The Ocean Knows First: What I Learned About El Niño While Building This Project

I grew up in Port Moresby, where we have only two seasons: dry and rainy. That is simply how life works here. When the dry season stretches longer than usual, we notice the heat, the dust, and sometimes the water rationing. For most of us in the city, the effects are inconvenient but manageable.

For a long time, that was my understanding of El Niño — a prolonged dry spell in Port Moresby. Something to complain about, perhaps, but nothing more. I did not think much beyond that.

Then I entered the Pacific Dataviz Challenge 2026.

What I Discovered

I approached this project with a straightforward goal: build an interactive piece using data from the SPC / Pacific Data Hub. Create something visually compelling. Call it complete.

The process turned out to be more illuminating than I expected.

The data revealed a pattern I had not fully appreciated. When sea surface temperatures in the Niño 3.4 region of the Pacific Ocean rise, rainfall across Papua New Guinea drops significantly — often months later. The numbers were striking:

Eight of PNG’s ten driest years since 1979 have been El Niño years. The correlation between the Oceanic Niño Index and our rainfall is -0.64. The average rainfall anomaly during El Niño years is -5.9 index points, compared to +3.8 in other years.

These statistics were interesting, but they did not capture the full story. That came when I traced the consequences further.

The Frost

I grew up in the city. I had never seen frost. I did not even know how or why Papua New Guinea experienced frost at all. This was one of the first revelations of the project.

El Niño does not simply stop the rain. It also clears the skies over the highlands. Without cloud cover, the ground loses heat rapidly at night. Temperatures drop below freezing at altitudes above 2,500 metres. The frost that follows kills kaukau gardens — the sweet potato that sustains millions of highland families.

Entire harvests can be destroyed overnight. For communities already coping with months of reduced rainfall, this is devastating.

I had to sit with that for a moment. A dry spell in Moresby means I complain about the heat. A dry spell in the highlands means people lose their food.

The Floods

There is another dimension to this cycle that is seldom discussed.

When the drought eventually breaks and the rains return, the parched soil cannot absorb the water. It has become too hard, too cracked. The water runs off instead of soaking in. Dry riverbeds fill rapidly and become flash floods. The same communities that endured months without water now face the threat of inundation.

Drought, frost, floods. One climatic event, multiple disasters.

The Project

The Ocean Knows First is my entry for the Pacific Dataviz Challenge. It is a scrollytelling website — nine chapters that guide the reader from the coast to the highlands, illustrating how El Niño develops and what it means for Papua New Guinea.

The site was built using SvelteKit for interactivity, exported as a static build, and hosted on GitHub Pages. Data was sourced from the SPC / Pacific Data Hub climate-change dataflows: rainfall anomalies, sea surface temperatures, crop figures, and the monitoring network. The Oceanic Niño Index came from NOAA CPC. Coastlines are from Natural Earth.

The warm-pool map and ocean cross-section are diagrams rather than live data. I created these to make the science more accessible. Several AI tools — Claude, Grok, and DeepSeek — assisted with aspects of the build, but the story, the design, and the insights are my own.

Figure 1: PNG and the Niño 3.4 region,

Figure 2: cross-section showing how El Niño shifts Pacific currents.

Figure 3: Yearly ONI (1979–2025) compared to SPC’s PNG rainfall. The major El Niño years — 1982, 1997, 2015 — are referenced throughout.

Figure 4a and 4b: One dry year traced from sea level to the frost line.

Figure 5: 2026’s monthly progression compared to earlier El Niño events.

A Note on the Data

It is important to clarify that this is not a forecast for any specific province. The relationship between ENSO and rainfall is not uniform across PNG — I make this explicit in the piece. I also did not collect new data. My aim was simply to make existing public data more accessible.

The rainfall data is presented as an index around zero, not in millimetres. This is how the data was provided. While the scale is relative, the ranking of dry years remains accurate. The piece also includes background on national emissions and the monitoring network that makes this data possible.

What I Hope Others Take Away

I built this project because I wanted to understand something. What I discovered was more significant than I had expected.

Port Moresby experiences El Niño primarily as heat and dust. But other parts of the country endure hunger, frozen gardens, rivers that disappear, and floods that follow. Most of us in the city do not see this. I did not see it — until I began examining the data.

I hope other Papua New Guineans and Pacific Islanders find this piece useful. I hope it helps connect what we hear on the news with what is happening on the ground — and in the ocean. The ocean gives us warning, months in advance. We need only to know how to read it.

Neo Malesa
Port Moresby