What was done
The authors developed a 777-year-long annually-resolved record of landfalling tropical cyclones in northeast Australia based on analyses of isotope records of tropical cyclone rainfall in an annually-layered carbonate stalagmite from Chillagoe (17.2°S, 144.6°E) in northeast Queensland.

What was learned
Perhaps the most important discovery of Nott et al.'s investigation was the finding that "the period between AD 1600 to 1800" - when the Little Ice Age held sway throughout the world - "had many more intense or hazardous cyclones impacting the site than the post AD 1800 period," when the planet gradually recovered from this cold interlude and began to warm at a rate that rose to ultimately become what climate alarmists typically characterize as unprecedented over the past millennium or more, and when temperatures rose to a level they claim was equally unprecedented.

What it means
The four researchers write that "the only way to determine the likely future behavior of tropical cyclones is to first understand their history from high resolution records of multi-century length or greater." Based on (1) this obvious truth, (2) their specific findings, and (3) the similar findings of Donnelly and Woodruff (2007) and Nyberg et al. (2007) in the Northern Hemisphere, it would appear that global warming at the very least will not lead to an increase in the frequency of occurrence of intense hurricanes over wide reaches of the globe, contrary to what climate alarmists such as Al Gore vociferously contend.

References
Donnelly, J.P. and Woodruff, J.D. 2007. Intense hurricane activity over the past 5,000 years controlled by El Niņo and the West African Monsoon. Nature 447: 465-468.

Nyberg, J., Malmgren, B.A., Winter, A., Jury, M.R., Kilbourne, K.H. and Quinn, T.M. 2007. Low Atlantic hurricane activity in the 1970s and 1980s compared to the past 270 years. Nature 447: 698-701.