The Intergovernmental Panel on Climate Change has documented wide-ranging changes to the world's coasts and oceans, with significant further change predicted. Impacts on coastal and underwater heritage sites, however, remain relatively poorly understood. The authors draw on 30 years of research into coastal and underwater archaeological sites to highlight some of the interrelated processes of deterioration and damage. Emphasising the need for closer collaboration between, on one hand, archaeologists and cultural resource managers and, on the other, climate and marine scientists, this article also discusses research from other disciplines that informs understanding of the complexity of the interaction of natural and anthropogenic processes and their impacts on cultural heritage.

The Decade of Ocean Science for Sustainable Development 2021-2030 is a UN initiative that promotes a common framework for supporting stakeholders in studying and assessing the health of the world's oceans. The initiative also presents a vital opportunity to improve the integration of archaeology within the marine sciences. With the First Global Planning Meeting of the Decade held in Copenhagen at the National Museum of Denmark in May 2019, steps are already being taken to make the best of this opportunity, and the resulting creation of an Ocean Decade Heritage Network is proposed as a way forward to continue to raise awareness in the cultural heritage community about the Decade and to facilitate information sharing regarding this endeavour.

New and updated multi-century tree-ring chronologies from living oak trees, remnants, and archeological beams from across the Driftless Area of southwest Wisconsin and northeast Iowa, USA, were developed to fill a spatial gap in the network of available tree-ring chronologies. We produced a robust 303-year summer drought reconstruction (June–August Palmer’s Modified Drought Index (PMDI): r 2 = 0.45) that identified clusters of extreme droughts and pluvials (PMDI ≤ –4.0 or ≥ 4.0) in the early 1700s and more even distributions of drought conditions, with the exception of the post 1930s period when drought became relatively infrequent. Compared to the Living Blended Drought Atlas (LBDA) and the North American Drought Atlas (NADA), our reconstruction more accurately represented moderate moisture conditions across the Driftless Area, the NADA and LBDA more closely represented extreme pluvials, and our reconstruction and the LBDA better represented extreme drought years. The three reconstructions largely captured the same high-frequency variability in drought conditions and differed most at low frequencies. Significant correlations were identified between our reconstruction and corn ( r = 0.30, n = 91, p = 0.002) and soybean ( r = 0.25, n = 81, p = 0.012) yields, with the strength of the correlations increasing over recent decades suggesting a tighter coupling of interannual climate variability and crop productivity in the region. Superposed epoch analyses indicated significantly wetter conditions in the Driftless Area two years after major volcanic eruptions. In the context of long-term climatic variability, the Driftless Oaks drought reconstruction demonstrated that drought and pluvial conditions more extreme than those experienced during the instrumental record have occurred in the past.

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Groundwater depletion is a concern around the world with implications for food security, ecological resilience, and human conflict. Long-term perspectives provided by tree ring-based reconstructions can improve understanding of factors driving variability in groundwater elevations, but such reconstructions are rare to date. Here, we report a set of new 546-year tree-ring chronologies developed from living and remnant longleaf pine (Pinus palustris) trees that, when combined with existing bald cypress (Taxodium distichum) tree-ring chronologies, were used to create a set of nested reconstructions of mean annual groundwater elevation for North Central Florida that together explain 63% of the variance in instrumental measurements and span 1498–2015. Split calibration confirms the skill of the reconstructions, but coefficient of efficiency metrics and significant autocorrelation in the regression residuals indicate a weakening relationship between tree growth and groundwater elevation over recent decades. Comparison to data from a nearby groundwater well suggests extraction of groundwater is likely contributing to this weakening signal. Periodicity within the reconstruction and comparison with global sea surface temperatures highlight the role of El Niño-Southern Oscillation (ENSO) in driving groundwater elevations, but the strength of this role varies substantially over time. Atlantic and Pacific sea surface temperatures modulate ENSO influences, and comparisons to multiple proxy-based reconstructions indicate an inconsistent and weaker influence of ENSO prior to the 1800s. Our results highlight the dynamic influence of ocean-atmospheric phenomena on groundwater resources in North Central Florida and build on instrumental records to better depict the long-term range of groundwater elevations.