Dr. Dillon Amaya

Hi, thanks for having me.

At its most basic level, an El Nino is just simply a warming of the eastern equatorial Pacific Ocean.

Typically, we define it as a period of time where that pocket of ocean gets more than about half a degree Celsius for five consecutive three-month averages.

Yeah, typically El Niños occur about every three to five years, and they're often paired with La Niña events, which is sort of the cold phase of what we call the El Niño-Southern Oscillation, which is sort of the total package.

That's a really, really interesting science question.

It's something that we're actively trying to understand better as climate models get better and better.

Right now, we do know that every El Niño is going to be warmer than the last, and that's primarily because of something like global warming.

Yeah, primarily because we expect this event to be really big.

By big, we mean something like 2 degrees Celsius warmer than normal.

And that may not sound like a lot, you know, jumping into the ocean in that part of the world.

You may not be able to notice the difference on your skin, but the atmosphere and the broader climate system definitely will notice the difference.

Right now, the models give it about a 25% chance of a very strong, strong or moderate strength El Nino developing this summer and into the fall and winter.

Well, to understand exactly how an El Nino happens, you kind of have to have a sense for, you know, what are normal conditions along the equatorial Pacific.

Generally speaking, we have what are called the trade winds, which are these east to west winds along the surface of the ocean.

And that pushes warm water from the eastern equatorial Pacific all the way to the western equatorial Pacific.

I'm talking over by Indonesia.

And if those winds were to relax for long enough periods of time, a lot of that warm water sloshes all the way back to the eastern equatorial Pacific over by the coast of places like Peru.

And that can cause dramatic increases in temperature in that part of the world.

In short, El Nino can drive wholesale changes in atmospheric circulation and precipitation patterns all over the world.

And the reason for that is because it's really dragging rainfall from places where it normally happens, like the Western Equatorial Pacific,