Archives for October 8, 2007

From ABC News:

New northern ice age could send refugees to Aust

A new study from the Australian National University (ANU) has found that this country may not be as severely affected by a new ice age as countries in the Northern Hemisphere.

ANU paleoclimatologist Timothy Barrows and his fellow researchers used a new dating technique that measures the radioactive elements in some rocks.

Dr Barrows explains that Europe is at risk of a new ice age as a result of global warming.

“There are some fears that warming in the Northern Hemisphere, particularly around the Greenland ice sheet, might cause quite a bit of meltwater to come into the North Atlantic Ocean,” he said.

Read the whole article.

Excellent piece here from John McLean entitled ‘Ignoring a Natural Event to Blame Humans.’

In the last week of September 2007 we had yet another example of a well-recognized natural climate event being ignored in order to sell the notion that mankind is responsible for global warming. Maybe it was deliberate or maybe just ignorance, but you’d think that capable scientists would look closely at prior research and the data and not just be activists for their latest cause.

This time it was Power and Smith, from Australia’s CSIRO and Bureau of Meteorology respectively, who were reporting a weakened Walker Circulation over the last 30 years and a concurrent period of unprecedented El Niño dominance [note 1], both of which they blamed on human activity.

Last year in May it was Vecchi et al [2] who told us that the same Walker Circulation had weakened by 3.5% since the mid-1800s and there that there was a just 1% probability that this was due to natural events. Vecchi and Soden [3] recently continued their line of argument from 2006 by claiming that an ensemble of 23 climate models confirms that weakening of the Walker Circulation is to be expected under anthropogenic warming.

These three papers seem to be the product of researchers lost in their computer simulations and putting the virtual reality of computer models ahead of observational reality.

What they attribute to human activity are natural events that have been well described by other researchers.

Read the full article.

There is also a follow up article by Joseph D’Aleo enitled ‘More on The Great Pacific Climate Shift and the Relationship of Oceans to Temperatures and Arctic Ice’

In a recent guest blog, John McLean explained how Australia’s CSIRO and Bureau of Meteorology (Power and Smith) respectively were reporting a period of unprecedented El Niño dominance the last 30 years, which they blamed on human activity. Last year in May it was Vecchi who told us there was a just 1% probability that this was due to natural events.

On The Weather Channel blogs, meteorologist Stu Ostro, also found a similar continuity shift in weather pattern starting 30 years ago. Blog comments back to Stu and John McLean’s blog here showed how the change had precious little to do with anthropogenic factors but was a large scale cyclical climate shift known for decades as the Great Pacific Climate Shift.

Later on it was shown to be the latest change in a cyclical regime change given the name Pacific Decadal Oscillation by Mantua et al. This followed research showing decadal like ENSO variability by Zhang et al. in 1993.
They found the Pacific Ocean temperature regime and overlying pressure patterns tended to persist in one mode for two or three decades and then flip to very nearly the opposite mode for a similar period.

Read more.

3 relevant papers:

GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L06712, doi:10.1029/2005GL025052, 2006

Long-term behaviour of ENSO: Interactions with the PDO over the past 400 years inferred from paleoclimate records

Danielle C. Verdon1 and Stewart W. Franks1

[1] This study uses proxy climate records derived from paleoclimate data to investigate the long-term behaviour of
the Pacific Decadal Oscillation (PDO) and the El Nin˜o Southern Oscillation (ENSO). During the past 400 years,
climate shifts associated with changes in the PDO are shown to have occurred with a similar frequency to those
documented in the 20th Century. Importantly, phase changes in the PDO have a propensity to coincide with
changes in the relative frequency of ENSO events, where the positive phase of the PDO is associated with an
enhanced frequency of El Nin˜o events, while the negative phase is shown to be more favourable for the development of La Nin˜a events.

HYDROLOGICAL PROCESSES INVITED COMMENTARY Hydrol. Process. 16, 559–564 (2002) DOI: 10.1002/hyp.600

Assessing hydrological change: deterministic general circulation models or spurious solar correlation?

Stewart W. Franks Centre for Environmental Dynamics, University of Newcastle, Callaghan 2308, New South Wales, Australia

Atmospheric greenhouse gas concentrations are at an historic high, and this must lead to strong concerns over our future climate. However, it is not often appreciated that solar activity is also at an historic high [from 400 years of solar observations (Hoyt and Schatten, 1997)]. The problem of disaggregating these factors in temperature trends is largely due to long-term upward trends of both factors. However, through the use of a simple non-linear ARX[1] model, it has been shown that temperature trends over the 20th century display some coherence with solar irradiance. It should therefore be considered that documented hydrological changes in regional climates, available via the IPO/PDO indices, may be driven by solar–terrestrial interactions. Until GCMs can elucidate the mechanisms of hydrological variability, then any projections of long-term future climate changes must be viewed with obvious caution.

GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 2, 1035, doi:10.1029/2002GL015992, 2003

Multi-decadal variability of flood risk

Anthony S. Kiem, Stewart W. Franks, and George Kuczera School of Engineering, University of Newcastle, Callaghan, New South Wales, Australia

[1] Recent research has highlighted the persistence of multi-decadal epochs of enhanced/reduced flood risk across
New South Wales (NSW), Australia. Recent climatological studies have also revealed multi-decadal variability in the
modulation of the magnitude of El Nin˜o/Southern Oscillation (ENSO) impacts. In this paper, the variability of flood risk
across NSW is analysed with respect to the observed modulation of ENSO event magnitude. This is achieved
through the use of a simple index of regional flood risk. The results indicate that cold ENSO events (La Nin˜a) are the
dominant drivers of elevated flood risk. An analysis of multidecadal modulation of flood risk is achieved using the interdecadal Pacific Oscillation (IPO) index. The analysis reveals that IPO modulation of ENSO events leads to multi-decadal epochs of elevated flood risk, however this modulation appears to affect not only the magnitude of individual ENSO events, but also the frequency of their occurrence. This dual modulation of ENSO processes has the effect of reducing and elevating flood risk on multi-decadal timescales. These results have marked implications for achieving robust flood frequency analysis as well as providing a strong example of the role of natural climate variability.