1 00:00:02,040 --> 00:00:07,040 Speaker 1: Welcome to brain stuff from how stuff works, Hey, brain stuff, 2 00:00:07,080 --> 00:00:11,520 Speaker 1: Lauren Vogel bomb here. Normally snow looks white. This is 3 00:00:11,560 --> 00:00:14,080 Speaker 1: because the ice crystals that make up clusters of snow 4 00:00:14,120 --> 00:00:18,120 Speaker 1: reflect and scatter every color frequency in the visible light spectrum. 5 00:00:18,160 --> 00:00:20,680 Speaker 1: So when sunlight bounces off of a snow bank, all 6 00:00:20,680 --> 00:00:23,920 Speaker 1: those colors blend together, giving the snow a white appearance. 7 00:00:24,520 --> 00:00:27,960 Speaker 1: Or at least that's what usually happens. Every so often, 8 00:00:28,000 --> 00:00:30,560 Speaker 1: though mother Nature throws as a curveball with a blanket 9 00:00:30,600 --> 00:00:33,920 Speaker 1: of non white snow. Plenty of the Elder was a 10 00:00:34,000 --> 00:00:37,000 Speaker 1: Roman naturalist who lived from twenty three to seventy nine. 11 00:00:38,040 --> 00:00:40,520 Speaker 1: In one of his books, he wrote about red tinted snow, 12 00:00:40,800 --> 00:00:44,800 Speaker 1: which ancient travelers sometimes encountered. His hypothesis was that snow 13 00:00:44,880 --> 00:00:47,560 Speaker 1: changes color as time goes by, like a rusting piece 14 00:00:47,600 --> 00:00:51,440 Speaker 1: of iron snow itself. Plenty wrote reddens with old age, 15 00:00:52,760 --> 00:00:55,320 Speaker 1: and reports of crimson colored snow kept pouring in over 16 00:00:55,320 --> 00:00:58,240 Speaker 1: the next two millennia. To figure out what's really going on, 17 00:00:58,360 --> 00:01:01,720 Speaker 1: we spoke via email with climates scientist Randalls Serveny. He 18 00:01:01,800 --> 00:01:04,640 Speaker 1: reports people in the dark and Middle Ages were often 19 00:01:04,640 --> 00:01:07,920 Speaker 1: freaked out by it. A professor at Arizona State University. 20 00:01:08,000 --> 00:01:10,959 Speaker 1: Serveny dedicated an entire book to weird weather stories in 21 00:01:11,000 --> 00:01:14,360 Speaker 1: two thousand five, titled Freaks of the Storm. It includes 22 00:01:14,400 --> 00:01:17,760 Speaker 1: a passage on red snow. As Serveny points out, there 23 00:01:18,000 --> 00:01:20,600 Speaker 1: Charles Darwin himself once came across white snow in the 24 00:01:20,680 --> 00:01:23,839 Speaker 1: Andes Mountains that turned blood red as it thawed. Another 25 00:01:23,880 --> 00:01:27,440 Speaker 1: important figure who witnessed the tinted precipitation was Sir John Ross, 26 00:01:27,480 --> 00:01:31,240 Speaker 1: a British naval officer and Arctic explorer. A reddish or 27 00:01:31,280 --> 00:01:35,120 Speaker 1: pinkish snow isn't just a historical curiosity. It's still being observed. 28 00:01:35,600 --> 00:01:38,800 Speaker 1: In February, for instance, a puddle of red water that 29 00:01:38,920 --> 00:01:42,039 Speaker 1: turned out to be melted vermillion snow was found in 30 00:01:42,080 --> 00:01:46,960 Speaker 1: Glacier National Park. So what's the mechanism behind this? In 31 00:01:47,000 --> 00:01:51,200 Speaker 1: some cases, scarlet dust may be a contributing factor. Serveny said. 32 00:01:51,560 --> 00:01:54,440 Speaker 1: Many of the historic blood snows of Europe are associated 33 00:01:54,480 --> 00:01:57,880 Speaker 1: with moisture mixing with red Saharan dust that's blown northward 34 00:01:57,920 --> 00:02:00,680 Speaker 1: into Europe, which then falls out as either red rain 35 00:02:00,840 --> 00:02:04,000 Speaker 1: or snow. But it turns out that more often than not, 36 00:02:04,520 --> 00:02:08,359 Speaker 1: red snow is the product of algae and as scientists 37 00:02:08,360 --> 00:02:11,880 Speaker 1: have learned recently, the stuff is also contributing to climate change. 38 00:02:12,919 --> 00:02:14,959 Speaker 1: We've known for some time now that red or pink 39 00:02:15,000 --> 00:02:17,920 Speaker 1: snow is generally caused by select types of green algae, 40 00:02:18,000 --> 00:02:22,120 Speaker 1: including these species Clematomons novellis. These life forms live in 41 00:02:22,240 --> 00:02:25,280 Speaker 1: high altitude snow fields around the world. Although they are 42 00:02:25,320 --> 00:02:28,400 Speaker 1: technically green in color, the algae produce a red pigment 43 00:02:28,520 --> 00:02:31,760 Speaker 1: during the warm seasons. Doing so helps protect the organisms 44 00:02:31,760 --> 00:02:36,360 Speaker 1: from excessive solar radiation. We also spoke with biologist Arwin Edwards, 45 00:02:36,400 --> 00:02:40,000 Speaker 1: a research fellow at everyst With University in Wales. He said, 46 00:02:40,360 --> 00:02:43,160 Speaker 1: I think of the red pigment as a sunscreen. He 47 00:02:43,240 --> 00:02:46,560 Speaker 1: explained the life cycle of this and related types of alga. 48 00:02:46,919 --> 00:02:50,120 Speaker 1: During the winter, the organisms go dormant. Once spring arrives, 49 00:02:50,160 --> 00:02:52,120 Speaker 1: they make their way toward the surface of the snow 50 00:02:52,160 --> 00:02:55,160 Speaker 1: and then bloom. But in order to grow, the life 51 00:02:55,160 --> 00:02:57,720 Speaker 1: forms need liquid water in the form of wet snow 52 00:02:57,760 --> 00:03:00,840 Speaker 1: in order to photosynthesize. This is another reason why the 53 00:03:00,880 --> 00:03:04,720 Speaker 1: red pigment is so useful. Dark colored objects absorb more 54 00:03:04,800 --> 00:03:08,240 Speaker 1: heat than light colored ones. In snowy fields where Clematomonis 55 00:03:08,280 --> 00:03:11,560 Speaker 1: is present, you'll find dense communities of the microorganisms. A 56 00:03:11,639 --> 00:03:14,760 Speaker 1: single millimeter that's point zero three inches of snow can 57 00:03:14,800 --> 00:03:18,040 Speaker 1: contain five hundred thousand of these life forms. So in 58 00:03:18,080 --> 00:03:20,400 Speaker 1: a large cluster of the algae starts to release red 59 00:03:20,400 --> 00:03:23,200 Speaker 1: pigment in mass, they darken the snow they're living in. 60 00:03:23,600 --> 00:03:26,360 Speaker 1: As a result, the snow itself adopts a pinkish look. 61 00:03:26,960 --> 00:03:30,800 Speaker 1: It also begins to melt. So is this a cause 62 00:03:30,800 --> 00:03:34,600 Speaker 1: for concern? In twice sixteen, the journal Nature published a 63 00:03:34,639 --> 00:03:37,400 Speaker 1: report written under the leadership of Stephanie Lutts, then a 64 00:03:37,480 --> 00:03:40,440 Speaker 1: scientist at the University of Leeds. Edwards was one of 65 00:03:40,440 --> 00:03:43,200 Speaker 1: her co authors. After looking at forty samples of the 66 00:03:43,200 --> 00:03:47,080 Speaker 1: scarlet material from glaciers in Iceland, Norway, Greenland and Sweden, 67 00:03:47,360 --> 00:03:52,000 Speaker 1: the researchers reached a harrowing conclusion. Edwards said, our paper 68 00:03:52,120 --> 00:03:54,160 Speaker 1: is one of the first of several which have identified 69 00:03:54,200 --> 00:03:57,600 Speaker 1: a five to fift percent acceleration of glacier melting rates 70 00:03:57,760 --> 00:04:00,440 Speaker 1: as a result of algae on the glacier surface us 71 00:04:00,480 --> 00:04:05,160 Speaker 1: a biological darkening effect. Put another way, glacial snow melts 72 00:04:05,240 --> 00:04:08,760 Speaker 1: five to fifteen percent more rapidly when Clementomonus or similar 73 00:04:08,800 --> 00:04:11,880 Speaker 1: types of algae are present, and that's not good news. 74 00:04:12,880 --> 00:04:16,880 Speaker 1: University of Bristol glaciologist Alejandra Anisio was a co author 75 00:04:16,920 --> 00:04:20,520 Speaker 1: on that Nature paper. Summing up the problem in an 76 00:04:20,520 --> 00:04:24,479 Speaker 1: email exchange, he said, basically, because of the darker coloration 77 00:04:24,520 --> 00:04:26,919 Speaker 1: of snow with the presence of the algae, the snow 78 00:04:26,960 --> 00:04:30,279 Speaker 1: absorbs more of the solar radiation, which increases retention of 79 00:04:30,320 --> 00:04:33,240 Speaker 1: heat and melting of the snow. The process is not 80 00:04:33,360 --> 00:04:36,080 Speaker 1: insignificant and must be taken into account if we want 81 00:04:36,120 --> 00:04:38,880 Speaker 1: to understand how fast glaciers and ice sheets will melt 82 00:04:38,960 --> 00:04:42,920 Speaker 1: with global warming. Also, there may be a self perpetuating 83 00:04:42,920 --> 00:04:46,400 Speaker 1: feedback loop at work here. The red tinted algae melts snow, 84 00:04:46,560 --> 00:04:48,960 Speaker 1: which enables more of the algae to grow, which leads 85 00:04:49,000 --> 00:04:53,320 Speaker 1: to even more melted snow, and so on. But let's 86 00:04:53,400 --> 00:04:55,520 Speaker 1: shift gears for a moment and talk about one of 87 00:04:55,560 --> 00:04:59,600 Speaker 1: the red snow's weirdest qualities. It's sent People who come 88 00:04:59,600 --> 00:05:02,480 Speaker 1: across the algae laden snow sometimes report that it has 89 00:05:02,520 --> 00:05:06,279 Speaker 1: a sweet watermelon like scent. For the record, Edward says 90 00:05:06,320 --> 00:05:09,279 Speaker 1: he's never detected the odor himself, but that it's probably 91 00:05:09,320 --> 00:05:12,760 Speaker 1: the byproduct of those red pigments. Some popular science writers 92 00:05:12,800 --> 00:05:15,280 Speaker 1: have also advised against eating red snow because it has 93 00:05:15,320 --> 00:05:18,640 Speaker 1: been reported to cause gastric problems, perhaps due to the 94 00:05:18,720 --> 00:05:23,240 Speaker 1: algae other decaying material or mineral dusts and snow can 95 00:05:23,320 --> 00:05:26,719 Speaker 1: come in other colors as well. In January eighteen, Central 96 00:05:26,800 --> 00:05:30,240 Speaker 1: Kazakhstan received a layer of black tinted snow. This may 97 00:05:30,240 --> 00:05:33,360 Speaker 1: have been the result of industrial pollution. Additionally, there are 98 00:05:33,360 --> 00:05:36,599 Speaker 1: some types of algae that create yellowish snow. Of course, 99 00:05:36,680 --> 00:05:38,960 Speaker 1: as any third grader or dog owner can tell you, 100 00:05:39,240 --> 00:05:47,039 Speaker 1: that's not the only way to get yellow snow. Today's 101 00:05:47,040 --> 00:05:50,000 Speaker 1: episode was written by Mark Mancini and produced by Tyler Clang. 102 00:05:50,360 --> 00:05:52,960 Speaker 1: For more on this and lots of other rose tinted topics, 103 00:05:53,040 --> 00:06:06,719 Speaker 1: visit our home planet, how stuff works dot com.