ENSO (is taking over my life)

It’s been awhile since I’ve posted some hard-core science (and I’m totally a day late on my Wednesday post-day), so I felt this week was as good as any to let you all in on my not-so-well-kept secret of a PhD project that has been taking over my life. The topic: paleo-ENSO.

To start, let me define what the heck that means. Paleo = ancient. ENSO = El Nino Southern Oscillation…so I will be studying ancient El Niño Southern Oscillation. Still have no idea what ENSO is? Well for one, you should. And two, ENSO is the leading mode of climate variability on Earth today. In non-ENSO-studying-PhD-student terms, ENSO is incredibly important for short term changes in climate and has a massive impact on weather, precipitation and drought patterns around the world, including the current drought and resultant fires slamming Indonesia (click here for good review on the variable impacts of El Niño around the world — I promise it’s not a trap). ENSO is initiated in equatorial Pacific (you know, the region in the Pacific ocean that’s closest to the equator), but that doesn’t stop it from dipping it’s selfish hands in everyone else’s business.


 

Diverging from the paleo for a bit, let me explain a bit more about ENSO.

ENSO includes two very prominent phases, which I’m sure you are at least somewhat familiar with in the deepest parts of your brain: El Niño (“warm” episode) and La Niña (“cold” episode).

El Niño

El Niño is the “warm” phase of ENSO. I put warm in quotations because the warm refers to sea surface temperature anomalies (the difference between observed sea surface temperature and average or normal sea surface temperature) in a very specific location in the eastern equatorial Pacific, which is referred to by all us fancy scientists as the Cold Tongue (named because under normal conditions, this area is cool). Simply put, during an El Niño event (like the one that we are in right now), the water in the Cold Tongue warms up.

Now, this sea surface temperature warming doesn’t just sit there all by itself doing nothing–the atmosphere wants to play too (sometimes). And when the atmosphere decides to play ball, that’s when things get interesting. Anomalous warming in the eastern equatorial Pacific (often, but not always) triggers a response in the atmosphere, which results a shift in atmospheric circulation. This shift in atmospheric circulation brings rain to the southwestern US and northwestern South America, and drought to Indonesia, parts of northeastern Australia and even South Africa.

La Niña

La Niña is the “cold” phase of ENSO. Again, I put the cold in quotations because the cold refers to sea surface temperature anomalies in the Cold Tongue of the eastern equatorial Pacific. During a La Niña event, the water in the Cold Tongue gets colder (yes… it does that). The atmosphere feels these cooler temperatures (just as it feels the warmer sea surface temperatures during an El Niño) and “cool” stuff happens. An opposite shift in atmospheric circulation brings rain to Indonesia, northeastern Australia and South Africa and drought to the southwestern US and northwestern South America.

Some final notes on ENSO before I move back to the paleo side of things:

(1) Not all El Niño or La Niña events are the same–there is a lot of variability in how these events present themselves both in the ocean and the atmosphere and in what impacts are felt around the globe.

(2) If the atmosphere doesn’t want to play ball, a full blown El Niño or La Niña event is highly unlikely. (Case and point, last year’s failed El Niño).

(3) El Niño events tend to me much stronger in amplitude than La Niña events, and therefore tend to gather more interest in the popular media. (There are also scientists who believe that La Niña events are simply just a slight amplification of normal conditions, and therefore not a “real” event… but that’s a discussion for another time).


Okay, now back to the paleo.

Why study paleo-ENSO?

(1) Paleo for paleo’s sake.

It’s interesting! The Earth is cool, guys, and studying everything about it is super exciting (#geologyrocks). But sad-face, I had to pick one topic to focus on for the next few years and ENSO just won me over.

To get more serious: The way in which ENSO presents itself today in the modern is likely not how ENSO presented itself in the past. Studying ENSO in the past can help us better understand the phenomenon itself. (But really, it’s just super cool).

(2) Paleo for the future’s sake.

Scientists have no idea how climate change will effect ENSO. Models disagree about how variable (i.e. how often El Niño and La Niña events occur) ENSO will be in the future. One way to resolve this issue is to test models against data collected from ancient time periods to observe how well these models simulate paleo-ENSO (i.e. run these models for a time period we understand well in the past and compare the model outputs to non-model data from the same time period). Any divergences between these models and robust (i.e. accurate, precise and thoroughly vetted) ancient data would suggest a huge misunderstanding of the basic physics of ENSO in the models. However, in order to do this you need really, really good data. And for anything older than ~10,000 years, we don’t have that. And this is where I (super-paleo-ENSO-PhD-student) come in.

To condense that whole paragraph down into one sentence: Understanding ENSO in the past is vital for understanding how ENSO will change in the future.


Okay cool, but how do you study paleo-ENSO?

GEOCHEMISTRY!

Specifically carbonate geochemistry (see my about me bonus for a lengthy discussion). I’m not going to get into all the dirty details, but simply put, scientists can extract a glorious amount of climate information from carbonates. One of these things is sea surface temperature. And when sea surface temperature data is collected from ENSO affected regions in the equatorial Pacific Ocean (particularly those regions which are being used to monitor ENSO today)–BAM, you have a way to reconstruct ENSO. Now of course there a lot of complicated things that go into this sort of analysis, such as the need for high resolution records (i.e. a record that preserves the short-term variability of ENSO) and incorporating other proxy data results from around the world, but it can AND has been done. (And I’m going to do it–for a period of Earth’s history for which we have absolutely no idea what in the world ENSO was doing).


 

I’ve spent most of this semester learning all things ENSO. I’ve written a National Science Foundation Graduate Research Fellowship Program proposal on it. I’m collecting all the papers I can find about it. I’ve been talking to members of my PhD committee about it.

And the best part… I get to do this for five years.

#HappyENSOing

 

 

 

 

 

 

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