Don't blame the Sun for all global warming woes

Sep 20, 2005

Blaming the Sun for all the woes related to global warming looks less tenable an argument following the publication of a research paper on climate cycles in the latest issue of the Journal of Quaternary Science.

There have been several ideas as to what has been driving climate change over the past 10,000 years, according to the paper’s lead author and radiocarbon dating expert Dr Chris Turney from the University of Wollongong’s GeoQuEST Research Group at the School of Earth and Environmental Sciences.

He and his international co-researchers have concluded in their paper titled, “Testing solar forcing of pervasive Holocene climate cycles” that solar activity is not the primary force.

Dr Turney said the interest in what drives climate change has intensified in recent years with the identification of climate cycles, of which the Medieval Warm Period and Little Ice Age are the most recent examples.

A popular view pinpoints changes in the Sun's output for driving these changes, he said. Several records have been produced from North Atlantic Ocean sediment cores that show these climate cycles apparently correlate to the Sun's past activity. To get a handle on the long-term behaviour of the Sun, scientists have looked at how it controls changes in the radioactivity of the air. By measuring changes in the radioactive version of carbon preserved in tree rings, a precise year-by-year record of the Sun’s activity can be made.

He said to test this idea he and his co-researchers at Queens University Belfast in the UK looked at the 7,468 year-long Irish bog oak record. The trees have been preserved growing on the bog surfaces in the past when the surface was dry enough to colonise.

“By matching the distinctive tree ring patterns, an absolute, year-by-year record of the number of trees growing on the bogs can be made. Amazingly, this measure of tree population mirrors the climate cycles over the past 10,000 years. Basically, when the Atlantic waters get cooler, Ireland gets wetter. So when the North Atlantic sneezes, Ireland gets a cold,” Dr Turney said.

Fortunately, Dr Turney said the Irish trees have also been used to develop the global record of past changes in atmospheric radiocarbon content so the research team had no uncertainties in correlating changes in the climate cycles to changes in the Sun's output.

Here, the team found no simple relationship between the Sun's activity and climate change in the North Atlantic region.

“If it is the Sun it’s a lot more complicated than many people have claimed – and this is of enormous importance to the global warming debate.

“Many who don't believe humans are causing what is happening in today's climate blame the Sun but it’s not as simple as that,” Dr Turney said.

For further information contact Dr Chris Turney on (02) 4221 3561/4221 5906 or mobile 0408 678989.

For more information, contact:
University of Wollongong
Ph: (02) 4221 5942; fax (02) 4221 3128


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