(Kevin Wave continues to strengthen and propagate across the Pacific Ocean. Image source: NOAA’s Climate Prediction Center.)
Record global temperatures, extraordinarily severe storms for the US West Coast and telegraphing on through the Central and Eastern US, a disruption of the Asian Monsoon and various regional growing seasons, record heat and drought in Northern Australia, severe drought and fires in the Amazon, the same throughout Eurasia and into the Siberian Arctic, another potential blow to Arctic sea ice. These and further extreme impacts are what could unfold if the extraordinarily powerful Kelvin Wave now racing toward the Pacific Ocean surface continues to disgorge its heat.
The most recent update from NOAA shows that the monster Kelvin Wave we reported on last week has continued to grow and intensify even as it shows no sign of slowing its rather ominous emergence from waters off the west coast of South America.
The pool of 4-6+ degree Celsius above average temperatures continues to widen and lengthen, now covering 85 degrees of longitude from 170 East to 105 West. Perhaps more disturbing is the fact that the zone of extreme 6+ C temperature anomalies has both widened and extended, covering about 50 degrees of longitude and swelling to a relative depth of about 30-40 meters. This is an extraordinarily intense temperature extreme that well exceeds those observed during the ramp-up to the record 1997-98 El Nino event.
Meanwhile, a smaller, but still disturbing, zone of 3-6+ C above average temperatures has now developed just 100 feet below the surface along a line near 100 degrees West Longitude. It is a very strong heat pulse, the head of the Kelvin Wave that by late March had pushed its nose up in the Eastern Equatorial Pacific.
(Deep, hot Pacific Ocean water continues to shift east. Image source: NOAA’s Climate Prediction Center.)
In the above NOAA graph we can see the hot, deep pool in the Western Pacific gradually flowing eastward, spreading out and shallowing as it begins to dump its heat content back into the atmosphere. A return of stored ocean heat that will, likely, spike global atmospheric temperature values all while sparking off a series of very extreme weather events.
Warm Storms Continuing to Pull Heat Eastward and Upward
The west-to-east progression and upwelling of Pacific Ocean heat is currently facilitated by low pressure systems lining up along the equator. The lows are fed by heat and evaporation bleeding off the Pacific Ocean surface. This heat enhances the formation of thunderstorms that join into larger, heat-driven cyclonic systems. The countervailing circulations of these systems act to slow the trade winds while allowing the hot pool to spread further and further east.
It is a pattern that tends to emerge at the beginning of most El Nino events. A self-reinforcing cycle that draws energy from ocean surface heat even as its intensity is enhanced more and more by heat transfer from the depths.
(GFS model guidance through April 13 shows a persistent cyclone off New Guinea interrupting the trade winds — lower left — even as a long trough is predicted to form over the Eastern Pacific just north of the Equator — lower right. This pattern would tend to enhance the formation of El Nino conditions throughout the forecast period. Image source: NOAA)
It is the kind of cycle in which the excess Ocean heat, amplified by human-caused global warming, and long stored in the Pacific, as Dr. Kevin Trenberth well observed, may now be coming back to haunt us.
Conditions of a Human-Altered ENSO Cycle Compared to the Most Recent Warming at the End of the Last Ice Age
The La Nina to El Nino cycle (ENSO) is part of a larger ocean and air energy transfer pattern in which heat is periodically stored in the vast equatorial waters of the Pacific before being returned again to the atmosphere. In a normal climate state, this dance of heat energy between the airs and the waters would result in simple periodic variation appearing at the peak of either La Nina (atmospheric cool extreme) or El Nino (atmospheric warm extreme). But because human warming has now added a very strong and rapid heat forcing to this natural cycle of variability, La Nina periods have displayed slower rates of atmospheric warming (where they should have showed cooling) and El Nino periods have often resulted in temperatures spiking to new global records.
Natural variation, in this case, rests on a curve that we are forcing to bend inexorably upward.
Of the .8 degrees Celsius worth of annual global warming experienced since the 1880s, about .15 C, or nearly 20 percent of this warming, occurred during the powerful 1997-98 El Nino event in which vast amounts of stored ocean heat returned to the atmosphere. Since 1998, the Pacific Ocean has undergone a long period of La Nina events in which a large store of atmospheric heat was transferred to the global ocean system. But despite this enormous heat transfer, global temperatures continued to climb with new records achieved in 2005 and 2010 during relatively weak to moderate El Nino events.
For the currently emerging El Nino, all indications point toward it being as strong or stronger than the extraordinarily powerful 1997-98 El Nino, perhaps readying to raise global temperatures by another .15 C or more.
(April 1 Sea Surface Temperature Anomaly Map shows a band of 1-3 C above average temperatures covering the Equatorial Pacific. It’s a marked difference from the slightly cooler than average conditions that have dominated for much of the past year. Given the current Pacific Ocean weather context and the very strong Kelvin Wave lurking just beneath the surface, it appears to be the start of a powerful El Nino phase. Image source: NOAA/ESRL)
For context, the difference between the 1880s and the last ice age was about 4 degrees Celsius. A temperature change that took about 10,000 years to complete. The total current warming of .8 C is equal to about 20% of the difference between the 19th Century and an ice age, but on the side of hot. This warming occurred at extraordinary velocity, over the course of little more than a century. An extreme pace of warming now between 30 and 40 times faster than that at the end of the last ice age. A pace of global heat accumulation that has not been seen in at least 65 million years.
Under business as usual fossil fuel emissions, even that very rapid pace of warming could more than triple over the coming decades, producing a warming equivalent to what occurred during the end of the last ice age over the course of 10,000 years in less than 200. A disastrous pace that will wreck untold harm on the world’s weather systems, climates, ocean systems, geographies and ecologies should it emerge. A pace of warming that likely has no corollary even in the Permian Hot House Extinction Event of 250 million years ago.
In the current cycle of human warming, a strong El Nino can push that measure by as much as 5% or more in just a single year. So we may well see global average temperatures of 1 C higher than 1880s values by the end of 2014-2015 should the current and very powerful El Nino continue to emerge.