The discussion on the IOD has been about the phase of any expected IOD.
And at this stage if an observable phase of the IOD is not already obvious and observable then in all likelihood any tendency for a reasonably strong phase of either colour is probably disappearing into the blue yonder where all still born IOD's go.
Nor was there a decent cyclone in the Bay of Bengal in that critical time slot of the April May, June period which appears to be one of the major triggers for the larger percentage, but certainly not all of the recent positive IOD's.
In fact the data says there has been NO cyclones in the Northern Indian Ocean, ie; the Arabian Sea and the Bay of Bengal in 2012.
Still possible but far less likely now as one of the probable triggers for a positive IOD, a severe Bay of Bengal cyclone,
This then goes a long way towards ruling out a strong positive IOD. 2012 North Indian Ocean cyclone season
For some background on those very warm Indian Ocean SST's we can look at the ocean guru, Bob Tisdale's site "Climate Observations"
to gain an insight to the changes and influences on the Indian ocean temperatures, both at depth and it's SST's.
This quote [ amongst many along the same lines from Bob ] from a reply to a comment on his post Guilyardi et al (2009) “Understanding El Niño in Ocean-Atmosphere General Circulation Models: progress and challenges”
[ The ENSO guys should take a look at this as well as those who have founded their beliefs and ideology in global warming on the basis of the predictive capacity of climate models.]
From Tisdale's reply to a commenter;
John Moore: Let’s divide the global oceans into three subsets.
The North Atlantic has the additional variability of the AMO on top of the warming of the other ocean basins. There is evidence that its warming may have peaked already so the North Atlantic’s influence on global sea surface temperatures should slow and then reverse. From the mid-1940s to the mid-197os, the North Atlantic was experiencing minor cooling, so it helped to slow the warming rate of the global oceans. Do we expect that to happen again? I can’t see any reason why it won’t.
The South Atlantic-Indian-West Pacific data is where those upward steps occur.
Basically, the upward steps are related to the amount of warm water that’s left over after the major El Niño events. The warm water gets carried into the west Pacific and eastern Indian Oceans and then migrates from there. Some of warm water starts on the surface, and some of that warm water was originally below the surface and rose to the surface via gravity as years passed. There were no super El Niño events, as far as the SST records show, during the mid-1940s to mid-1970s cooling period so there are no references during that period for the upward shifts. If we don’t have any more super El Niño events, and if we’re now shifting over to a period when even lesser El Niño events occur less often, then that South Atlantic-Indian-West Pacific subset SHOULD flatten.
I know your question pertained to those periods between the major El Niño events and whether CO2 is influencing how quickly that subset cools between them. That’s why I prefaced the answer with those two subsets. Because it leads us to the question: is there any evidence that CO2 warms the global oceans? The fact that the East Pacific Ocean has not warmed in 30 years really contradicts the assumption that CO2 drives the warming of the global oceans. It throws a wrench in the whole works. It’s really tough to show that CO2-related downward longwave radiation has any impact on sea surface temperatures with the East Pacific data so flat. The models tell us that subset should have warmed about 0.42 deg C to 0.45 deg C, but it hasn’t warmed at all
And for the future, all that ENSO water ain't doing what the models say it should be doing so the long term ramifications for the Indian Ocean will likely be a cooling in the years ahead as a fair proportion of the westward flow of the ENSO / central equatorial Pacific surface waters [ some goes north out of the Pacific Warm Pool up past Japan in the huge Kuroshio Current
] head out of the major Western Pacific Warm Pool through the Indonesian Through Flow into the Indian Ocean.
IO sub surface flows are probably not well enough known at this stage to indicate how fast and where these cooler eastern and central Pacific origin waters will finish up in the Indian Ocean so don't take it as a given that we are facing a series of pos IOD's ie; warm waters in the western IO and cool waters in the Eastern IO.
Secondly the IOD appears to be fairly location specific with it's warm and cold surface pools to create a definite IOD phase and this also plays a role in the formation of a IOD phase if there is going to be such an IOD Phase.
For the ENSO guys and the longer term Indian Ocean SST's this graph also from Tisdale's comment reply has some significance;
The models and the reality