Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for November 26, 2006

More Than One Striped Possum: A Note from Neil Hewett

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Hi Jennifer,

I photographed this striped possum (Dactylopsila trivirgata) at Cooper Creek Wilderness on the 21st October, 2006, and I was very pleased to see that this photograph of a striped possum, was in fact, two.

Sparsely distributed throughout the wet tropics and along the east coast of Cape York (Australia), the species is spectacularly acrobatic and most frequently found after hearing it crash into overhead vegetation.

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Striped possum carrying young, Cooper Creek Wilderness, 21st October 2006

It forages by welting rotten tree material and listening carefully for beetle larvae, which it extricates with its specialised elongate fourth digit on the front feet.

At Cooper Creek Wilderness we are hoping for the onslaught of the heavy wet in the not too distant future, when the sounds of striped possums will be overwhelmed by a menagerie of treefrogs and insects.

Neil

Wrong ‘Shot’ at Atlantic Conveyor Belt Speed?

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Last year Harry Bryden published a paper* in the journal Nature which indicated that there had been a 30 percent decline in the northward flow of warm water in the Atlantic Ocean. This was interpreted by many as another sign of climate change with potentially catastrophic consequences.

Also known as the ‘Atlantic Conveyor Belt’, this warm, north flowing current was made famous in the movie ‘The Day After Tomorrow’ where global warming, in particular the melting of polar ice caps, resulted in the ‘Atlantic conveyor’ stopping and North America freezing over.

Professor Bryden is part of an international monitoring program known as the Rapid Climate Change (RAPID) Program and since the Nature paper, they have collected some more data. This new data was discussed late last month with a meeting of scientists in Birmingham.

According to a new article** in the journal Science by Richard Kerr, 95 percent of the scientists at the Birmingham meeting concluded that there has been NO significant change in the overall flow of the North Atlantic conveyor and that the 30 percent finding was somewhat premature.

Importantly, more intensive monitoring has shown that variations in flow within as single year can be “as large as the changes seen from one snapshot to the next during the past few decades”.

This now appears to be the problem with Bryden’s findings as published by Nature: that is the initial findings was misleading because it just compared a 2004 snapshot with four earlier instantaneous surveys (snapshots) back to 1957.

But the popular press hasn’t caught on.

According to The Guardian, reporting on the Birmingham meeting: “Scientists have uncovered more evidence for a dramatic weakening in the vast ocean current that gives Britain its relatively balmy climate by dragging warm water northwards from the tropics. The slowdown, which climate modellers have predicted will follow global warming, has been confirmed by the most detailed study yet of ocean flow in the Atlantic.”

Gavin over at Real Climate, apparently attended the Birmingham meeting and at his blog asks how could the Guardian have got it so wwrong: “The Guardian story, which started scientists have uncovered more evidence for a dramatic weakening in the vast ocean current that gives Britain its relatively balmy climate was in complete opposition to the actual evidence presented … how could the reporting be so wrong?”

Well, if you read the report on the meeting at BBC News, it appears Professor Bryden is not part of the ’95 percent consensus’. He is still saying it is slowing, just revised down his estimate from 30 percent to 10 percent: “We concluded that there was some evidence of a small decrease but not as big as we reported in the Nature paper last year ….But we have had a decrease… in the order of 10% of the overturning circulation in the past 25 years.”

Maybe if the BBC reporter had asked Professor Bryden what the slowing has been over the past 50 years, he would have reply, not significant, no slowing? But instead the reporter let the Professor pick a 25 year interval?

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* Bryden, H.L., et al., 2005. Slowing of the Atlantic meridional overturning circulation at 25ºN. Nature, 438, 655-657.

** Kerr, R. A., 2006. False Alarm: Atlantic Conveyor Belt Hasn’t Slowed Down After All, Science, 314, 1064, doi: 10.1126/science.314.5802.1064a

Thanks to Paul Biggs for sending in the link to the article by Richard Kerr and also comment that: “it is time that the Gulf Stream slow down, used by climate alarmists, was finally laid to rest. It has long been known that the Gulf Stream is primarily driven by westerley winds and the earth’s rotation.”