to centennial timescales. Natural modes of variability – including the North Atlantic Oscillation and Pacific Decadal Oscillation – interact with anthropogenic greenhouse-gas and aerosol forcing to produce spatially heterogeneous trends, manifesting as more intense droughts, altered flood frequencies and shifts in seasonal water availability. Coastal basins such as the Apalachicola-Chattahoochee-Flint and Savannah display accelerating winter rainfall but declining summer freshwater pulse, while inland systems show complex interplay between recharge, evapotranspiration and temperature rise. These changes have direct implications for water resource management, biodiversity conservation and agricultural productivity in a region that is both a biodiversity hotspot and economically reliant on consistent freshwater supplies. Enhanced observations and modelling have shed light on emerging hot spots of change, informing adaptive strategies to mitigate flood risk, maintain ecosystem services and allocate water among competing demands.

Research from Nature Portfolio

Recent studies have characterised how maximum summer temperatures and moisture content jointly control heat-stress patterns and the spatial extent of the warming hole in the southeastern United States. Analyses of multiple gridded climatologies and reanalysis datasets reveal that humid air amplifies heat stress in the core southeast, even as moisture increases tend to mask warming signals in the Midwest. The warming hole, once identified by cooling relative to the continental mean, has diminished in amplitude when heat-index metrics are used. Comparison across data products highlights the importance of dataset choice for long-term trend detection and underscores the role of moisture–temperature interactions in modulating regional climate change impacts.

Climate Variability and Change in Southeast U.S. River Basins publication trend

The graph below shows the total number of articles in climate variability and change in southeast u.s. river basins across all publications each year (not limited to Nature Index journals).

Technical terms

Climate variability: Natural fluctuations in climate patterns over seasonal to multi-decadal timescales.

Warming hole: A region exhibiting muted or negative temperature trends relative to surrounding areas under global warming.

Timing of emergence: The first year when a climate change signal becomes statistically distinct from natural variability.

Indicator of Hydrologic Alteration (IHA): A set of metrics quantifying changes in streamflow characteristics such as magnitude, frequency and duration of flows.

References

1. Changes in United States Summer Temperatures Revealed by Explainable Neural Networks. Earth's Future (2024).
2. Timing and seasonality of the United States ‘warming hole’. Environmental Research Letters (2017).
3. Contiguous US summer maximum temperature and heat stress trends in CRU and NOAA Climate Division data plus comparisons to reanalyses. Scientific Reports (2018).
4. Hydrologic Characteristics of Streamflow in the Southeast Atlantic and Gulf Coast Hydrologic Region during 1939–2016 and Conceptual Map of Potential Impacts. Hydrology (2018).