After the Queensland floods, Stewart Franks’ research on the interaction of El Nino-Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO) driving cycles of drought and flood in Australia has been advanced as the rebuttal to the proposition by some politicians and scientists that anthropogenic climate change has had a role in recent events. And that the sceptic position forms a more rational and unique unheard insight into the climate system. That indeed it is business as usual, there is nothing to worry about except mopping up, and that the average rainfall of Queensland is (drought + flood) divide by 2.
Franks’ proposition is well based on physical processes and observed data. Of course there have been other supporters of the same position from various fields:
Peter Helman suggests cycles of beach erosion are influenced by IPO cycles, “The impact of sea level rise during the last few decades has not been expressed due to low storm energy (Callaghan and Helman 2008). Climate variability determines when and how sea level change will occur on the coast. Sea level oscillates with decadal and annual climate variability. Over decades, sea level changes are related to oscillation phases of IPO (Figure 3). It has been shown that during phases of negative IPO La Ninã events are more frequent (Verdon 2007), sea level rises at a faster rate than the long term trend (Goring and Bell 2001) and is higher than the long term trend with high storm energy, are periods of coastal erosion (Helman 2007). The longest period of negative IPO recorded was from the late 1850’s to the early 1890’s and the most recent was from the late 1940’s to the late 1970’s. Both of these periods resulted in major changes and erosion of the coastline (Helman 2007).
Francis Chiew (2003) “The relationship between hydroclimate and El Niño/Southern Oscillation has been used in forecasting rainfall and streamflow. A lag correlation analysis using rainfall and streamflow data from 284 Australian catchments that show that the ENSO-hydroclimate relationship is a lot stronger when the Inter-decadal Pacific Oscillation (IPO) phase is negative compared to when it is positive. The remarkable contrast in the hydroclimate-ENSO relationship between the two IPO phases suggests that the IPO should be considered in developing forecast models, particularly for long lead-time”
McKeon et al (2004) note: “In eastern Australia, good seasons occurred in the early 1890s, late 1910s, early 1920s, mid 1950s, early 1970s and late 1990s. Because of the work of Power et al. (1999), we now suspect that quasi-decadal changes in the Pacific Ocean sea surface temperatures (the Inter-decadal Pacific Oscillation or IPO) may result in the amplification of the effects of La Niña conditions on rainfall in eastern Australia (IPO negative phase). The retention of high stock numbers through subsequent drought periods resulted in the regional degradation episodes. Thus the impact of current favourable seasons in eastern Australia on stock numbers should be closely monitored as an early indicator of increasing risk of degradation, especially when the mode of Pacific Ocean behaviour returns to conditions that appear to make ‘big wets’ unlikely (i.e. positive IPO condition). Historical evidence indicates that where conservative stocking policies have been adopted, or when rapid reduction in stock numbers occurred in response to the onset of drought, degradation appears to have been minimal.”
We should also not forget the irony that seminal research on the physical basis of the IPO has been done by the Bureau of Meteorology (Power) and the Hadley Centre (Folland), alleged centres of the great “AGW conspiracy”.
And in terms of Bob Carter’s proposed Plan B there is one experimental long lead forecast system, SPOTA, that uses ENSO and the IPO to make a long lead forecast for Queensland. Interestingly this system uses gradients of seas surface temperature across regions not sea surface temperature boxes in an attempt to “climate change proof” the forecast i.e. the Norfolk Hawaii Index (NHI); and 2) the South West Pacific Index (SWPI)
So is there any evidence for any AGW effect (or interaction) on Australia’s rainfall climate in a sea of natural variability and how would you even find it?
Part 2 will discuss any evidence for AGW influence.