You have a gazillion gallons of warm water and ...

So just what is happening with El Niño and why should you care??

For hundreds of years along the rocky coasts of Peru, fisherman noticed that about every half dozen years the water would warm up, the fish would go away or die off, and the weather would get stormy. The fishermen didn't know what caused this, but their fathers, grandfathers, and further back knew of these regular changes. Since it always coincided with Christmas time, they named it "The Child", or "El Niño" in reference to the birth of Jesus.

We now have strong evidence that El Niño events have been occurring for over 7,000 years!

In the 21st century we have a much better understanding of what happens that caused this warm water along Peru. One of the reasons we talk about it so much is that it affects the entire Pacific Ocean and well beyond. Scientists can see records of regular El Niños in sedimentary records (the sediment layers in the bottom of the ocean and lakes). We now have strong evidence that El Niño events have been occurring for 7,000 years (Cobb et al., 2013)!

To fully understand El Niño and the changes it brings, we need to understand what a normal year looks like in the Pacific.

Under normal conditions, the winds along the equator blow from east to west. These winds are so regular, that sailing ships would rely on them to sail west along the equator to trade goods and called these winds the "trade winds". The winds also cause the water to move from the east to west along the ocean's surface (Figure 1). Since the equator is also where we have a lot of sun heating the water, the trade winds in the Pacific push this warm water to the west.

Figure 1. Typical conditions in the Pacific Ocean with the trade winds blowing to the west pushing warmer water to the western side of the Pacific. (Image from NASA).

Figure 1 shows the warm water (red) moving to the west due to the trade winds. Two important things happen with this mass of warm water moving west. First, the warm water is generally depleted of nutrients. The critters living in the ocean surface have essentially used up all of the nutrients or they have settled down to deeper water. Under normal conditions the ocean replenishes these nutrients through "upwelling" on the eastern Pacific.  When the mass of warm water moves west, it is replaced by deeper cooler ocean water that has a lot of nutrients.  The upwelling helps cycle nutrients back into the ocean surface and keeps the fish and other ocean creatures happy.

These "normal" conditions are like clockwork. For centuries sailors and fishing communities throughout the pacific documented and relied on these regular currents and winds. Any change from normal conditions created a lot of problems to folks relying on the ocean for food and livelihood.

Every half dozen or so years (two to seven more accurately), the coastal people in Peru and Ecuador would notice large fish kills and a general decrease in all fish populations. As mentioned, it happened regularly enough that they named it El Niño since it typically peaked around Christmas time. So what's happening?

Warm water sticking around in the eastern pacific plays havoc with the entire ocean ecosystem

The trade winds die off and even reverse periodically. There are multiple theories as to why this happens, but still no definite conclusion.  The fact is that it happens, and fairly regularly. The slackened and reversed trade winds stop pushing the warm water west and allow it to "slosh" back to the east. Warm water sticking to the eastern pacific plays havoc with the ocean ecosystem and weather patterns.  Figure 2 below shows El Niño conditions with warmer water on the eastern side. The warm water creates lower pressures due to the rising air and the lower pressures bring moisture aloft to form more clouds and alter the normal jet streams. All in all this typically means wetter and stormier weather!

Figure 2. El Niño conditions in the Pacific Ocean. The trade winds have died off and allow warm water to come back to the east side of the Pacific along the coast of the Americas (Image from NASA).

As we saw earlier, the warm water is generally depleted of nutrients. The El Niño conditions allow the warm water to stick around in the eastern Pacific.  The normal upwelling that brings the nutrients back to the ocean surface is shut down. Without these nutrients the critters modify their migration patterns and can even die off resulting in the fish kills the Peruvian fishermen would observe.

The cause of El Niño: Generally slackened trade winds, which normally push warm water to the western pacific, allow warm water to build up along the eastern pacific.

The results of El Niño: Warmer water along the western pacific results in wetter and generally stormier weather along the western pacific basin. The warm water is nutrient depleted which causes many changes in the ocean ecosystem including animal migration alterations and even fish kills.

What's the ocean doing now?

The Office of Satellite and Product Operations at NOAA compiles maps of Sea Surface Temperatures (SST) from a number of observational satellites in orbit. You can view these at any time here. The most common way to look for changes or differences in SST is through what's called the anomaly. The SST anomaly is the long term average SST is subtracted from the present SST. A negative value means the ocean is colder than average and a positive value means the ocean is warmer.

Armed with SST anomalies, we can take the first peak at what is happening in the Pacific. If we take a look at September of last year (2014), it gives us something to compare this year with. Figure 3 below is the SST anomaly from the 29th of September 2014. Generally the Pacific was warmer, but its a distribution of warm and cold within a few degrees of normal. Nothing that exciting or alarming. Technically the El Niño conditions we are seeing now started to rear their head in 2014, but all in all we didn't see much of a traditional El Niño effect last winter.

Figure 3. Sea Surface temperature anomaly from January 2015. (Image from NOAA).

Let's catch up to 2015. September 28th, 2015 is plotted  in Figure 4. Compare the amount of red and orange with Figure 3 above. We see a huge mass of water extended from the eastern pacific across the equator.  This water is 3 to 5 degrees C (nearly 10 degrees F) warmer through these areas There is a huge blob of warm water built up in the eastern pacific! This definitely has all the makings of a powerful El Niño.

Figure 4. Sea Surface temperature anomaly from September 2015. (Image from NOAA). 

There is a lot of heat energy there, but it's been slow in building compared to other El Niño's

Scientists called the 1997 El Niño a "super" El Niño. It was devastating to many coastal communities causing landslides and flooding along the eastern coast of the Pacific Ocean and drought and famine throughout other portions of the globe! So how does that factor into the situation setting up presently. Below is a video from NCAR comparing SST anomalies from 1997 and present.  One thing is fairly apparent, the patterns are of similar size and magnitude. While there are many other factors governing how much the El Niño will ultimately affect us, one things is certain, something sizable is setting up. One forecaster has likened it to a slow moving trainwreck. There is a lot of heat energy there, but it's been slow in building compared to other El Niño's. Overall scientists agree it will be a strong one!

We'll continue to monitor and provide regular updates here. Follow our newsletter by signing up at the WaveClock website.  Be sure and check out some of our latest WaveClocks available now on ETSY so you can monitor El Niño this winter in REAL TIME!!

Thanks for reading on and talk to you soon!
Craig


Cobb, K.M., N. Westphal, H. Sayani, E. Di Lorenzo, H. Cheng, R.L. Edwards, C.D. Charles, Highly variable El Nino-Southern Oscillation throughout the Holocene, Science DOI: 10.1126/science.1228246, 2013.