Expanding Climate Stripes
Tomorrow, June 21, is Show Your Stripes Day, an annual event meant to draw awareness to climate change. The stripes are a bar-code-like pattern of blue and red bands that represent a rise in average surface temperatures over the past 150 years. This design has appeared on posters, neckties, and buildings. Now the Show Your Stripes organizers have added new stripes that depict recent temperature changes in both the upper atmosphere and the deep ocean. They have also prepared stripes that show expected temperature changes depending on future-emission scenarios [1].
The warming-stripes idea came about in 2018, when Ed Hawkins, a climate scientist at the University of Reading in the UK, was asked to speak at a book festival. The venue called for a less technical depiction of climate data than the usual graphs. “I wanted a way of talking about climate change in a way that a book-festival audience might be more receptive to,” Hawkins says.
Inspired by a climate-themed blanket that his Reading colleague, Ellie Highwood, had crocheted the year before, Hawkins designed a simple stripe pattern with a distinct blue–red color palette. “Blue is naturally associated with cold, and red is naturally associated with hot,” he says. “When I put the stripe design up on the screen at the festival, I could tell from people’s eyes that they got it.”
The first stripe pattern used local temperature data from the town where the festival was held. But the same color scheme can be applied to data from other cities, as well as to the planet as a whole (go to the Show Your Stripes website to generate a pattern for a particular location). The global stripe pattern (Fig. 1) is based on more than a billion individual thermometer measurements. In the pattern, temperatures below and above an average temperature are represented in blue and red colors, respectively, with the average being taken over the years 1961–2010.
The stripe idea quickly went viral. Several TV meteorologists began including stripes in their broadcasts. The design was worn by a professional soccer team and by models in a fashion show. People put the stripes on cars and books and projected them onto buildings and other monuments. Several striped paraphernalia are showcased on Show Your Stripes, as well as on the site of Climate Central, a nonprofit group of climate scientists and communicators.
“The design is simple, broadly appealing, and easy to understand,” says Bernadette Woods Placky, chief meteorologist for Climate Central. “It opens up climate conversations in a way that other things don’t.” She says June 21 was selected as Show Your Stripes Day because that is the start of summer and the onset of many extreme weather events. “The day really is a moment to help draw attention to the seriousness of climate change and what can be done about it,” Woods Placky says.
Hawkins, Woods Placky, and their colleagues have now applied the stripe format to other climate data [1], in particular, global temperature changes in the atmosphere and ocean (Fig. 2). The measurements cover the years from 1960 to 2024. The ocean stripes are divided according to depth, going down to 1500 m below the surface. Water temperatures have increased over the years, reflecting the warming trend on land.
The atmosphere data, however, shows a cooling trend—particularly in the stratosphere (covering altitudes from 10 to 50 km). These lower temperatures are expected, Hawkins says. “It’s a key fingerprint that climate change is caused by human activity.” He explains that the release of carbon dioxide and other greenhouse gases from fossil-fuel burning causes more heat to be retained in the lower atmosphere. The upshot is that less heat reaches the upper atmosphere, causing the corresponding temperatures decline.
The researchers created other stripe designs that extended over longer time periods. One pattern showed two possible climate futures—one based on rapid action (net zero emission by the 2050s) and the other showing delayed action (Fig. 3). The delayed-action scenario had stripes of darker red. “It really is critical to help the public understand what’s at risk with our changing climate and the seriousness of it,” Woods Placky says. She says that extreme weather events, such as heat waves and hurricanes, will become more frequent as the planet warms more.
“We have choices about what we do next,” Hawkins says. He says some of that is government policy, but individual choices also matter. People can choose what they eat, how they travel, and which products they buy. “If you can build up a groundswell of support for a particular way of living, then the companies will follow that, as well as the politicians eventually.”
–Michael Schirber
Michael Schirber is a Corresponding Editor for Physics Magazine based in Lyon, France.
References
- E. Hawkins et al., “Warming stripes spark climate conversations: From the ocean to the stratosphere,” Bull. Am. Meteorol. Soc. 106, E964 (2025).