Dr. Michael Asten writes to alert me of this article in the Australian, with this advice:
The overwhelming conclusion ought to be that cycles should be built into at least some of the climate models in order to explore scenarios. But I fear we might still be another decade away from seeing that happen.
I suspect he is right, as I do Stephan Rahmstorf who says:
“if the system (is cyclic), we’d expect the opposite. In 30 years’ time we will know for sure.”
From: The Australian
Today’s global warming is well within historic range
by: Michael Asten January 28, 2013 12:00AM
US President Barak Obama vows action on climate change with the declaration “none can avoid the devastating impact of raging fires and crippling drought and more powerful storms”.
It was an appeal using rhetoric and not science because the most severe impacts of these natural disasters come from the challenge of managing increased population or changed population demands, not changes in the events per se.
Great fires are a regular feature of North American and Australian landscapes, and their human impact is worst when they reach housing or infrastructure built among trees, on the edge of bushland that has not been cleared by “cool” burn-offs.
Civilisations have been hit by droughts since the Nile delta drought of 4200 years ago destroyed Egypt’s old kingdom, leaving the pyramids as witness.
As global citizens, we still have much to learn about the management of water, it seems, whether in our Murray-Darling backyard or in the Sahel of Africa.
The term “powerful storms” summons up graphic images of Hurricane Sandy, which devastated New York – except it was no longer hurricane-strength when it, like a dozen others in written history, struck.
But the Manhattan area it flooded contained huge areas of high-density development on reclaimed swamps, ponds and what was riverbed before civilisation drained, dozed and filled to provide for the population of one of the world’s greatest cities. When New York has absorbed the lessons from this, it will be able to pass on advice and technology to places such as Bangladesh.
A growing number of mainstream scientists agrees there is evidence for such cycles as drivers of climate change, although debate on causes and mechanisms is strong. By way of example, I note three recent papers that find evidence for long-term cycles influencing the Earth’s climate.
Weichao Wu of the Peking University and colleagues studied sea-surface temperature records preserved in deep-sea sediments near Okinawa in the Pacific Ocean, and found evidence for multiple cyclic temperature variations over the past 2700 years.
The most interesting temperature peaks correspond to medieval, Roman and possibly Minoan warming periods of about 900, 1800 and 2500 years ago.
The paper is significant in that it concludes that the current rate of global temperature change lies in the same range as that of those historical warming periods.
This suggests we have evidence that challenges current climate orthodoxy on two grounds, first by suggesting that such warming events were global not local European phenomena, and second that current warming is not unprecedented in the historical record.
While we read many claims by oceanographers of an increasing rate of rise in sea-levels associated with increased atmospheric carbon dioxide, an alternative interpretation of observed data is made in a recent analysis by Don Chambers of the University of South Florida and colleagues.
Chambers poses the question: “Is there a 60-year oscillation in sea-level?” and shows evidence that the answer is probably yes.
I read his data and find it is arguable that the upswing of that oscillation is responsible for about half of the current 3mm/year rate of rise, leaving the background rate of rise at about 1.7mm, where it has been for 110 years.
Intergovernmental Panel on Climate Change lead author Stefan Rahmstorf, writing in the climate scientists’ blogsite Real Climate this month, commented on whether the data supports an interpretation of cycles, or non-cyclic shifts associated with changes in aerosols and current increases in greenhouse gases.
Rahmstorf concludes in favour of the latter but ends with the objective and open-minded comment “if the system (is cyclic), we’d expect the opposite. In 30 years’ time we will know for sure.”
A third work that may eventually prove immensely important in understanding cycles in climate change is a study by JA Abreu of the prestigious Swiss university ETH, with co-authors including Australia’s 1995 Australia Science Prize winner Ken McCracken.
Abreu reconstructs a history of solar sunspot cycles over the past 10,000 years from elemental isotopes created by cosmic rays impinging on the atmosphere, subsequently preserved in Greenland ice-core records.
The mechanisms of sun-spot, solar magnetic field and cosmic ray interactions are complex and will be intensely studied, but the associations illustrated here demand consideration when we seek to model our future climate.
The devastating impacts of extreme climate events of which Obama speaks have always been with us, and we have to expect that the human tragedies they bring will be exacerbated by growth in global population.