What was done
The authors developed a 14,000-year record of Holocene climate based primarily on the relative abundance of the planktic foraminifer Globigerinoides sacculifer found in two sediment cores extracted from the Gulf of Mexico (GOM).

What was learned
In reference to North Atlantic millennial-scale cool events 1-7 identified by Bond et al. (2001) as belonging to a pervasive climatic oscillation with a period of approximately 1500 years, Poore et al. say of their own study that distinct excursions to lower abundances of G. sacculifer "match within 200 years the ages of Bond events 1-6," noting that "major cooling events detected in the subpolar North Atlantic can be recognized in the GOM record."  They additionally note that "the GOM record includes more cycles than can be explained by a quasiperiodic 1500-year cycle," but that such centennial-scale cycles with periods ranging from 200 to 500 years are also observed in the study of Bond et al., noting further that their results "are in agreement with a number of studies indicating the presence of substantial century-scale variability in Holocene climate records from different areas," specifically citing the reports of Campbell et al. (1998), Peterson et al. (1991) and Hodell et al. (2001).  Last of all, they discuss evidence that leads them to conclude that "some of the high-frequency variation (century scale) in G. sacculifer abundance in our GOM records is forced by solar variability."

What it means
In introducing their paper, Poore et al. report that "North Atlantic marine and mountain glacier data suggest that climate throughout the Holocene has oscillated between warm and cold end-members with the Medieval Warm Period and Little Ice Age representing the most recent examples of the cycle extremes."  Now, their study suggests that this same millennial-scale oscillation of climate is also evident in the Gulf of Mexico, adding to the burgeoning wealth of evidence that this phenomenon is of global extent.

References

Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M.N., Showers, W., Hoffmann, S., Lotti-Bond, R., Hajdas, I. and Bonani, G.  2001.  Persistent solar influence on North Atlantic climate during the Holocene.  Science 294: 2130-2136.

Campbell, I.D., Campbell, C., Apps, M.J., Rutter, N.W. and Bush, A.B.G.  1998.  Late Holocene ca.1500 yr climatic periodicities and their implications.  Geology 26: 471-473.

Hodell, D.A., Brenner, M., Curtis, J.H. and Guilderson, T.  2001.  Solar forcing of drought frequency in the Maya lowlands.  Science 292: 1367-1370.

Peterson, L.C., Overpeck, J.T., Kipp, N.G. and Imbrie, J.  1991.  A high-resolution Late Quaternary upwelling record from the anoxic Cariaco Basin, Venezuela.  Paleoceanography 6: 99-119.