The scorching colors of a large volcanic blast can stain sunsets around the world for years after the initial eruption cools down. Droplets of sulfuric acid spewed into the atmosphere scatter away blue light, creating vivid crimson twilights. Inspired by these stunning sunsets, famous artists included the fiery colors in the backgrounds of their paintings, such as the above 1818 piece Woman before the Setting Sun by German artist Caspar David Friedrich. Two years earlier, the ash from an unusually large number of major volcanic eruptions reflected so much sunlight that 1816 became known as the year without a summer. Researchers wondered if similar sunset paintings could double as snapshots of volcano-induced climate change. The team compared the proportion of red and green hues in the skies of hundreds of sunset paintings produced between 1500 and 2000. Regardless of artistic style, paintings created soon after volcanic eruptions had redder skies than those painted during periods of low volcanic activity, the researchers report online today in Atmospheric Chemistry and Physics. The researchers say their results agree with other indicators of historic atmospheric pollutant levels, such as ice cores. Because these existing indicators provide limited evidence for short-term trends due to their scarcity, the researchers hope their work provides climate scientists a colorful new spectrum of data to fill in the gaps.