Australian tropical cyclone activity lower than at any time over the past 550-1,500 years.
The assessment of changes in tropical cyclone activity within the context of anthropogenically influenced climate change has been limited by the short temporal resolution of the instrumental tropical cyclone record (less than 50 years). Furthermore, controversy exists regarding the robustness of the observational record, especially before 1990. Here we show, on the basis of a new tropical cyclone activity index (CAI), that the present low levels of storm activity on the mid west and northeast coasts of Australia are unprecedented over the past 550 to 1,500 years. The CAI allows for a direct comparison between the modern instrumental record and long-term palaeotempest (prehistoric tropical cyclone) records derived from the (18)O/(16)O ratio of seasonally accreting carbonate layers of actively growing stalagmites. Our results reveal a repeated multicentennial cycle of tropical cyclone activity, the most recent of which commenced around AD 1700. The present cycle includes a sharp decrease in activity after 1960 in Western Australia. This is in contrast to the increasing frequency and destructiveness of Northern Hemisphere tropical cyclones since 1970 in the Atlantic Ocean and the western North Pacific Ocean. Other studies project a decrease in the frequency of tropical cyclones towards the end of the twenty-first century in the southwest Pacific, southern Indian and Australian regions. Our results, although based on a limited record, suggest that this may be occurring much earlier than expected.
Earth and Environmental Sciences, James Cook University, Cairns, Queensland 4870, Australia.
Jordahna
J
Haig
Earth and Environmental Sciences, James Cook University, Cairns, Queensland 4870, Australia.
Jonathan
J
Nott
1] Department of Geochemistry, Utrecht University, Utrecht 3508 TA, The Netherlands [2] Geology Department, Royal Netherlands Institute for Sea Research, Den Hoorn (Texel) 1797 SZ, The Netherlands.
Gert-Jan
GJ
Reichart
D001267:Atlantic Ocean; D001315:Australia; D002247:Carbon Isotopes; D002254:Carbonates / Q000032:analysis / Q000737:chemistry; D055867:Cyclonic Storms / Q000706:statistics & numerical data*; D057232:Global Warming / Q000706:statistics & numerical data; D049668:History, 15th Century; D049669:History, 16th Century; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049674:History, 21st Century; D049690:History, Ancient; D049691:History, Medieval; D006802:Human Activities; D010103:Oxygen Isotopes; D010140:Pacific Ocean; D011891:Rain; D012621:Seasons; D014329:Tropical Climate
D002247:Carbon Isotopes; D002254:Carbonates; D010103:Oxygen Isotopes