Rainfall dynamics in Barbuda during the Little Ice Age

Summary of our new research paper on effective rainfall in Barbuda, Lesser Antilles

The coring team in Barbuda
The coring team in Barbuda

Established palaeoclimate records (E.g. Haug et al., 2001; Hodell et al., 2005; Lane et al., 2011) suggest that aridity was widespread across the Caribbean during the Little Ice Age (ca. 1400 – 1850 CE). Such dry conditions are hypothesised to result from cooler tropical sea surface temperatures and a southward migration of the Atlantic ITCZ. To determine whether arid conditions were present in the northeastern Caribbean during this period, we developed a new sediment-based reconstruction of effective rainfall from Freshwater Pond in Barbuda.

Freshwater Pond, Barbuda
Freshwater Pond, Barbuda

Freshwater Pond (17°36′05″N, 61°47′28″W; ~ 6 m a.s.l.) is a permanent inland fresh- to brackish-water lake which is closed hydrologically and situated on the Codrington Limestone Group. Its late-Holocene origin is thought to be the result of rising eustatic sea level that reached its present-day maximum level ca. 3000 yr BP (Fairbanks, 1989) and the subsequent development of a rainfall-derived freshwater lens, which rests above the underlying saltwater table (Brasier and Donahue, 1985). Consequently, the pond is very sensitive to precipitation variability (Stoddart et al., 1973).

Fig 3. Comparison of proxy-based evidence from the Freshwater Pond sediment record with AMO and ENSO indices. Source: Burn et al. (2016)
Fig 3. Comparison of proxy-based evidence from the Freshwater Pond sediment record with AMO and ENSO indices. Source: Burn et al. (2016)

Results of microfossil analyses from the sediment record at Freshwater Pond (Fig 3) challenge the occurence of uniformly-dry conditions across the Caribbean Region during the Little Ice Age. Comparisons between this proxy-evidence and tree-ring based indices of the Atlantic Multidecadal Oscillation (AMO) and El Nino Southern Oscillation (ENSO) indicate that effective rainfall in Barbuda was highly variable at that time and appears to be influenced by the interplay between different Atlantic and Pacific modes of climate varibility.

Please visit the publishers website to access the paper or download a copy of the final accepted manuscript here.

References:

Brasier M and Donahue J (1985) Barbuda – An emerging reef and lagoon complex on the edge of the Lesser Antilles island arc. Journal of the Geological Society 142: 1101–1117.

Burn MJ, Holmes JA, Kennedy LM et al. (2016) A sediment-based reconstruction of Caribbean effective precipitation during the ‘Little Ice Age’ from Freshwater Pond, Barbuda. The Holocene 26(8): 1237-1247.

Fairbanks RG (1989) A 17,000-year glacio-eustatic sea level record: Influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation. Nature 342: 637–642.

Haug GH, Hughen KA, Sigman DM et al. (2001) Southward migration of the intertropical convergence zone through the Holocene. Science 293: 1304–1308.

Hodell DA, Brenner M, Curtis JH et al. (2005) Climate change on the Yucatan Peninsula during the Little Ice Age. Quaternary Research 63: 109–121.

Lane CS, Horn SP, Orvis KH et al. (2011) Oxygen isotope evidence of Little Ice Age aridity on the Caribbean slope of the Cordillera Central, Dominican Republic. Quaternary Research 75: 461–470.

Stoddart D, Bryan G and Gibbs P (1973) Inland mangroves and water chemistry, Barbuda, West Indies. Journal of Natural History 7: 33–46.