Issue 55: La Niña
December 15, 2022
In this week’s issue: We explore the La Niña climate phenomenon; an antipodal reef and shoal bridge the Earth; and a lake shifts colors in Mongolia.
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Feature Story: La Niña
If you’ve ever been on a plane during a toddler’s tantrum or the opening of an old tuna sandwich, you know all too well how interlinked (and inescapable) the air is. The processes that move, shape, and dictate Earth’s atmosphere are far more complex than a plane’s. But there are still some local phenomenons that have a direct and measurable impact on the global system. And two of these are particularly influential: El Niño and La Niña.
Earth’s climate is on a quest to stabilize itself. And we’re on a quest to transform discussions about the weather from small talk to big. So as La Niña enters its third winter in a row, we’re taking a look at its imposing fluctuation: how it works, what it looks like, and what it all means.
The equatorial Pacific Ocean generally rests at a neutral state. But every 3 to 7 years it oscillates between El Niño’s warmer-than-average sea surface temperature (SST) and La Niña’s lower-than-average SST. Together this irregular climate pattern is called ENSO. During La Niña periods strong trade winds blow warm water towards Asia and Australia, affecting local weather with either too much or too little water. El Niño is its equal and opposite reaction, doing everything La Niña does but in reverse.
Graphics of temperature spikes and trade winds during these periods look like a Star Wars space battle, with masses of red and blue firing like lasers across the Pacific. But these maps are indicative of a larger disruption. By altering normal weather patterns, La Niña and El Niño tend to flood some areas while drying others. La Niña is typically associated with increased rainfall in Asia, Australia, and the Pacific Northwest, and drought-like conditions in parts of South America and the Southwest US.
But La Niña has catastrophic consequences for non-Pacific-adjacent countries as well. What comes up must come down. And in the case of La Niña that means a give-and-take with moisture. Pakistan’s horrific floods this summer were partially driven by La Niña’s shift of water away from the southern US and towards Asia.
Like a soccer match, it takes one of our satellites just over 90 minutes to lap the globe (but with more Doves and fewer dives). Meaning that one of them could ostensibly capture images of drought in Brazil and a flood in Australia 45 minutes apart (more on antipodes later). Earth’s climate is massive, but observing its interconnectedness is easier than it has ever been before. And over the past few years we’ve watched, measured, and shared the extent of these variations.
La Niña-related damages from floods and fires are easy to spot in satellite images. But we can also use sets of satellite data to map just how much water is in the surface layer of soil. Certain satellites can measure passive microwave radiation coming from Earth. And since the signal is strongly reduced by the presence of water molecules, these sensors can easily detect moisture differences in the land. Maps generated from this data show just how stark these gradients can be in regions like the US Midwest.
These data-maps depict a particularly disturbing trend for the world’s largest tropical wetland, Pantanal. The past three La Niña winters have helped push the region further into drought. As the wetland dries it becomes more vulnerable to fires. And, as its name suggests, it’s an ecosystem conditioned to abundant moisture.
Here’s the thing: the greater the climate variance, the more unpredictable and extreme resulting climate events will be. But we have tools to help rein in the variables. And that helps us prepare for ENSO’s unequal distribution of rainfall — a pattern that’s exacerbated by our tinkering with the climate. We may not be able to stop the floods or the droughts. But we can remember that we live within a complex system, are at the whim of something far more powerful, and then do our best to make do within these parameters.
Antipodes
Ever wondered where you’d end up if you dug a hole through the Earth under your feet? Well there’s a good chance it would be in water. But if you did hit land, it likely wouldn’t look much like where you’re standing right now. Points like these are called antipodes: diametric opposites that are as far away from each other as possible. And while most are unalike — think London and New Zealand — others are surprisingly similar. Here’s a reef in the Red Sea with its near-antipode, a shoal in Hawaii.
What in the World: Khar-Us Lake
While some places far apart look similar to each other, others don’t even look like themselves after a few months. Khar-Us Lake is one of a few in Mongolia’s Great Lake Depression. Reed islands along the shore change with the season while freshwater freezes, creating nearly unrecognizable scenes over the months.
