Incoherency in Central American Hydroclimate Proxy Records Spanning the Last Millennium

Abstract

Continued global warming is expected to result in reduced precipitation and a drier climate in Central America. Projections of future changes are highly uncertain, however, due to the spatial resolution limitations of models and insufficient observational data coverage across space and time. Paleoclimate proxy data are therefore critical for understanding regional climate responses during times of global climate reorganization. Here we present two lake‐sediment based records of precipitation variability in Guatemala along with a synthesis of Central American hydroclimate records spanning the last millennium (800–2000 CE). The synthesis reveals that regional climate changes have been strikingly heterogeneous, even over relatively short distances. Our analysis further suggests that shifts in the mean position of the Intertropical Convergence Zone, which have been invoked by numerous studies to explain variability in Central American and circum‐Caribbean proxy records, cannot alone explain the observed pattern of hydroclimate variability. Instead, interactions between several ocean‐atmosphere processes and their disparate influences across variable topography appear to have resulted in complex precipitation responses. These complexities highlight the difficulty of reconstructing past precipitation changes across Central America and point to the need for additional paleo‐record development and analysis before the relationships between external forcing and hydroclimate change can be robustly determined. Such efforts should help anchor model‐based predictions of future responses to continued global warming.

The influence of tropical Atlantic sea-surface temperatures and the North Atlantic Subtropical High during the Maya Droughts

“…While heterogeneity is a common feature of Central American hydroclimate during the Late-Holocene (Obrist-Farner et al, 2023; Steinman et al, 2022), there appears to be a uniquely consistent hydroclimate signal in the Maya Lowlands between 800 and 1300 CE. Modeled simulations of atmospheric circulation and consequent precipitation responses suggest that dry intervals recorded in many Central American paleoclimate reconstructions during the Maya Droughts could have been the result of a westward expansion and strengthening of the NASH (Bhattacharya et al, 2017).…”

“…Lake Izabal and Rey Marcos cave), and some indicating absent or negligible variability (e.g. Lake Kail) (Kennett et al, 2012; Obrist-Farner et al, 2023; Stansell et al, 2020; Winter et al, 2020). Nevertheless, some linkages are still evident between cooling events in the tropical Atlantic and major drought events recorded in our data from Petén Itzá during the LIA.…”

“…To this end, considerable work has been conducted regarding Central American hydroclimate spanning the Late-Holocene (e.g. Douglas et al, 2015; Kennett et al, 2012; Obrist-Farner et al, 2023; Steinman et al, 2022; Winter et al, 2020). However, a complete understanding of the most important synoptic and global drivers of local scale hydroclimate change in Central America remains elusive (Obrist-Farner et al, 2023).…”

“…Douglas et al, 2015; Kennett et al, 2012; Obrist-Farner et al, 2023; Steinman et al, 2022; Winter et al, 2020). However, a complete understanding of the most important synoptic and global drivers of local scale hydroclimate change in Central America remains elusive (Obrist-Farner et al, 2023). This is due in part to the numerous geomorphic, oceanic, and atmospheric factors that have been demonstrated to impact Central American climate, across various temporal and spatial scales (Cabos et al, 2019; Imbach et al, 2018).…”

Distinct Modes of Aged Soil Carbon Export in a Large Tropical Lake Basin Identified Using Bulk and Compound‐Specific Radiocarbon Analyses of Fluvial and Lacustrine Sediment

“…Lake Izabal is the largest lake in Guatemala, and is fed by a large and complex network of rivers (Obrist‐Farner et al., 2020). Lake Izabal also contains a deep sedimentary record that spans millions of years, and could be a valuable repository of paleoclimate data (Bartole et al., 2019; Duarte et al., 2021; Obrist‐Farner et al., 2022, 2023), including reconstructions based on leaf wax isotope data. We sampled sediments from across the LIB, including three major rivers that feed the lake, as well as the lake itself and marshes adjacent to the Polochic river delta.…”