PACIFIC DATAVIZ CHALLENGE 2026

When Water Changes, Everything Changes

My father is from Vaiafai, Iva, in Savai'i, and much of our aiga still lives there. I grew up in Aotearoa with a Māori mum and a Samoan dad. That connection is where this story begins.

Water is part of how ordinary life is held together: food, travel, gathering and care. The public records here cannot speak for every village, or explain every change. They can show a shift that deserves attention. In 2020, Samoa recorded its highest annual rainfall anomaly. By 2022, only 1998 had been lower.

That is not a story about one village. It is a reason to ask whether plans made for an average year can hold when the year arrives differently.

2020 rainfall anomaly+27.3 mmSamoa-wide official indicator
2022 rainfall anomaly−20.7 mmSamoa-wide official indicator
2024 SST anomaly+0.8°CSamoa EEZ aggregate

Source: SPC/Pacific Data Hub rainfall anomaly and EEZ SST anomaly; retrieved 2026-08-17.

A family place in Savai'i, with a coconut palm, shoreline, homes and a person on stairs.
Fale aiga. Water is part of the everyday setting of this story.
ACT 1 · WHEN WATER CHANGES

Water has a rhythm. The records show why it cannot be taken for granted.

In 2020, Samoa's official annual rainfall indicator rose above its reference average. Two years later, it was below it. The records do not explain the change. They show that a plan built for one kind of year may be tested by another.

Samoa-wide official indicator

A wet-to-dry reversal in three annual readings

1991 to 2020 baseline

In three annual readings, +27.3 mm in 2020 became −18.1 mm in 2021 and −20.7 mm in 2022. These are annual Samoa-wide anomalies.

Annual precipitation anomaly in millimetres, with reported standard error. Positive and negative values are relative to this dataset’s own baseline.

Source: Pacific Community (SPC), Pacific Data Hub .Stat, RAIN_ANOM · Samoa-wide · annual · 1991 to 2020 baseline · frozen derived data.

Samoa EEZ aggregate

The warming ocean is the background condition

1971 to 2000 baseline

2024: +0.8°C in the EEZ annual series. This is not a coastal or inshore temperature record and is not evidence that SST caused a rainfall outcome.

Annual mean sea-surface-temperature anomaly across Samoa’s Exclusive Economic Zone.

Source: Pacific Community (SPC), Pacific Data Hub .Stat, SST_ANOM · Samoa EEZ aggregate · annual · 1971 to 2000 baseline · frozen derived data.

READ BEFORE INTERPRETING

What these records can and cannot tell us

They can

  • show conditions national plans should be tested against;
  • make sharp reversals easier to see;
  • document one response after a major crop shock.

They cannot

  • describe one village, catchment, farm or household;
  • show what caused a rainfall or crop outcome;
  • choose a local response without local evidence and consent.
ACT 2 · WHEN RAIN ARRIVES ON DIFFERENT TERMS

A seasonal pattern can be familiar without making a particular month predictable.

The near-Upolu grid point has a wet and dry rhythm across the year. A familiar season can still bring an unfamiliar month. Start with an episode, then test another year and month.

Coarse MERRA-2 grid-cell estimate near central Upolu

A within-model monthly average gives orientation, not a local forecast

1981 to 2025 calendar-month record mean

This coarse modelled estimate is used to compare months within the same record. It is not used as local rainfall, a rain-gauge reading or a Samoa-wide estimate.

NASA POWER/MERRA-2 PRECTOTCORR at −13.83°, −171.75°. Mean daily precipitation in mm was multiplied by calendar days. Accessed for this build in August 2026.

Source: NASA POWER API, PRECTOTCORR · MERRA-2 grid cell · retrieved 2026-08-18 · API v2.9.7 · frozen derived data.

WATER STRESS TEST

Choose a historical water condition worth testing

Each preset explains why the date matters. Use the year and month controls to explore another condition.

SELECTED EPISODE

April 2016: unusually wet month

What happened

Evidence scope

Planning question

What it cannot determine

Monthly profile

All monthly values are shown only as departures from the same calendar month’s 1981 to 2025 record mean.

Official Samoa-wide or EEZ indicators

National and ocean context

Samoa rainfall anomaly

Not reportedAnnual, Samoa-wide, 1991 to 2020 baseline

Samoa EEZ SST anomaly

Not reportedAnnual, EEZ aggregate, 1971 to 2000 baseline
Modelled grid point near central Upolu

April in 2016

Modelled monthly departure

Not reportedRelative to the same calendar month’s 1981 to 2025 record mean

Source: NASA POWER API, PRECTOTCORR · MERRA-2 grid cell at −13.83°, −171.75° · calendar-month departures only · frozen derived data.

Food-resilience history

Taro yield in 2016

Reported taro yield

Not reportedAnnual national/country series, descriptive only
Coarse MERRA-2 grid-cell estimate near central Upolu

Every month compared with its own record mean

−211 mm drier · 0 · +358 mm wetter

On mobile, use the year and month controls above. The heat map remains available as an overview.

April 2016 is the wettest departure in this 1981 to 2025 grid-point record (+358 mm); February 1998 is the driest (−211 mm). Those are historical modelled values at one grid point, not local impact reports.

Keyboard: focus the grid once, then use arrow keys to move by month or year; press Enter to load a cell into the explorer. Only one heat-map cell is in the tab order.

Source: NASA POWER API, PRECTOTCORR · MERRA-2 grid cell · 1981 to 2025 calendar-month record mean · frozen derived data.

ACT 3 · FOOD NEEDS OPTIONS

When conditions shift, food systems need more than one way to respond.

The 1993 taro-leaf-blight outbreak was a disease crisis, not evidence of a climate effect. FAO documents a response built around a broader genetic base, regional exchange and on-farm farmer evaluation. That makes the history relevant to adaptation, even though this yield series cannot assign causes by itself.

Food-resilience history

The documented outbreak, the 1994 low and a partial recovery

Annual taro yield · kg/ha

Recorded series: 3,409.1 kg/ha in 1993; 1,500 kg/ha in 1994; 5,000 kg/ha in 2000; 5,574.6 kg/ha in 2024. The series was already falling before the documented outbreak, and 2024 remains below earlier peaks. It describes yield, not causes.

FAO documents the 1993 outbreak and a participatory improvement programme involving farmers, researchers, regional networks and a broader genetic base.

Yield source: Pacific Community (SPC), Pacific Data Hub .Stat, Samoa taro yield · country-level · annual · kg/ha · 1961 to 2024. Outbreak history: FAO taro improvement programme.

A CURRENT POLICY CONNECTION

More options remain part of Samoa’s adaptation agenda.

The blight was not a climate event. It shows why a food system needs more than one option when a major shock arrives.

Samoa’s NDC 3.0 sets a 2035 target to develop and distribute at least three climate-resilient crop varieties adapted to Samoa’s agro-ecological zones. It also states that adoption requires consent from farmers and commercial and community-based farms.

Read Samoa’s NDC 3.0
ACT 4 · PLAN FOR THE RANGE, DECIDE IN PLACE

National data can identify the tests. Communities determine the response.

Samoa's NDC 3.0 says Community Integrated Management plans enable each of Samoa's 368 villages to identify locally relevant adaptation measures and draw on local knowledge. This story identifies the pressure. People in place decide what response belongs there.

1

Stress-test national plans

Test wet years, dry years and unusual months, not one average scenario.

2

Match evidence to the decision

National, EEZ and grid-point evidence can frame questions. It cannot replace local observations or judgement.

3

Build adaptive options

Crop diversity, farmer-led trials, community planning, local knowledge and consent are resilience infrastructure.

My family connects me to a Samoa larger than any chart. Water supports the ordinary work of aiga: food, travel, gathering and care. The data cannot tell a village which choice belongs in its place. It can make the pressure visible. The decision stays with the people who live with it.

When water changes, everything changes. Plans need to hold when the year arrives differently, and remain answerable to the people who live with them.
APPENDIXMethods, data and limitations

Pacific climate context

Pacific climate context

Niño 3.4 is retained here as context only. It is not a Samoa rainfall or taro-causation label.

Monthly distribution mechanics

Each box contains 45 observations for the same calendar month. Box = middle 50%; whiskers = 1.5×IQR; dot = median.

How the evidence is located

This map gives island context only. The orange point is the disclosed MERRA-2/POWER monthly model coordinate near central Upolu. The Samoa-wide rainfall, country-level taro and EEZ SST series do not have a local collection point shown here.

MERRA-2/POWER model point near central UpoluSamoa land outline for orientation

Map outline: Natural Earth 10m Admin 0 Countries, public domain; island context only.

Data treatment and limitations

  • Missing values remain missing; they are never converted to zero.
  • Rainfall, SST, taro yield and Niño 3.4 retain separate units, baselines and spatial scopes.
  • No displayed alignment is treated as causal evidence.
  • Raw source captures and deterministic transformations are retained in the project repository.

Sources

SPC requires users to follow the applicable dataset licence and attribution requirement. The public catalogue exposes no dataset-specific licence text for these two indicators; see the licence matrix. The entry is not represented as cleared for final submission until SPC confirms the applicable reuse terms.

Reproducibility record, frozen inputs and transformation scripts

Authorship and development process

The entrant conceived the question, selected the datasets and transformations, interpreted the results, and made the cultural, narrative and visual-design decisions. AI-assisted work was limited to coding support, debugging, accessibility checks and wording alternatives. The entrant retains final editorial and submission responsibility.

This production URL is intended to remain publicly accessible through 31 August 2029.

Return to the story

Act 1 of 4