Visualization of the average temperature over the Lower 48 states, 1895 to 2017, using NOAA data. Each stripe is color-coded to represent the temperature of a particular year. (Ed Hawkins)

Temperatures over both the Lower 48 United States and the planet have steadily warmed in recent decades. Ed Hawkins, a climate scientist at the University of Reading in Britain, sought to illustrate this warming in the most straightforward way possible.

So he created visualizations of the course of temperature over time using strictly a series of color-coded stripes. You might mistake them for modern art, carpet patterns or perhaps flags. But they are scientific representations that unambiguously reveal a long-term warming signal.

The blue stripes portray cooler years, while the reds are hot. The darkest shades of blue and red depict those cold and hot years that were most extreme.

For the both the Lower 48 states and the planet, the progression from more blue to more red over time is crystal clear.

“I wanted to communicate temperature changes in a way that was simple and intuitive,”  Hawkins said in an email. “This visualization removes all the distractions of standard graphs and allows the viewer to just see the long-term trends and variations in temperature without needing to interpret anything else.”

For the Lower 48 visualization (above), you don’t need to be told that the four warmest years on record (2015, 2017, 2016, and 2012) have occurred since 2012 and that eight of the 10 warmest years have happened since 1998. The visualization shows you.

The progression from blue to red for the whole planet (below) is even more stark, due to less year-to-year and decade-to-decade variability in temperature. It plainly illustrates that the four warmest years on record happened over the last four years and that 17 of the 18 warmest years have occurred since 2001.


(Ed Hawkins)

These stripes are among many  visualizations Hawkins has constructed that have resonated among science communicators. His best-known visualizations are his “climate spirals,” which debuted two years ago.

They present an animated series of expanding circles, which are also elegant and compelling illustrations of the warming planet.