Feverish Waters
Sea surface temperatures (SSTs) have been rising continuously over the past century, and record temperatures have been recorded for several years in the last decade. The trend is, unfortunately set to continue, with record-high levels being recorded for the year 2023 - and likely also 2024.
This data is frequently either shown as a time series or as a bar chart, depicting the temperature anomalies for a given year and over time. These charts are straightforward ways to communicate this data, but what if we tried to use a different visual representation? How can the audience be drawn in to engage with the information on a different, maybe even more abstract, emotional level?
The graphic created features a series of sunbursts that are placed on a spiral, which represents the passing of time. Each sunburst is the equivalent to one data point, which is the recorded SSTs anomalies relative to the 20th century baseline in a given year.
The colours were carefully selected to not only resemble the varying depths of the ocean, but to also convey the alarming changes over time and the urgency for action.
The greatest challenge was to visually encode the sunbursts with the data values. Both size and colour were used to encode the same temperature anomalies, thereby giving the viewer a more clear and intuitive understanding of the observed magnitude of change. The focus of the story is specifically the years 2012-2022, which have experienced the highest levels of warming. To add some context and demonstrate that this is a trend that has started since the 1970s, additional years were added to the spiral (1922, 1970, 1980, 1990, and 2000), with 1922 representing the temperatures 100 years ago. By studying the annotated line chart accompanying the main visual, the viewer is also invited to study the historic upward trend over time.
The source data is from the US National Oceanic and Atmospheric Administration.[1]
