A cycling between warm ocean surface waters and cool ocean surface waters in the Eastern Pacific called El Nino and La Nina, for centuries, has been a primary driver of relative atmospheric warmth and coolness. During the times when the Eastern Pacific disgorged its heat, the Earth’s atmosphere warmed. And during times when the same region cooled, a portion of atmospheric heat was taken back and transferred into the world’s oceans.
(ENSO Index since 1950. Image source: ESRL/NOAA.)
Since about 1300 CE, this cycling governed the top and bottom ends of average global climate. Temperatures during this time remained within about .3 degrees Celsius of a very stable base line. But beginning around 1900, that cycle was broken, with unprecedented and rapidly increasing warmth proceeding along with an explosive human use of fossil fuels.
Since that time, and especially since the late 1970s, the regular El Nino and La Nina cycle has been a less and less reliable governor of atmospheric temperatures. Certainly the El Nino years were generally hotter — a majority of El Nino years since 1980 were record hot ones. And the La Nina years were definitely cooler. But the overall temperature curve skewed upward and even La Nina years featured within the range of top ten hottest years on record with increasing frequency.
The past five year trend only showed a more extreme amplification, when taken in the broader context of an ongoing ocean heat transfer.
The last El Nino year, 2010, was also the last hottest year on record. Being a relatively lack-luster El Nino, with only moderate warm temperature departures for the Eastern Pacific, it is abundantly clear that human-caused global warming was the underlying driver for this record breaker.
(Global Temperature variation since 1880. Image and data source: NASA GISS.)
In the years that followed, 2011 and 2012 featured La Ninas while 2013 was a year in which the Eastern Pacific is neither warm nor cool (ENSO neutral).
In a normal world, under normal climate conditions, such a long period of cool surface waters covering the Eastern Pacific would have driven global temperatures down below typical averages. The vast waters would have sucked heat out of the air and deposited it into the oceans. And, as we will see below, it did suck a massive amount of heat out. But not enough even to bring global temperatures back into the average range, much less put it below the average (both NASA and NOAA show 2011-2013 as top 10 hottest years on record). This is very concerning, especially when we consider, as we do below, that the rate of atmosphere to ocean heat exchange is currently unprecedented.
Despite four years of ongoing coolness in the Eastern Pacific and of a much more vigorous than usual mixing of ocean and atmosphere, global surface temperatures have remained at or near record highs during a time that should have featured a down-turn. Meanwhile, ocean heat content spiked.
And the start of 2014 is no exception.
Third Hottest January On Record
Come January 2014 with ENSO still remaining on the cool side of neutral, reports from NASA GISS show January 2014 was the third hottest in the climate record since measurements began in 1880. NASA’s Land-Ocean Temperature Index reveals temperatures for the month at .70 degrees Celsius hotter than the 1950 to 1980 average and .90 degrees Celsius hotter than the annual average for 1880.
(Global Surface Temperature Anomaly in degrees Celsius of departure from the, already warmer than normal, 1951-1980 average. Image source: NASA GISS.)
By contrast, January of 2002 and 2003, which were both El Nino years, tied for second hottest in the record at .72 degrees Celsius hotter than the average while 2007, also an El Nino year, showed January at .93 C hotter than average. So the temperatures we are seeing this year, a year in which the Eastern Pacific is still sucking up atmospheric heat, are nearly as warm as recent times in which that same vast stretch of ocean was bleeding heat back to the airs above it.
For atmospheric temperatures to be so hot without the presence of El Nino is, today, an ominous sign for many reasons. First, we are seeing amazing heat spikes in the Arctic. And these spikes largely drove the January temperature anomaly — a clear sign that northern polar amplification is becoming a powerful driver of continued atmospheric warming in its own right. One that may play a harmonic role with the ENSO cycle as the next few decades progress. Second, we may be beginning to see that the ocean, which has taken up so much excess atmospheric heat is starting to lag as a sink even as it is grudgingly shoved back toward dumping a portion of that extraordinary excess warmth into the atmosphere.
As mentioned above, we have seen an unprecedented transfer of heat into the surface, middle and deep ocean over the past decade. And the Argo float graph below bears a stark testimony to this transfer:
(Image source: L Hamilton. Image data: NOAA. Produced for The Arctic Ice Blog. Note the extraordinarily steep slope indicating recent ocean warming.)
Note the huge jump in ocean heat content that began in 2001 just as the most recent negative PDO and La Nina cycle began to kick in. This vast heat content is now a latent source for atmospheric warming that will, as many scientists note, almost certainly come back to haunt us once the ocean heat uptake mechanism is exhausted.
This Unprecedented Heat Transfer
The graph above provides us with much cause for concern, as ocean heat is certainly spiking. But a recent study provides yet another important indicator — an extraordinary jump in trade wind intensity.
A primary driver of the strength of La Nina and its ability to transfer atmospheric heat into the oceans is the corresponding strength of the east to west trade winds blowing across the Pacific. A strong trade wind blowing over South America and shoving a huge pile of water across the Pacific from east to west generates vigorous upwelling. The strong upwelling, in turn, transfers relatively cool deep ocean waters to the surface, where they take up atmospheric heat. When the trades weaken, the opposite occurs and warmth builds up in the surface waters along with a corresponding shift to El Nino.
Given these factors, it is important to note that a recent study has found that the trade winds over the past decade have been their strongest since at least 1910 with the wind continuing to strengthen and intensify well into 2012.
(Global temperature and wind anomalies with IPO overlay. Negative departures in the lower graph indicate unprecedented trade wind strength through 2012. Image and data source: England Study. Note — IPO stands for Interdecadal Pacific Oscillation, a condition related to El Nino and La Nina cycling over decadal periods.)
With such strong trade winds blowing over the Eastern Pacific, we are seeing an unprecedented transfer of heat from the atmosphere to the ocean (validated by both the trade winds data and the Argo float data). And given the strength of this transfer, we should be seeing some of the strongest La Ninas on record. But the ocean is now too warm for that, so instead we are seeing consistent La Ninas of normal caliber over the past 14 year period. A set of La Nina’s consistent enough to shift the Pacific Oscillation into a negative mode and, according to the England study, to temporarily suppress overall atmospheric warming by between .1 and .2 degrees Celsius.
And what this means is that when we see the period of consistent La Ninas end and shift to a time of more consistent El Nino events, that .1 to .2 degree Celsius heat transfer from atmosphere to ocean will stop and we will likely see a correspondingly rapid jump in air temperatures.
In a recent interview with The Guardian, England noted:
“the heat uptake is by no means permanent: when the trade wind strength returns to normal – as it inevitably will – our research suggests heat will quickly accumulate in the atmosphere. So global temperatures look set to rise rapidly …”
Model runs conducted by the England study that take into account trade wind strength and rate of heat transfer into the oceans show an extraordinarily vigorous increase in global temperatures of .2 C to .4 C by 2020 once the global trade winds return to normal. This, potentially very rapid, jump in atmospheric temperatures could be seen over a very short period during the next six years once the trade winds abate and the Eastern Pacific settles again into a more consistent period of El Ninos.
Models Show El Nino May be on the Horizon for 2014
Meanwhile, NOAA models are also beginning to hint that the hammer of Pacific Ocean heat may well be starting to fall. A majority of model runs, as of late January, were showing El Nino emerging in the Pacific by summer of 2014. Five models showed El Nino on the 9 month horizon, while two showed La Nina and three showed ENSO neutral conditions.
The NOAA Earth Systems Research Laboratory explained these findings:
Of the 10 nearest ranked December-January cases since 1950, FIVE rose to at least weak El Niño status within the next nine months (two within the next three months), while the count of weak or stronger La Niña rankings added up to two cases (1961 and 1967) after nine months. This confirms a noteworthy shift in the odds towards El Niño development in 2014 that was first pointed out two months ago. Compared to last month, the number of cases ending up as ENSO-neutral has dropped to 6 in three months, 5 in six months, and only 3 in nine months (September-October).
… While ENSO-neutral conditions are the safest bet for the next few months, a transition towards El Niño by mid- or late 2014 would not be surprising, perhaps even overdue.
How the Temperature Jump May Unfold
In light of the above reports, it is important to again state how rapid an atmospheric temperature increase of .2 to .4 C over the course of six years is. By comparison, the average decadal increase has been about .15 to .2 C for each 10 year period since the 1970s. So the England study suggests that atmospheric heating could double the usual rate between now and 2020.
What we would expect under such conditions is a gradual abatement of the current and unprecedented trade wind strength over the Pacific Ocean. As the trades weaken, the pool of very hot, deep water east of Australia and the Philippines would begin to shift eastward even as the Eastern Pacific took on uncharacteristic warmth. The long period of mixing with a rapidly heating atmosphere will have created an amazingly large and deep pool of hot water whose intensely high temperature anomalies become increasingly evident at the surface. The hot zone, in this case, exceeds even the extreme anomalies seen during 1998 for this critical region and a massive heat dump into the atmosphere begins.
At this point, single year variations above past record highs may reach or exceed +.1 C or more for multiple years running.
The unprecedented heat bleed from the Pacific doesn’t occur without a number of severe weather consequences. Especially under the gun for this, most recent, potential event of human caused climate change is California and the Desert Southwest. Having labored under drought since the early 2000s, the region sees a radical shift to unprecedented stormy conditions. During winter, a massive flow of heat driven moisture rides up from the Pacific and arcs over California carrying with it a stream of storms. The stormy period drags out for weeks, beginning to resemble the megastorm of centuries past. Cities and industries laboring under the strain of too little water see a sudden and radical, though brief, shift in the opposite direction. California, under the gun for tens of billions of dollars in damages from water shortages and drought instead falls under the gun for possibly hundreds of billions of dollars in storm damages.
El Nino related weather extremes crop up in Africa, Australia, the US East Coast, India, the Pacific Northwest, and in other locations. In all cases the extremes are far more radical than for a typical El Nino year.
Under such a regime, it is likely that global surface temperatures could reach 1 degree Celsius above the 1950 to 1980 average and 1.2 degrees Celsius above the average seen during 1880 by 2020. Very dangerous warming and related extreme weather would be well underway at this time under such conditions along a path toward an even more difficult and violent climate scenario to follow.
Recent Intensification of Wind-Driven Circulation in the Pacific
Unprecedented Trade Wind Strength is Shifting Global Warming to the Oceans
The Pacific Arkstorm
NASA’s Land-Ocean Temperature Index
Arctic Heat Pushes Sea Ice to Record Low Levels in Early February
The Arctic Ice Blog
The NOAA Earth Systems Research Laboratory