As prominent ocean researcher and climate scientist Dr. Kevin Trenberth presciently noted during recent years — an observed spike in ocean heat content over the past decade may well be coming back to haunt us.
Earlier this year the most intense sub-sea Kelvin Wave on record raged across the Pacific Ocean. Driven eastward by a series of strong westerly wind bursts, it traveled just below the surface, running out to collide with South America. By April, it had arrived in the traditional El Nino spawning grounds of the Eastern Equatorial Pacific where it retained an extreme intensity. There it sprawled, snuffing off the cold deep water upwelling that over the past few years has kept surface water temperatures in this critical region slightly cooler than average.
And so, from late March through mid-May, the Eastern Pacific warmed.
A surface warm pool sprang off the back of this beast, growing even as it continued to gather heat, radiating it back into the atmosphere. By yesterday, temperature anomaly values over this growing region had increased to between 1 and 3 C above average with local spikes up to +3.9 C — a far above normal temperature departure for ocean surface waters, especially near the stable equator. But if trends hold, this is just the beginning. An early start to what could be a record-setting event.
(Today’s GFS model summary of global sea surface temperature anomalies. See the mottled red just off South America? That’s the head of an extraordinarily strong and massive Kelvin Wave breaking the surface. Image source: University of Maine.)
Today’s GFS global ocean temperature anomaly map shows the entire Equatorial Pacific well in the El Nino range at +0.60 C. The strong +1 to +3 C or greater hot zone, shown in orange to deep-red, stretches from about 140 West to 80 West Latitude along the equator and shows continued slow intensification.
Note that global sea surface temperatures for today are at an extraordinary +1.12 C above already warm 1979 to 2000 values. This marks more than a week of 1 C or greater positive ocean surface temperature anomalies. The very definition of Trenberth’s ocean heat content coming back to haunt us.
The El Nino Clock Begins
Meanwhile, NOAA weekly anomaly readings also show continued progression toward surface warming. Overall, the Nino zone 4 in the Central Pacific was at +0.8 C, the Nino 3.4 zone in the East- Central Pacific +0.5 C, the Nino 3 zone in the Eastern Pacific +0.6 C, and the Nino 1+2 zone just off the coast of Equatorial South America a very high +1.2 C. Overall, this shows strong warming over the broad Nino sector with the key Nino 3.4 zone flipping into low El Nino levels this week.
The emergence of Nino 3.4 into +0.5 C or greater territory marks the start point for the NOAA El Nino clock. For NOAA to declare El Nino, the Nino 3.4 zone must remain at +0.5 C or above for multiple months running. And forecast models, at this time, show nearly an 80% likelihood of just such an event for 2014.
So this week’s readings represent the crossing of a new threshold toward El Nino and certainly warrant further tracking.
Monster Kelvin Wave in Not-so-Cool Phase
The extreme Kelvin wave that raged across the Pacific from February through April still appears monstrous even though it has now entered its supposedly cool, upwelling phase. Pressed against the coast of South America, the heat has deflected both upward and downward through the water column. The result is both a continued heating at the surface and a downward thrust of 1-2 C above average water temperatures into the 400 meter below surface zone. And so here we have a continued down-thrust of the 20 C isotherm, priming the Pacific for another west-to east rush of deep ocean heat later this year.
(This is supposed to be the Kelvin Wave’s cool phase. It’s not looking very cool. Image source: NOAA.)
Overall, the still amazingly hot Kelvin Wave is upwelling. So it should also be cooling. And it has. A little. But what is extraordinary is the amount of heat it has retained even as it rises. Here we see an enormous slug of 5-6 + C above average water rising as high as 40 meters beneath the surface. Maintenance of this high heat content even while upwelling is an insane feat of heat propagation. Should these readings hit the surface, we really will be witnessing a monster event.
Already, the warming Eastern Pacific appears to be having a broader atmospheric affect. According to NASA, global surface temperatures spiked to their second highest level on record in April. Meanwhile, GFS model analysis shows May daily surface temperature values in the range of +0.7 to +1.0 C or higher above the 1950 to 1981 average globally. A continuation of these high temperatures would be enough to put May at first or second hottest on record and set a trend for 2014 to break global high temperature records last seen in 2010. So the early and not yet fully developed ocean surface heating we are seeing from our developing El Nino appears to have already come back to haunt us. But what we see now is minor compared to what could emerge.
With the sub-surface waters remaining so extraordinarily warm even through the upwelling/cool phase of the current Kelvin Wave, the Pacific is now primed for a second hot pulse to feed the monster now rising off South America. The new, reinforcing heat pulse will require another series of west wind back bursts at the surface between 160 East and 170 West Longitude to drive it. And atmospheric conditioning for the development of these winds appears well in play. Should it happen, we are likely to get a taste of what Dr. Trenberth really meant.
Dr. Trenberth Hints at PDO Flip
Along with these sobering thoughts, I leave you an excellent related interview Peter Sinclair conducted with Dr. Kevin Trenberth. In the interview, Trenberth predicts a + 0.2 to 0.3 C rise in global average temperatures due to Pacific Ocean surface heating and hints that a flip in the Pacific Decadal Oscillation (PDO) from its current cool (negative) phase to a new warm (positive phase) may well be underway. Such a flip would indeed mean that a rapid spike in global surface temperatures is in the offing: