Wednesday, April 13, 2011

Queensland climate becoming more extreme according to coral reef record



The Queensland climate is becoming more extreme with more frequent rain and drought events since the nineteenth century according to research on coral reef cores published in the scientific journal, Paleoceanography by Dr Janice Lough from the Australian Institute of Marine Science in April 2011.


The research looks at cores obtained from coral formations on the Great Barrier reef. Using these long coral cores has allowed Australian Institute of Marine Science (AIMS) scientists such as Dr Lough to reconstruct northeast Queensland summer rainfall for more than 300 years back to the late 17th century and to examine past climate variability and change.

Dr Lough said in a February media release : "At AIMS we have Australia's most comprehensive library of coral cores, from long-lived Porites corals on the Great Barrier Reef.

"The cores have annual bands, similar to tree rings. They give us a record of the ocean environment throughout the coral's life, dating back several centuries, before weather and climate were monitored with rain gauges and thermometers." she said.

Freshwater flood events are recorded in long-lived, annually banded massive coral skeletons as luminescent lines. The bright luminescent lines in coral cores were discovered by AIMS scientists in the 1980s. The intensity of river flood events can be read in the coral cores via an ultra violet light and measured using a custom-built luminometer at AIMS.

"This new reconstruction tells us that the 1973-1974 summer wet season was the wettest in at least the past three centuries," Dr Lough said. "Queensland rainfall is characterised by very high variability. Extreme wet and extreme dry events have always occurred. But now we have evidence that those events are occurring more frequently than in earlier centuries, often with devastating effects."

The research will be submitted to the State Government's judicial inquiry in to the recent floods in SE Queensland.

"The fact that extreme wet and extreme dry weather will happen more often and can potentially impact on thousands of people and millions of dollars worth of property, is something that the community will have to consider," Dr Lough said.

Although the research does not make a direct link between climate change and the recent Queensland floods the abstract concludes: "Since the late 19th century average rainfall and its variability have significantly increased, with wet and dry extremes becoming more frequent than in earlier centuries. This suggests that a warming global climate maybe associated with more variable tropical Queensland rainfall. "

Sources:
* Australian Institute of Marine Science media release Feb 9, 2011 - Queensland climate becoming more extreme says AIMS researcher
* Paleoceanography Abstract - Lough, J. M. (2011), Great Barrier Reef coral luminescence reveals rainfall variability over northeastern Australia since the 17th century, Paleoceanography, 26, PA2201, doi:10.1029/2010PA002050.
* ABC radio PM, April 5, 2011 - Scientists look to corals for climate answers
* Photo from AIMS website - AIMS scientists use a special drill rig to collect coral core samples from some of the oldest corals in Australia. Photographer - Eric Matson