1 00:00:00,833 --> 00:00:03,900 ♪ ♪ 2 00:00:06,700 --> 00:00:10,442 NARRATOR: What happens when a frozen world locked away for millennia 3 00:00:10,466 --> 00:00:13,133 starts to thaw? 4 00:00:14,533 --> 00:00:17,942 {\an1}In 2014, a helicopter crew flying over Siberia 5 00:00:17,966 --> 00:00:20,842 {\an1}discovers something mysterious: 6 00:00:20,866 --> 00:00:23,842 {\an1}a crater more than 80 feet wide 7 00:00:23,866 --> 00:00:27,300 {\an1}and deeper than a 15-story building. 8 00:00:28,366 --> 00:00:30,809 {\an1}Sinkholes are nothing new, 9 00:00:30,833 --> 00:00:34,333 {\an1}but this is no ordinary sinkhole. 10 00:00:38,400 --> 00:00:40,709 SUSAN NATALI: The ground has exploded. 11 00:00:40,733 --> 00:00:43,942 There's no way... This is not real. 12 00:00:43,966 --> 00:00:48,776 NARRATOR: More Siberian craters have since been discovered. 13 00:00:48,800 --> 00:00:51,733 {\an1}There's even evidence they may be appearing in Alaska. 14 00:00:53,600 --> 00:00:55,609 TAYLOR SULLIVAN: The lake bottom went from being 15 00:00:55,633 --> 00:00:57,966 flat, flat, flat, and then it just dropped out. 16 00:00:59,666 --> 00:01:03,776 NARRATOR: And they show no sign of stopping. 17 00:01:03,800 --> 00:01:07,576 {\an1}Now, scientists from around the globe race to understand 18 00:01:07,600 --> 00:01:09,609 a hidden world: 19 00:01:09,633 --> 00:01:12,576 permafrost, a layer of frozen earth 20 00:01:12,600 --> 00:01:16,509 {\an1}spanning a quarter of the Northern Hemisphere's land mass. 21 00:01:16,533 --> 00:01:21,009 {\an8}This ancient freezer is beginning to thaw, 22 00:01:21,033 --> 00:01:23,942 {\an1}revealing its deepest secrets... 23 00:01:23,966 --> 00:01:26,409 {\an1}Pretty exciting, this is a mammoth bone right here. 24 00:01:26,433 --> 00:01:31,109 {\an8}NARRATOR: releasing over half a billion tons of carbon every year... 25 00:01:31,133 --> 00:01:33,042 JANELLE SHARP: It was just insane, like, the water 26 00:01:33,066 --> 00:01:34,876 {\an1}is boiling around you. 27 00:01:34,900 --> 00:01:37,576 NARRATOR: and threatening local communities. 28 00:01:37,600 --> 00:01:39,709 LARS NELSON: Houses need to be torn down. 29 00:01:39,733 --> 00:01:41,909 We're in the middle of a housing crisis. 30 00:01:41,933 --> 00:01:43,909 ♪ ♪ 31 00:01:43,933 --> 00:01:46,742 NARRATOR: Are the craters warning shots for our climate future? 32 00:01:46,766 --> 00:01:50,076 {\an1}KATEY WALTER ANTHONY: That is not included in climate models. 33 00:01:50,100 --> 00:01:53,309 {\an1}That's a scary wildcard in the climate change story. 34 00:01:53,333 --> 00:01:56,109 NARRATOR: What new dangers lurk beneath 35 00:01:56,133 --> 00:01:59,509 {\an1}this vast frozen landscape? 36 00:01:59,533 --> 00:02:03,942 {\an1}And could they warm our planet even further? 37 00:02:03,966 --> 00:02:05,776 "Arctic Sinkholes." 38 00:02:05,800 --> 00:02:08,442 {\an1}Right now, on "NOVA." 39 00:02:08,466 --> 00:02:16,466 ♪ ♪ 40 00:02:31,133 --> 00:02:37,209 {\an1}(wildlife chirping, chittering) 41 00:02:37,233 --> 00:02:40,676 NARRATOR: The Yamal peninsula, Siberia. 42 00:02:40,700 --> 00:02:47,176 47,000 square miles of freezing tundra. 43 00:02:47,200 --> 00:02:49,876 ♪ ♪ 44 00:02:49,900 --> 00:02:51,909 {\an1}Located in Northern Russia, 45 00:02:51,933 --> 00:02:55,133 {\an1}the Yamal lies well above the Arctic Circle. 46 00:02:58,533 --> 00:03:02,209 {\an1}It's home to around 10,000 Indigenous Nenet people, 47 00:03:02,233 --> 00:03:05,500 {\an1}most living as nomadic reindeer herders. 48 00:03:06,866 --> 00:03:08,809 ♪ ♪ 49 00:03:08,833 --> 00:03:14,009 In their language, Yamal means "end of the land." 50 00:03:14,033 --> 00:03:16,376 It's now beginning to look like it. 51 00:03:16,400 --> 00:03:19,276 {\an8}♪ ♪ 52 00:03:19,300 --> 00:03:22,776 {\an7}Giant craters were spotted in the North of Russia. 53 00:03:22,800 --> 00:03:27,133 {\an7}They popped up out of nowhere in the Yamal peninsula. 54 00:03:28,800 --> 00:03:32,476 {\an8}NATALI: When I first heard about the crater, I didn't believe it. 55 00:03:32,500 --> 00:03:33,876 {\an7}I actually thought it was a made-up story. 56 00:03:33,900 --> 00:03:36,076 ♪ ♪ 57 00:03:36,100 --> 00:03:37,709 MARINA LEIBMAN: Believe me, I remember this date, 58 00:03:37,733 --> 00:03:39,976 {\an7}and I will remember it forever, 59 00:03:40,000 --> 00:03:43,442 because it was absolutely exciting, 60 00:03:43,466 --> 00:03:46,533 {\an1}something I have never seen before. 61 00:03:48,533 --> 00:03:52,809 {\an8}NARRATOR: The mysterious crater is 150 feet deep. 62 00:03:52,833 --> 00:03:54,842 {\an7}Filled up with rainwater, 63 00:03:54,866 --> 00:03:58,733 {\an7}its volume is greater than ten Olympic swimming pools. 64 00:03:59,866 --> 00:04:02,976 {\an1}The striking images go viral worldwide 65 00:04:03,000 --> 00:04:06,442 {\an1}because no one can answer, what caused it? 66 00:04:06,466 --> 00:04:12,842 ♪ ♪ 67 00:04:12,866 --> 00:04:15,409 Vasily Bogoyavlensky is an expert 68 00:04:15,433 --> 00:04:17,333 {\an1}on the geology of the Yamal. 69 00:04:20,333 --> 00:04:22,809 {\an1}With other scientists, he choppers out to the scene. 70 00:04:22,833 --> 00:04:30,100 ♪ ♪ 71 00:04:32,066 --> 00:04:34,442 {\an8}BOGOYAVLENSKY: When we just came to this crater, of course, 72 00:04:34,466 --> 00:04:39,476 {\an7}we didn't know for sure what was there. 73 00:04:39,500 --> 00:04:42,276 {\an7}We never saw something like that, never. 74 00:04:42,300 --> 00:04:46,109 ♪ ♪ 75 00:04:46,133 --> 00:04:49,376 NARRATOR: This isn't the first massive pit to open up. 76 00:04:49,400 --> 00:04:53,042 (people crying out) 77 00:04:53,066 --> 00:04:57,009 ♪ ♪ 78 00:04:57,033 --> 00:04:59,109 Across the world, gaping sinkholes 79 00:04:59,133 --> 00:05:00,709 {\an1}have appeared due to water 80 00:05:00,733 --> 00:05:04,342 {\an1}or erosion weakening the ground beneath, 81 00:05:04,366 --> 00:05:06,942 {\an1}swallowing cars whole 82 00:05:06,966 --> 00:05:11,466 {\an1}and wreaking havoc in towns and cities. 83 00:05:12,633 --> 00:05:15,109 {\an1}But while the Yamal crater looks at first 84 00:05:15,133 --> 00:05:16,909 {\an1}like an ordinary sinkhole, 85 00:05:16,933 --> 00:05:21,509 {\an1}there's something unusual visible around the edges. 86 00:05:21,533 --> 00:05:23,109 {\an1}(Bogoyavlensky speaking Russian) 87 00:05:23,133 --> 00:05:25,442 ♪ ♪ 88 00:05:25,466 --> 00:05:29,809 NARRATOR: Most sinkholes have a rim that is flat, not raised. 89 00:05:29,833 --> 00:05:33,142 And while sinkholes collapse inwards, 90 00:05:33,166 --> 00:05:39,876 {\an1}the team discovers debris spread far outside the crater. 91 00:05:39,900 --> 00:05:42,476 {\an1}Pieces of rocks and ice are flying, 92 00:05:42,500 --> 00:05:45,276 sometimes in quite long distance, 93 00:05:45,300 --> 00:05:49,676 {\an1}from 200 meters to 500 meters. 94 00:05:49,700 --> 00:05:53,376 And in one case, it was distance to 900 meters. 95 00:05:53,400 --> 00:05:55,676 NARRATOR: Debris like this 96 00:05:55,700 --> 00:05:58,809 {\an1}can be thrown out by the impact of an asteroid. 97 00:05:58,833 --> 00:06:02,376 {\an7}But there are no other signs of a massive object 98 00:06:02,400 --> 00:06:05,842 {\an8}striking Earth. 99 00:06:05,866 --> 00:06:07,909 {\an8}For the scientists, that leaves only one 100 00:06:07,933 --> 00:06:09,966 {\an7}reasonable explanation. 101 00:06:11,333 --> 00:06:16,033 {\an1}A gigantic natural explosion. 102 00:06:18,600 --> 00:06:19,842 NATALI: I don't know if there are many 103 00:06:19,866 --> 00:06:23,742 {\an1}Earth system processes that have never occurred... 104 00:06:23,766 --> 00:06:24,809 {\an1}I mean, in my lifetime, 105 00:06:24,833 --> 00:06:27,276 {\an1}or at least to scientific understanding... 106 00:06:27,300 --> 00:06:28,942 {\an1}that have never occurred and that we're starting to see 107 00:06:28,966 --> 00:06:32,409 as a new process. 108 00:06:32,433 --> 00:06:37,276 NARRATOR: So what could have provided the power for such a massive blast? 109 00:06:37,300 --> 00:06:41,009 {\an1}There is no sign of lava or volcanic rock, 110 00:06:41,033 --> 00:06:44,642 {\an1}so this clearly isn't a volcano. 111 00:06:44,666 --> 00:06:47,409 {\an1}But exploring inside the crater, 112 00:06:47,433 --> 00:06:49,709 {\an1}sampling the air and water at the bottom, 113 00:06:49,733 --> 00:06:52,909 {\an1}the scientists do discover an intriguing clue: 114 00:06:52,933 --> 00:06:58,309 {\an1}unusually high levels of a single gas, methane. 115 00:06:58,333 --> 00:07:01,642 ♪ ♪ 116 00:07:01,666 --> 00:07:04,476 {\an1}Used for cooking and heating, 117 00:07:04,500 --> 00:07:08,076 {\an1}methane is a flammable gas made from carbon and hydrogen. 118 00:07:08,100 --> 00:07:09,942 (exploding) 119 00:07:09,966 --> 00:07:13,842 {\an1}When combined with air, it ignites easily. 120 00:07:13,866 --> 00:07:16,776 ♪ ♪ 121 00:07:16,800 --> 00:07:19,076 BOGOYAVLENSKY: So this is huge bomb. 122 00:07:19,100 --> 00:07:21,266 Methane bomb. 123 00:07:25,633 --> 00:07:27,342 NARRATOR: But before scientists can determine 124 00:07:27,366 --> 00:07:30,433 {\an1}where the methane came from... 125 00:07:32,133 --> 00:07:36,542 {\an1}...more giant craters are discovered. 126 00:07:36,566 --> 00:07:41,033 {\an1}Investigating, scientists find new evidence of methane. 127 00:07:42,766 --> 00:07:47,109 Since 2014, at least eight confirmed craters 128 00:07:47,133 --> 00:07:50,366 {\an1}have been found on or close to the Yamal. 129 00:07:54,000 --> 00:07:55,942 {\an1}But the growing number of craters 130 00:07:55,966 --> 00:07:59,576 {\an1}isn't the scientists' only concern. 131 00:07:59,600 --> 00:08:02,176 {\an1}They notice a climate connection. 132 00:08:02,200 --> 00:08:05,209 (birds twittering) 133 00:08:05,233 --> 00:08:08,209 2014, when the first crater appears, 134 00:08:08,233 --> 00:08:11,909 {\an1}followed one of the hottest years on record in Russia. 135 00:08:11,933 --> 00:08:15,109 {\an1}And all the craters are discovered during a period 136 00:08:15,133 --> 00:08:18,366 {\an1}of uncharacteristically warm weather in Siberia. 137 00:08:21,700 --> 00:08:25,042 {\an1}Since the late 19th century, the average global temperature 138 00:08:25,066 --> 00:08:28,342 {\an1}has risen around two degrees Fahrenheit. 139 00:08:28,366 --> 00:08:31,376 But the Arctic is warming faster. 140 00:08:31,400 --> 00:08:33,609 {\an1}It's currently heating up around twice as fast 141 00:08:33,633 --> 00:08:35,676 {\an1}as the rest of the planet. 142 00:08:35,700 --> 00:08:38,376 ♪ ♪ 143 00:08:38,400 --> 00:08:40,009 {\an1}The scientists begin to ask: 144 00:08:40,033 --> 00:08:45,509 {\an1}could the explosive craters be connected to climate change? 145 00:08:45,533 --> 00:08:48,742 {\an1}If so, what might they be telling us 146 00:08:48,766 --> 00:08:50,842 {\an1}about Earth's climate future? 147 00:08:50,866 --> 00:08:58,066 ♪ ♪ 148 00:09:00,166 --> 00:09:04,109 {\an1}While scientists on the Yamal study the crater, 149 00:09:04,133 --> 00:09:07,309 {\an1}elsewhere in the Arctic, another team is about to discover 150 00:09:07,333 --> 00:09:09,442 {\an1}new pieces of the puzzle. 151 00:09:09,466 --> 00:09:12,976 {\an1}This time, in Alaska. 152 00:09:13,000 --> 00:09:15,609 ♪ ♪ 153 00:09:15,633 --> 00:09:18,666 Kotzebue, near Alaska's northwest coast. 154 00:09:20,033 --> 00:09:24,533 {\an7}In 2017, a local pilot reports a lake that's behaving oddly. 155 00:09:26,866 --> 00:09:28,076 {\an1}Now, a team of scientists 156 00:09:28,100 --> 00:09:30,809 {\an1}that had been investigating returns to the site 157 00:09:30,833 --> 00:09:33,042 {\an1}to continue its work. 158 00:09:33,066 --> 00:09:35,142 {\an1}PHIL HANKE: So we just left Kotzebue, 159 00:09:35,166 --> 00:09:38,009 and then we crossed the Kotzebue Sound, 160 00:09:38,033 --> 00:09:41,709 and into the mouth of the Noatak, 161 00:09:41,733 --> 00:09:45,076 {\an1}which was this, like, beautiful, sweeping landscape. 162 00:09:45,100 --> 00:09:48,233 SHARP: Look, there's the lake right there! 163 00:09:49,266 --> 00:09:51,176 Man, that's exciting! 164 00:09:51,200 --> 00:09:57,542 ♪ ♪ 165 00:09:57,566 --> 00:10:02,800 NARRATOR: Far from the nearest town lies Esieh Lake. 166 00:10:04,133 --> 00:10:08,576 {\an1}Field technician Phil Hanke proceeds cautiously, 167 00:10:08,600 --> 00:10:11,476 {\an1}hoping to avoid surprises. 168 00:10:11,500 --> 00:10:12,742 Hey, bear! 169 00:10:12,766 --> 00:10:13,809 {\an1}SHARP: Hey, bear! 170 00:10:13,833 --> 00:10:16,442 HANKE: Hey, bear! 171 00:10:16,466 --> 00:10:18,000 Bear scat. 172 00:10:18,966 --> 00:10:19,943 Well, there's, uh, 173 00:10:19,967 --> 00:10:21,976 {\an1}definitely bears around here, 174 00:10:22,000 --> 00:10:23,809 so we're going to have to take that into account 175 00:10:23,833 --> 00:10:26,376 when setting up camp. 176 00:10:26,400 --> 00:10:30,009 ♪ ♪ 177 00:10:30,033 --> 00:10:31,942 NARRATOR: Esieh Lake is located on the lands of 178 00:10:31,966 --> 00:10:36,042 {\an1}the Indigenous Inupiat people. 179 00:10:36,066 --> 00:10:39,476 {\an1}The state is home to over 13,000 Inupiaq people, 180 00:10:39,500 --> 00:10:43,500 {\an1}whose traditional lands stretch across Northern Alaska. 181 00:10:44,766 --> 00:10:47,109 {\an1}One of the scientists on the team has special ties 182 00:10:47,133 --> 00:10:51,076 to this community. 183 00:10:51,100 --> 00:10:53,476 {\an7}My name is Janelle Sharp, my Inupiaq name is Anausuk. 184 00:10:53,500 --> 00:10:55,276 My mom is originally from Kotzebue. 185 00:10:55,300 --> 00:10:57,342 {\an1}My family is from this region. 186 00:10:57,366 --> 00:10:59,709 {\an1}And so this project is really 187 00:10:59,733 --> 00:11:01,109 {\an1}special to me, because it's kind of, like, 188 00:11:01,133 --> 00:11:02,876 {\an1}me coming back to my roots. 189 00:11:02,900 --> 00:11:04,976 ♪ ♪ 190 00:11:05,000 --> 00:11:08,142 NARRATOR: In 2017, Sharp and other scientists 191 00:11:08,166 --> 00:11:10,742 {\an1}asked the local community to help them identify 192 00:11:10,766 --> 00:11:14,642 unusual features in the wilderness. 193 00:11:14,666 --> 00:11:18,842 {\an1}A pilot named Eric Sieh told them that while flying over 194 00:11:18,866 --> 00:11:22,876 the area, he'd spotted something unusual. 195 00:11:22,900 --> 00:11:24,776 ♪ ♪ 196 00:11:24,800 --> 00:11:27,242 SHARP: If you fly low enough, even from the air, 197 00:11:27,266 --> 00:11:28,542 {\an1}you can see the bubbling. 198 00:11:28,566 --> 00:11:30,476 ♪ ♪ 199 00:11:30,500 --> 00:11:32,042 HANKE: It's just mysterious. 200 00:11:32,066 --> 00:11:33,942 {\an7}It looks like a Jacuzzi. 201 00:11:33,966 --> 00:11:36,409 {\an7}And so you, you get up to it, and you can hear this... 202 00:11:36,433 --> 00:11:39,376 {\an8}(imitates bubbling) 203 00:11:39,400 --> 00:11:42,709 {\an1}Like, the water is boiling around you. 204 00:11:42,733 --> 00:11:44,376 {\an1}(water bubbling loudly) 205 00:11:44,400 --> 00:11:48,776 ♪ ♪ 206 00:11:48,800 --> 00:11:51,709 NARRATOR: On their first visit, the team wanted to investigate, 207 00:11:51,733 --> 00:11:54,809 {\an7}what's causing the bubbles? 208 00:11:54,833 --> 00:11:56,142 {\an8}SHARP: We took gas samples, 209 00:11:56,166 --> 00:11:58,842 {\an1}and then those were sent to the lab for analysis, 210 00:11:58,866 --> 00:12:04,442 {\an1}and they found that it is a super-high amount of methane. 211 00:12:04,466 --> 00:12:06,476 NARRATOR: Methane leaks, known as seeps, 212 00:12:06,500 --> 00:12:08,809 {\an1}have been found elsewhere in the Arctic. 213 00:12:08,833 --> 00:12:12,233 But they're usually much smaller. 214 00:12:13,666 --> 00:12:16,809 {\an1}The team's measurements reveal that Esieh Lake is belching out 215 00:12:16,833 --> 00:12:21,242 {\an1}over ten tons of methane every day. 216 00:12:21,266 --> 00:12:23,542 SULLIVAN: This is the highest flux 217 00:12:23,566 --> 00:12:27,700 {\an7}methane seep that humans have discovered in the Arctic. 218 00:12:29,300 --> 00:12:31,776 {\an1}The amount of methane you see is staggering. 219 00:12:31,800 --> 00:12:37,209 ♪ ♪ 220 00:12:37,233 --> 00:12:38,942 NARRATOR: From the shore, it's difficult to see 221 00:12:38,966 --> 00:12:43,276 where the methane is coming from. 222 00:12:43,300 --> 00:12:46,709 So the team decides to get closer to the source. 223 00:12:46,733 --> 00:12:50,242 SULLIVAN: Hypothermia is obviously the main danger. 224 00:12:50,266 --> 00:12:52,642 {\an1}Second is me getting air. 225 00:12:52,666 --> 00:12:56,376 {\an1}I'm very curious about what's down there. 226 00:12:56,400 --> 00:13:01,633 ♪ ♪ 227 00:13:07,500 --> 00:13:11,976 NARRATOR: Sullivan finds that the lake is shallow... just a few feet deep. 228 00:13:12,000 --> 00:13:13,942 But then, he follows the lake floor 229 00:13:13,966 --> 00:13:17,166 towards the source of the bubbles. 230 00:13:19,900 --> 00:13:21,109 SULLIVAN: I was kicking really hard 231 00:13:21,133 --> 00:13:22,342 {\an1}to stay down along the bottom, 232 00:13:22,366 --> 00:13:24,142 {\an1}and I was moving my hands along it. 233 00:13:24,166 --> 00:13:26,809 {\an1}And it went from this mushy lake bottom 234 00:13:26,833 --> 00:13:29,209 {\an1}that was flat, flat, flat, 235 00:13:29,233 --> 00:13:30,509 {\an1}and then it just dropped out. 236 00:13:30,533 --> 00:13:37,076 ♪ ♪ 237 00:13:37,100 --> 00:13:39,409 SULLIVAN: That gets deep so quickly. 238 00:13:39,433 --> 00:13:41,742 {\an4}HANKE: Yeah. It's like you're on the bottom, 239 00:13:41,766 --> 00:13:43,976 you're on the bottom, bottom's gone. 240 00:13:44,000 --> 00:13:47,642 NARRATOR: Sullivan finds the methane bubbles are streaming up 241 00:13:47,666 --> 00:13:49,976 {\an1}from the hole in the lake floor. 242 00:13:50,000 --> 00:13:51,076 SULLIVAN: The bubbling, 243 00:13:51,100 --> 00:13:52,342 {\an1}it, it sounded like seeping gas, 244 00:13:52,366 --> 00:13:54,442 {\an1}as if it was even from a propane tank. 245 00:13:54,466 --> 00:13:58,309 {\an8}♪ ♪ 246 00:13:58,333 --> 00:13:59,476 {\an8}HANKE: How'd it go? 247 00:13:59,500 --> 00:14:01,476 {\an7}SULLIVAN: Still going down! SHARP: Wow. 248 00:14:01,500 --> 00:14:03,309 {\an8}(breathing heavily) 249 00:14:03,333 --> 00:14:07,676 {\an8}NARRATOR: With the lake bottom too dark to see, 250 00:14:07,700 --> 00:14:10,733 {\an7}the team deploys a sonar scan. 251 00:14:13,233 --> 00:14:17,876 {\an7}Most of this bed is around three feet deep. 252 00:14:17,900 --> 00:14:19,376 {\an7}But beneath the streams of bubbles, 253 00:14:19,400 --> 00:14:23,776 {\an7}the ground abruptly falls away, 254 00:14:23,800 --> 00:14:26,442 {\an7}at its deepest reaching 50 feet. 255 00:14:26,466 --> 00:14:27,776 {\an7}Why does a lake floor 256 00:14:27,800 --> 00:14:34,476 {\an7}otherwise flat and shallow contain such a massive hole? 257 00:14:34,500 --> 00:14:36,276 {\an1}(rotor blades whirring) 258 00:14:36,300 --> 00:14:38,776 {\an1}On the Yamal, scientists believe a methane leak 259 00:14:38,800 --> 00:14:41,600 {\an1}blew out a huge crater. 260 00:14:42,933 --> 00:14:46,209 {\an7}Esieh Lake is another sign within the Arctic 261 00:14:46,233 --> 00:14:50,833 {\an7}that beneath the surface, methane is stirring. 262 00:14:52,000 --> 00:14:53,209 {\an1}So could more craters... 263 00:14:53,233 --> 00:14:56,642 And more methane... Be on the way? 264 00:14:56,666 --> 00:14:58,076 ♪ ♪ 265 00:14:58,100 --> 00:15:01,176 As well as methane, there's one more clue that links 266 00:15:01,200 --> 00:15:03,542 Esieh Lake and the Yamal craters. 267 00:15:03,566 --> 00:15:05,276 (birds twittering) 268 00:15:05,300 --> 00:15:10,176 {\an1}Both are located on the same type of frozen terrain: 269 00:15:10,200 --> 00:15:12,876 permafrost. 270 00:15:12,900 --> 00:15:16,709 ♪ ♪ 271 00:15:16,733 --> 00:15:19,442 {\an1}Most permafrost is found in the land masses 272 00:15:19,466 --> 00:15:20,809 {\an1}of high northern latitudes, 273 00:15:20,833 --> 00:15:25,576 {\an1}including Russia, Canada, and most of Alaska, 274 00:15:25,600 --> 00:15:31,266 {\an1}Covering an area almost as large as the U.S. and Canada combined. 275 00:15:32,566 --> 00:15:38,042 {\an1}Permafrost can stretch almost a mile beneath Earth's surface. 276 00:15:38,066 --> 00:15:40,942 {\an1}It's defined as any ground whose temperature remains at 277 00:15:40,966 --> 00:15:43,109 {\an1}or below 32 degrees Fahrenheit 278 00:15:43,133 --> 00:15:46,709 for two or more consecutive years. 279 00:15:46,733 --> 00:15:50,266 {\an1}But it can remain frozen for millennia. 280 00:15:51,733 --> 00:15:54,376 ♪ ♪ 281 00:15:54,400 --> 00:15:56,976 {\an1}Recently, rising Arctic temperatures have meant that 282 00:15:57,000 --> 00:16:00,566 {\an1}in some regions, the permafrost has started to thaw. 283 00:16:04,700 --> 00:16:06,642 (birds twittering) 284 00:16:06,666 --> 00:16:07,776 Just how fast 285 00:16:07,800 --> 00:16:10,876 {\an1}and the danger this may pose to our climate 286 00:16:10,900 --> 00:16:14,909 {\an1}is revealed 450 miles from Esieh Lake. 287 00:16:14,933 --> 00:16:19,876 {\an1}Near the town of Fox, in Interior Alaska, 288 00:16:19,900 --> 00:16:22,542 {\an1}something strange is happening in the woods. 289 00:16:22,566 --> 00:16:24,342 (birds twittering, branches rustling) 290 00:16:24,366 --> 00:16:26,876 ♪ ♪ 291 00:16:26,900 --> 00:16:28,176 TOM DOUGLAS: This is what people refer to 292 00:16:28,200 --> 00:16:30,309 {\an1}as this drunken forest. 293 00:16:30,333 --> 00:16:33,976 {\an1}You can see a bunch of these have kind of started to go. 294 00:16:34,000 --> 00:16:36,209 {\an1}They're just having a hard time getting enough rooting in 295 00:16:36,233 --> 00:16:38,442 to grow straight. 296 00:16:38,466 --> 00:16:41,609 NARRATOR: This forest sits on top of permafrost. 297 00:16:41,633 --> 00:16:45,876 {\an1}Scientist Tom Douglas has been tracking some 298 00:16:45,900 --> 00:16:47,442 {\an1}surprising changes taking place 299 00:16:47,466 --> 00:16:51,076 {\an1}as the permafrost starts to thaw. 300 00:16:51,100 --> 00:16:53,909 DOUGLAS: I mean, look at those huge birch trees. 301 00:16:53,933 --> 00:16:55,109 {\an1}They're literally just 302 00:16:55,133 --> 00:16:57,742 {\an1}riding down those slopes as it's all degrading. 303 00:16:57,766 --> 00:16:59,809 ♪ ♪ 304 00:16:59,833 --> 00:17:01,842 {\an1}I mean, this goes a good 20 or so meters below us. 305 00:17:01,866 --> 00:17:03,742 {\an1}This is a giant hole. 306 00:17:03,766 --> 00:17:06,509 {\an1}You can hear water in there. (water rushing) 307 00:17:06,533 --> 00:17:07,876 This whole landscape is just very slowly 308 00:17:07,900 --> 00:17:09,842 {\an1}sliding downhill with gravity. 309 00:17:09,866 --> 00:17:11,942 ♪ ♪ 310 00:17:11,966 --> 00:17:13,109 {\an1}This is a very dramatic 311 00:17:13,133 --> 00:17:15,676 {\an1}and very rapid change in the landscape here 312 00:17:15,700 --> 00:17:18,009 {\an7}that, again, we're seeing in a matter of years. 313 00:17:18,033 --> 00:17:21,709 {\an7}Not decades, not 20 years, not by 2100. 314 00:17:21,733 --> 00:17:23,842 {\an8}Since 2018. 315 00:17:23,866 --> 00:17:25,342 {\an1}It's pretty dramatic. 316 00:17:25,366 --> 00:17:27,242 ♪ ♪ 317 00:17:27,266 --> 00:17:31,809 NARRATOR: This rapid thaw is also affecting human settlements. 318 00:17:31,833 --> 00:17:33,976 Like Utqiagvik, the most northern city 319 00:17:34,000 --> 00:17:37,009 {\an1}in the United States. 320 00:17:37,033 --> 00:17:38,709 ♪ ♪ 321 00:17:38,733 --> 00:17:45,042 {\an1}This entire community sits on top of the Alaskan permafrost. 322 00:17:45,066 --> 00:17:48,942 Locals call it "the top of the world." 323 00:17:48,966 --> 00:17:50,309 ♪ ♪ 324 00:17:50,333 --> 00:17:52,142 GORDON BROWER: If you point that way, 325 00:17:52,166 --> 00:17:55,276 {\an1}that's Greenland over there. 326 00:17:55,300 --> 00:17:57,842 {\an8}Canada is over here. 327 00:17:57,866 --> 00:18:00,742 {\an7}And that way is, guess what. 328 00:18:00,766 --> 00:18:02,966 {\an8}(laughing): Russia. 329 00:18:04,500 --> 00:18:05,709 NARRATOR: Gordon Brower 330 00:18:05,733 --> 00:18:09,009 {\an1}is a Native Alaskan Inupiaq whaling captain. 331 00:18:09,033 --> 00:18:13,909 {\an1}His people have lived in this region for thousands of years. 332 00:18:13,933 --> 00:18:16,942 BROWER: Communities like these, they're special. 333 00:18:16,966 --> 00:18:19,642 {\an1}A lot of the cultures in the world 334 00:18:19,666 --> 00:18:23,209 are assimilated, and we're assimilated here, 335 00:18:23,233 --> 00:18:27,009 {\an1}but we brought our culture and our ways 336 00:18:27,033 --> 00:18:29,409 {\an1}to the future with us. 337 00:18:29,433 --> 00:18:33,276 {\an1}And you can come here and still see the same celebration 338 00:18:33,300 --> 00:18:36,509 that took place 10,000 years ago. 339 00:18:36,533 --> 00:18:38,776 ♪ ♪ 340 00:18:38,800 --> 00:18:42,976 NARRATOR: For five decades, Brower has been hunting in these waters, 341 00:18:43,000 --> 00:18:46,476 {\an1}part of an ancient Inupiaq tradition of living off the land 342 00:18:46,500 --> 00:18:49,142 and the sea. 343 00:18:49,166 --> 00:18:52,809 {\an1}We don't have Walmart or we don't have McDonald's up here. 344 00:18:52,833 --> 00:18:54,609 {\an1}We have other small restaurants 345 00:18:54,633 --> 00:18:56,576 {\an1}and other things to do like that. 346 00:18:56,600 --> 00:18:58,876 But the majority of food resources 347 00:18:58,900 --> 00:19:03,909 {\an1}are still hunted today: seals, whales, belugas, 348 00:19:03,933 --> 00:19:06,009 ducks, geese, 349 00:19:06,033 --> 00:19:08,542 caribou, wolves... 350 00:19:08,566 --> 00:19:15,200 All of those are still traded and used. 351 00:19:17,133 --> 00:19:18,576 NARRATOR: With little fresh food available 352 00:19:18,600 --> 00:19:22,309 {\an1}in winter, generations of Native Alaskans have depended on 353 00:19:22,333 --> 00:19:26,742 cellars carved out of the permafrost. 354 00:19:26,766 --> 00:19:30,076 BROWER: Well, we're in an ice cellar. 355 00:19:30,100 --> 00:19:34,242 {\an1}My folks used this ice cellar for years and years. 356 00:19:34,266 --> 00:19:36,709 {\an1}This is where I put a whale 357 00:19:36,733 --> 00:19:40,666 {\an1}and store it in trust for the community. 358 00:19:42,033 --> 00:19:45,842 NARRATOR: But thawing permafrost means this natural deep freeze 359 00:19:45,866 --> 00:19:48,442 {\an1}isn't as cold as it used to be. 360 00:19:48,466 --> 00:19:51,842 {\an1}As Brower discovered. 361 00:19:51,866 --> 00:19:55,009 BROWER: I had checked on the meat and told my brothers, 362 00:19:55,033 --> 00:19:57,376 {\an1}you know, "We got to pull that meat out. 363 00:19:57,400 --> 00:19:59,676 It's draining, and we don't want that." 364 00:19:59,700 --> 00:20:02,509 {\an1}I've resorted to pulling a whole whale out of there 365 00:20:02,533 --> 00:20:04,742 and putting it into walk-in freezers. 366 00:20:04,766 --> 00:20:07,276 ♪ ♪ 367 00:20:07,300 --> 00:20:10,409 NARRATOR: Thawing ice cellars aren't the only threat rising temperatures 368 00:20:10,433 --> 00:20:12,942 {\an1}pose to this community. 369 00:20:12,966 --> 00:20:16,276 {\an1}Recently, sea ice that used to protect the shore 370 00:20:16,300 --> 00:20:21,076 {\an1}from storms has begun to melt. 371 00:20:21,100 --> 00:20:23,342 BROWER: Storm surge is pretty dramatic. 372 00:20:23,366 --> 00:20:25,376 And it's going to 373 00:20:25,400 --> 00:20:28,409 {\an1}wreak havoc on your coastline here. 374 00:20:28,433 --> 00:20:31,442 {\an1}And the thing about is, when it's reaching the edge, 375 00:20:31,466 --> 00:20:34,142 a lot of the banks are permafrost-rich, 376 00:20:34,166 --> 00:20:36,609 {\an1}and it undercuts them. 377 00:20:36,633 --> 00:20:40,209 NARRATOR: Exposed by the storms, 378 00:20:40,233 --> 00:20:43,533 {\an1}permafrost is thawing and crumbling away. 379 00:20:46,300 --> 00:20:49,176 {\an1}Now communities like Utqiagvik 380 00:20:49,200 --> 00:20:52,309 {\an1}are trying to protect their homes. 381 00:20:52,333 --> 00:20:53,442 BROWER: These are all 382 00:20:53,466 --> 00:20:59,309 {\an1}our local efforts to stop the storm surge. 383 00:20:59,333 --> 00:21:02,700 {\an1}This is our way of trying to save the town. 384 00:21:04,900 --> 00:21:07,042 NARRATOR: With a retreating coastline 385 00:21:07,066 --> 00:21:08,942 {\an1}and warming ice cellars, 386 00:21:08,966 --> 00:21:13,433 {\an1}local communities are hit twice by thawing permafrost. 387 00:21:15,300 --> 00:21:20,042 But the big thaw is an Arctic-wide problem. 388 00:21:20,066 --> 00:21:22,442 NATALI: Through the next decades and century, 389 00:21:22,466 --> 00:21:24,809 we expect anywhere, across the Arctic, 390 00:21:24,833 --> 00:21:27,776 {\an8}between 30% and 70% of near-surface permafrost 391 00:21:27,800 --> 00:21:29,076 {\an8}will be lost. 392 00:21:29,100 --> 00:21:32,342 {\an1}That range partly has to do with just some uncertainty 393 00:21:32,366 --> 00:21:34,076 in the science, but largely has to do with 394 00:21:34,100 --> 00:21:36,209 {\an1}how much warming will happen in the future. 395 00:21:36,233 --> 00:21:41,742 NARRATOR: Arctic communities are facing the immediate effects now. 396 00:21:41,766 --> 00:21:44,676 {\an1}But scientists are concerned this loss has implications 397 00:21:44,700 --> 00:21:46,633 {\an1}for the entire planet. 398 00:21:48,466 --> 00:21:52,009 {\an1}So why is permafrost thaw so dangerous? 399 00:21:52,033 --> 00:21:56,142 {\an1}And what is the link to methane? 400 00:21:56,166 --> 00:21:59,576 (birds twittering) 401 00:21:59,600 --> 00:22:01,809 Back near Fox in Interior Alaska, 402 00:22:01,833 --> 00:22:04,842 {\an1}Tom Douglas is about to do something only possible 403 00:22:04,866 --> 00:22:07,076 {\an1}in a few places on Earth... 404 00:22:07,100 --> 00:22:12,066 Walk deep down into the permafrost itself. 405 00:22:15,366 --> 00:22:18,109 {\an1}The Fox permafrost tunnel reveals there's more 406 00:22:18,133 --> 00:22:20,466 {\an1}to permafrost than frozen earth. 407 00:22:22,800 --> 00:22:24,909 DOUGLAS: That's a horn. 408 00:22:24,933 --> 00:22:27,109 {\an1}That's from the longhorn steppe bison. 409 00:22:27,133 --> 00:22:28,676 {\an1}And they are extinct now, 410 00:22:28,700 --> 00:22:30,742 but back 18,000 to 40,000 years ago, 411 00:22:30,766 --> 00:22:34,376 you know, there were steppe bison here. 412 00:22:34,400 --> 00:22:35,343 Pretty exciting, 413 00:22:35,367 --> 00:22:37,309 {\an1}this is a mammoth bone right here. 414 00:22:37,333 --> 00:22:38,809 {\an1}You can just see kind of the 415 00:22:38,833 --> 00:22:41,009 {\an1}piece of it sticking out right there. 416 00:22:41,033 --> 00:22:43,942 It's pretty big. 417 00:22:43,966 --> 00:22:46,042 NARRATOR: The tunnel reveals that permafrost contains 418 00:22:46,066 --> 00:22:50,142 vast quantities of organic matter. 419 00:22:50,166 --> 00:22:52,009 {\an1}DOUGLAS: So these are, 420 00:22:52,033 --> 00:22:54,109 {\an1}these are sedges, kind of like grass. 421 00:22:54,133 --> 00:22:55,742 {\an1}And you can see that they, they're green. 422 00:22:55,766 --> 00:22:57,576 {\an1}They still have their chlorophyll in 'em. 423 00:22:57,600 --> 00:22:59,542 {\an1}They're also upside down. 424 00:22:59,566 --> 00:23:03,809 {\an1}This block fell into a water feature that then froze, 425 00:23:03,833 --> 00:23:07,809 {\an1}probably 20,000 or so years ago. 426 00:23:07,833 --> 00:23:10,276 ♪ ♪ 427 00:23:10,300 --> 00:23:12,142 NARRATOR: This ancient organic matter, 428 00:23:12,166 --> 00:23:15,676 {\an1}like all life on our planet, contains carbon. 429 00:23:15,700 --> 00:23:17,942 (birds twittering) 430 00:23:17,966 --> 00:23:20,576 {\an1}And is part of a vital Earth system called 431 00:23:20,600 --> 00:23:23,909 the carbon cycle. 432 00:23:23,933 --> 00:23:26,142 ♪ ♪ 433 00:23:26,166 --> 00:23:32,176 As they grow, plants absorb carbon dioxide. 434 00:23:32,200 --> 00:23:34,876 {\an1}When they die, they, or the animals that have eaten them, 435 00:23:34,900 --> 00:23:37,609 decompose, 436 00:23:37,633 --> 00:23:42,642 {\an1}releasing some of this carbon back into the atmosphere. 437 00:23:42,666 --> 00:23:46,409 {\an1}But in the freezing Arctic, 438 00:23:46,433 --> 00:23:48,342 {\an1}decomposition happens slowly. 439 00:23:48,366 --> 00:23:50,776 So over millennia, 440 00:23:50,800 --> 00:23:53,476 {\an1}a huge amount of organic matter became permafrost 441 00:23:53,500 --> 00:23:56,176 {\an1}before it could decompose, 442 00:23:56,200 --> 00:24:00,642 {\an1}its carbon frozen in time. 443 00:24:00,666 --> 00:24:02,376 DOUGLAS: In the late '90s into the 2000s, 444 00:24:02,400 --> 00:24:04,876 {\an1}people start to look at the stocks of carbon in permafrost. 445 00:24:04,900 --> 00:24:09,609 {\an1}And it's, it's a lot, it's about 1,400 billion metric tons. 446 00:24:09,633 --> 00:24:11,509 {\an1}It's almost twice as much carbon 447 00:24:11,533 --> 00:24:13,709 {\an1}as is currently in Earth's atmosphere. 448 00:24:13,733 --> 00:24:16,142 When we walked in, we noted that smell, right? 449 00:24:16,166 --> 00:24:20,276 {\an1}You're smelling ancient bacteria and carbon being oxidized. 450 00:24:20,300 --> 00:24:23,476 {\an1}It's almost like a, well, I've heard anything from, like, 451 00:24:23,500 --> 00:24:26,176 {\an1}a French cheese, to barnyard, 452 00:24:26,200 --> 00:24:28,909 {\an1}but it's kind of that organic, almost a late fall, 453 00:24:28,933 --> 00:24:30,509 {\an1}wet leaf kind of organic smell. 454 00:24:30,533 --> 00:24:33,909 {\an1}You are smelling permafrost carbon being oxidized. 455 00:24:33,933 --> 00:24:35,076 {\an1}And so the big question 456 00:24:35,100 --> 00:24:37,109 {\an1}is, that carbon that we smell, that's all over 457 00:24:37,133 --> 00:24:38,409 this tunnel walls, 458 00:24:38,433 --> 00:24:39,609 {\an1}what's its ultimate fate? 459 00:24:39,633 --> 00:24:41,353 {\an1}And there's a lot of people working on that. 460 00:24:42,766 --> 00:24:45,042 {\an8}NARRATOR: In other words, how much of this carbon 461 00:24:45,066 --> 00:24:47,042 {\an7}will end up in the atmosphere? 462 00:24:47,066 --> 00:24:50,666 {\an7}And most importantly, how fast? 463 00:24:53,000 --> 00:24:54,609 {\an8}♪ ♪ 464 00:24:54,633 --> 00:24:58,009 {\an7}Falmouth, Massachusetts. 465 00:24:58,033 --> 00:25:01,609 {\an7}3,000 miles from the ice tunnel. 466 00:25:01,633 --> 00:25:04,276 {\an7}Arctic ecologist Susan Natali investigates 467 00:25:04,300 --> 00:25:05,776 {\an7}samples of permafrost 468 00:25:05,800 --> 00:25:08,876 {\an7}to find out what happens when it thaws. 469 00:25:08,900 --> 00:25:12,209 {\an7}NATALI: So these are permafrost cores that were collected 470 00:25:12,233 --> 00:25:15,176 {\an7}from different locations across Alaska. 471 00:25:15,200 --> 00:25:18,042 {\an7}Some of these are really dark, like particularly this one. 472 00:25:18,066 --> 00:25:19,376 {\an8}And that dark color 473 00:25:19,400 --> 00:25:22,442 {\an1}means that that has a lot of carbon in it. 474 00:25:22,466 --> 00:25:24,376 ♪ ♪ 475 00:25:24,400 --> 00:25:28,442 NARRATOR: As permafrost warms, its carbon thaws. 476 00:25:28,466 --> 00:25:32,709 {\an1}And the carbon cycle starts up once again. 477 00:25:32,733 --> 00:25:35,576 {\an1}So that carbon then is available for microbes to break down. 478 00:25:35,600 --> 00:25:38,409 {\an1}And they use it for energy and they decompose it. 479 00:25:38,433 --> 00:25:39,809 And in that process, they're releasing 480 00:25:39,833 --> 00:25:41,076 {\an1}carbon dioxide or methane. 481 00:25:41,100 --> 00:25:43,176 ♪ ♪ 482 00:25:43,200 --> 00:25:47,900 NARRATOR: Carbon dioxide and methane are both greenhouse gases. 483 00:25:49,000 --> 00:25:52,509 {\an1}As Earth's surface absorbs energy from the sun, 484 00:25:52,533 --> 00:25:55,533 {\an1}it radiates some of it back out as heat. 485 00:25:57,800 --> 00:26:01,209 {\an1}In the atmosphere, greenhouse gases absorb this heat, 486 00:26:01,233 --> 00:26:03,876 {\an1}radiating part of its energy back at Earth 487 00:26:03,900 --> 00:26:07,409 {\an1}and heating up our planet. 488 00:26:07,433 --> 00:26:11,209 NATALI: Greenhouse gases are a concern because they trap heat. 489 00:26:11,233 --> 00:26:12,542 {\an1}They're helpful to us because 490 00:26:12,566 --> 00:26:15,042 they, they make this habitable planet, 491 00:26:15,066 --> 00:26:17,076 {\an1}but because there's too much in the atmosphere, 492 00:26:17,100 --> 00:26:19,176 {\an1}they're now making this an unhabitable planet, 493 00:26:19,200 --> 00:26:20,442 {\an1}or less habitable planet. 494 00:26:20,466 --> 00:26:22,576 ♪ ♪ 495 00:26:22,600 --> 00:26:25,442 NARRATOR: It's estimated that in the mid-18th century, 496 00:26:25,466 --> 00:26:29,076 {\an1}there were over 2,000 gigatons of naturally occurring 497 00:26:29,100 --> 00:26:33,133 {\an1}carbon-based greenhouse gases in the atmosphere. 498 00:26:35,166 --> 00:26:36,542 {\an1}With industrialization, 499 00:26:36,566 --> 00:26:38,542 {\an1}human-made greenhouse gas emissions 500 00:26:38,566 --> 00:26:41,276 {\an1}began to add to this amount. 501 00:26:41,300 --> 00:26:44,476 {\an1}By 2019, it's estimated the total had risen 502 00:26:44,500 --> 00:26:48,442 {\an1}to over 3,000 gigatons. 503 00:26:48,466 --> 00:26:50,176 {\an1}Over the last century and a half, 504 00:26:50,200 --> 00:26:52,409 {\an1}Earth's average temperature increased around 505 00:26:52,433 --> 00:26:55,342 {\an1}two degrees Fahrenheit. 506 00:26:55,366 --> 00:26:58,009 ♪ ♪ 507 00:26:58,033 --> 00:27:02,633 {\an1}Scientists agree human emissions caused this warming. 508 00:27:04,466 --> 00:27:06,709 But recently, they've become concerned 509 00:27:06,733 --> 00:27:09,242 greenhouse gases being released by permafrost 510 00:27:09,266 --> 00:27:13,042 might be driving temperatures higher, too. 511 00:27:13,066 --> 00:27:15,042 {\an7}As the name suggests, 512 00:27:15,066 --> 00:27:18,309 {\an8}permafrost is permanently frozen ground. 513 00:27:18,333 --> 00:27:19,277 {\an8}So we thought, 514 00:27:19,301 --> 00:27:21,642 {\an1}"Okay, this carbon is 515 00:27:21,666 --> 00:27:24,533 very stable, so nothing is going to happen." 516 00:27:26,533 --> 00:27:29,642 But as permafrost starts to thaw, 517 00:27:29,666 --> 00:27:31,800 this carbon becomes vulnerable. 518 00:27:34,066 --> 00:27:36,542 NARRATOR: Since the mid-'70s, 519 00:27:36,566 --> 00:27:37,942 {\an1}carbon dioxide emissions 520 00:27:37,966 --> 00:27:39,609 from the North Alaskan wilderness 521 00:27:39,633 --> 00:27:42,976 have spiked by more than 70%. 522 00:27:43,000 --> 00:27:47,176 {\an7}But while we know a lot about carbon dioxide, 523 00:27:47,200 --> 00:27:49,142 {\an8}the impact of another greenhouse gas 524 00:27:49,166 --> 00:27:52,909 {\an7}coming out of the permafrost is less widely known... 525 00:27:52,933 --> 00:27:58,442 {\an1}the very one escaping from the Yamal and Esieh Lake, 526 00:27:58,466 --> 00:28:01,542 methane. 527 00:28:01,566 --> 00:28:02,976 {\an1}Methane is really important, 528 00:28:03,000 --> 00:28:04,609 {\an1}because it's much more potent 529 00:28:04,633 --> 00:28:06,476 in terms of its ability to trap heat. 530 00:28:06,500 --> 00:28:10,209 {\an1}So it's about 30 times more powerful than carbon dioxide. 531 00:28:10,233 --> 00:28:12,909 ♪ ♪ 532 00:28:12,933 --> 00:28:15,009 NARRATOR: Luckily, while carbon dioxide 533 00:28:15,033 --> 00:28:17,642 {\an1}lasts centuries or longer in our atmosphere, 534 00:28:17,666 --> 00:28:21,342 methane only lasts around 12 years. 535 00:28:21,366 --> 00:28:24,676 {\an1}But as a far more potent greenhouse gas, 536 00:28:24,700 --> 00:28:27,842 {\an1}any large-scale increases in methane emissions 537 00:28:27,866 --> 00:28:31,676 {\an1}have climate scientists seriously concerned. 538 00:28:31,700 --> 00:28:34,909 ♪ ♪ 539 00:28:34,933 --> 00:28:36,876 {\an1}For now, more than half of methane emissions 540 00:28:36,900 --> 00:28:42,309 {\an1}come from human sources like fossil fuels and agriculture, 541 00:28:42,333 --> 00:28:45,709 {\an1}sources well understood by climate experts. 542 00:28:45,733 --> 00:28:48,442 But scientists are increasingly worried 543 00:28:48,466 --> 00:28:51,576 {\an1}about methane emissions from permafrost. 544 00:28:51,600 --> 00:28:54,476 So far, they don't know 545 00:28:54,500 --> 00:28:57,366 {\an8}how much methane the permafrost is releasing. 546 00:28:59,166 --> 00:29:01,376 {\an1}And that's a big problem. 547 00:29:01,400 --> 00:29:03,976 In order to control our temperature, 548 00:29:04,000 --> 00:29:06,176 we have a certain amount of carbon 549 00:29:06,200 --> 00:29:09,100 {\an1}that humans can release... That's our carbon budget. 550 00:29:10,500 --> 00:29:11,942 NARRATOR: In 2015, 551 00:29:11,966 --> 00:29:13,442 the international Paris Agreement 552 00:29:13,466 --> 00:29:18,042 set a target for limiting global warming. 553 00:29:18,066 --> 00:29:20,109 Its goal was to keep the temperature rise 554 00:29:20,133 --> 00:29:27,533 {\an1}to well below two, preferably to 1.5 degrees Celsius. 555 00:29:29,100 --> 00:29:30,142 {\an1}To stand a good chance 556 00:29:30,166 --> 00:29:32,976 of remaining below the 1.5-degree mark, 557 00:29:33,000 --> 00:29:36,242 {\an1}one estimate states that humans could release a maximum of 558 00:29:36,266 --> 00:29:41,842 {\an1}around 460 gigatons more carbon dioxide. 559 00:29:41,866 --> 00:29:45,809 {\an1}But recent climate calculations are based on computer models 560 00:29:45,833 --> 00:29:49,142 {\an1}with incomplete information. 561 00:29:49,166 --> 00:29:50,809 LEE: Unfortunately, 562 00:29:50,833 --> 00:29:53,009 a lot of these Earth system models 563 00:29:53,033 --> 00:29:56,976 {\an1}that contribute to such goals 564 00:29:57,000 --> 00:30:00,409 {\an1}do not take into account CO2 and methane emissions 565 00:30:00,433 --> 00:30:02,233 from permafrost. 566 00:30:03,633 --> 00:30:05,442 NARRATOR: The most recent carbon budgets 567 00:30:05,466 --> 00:30:09,242 have started to include permafrost carbon. 568 00:30:09,266 --> 00:30:12,309 {\an1}But some scientists believe they still underestimate 569 00:30:12,333 --> 00:30:16,309 the amount of carbon the warming Arctic will release, 570 00:30:16,333 --> 00:30:19,676 {\an1}making temperature goals harder to meet 571 00:30:19,700 --> 00:30:21,376 {\an1}and putting more pressure on societies 572 00:30:21,400 --> 00:30:25,409 to dramatically cut their emissions to compensate. 573 00:30:25,433 --> 00:30:27,509 NATALI: So we think we have 574 00:30:27,533 --> 00:30:28,742 a certain amount of greenhouse gases 575 00:30:28,766 --> 00:30:29,942 {\an1}that humans can release, 576 00:30:29,966 --> 00:30:31,076 but our target is wrong right now, 577 00:30:31,100 --> 00:30:32,509 because we're not accounting for 578 00:30:32,533 --> 00:30:33,809 potential permafrost emissions 579 00:30:33,833 --> 00:30:37,476 of methane and carbon dioxide. 580 00:30:37,500 --> 00:30:40,076 NARRATOR: Understanding the dynamics of thawing permafrost 581 00:30:40,100 --> 00:30:42,742 is now critical to predicting our climate future. 582 00:30:42,766 --> 00:30:47,709 {\an1}So how much methane is permafrost emitting each year? 583 00:30:47,733 --> 00:30:52,776 {\an1}And is this annual amount going to increase? 584 00:30:52,800 --> 00:30:56,033 (dogs yapping) 585 00:30:58,100 --> 00:30:59,176 HANKE: Good dogs! 586 00:30:59,200 --> 00:31:02,076 {\an1}Straight ahead, on by, on by, on by. 587 00:31:02,100 --> 00:31:04,276 NARRATOR: Fairbanks, Interior Alaska. 588 00:31:04,300 --> 00:31:06,709 Ecologist Katey Walter Anthony 589 00:31:06,733 --> 00:31:09,109 is heading out onto the frozen terrain. 590 00:31:09,133 --> 00:31:11,342 {\an1}HANKE: Haw! Haw! 591 00:31:11,366 --> 00:31:12,642 {\an1}Come on, Biggy, come on. 592 00:31:12,666 --> 00:31:14,509 (dogs whining) 593 00:31:14,533 --> 00:31:15,609 NARRATOR: Walter Anthony was 594 00:31:15,633 --> 00:31:19,009 among the first to study Esieh Lake. 595 00:31:19,033 --> 00:31:20,642 She's found concerning evidence 596 00:31:20,666 --> 00:31:22,942 {\an1}it's not the only lake in the permafrost region 597 00:31:22,966 --> 00:31:23,943 {\an1}that's releasing methane. 598 00:31:23,967 --> 00:31:28,542 ♪ ♪ 599 00:31:28,566 --> 00:31:30,476 WALTER ANTHONY: So when you spear the spot, 600 00:31:30,500 --> 00:31:32,709 if I hear gas coming out, 601 00:31:32,733 --> 00:31:35,309 I'm going to try to ignite it. 602 00:31:35,333 --> 00:31:36,842 {\an1}And if there's fire, we both need to get out of the way. 603 00:31:36,866 --> 00:31:37,777 {\an1}Okay. 604 00:31:37,801 --> 00:31:40,000 Ready? Yep. 605 00:31:44,166 --> 00:31:45,700 {\an8}Whoa... (flames roaring) 606 00:31:47,666 --> 00:31:49,242 {\an8}That got me. 607 00:31:49,266 --> 00:31:50,576 {\an8}Oh, shoot. 608 00:31:50,600 --> 00:31:51,543 {\an7}Am I on fire? 609 00:31:51,567 --> 00:31:53,409 {\an8}No... I was wondering. 610 00:31:53,433 --> 00:31:54,676 {\an8}(both chuckle) 611 00:31:54,700 --> 00:31:55,800 {\an7}What's smoking? 612 00:31:57,933 --> 00:32:00,442 {\an1}(laughing) You okay? 613 00:32:00,466 --> 00:32:02,742 {\an4}(laughing): Yeah, I'm fine. (laughing) 614 00:32:02,766 --> 00:32:05,009 {\an1}That was a good one. That was a good one. 615 00:32:05,033 --> 00:32:07,066 All right. 616 00:32:08,533 --> 00:32:10,209 NARRATOR: The methane comes from 617 00:32:10,233 --> 00:32:13,476 {\an1}organic matter in permafrost thawing and decomposing 618 00:32:13,500 --> 00:32:15,176 {\an1}at the bottom of the lake, 619 00:32:15,200 --> 00:32:20,476 then rising in methane bubbles to the surface. 620 00:32:20,500 --> 00:32:24,142 Across the Arctic, permafrost thaw 621 00:32:24,166 --> 00:32:28,509 is generating vast numbers of new lakes. 622 00:32:28,533 --> 00:32:29,510 As the soil warms, 623 00:32:29,534 --> 00:32:31,442 {\an1}ice beneath the surface melts, 624 00:32:31,466 --> 00:32:36,076 {\an1}causing the ground to slump and fill with water. 625 00:32:36,100 --> 00:32:38,842 {\an7}And once a lake is formed, you can't stop it, 626 00:32:38,866 --> 00:32:39,976 {\an7}because that water has heat, 627 00:32:40,000 --> 00:32:43,142 {\an1}and it causes the ground to thaw so fast. 628 00:32:43,166 --> 00:32:47,776 NARRATOR: The lakes then start releasing methane. 629 00:32:47,800 --> 00:32:50,109 WALTER ANTHONY: As the methane escapes, 630 00:32:50,133 --> 00:32:51,576 it causes more permafrost to thaw, 631 00:32:51,600 --> 00:32:52,909 {\an1}and more methane to be generated, 632 00:32:52,933 --> 00:32:54,976 {\an1}which is more warming, and you get what's called 633 00:32:55,000 --> 00:32:56,966 {\an1}a positive feedback cycle. 634 00:32:58,700 --> 00:33:00,342 NARRATOR: Positive feedback cycles 635 00:33:00,366 --> 00:33:01,842 {\an1}from permafrost regions 636 00:33:01,866 --> 00:33:04,609 {\an1}are another scenario not sufficiently accounted for 637 00:33:04,633 --> 00:33:07,309 {\an1}in current climate models. 638 00:33:07,333 --> 00:33:08,609 LEE: As permafrost thaws, 639 00:33:08,633 --> 00:33:11,309 greenhouse gases like CO2 and methane 640 00:33:11,333 --> 00:33:15,266 {\an1}will be released back to the atmosphere much faster. 641 00:33:16,900 --> 00:33:19,666 {\an1}Warming is causing more warming. 642 00:33:24,300 --> 00:33:27,509 NARRATOR: Due to positive feedback, permafrost emissions 643 00:33:27,533 --> 00:33:30,876 could increase the rate of warming, 644 00:33:30,900 --> 00:33:34,042 {\an1}compounding the need for humans to reduce their emissions 645 00:33:34,066 --> 00:33:37,866 if climate targets are to be met. 646 00:33:40,033 --> 00:33:43,376 {\an1}But permafrost carbon isn't the only potential driver 647 00:33:43,400 --> 00:33:46,900 {\an1}of a positive feedback cycle. 648 00:33:50,466 --> 00:33:52,876 {\an1}Permafrost is actually not the largest carbon reserve 649 00:33:52,900 --> 00:33:54,409 on Earth. 650 00:33:54,433 --> 00:33:56,742 There's much larger carbon reserve 651 00:33:56,766 --> 00:33:59,276 in Earth's crust as fossil carbon. 652 00:33:59,300 --> 00:34:03,342 But we often don't talk about this carbon. 653 00:34:03,366 --> 00:34:08,600 {\an1}This is because this carbon is considered very stable. 654 00:34:10,666 --> 00:34:12,109 NARRATOR: But some scientists 655 00:34:12,133 --> 00:34:15,876 now wonder if this mega source of carbon 656 00:34:15,900 --> 00:34:18,909 is as stable as they thought. 657 00:34:18,933 --> 00:34:20,176 Disturbing evidence 658 00:34:20,200 --> 00:34:24,566 {\an1}comes from the bubbles in Esieh Lake. 659 00:34:26,500 --> 00:34:28,509 Methane released by thawing permafrost 660 00:34:28,533 --> 00:34:30,876 has a particular chemical fingerprint. 661 00:34:30,900 --> 00:34:33,676 When the scientists at Esieh Lake 662 00:34:33,700 --> 00:34:35,376 studied the methane in the bubbles, 663 00:34:35,400 --> 00:34:39,476 {\an1}they discovered it originated deeper inside Earth. 664 00:34:39,500 --> 00:34:42,776 Much deeper. 665 00:34:42,800 --> 00:34:45,242 ♪ ♪ 666 00:34:45,266 --> 00:34:48,542 {\an1}Miles beneath the permafrost, deep in Earth's crust, 667 00:34:48,566 --> 00:34:53,409 lie huge fossil methane reservoirs. 668 00:34:53,433 --> 00:34:55,142 {\an7}While methane from permafrost 669 00:34:55,166 --> 00:34:58,209 {\an7}comes from organic matter thousands of years old, 670 00:34:58,233 --> 00:35:00,376 {\an8}fossil methane comes from organisms 671 00:35:00,400 --> 00:35:05,009 {\an8}that decomposed millions of years ago. 672 00:35:05,033 --> 00:35:07,209 {\an8}But if it's miles beneath the surface, 673 00:35:07,233 --> 00:35:10,742 {\an8}how is this methane getting through Earth's crust? 674 00:35:10,766 --> 00:35:12,500 {\an8}And why here? 675 00:35:15,400 --> 00:35:17,242 Above ground, 676 00:35:17,266 --> 00:35:21,042 the landscape itself gives scientists a clue. 677 00:35:21,066 --> 00:35:22,709 SULLIVAN: Looking up at the peaks around here, 678 00:35:22,733 --> 00:35:25,142 and studying the local geology, 679 00:35:25,166 --> 00:35:26,842 we know that this is 680 00:35:26,866 --> 00:35:29,233 {\an1}a highly fractured and faulted region. 681 00:35:32,933 --> 00:35:35,809 NARRATOR: As of 2021, Alaska is the most 682 00:35:35,833 --> 00:35:40,876 {\an1}seismically active state in the U.S. 683 00:35:40,900 --> 00:35:43,809 In the territory close to Esieh Lake, 684 00:35:43,833 --> 00:35:45,842 scientists have discovered a network 685 00:35:45,866 --> 00:35:49,076 {\an1}of geological fault lines. 686 00:35:49,100 --> 00:35:51,709 Although not on a tectonic plate boundary, 687 00:35:51,733 --> 00:35:55,676 {\an1}movements of Earth's crust have caused it to crack here. 688 00:35:55,700 --> 00:35:59,476 {\an1}The closest fault line discovered so far 689 00:35:59,500 --> 00:36:03,700 {\an1}is fewer than five miles from the lake. 690 00:36:05,300 --> 00:36:07,342 {\an1}Fault lines make cracks in Earth's crust 691 00:36:07,366 --> 00:36:11,976 {\an1}through which fossil methane can rise to the surface. 692 00:36:12,000 --> 00:36:13,676 Though it hasn't been confirmed, 693 00:36:13,700 --> 00:36:16,709 {\an1}the scientists suspect a fault line lies near, 694 00:36:16,733 --> 00:36:19,709 or directly beneath, Esieh Lake. 695 00:36:19,733 --> 00:36:23,242 {\an1}But if so, there's a mystery. 696 00:36:23,266 --> 00:36:25,442 Seismic evidence from the area suggests 697 00:36:25,466 --> 00:36:31,576 {\an1}Esieh Lake sits above 500 feet of still-frozen permafrost. 698 00:36:31,600 --> 00:36:34,809 This should form a rock-solid frozen barrier 699 00:36:34,833 --> 00:36:38,800 {\an1}trapping the fossil methane inside Earth. 700 00:36:40,733 --> 00:36:43,376 So how are these deep stocks of greenhouse gas 701 00:36:43,400 --> 00:36:47,066 {\an1}breaking through to the surface? 702 00:36:48,733 --> 00:36:50,776 {\an1}So far, the team's sonar scan 703 00:36:50,800 --> 00:36:55,309 {\an1}has revealed a 50-foot hole in the lake floor. 704 00:36:55,333 --> 00:36:58,542 But what if they could look deeper, 705 00:36:58,566 --> 00:37:02,076 {\an1}into the permafrost itself? 706 00:37:02,100 --> 00:37:03,742 {\an1}Geophysicist Nick Hasson 707 00:37:03,766 --> 00:37:07,042 joins the team, with technology used 708 00:37:07,066 --> 00:37:09,709 by the military. 709 00:37:09,733 --> 00:37:11,742 {\an1}75 just after the shrub. 710 00:37:11,766 --> 00:37:16,776 HASSON: I'm essentially scanning the permafrost 711 00:37:16,800 --> 00:37:18,709 {\an7}using a geophysical method called Very Low Frequency. 712 00:37:18,733 --> 00:37:22,942 NARRATOR: Very Low Frequency, or VLF, 713 00:37:22,966 --> 00:37:26,442 {\an1}measures a special kind of electromagnetic wave 714 00:37:26,466 --> 00:37:29,342 {\an1}as it moves through Earth. 715 00:37:29,366 --> 00:37:31,776 {\an1}These waves are sent out globally by the Navy 716 00:37:31,800 --> 00:37:35,176 to communicate with submarines. 717 00:37:35,200 --> 00:37:38,976 But as those waves pass through the Earth below, 718 00:37:39,000 --> 00:37:41,576 Hasson's equipment can pick them up. 719 00:37:41,600 --> 00:37:45,542 By measuring the speed the wave travels, 720 00:37:45,566 --> 00:37:47,076 {\an1}Hasson can tell whether the ground deep beneath him 721 00:37:47,100 --> 00:37:50,309 is frozen or not. 722 00:37:50,333 --> 00:37:51,709 When it moves through the ground, 723 00:37:51,733 --> 00:37:53,909 {\an1}if there's permafrost or ice, 724 00:37:53,933 --> 00:37:57,342 these waves are coming up against 725 00:37:57,366 --> 00:37:59,109 a lot of resistance. 726 00:37:59,133 --> 00:38:01,309 But if there's no permafrost or ice, 727 00:38:01,333 --> 00:38:04,942 {\an1}it quickly moves through. 728 00:38:04,966 --> 00:38:06,476 NARRATOR: If they're strong enough, 729 00:38:06,500 --> 00:38:08,376 {\an1}the electromagnetic VLF waves 730 00:38:08,400 --> 00:38:13,676 {\an1}should enable Hasson to see whatever lies beneath the lake. 731 00:38:13,700 --> 00:38:16,676 {\an1}And so we can scan the Earth similar to how a doctor 732 00:38:16,700 --> 00:38:18,433 {\an1}scans you with a MRI. 733 00:38:20,000 --> 00:38:21,876 NARRATOR: Esieh Lake is the biggest 734 00:38:21,900 --> 00:38:24,676 on-land methane seep yet found in the Arctic, 735 00:38:24,700 --> 00:38:28,700 {\an1}but no one has used VLF to look beneath it. 736 00:38:30,366 --> 00:38:32,042 Until now. 737 00:38:32,066 --> 00:38:33,076 HASSON: Wow. 738 00:38:33,100 --> 00:38:35,442 Fantastic signals. 739 00:38:35,466 --> 00:38:38,333 {\an1}Yeah, so I'm starting to notice a change. 740 00:38:42,600 --> 00:38:44,942 Well, we're over the largest seep, 741 00:38:44,966 --> 00:38:47,309 {\an1}and there's some sort of large anomaly 742 00:38:47,333 --> 00:38:49,742 happening right here where I'm located. 743 00:38:49,766 --> 00:38:52,376 {\an1}And the VLF is picking it up. 744 00:38:52,400 --> 00:38:54,109 It's very exciting. 745 00:38:54,133 --> 00:38:56,609 The signals are just outstanding. 746 00:38:56,633 --> 00:38:59,966 ♪ ♪ 747 00:39:01,333 --> 00:39:02,842 NARRATOR: Back at camp, 748 00:39:02,866 --> 00:39:05,642 {\an1}Hasson takes the first ever high-resolution glimpse 749 00:39:05,666 --> 00:39:08,200 beneath Esieh Lake. 750 00:39:10,066 --> 00:39:13,276 {\an1}This slice through 500 feet of ground below the lake 751 00:39:13,300 --> 00:39:16,609 reveals an anomaly. 752 00:39:16,633 --> 00:39:19,642 So the dark blue is the permafrost region. 753 00:39:19,666 --> 00:39:25,009 So anything that's light blue to red is thawed. 754 00:39:25,033 --> 00:39:27,109 {\an1}And so this shouldn't be here. 755 00:39:27,133 --> 00:39:31,209 {\an1}There should be permafrost covering this entire area. 756 00:39:31,233 --> 00:39:32,442 But for some reason, 757 00:39:32,466 --> 00:39:35,876 {\an1}what you can see here is a thaw chimney 758 00:39:35,900 --> 00:39:40,309 going from somewhere below 150 meters 759 00:39:40,333 --> 00:39:42,676 to the surface, 760 00:39:42,700 --> 00:39:45,576 where we see the rising bubbles. 761 00:39:45,600 --> 00:39:48,300 {\an1}And so this is really unique. 762 00:39:49,433 --> 00:39:51,509 NARRATOR: So far, the scientists have only seen 763 00:39:51,533 --> 00:39:54,476 {\an1}50 feet beneath the lake. 764 00:39:54,500 --> 00:39:59,233 {\an1}Now, Hasson's VLF image lets them look ten times deeper. 765 00:40:01,300 --> 00:40:05,676 {\an1}Below the lake stretches a deep layer of permafrost. 766 00:40:05,700 --> 00:40:07,476 But the scientists now know 767 00:40:07,500 --> 00:40:10,542 {\an1}this hasn't just thawed at the surface. 768 00:40:10,566 --> 00:40:13,576 {\an1}Instead, a chimney of material has thawed 769 00:40:13,600 --> 00:40:17,442 right through the frozen permafrost: 770 00:40:17,466 --> 00:40:19,742 {\an8}a warmer, semi-permeable passageway 771 00:40:19,766 --> 00:40:23,833 {\an7}through which fossil methane rises to the surface. 772 00:40:28,300 --> 00:40:30,642 {\an1}So, thawing permafrost means not one, 773 00:40:30,666 --> 00:40:34,376 {\an1}but two sources of methane for our atmosphere. 774 00:40:34,400 --> 00:40:36,509 As it warms, 775 00:40:36,533 --> 00:40:39,676 permafrost releases its own methane gas. 776 00:40:39,700 --> 00:40:42,742 And as thaw chimneys form within it, 777 00:40:42,766 --> 00:40:45,476 {\an1}they provide an escape route for fossil methane 778 00:40:45,500 --> 00:40:48,733 {\an1}that has been safely trapped for millions of years. 779 00:40:52,500 --> 00:40:56,809 {\an1}Scientists estimate there are around 1.3 trillion tons 780 00:40:56,833 --> 00:40:59,466 of methane stored beneath the Arctic. 781 00:41:00,766 --> 00:41:03,742 {\an1}That's nearly 250 times as much methane 782 00:41:03,766 --> 00:41:07,209 as there is in Earth's atmosphere today. 783 00:41:07,233 --> 00:41:10,976 So is Esieh Lake's thaw chimney unique? 784 00:41:11,000 --> 00:41:13,700 Or is fossil methane escaping elsewhere? 785 00:41:15,266 --> 00:41:18,142 {\an1}While the leak in Esieh Lake is unusually large, 786 00:41:18,166 --> 00:41:19,942 {\an1}smaller seeps of fossil methane 787 00:41:19,966 --> 00:41:23,066 are being discovered across the Arctic. 788 00:41:24,666 --> 00:41:28,076 In Alaska alone, over 70 sites have been found. 789 00:41:28,100 --> 00:41:30,433 ♪ ♪ 790 00:41:31,666 --> 00:41:33,976 {\an1}There's no current sign the entire reserve 791 00:41:34,000 --> 00:41:36,576 of fossil methane is moving toward the surface. 792 00:41:36,600 --> 00:41:40,209 But the appearance of even small amounts 793 00:41:40,233 --> 00:41:45,409 {\an1}of this ancient greenhouse gas has some scientists concerned. 794 00:41:45,433 --> 00:41:47,709 WALTER ANTHONY: If permafrost thawed, 795 00:41:47,733 --> 00:41:51,142 {\an7}then that's a scary wildcard in the climate change story, 796 00:41:51,166 --> 00:41:52,842 {\an1}because we think there's a huge amount 797 00:41:52,866 --> 00:41:54,176 {\an1}of methane and natural gas 798 00:41:54,200 --> 00:41:56,809 {\an1}trapped inside permafrost and under permafrost. 799 00:41:56,833 --> 00:41:58,909 So if permafrost becomes like Swiss cheese, 800 00:41:58,933 --> 00:42:01,376 {\an1}with lots of holes in it, 801 00:42:01,400 --> 00:42:05,109 {\an1}then you can have chimneys where that gas is erupting out. 802 00:42:05,133 --> 00:42:07,776 {\an1}And that is not included in climate models. 803 00:42:07,800 --> 00:42:09,742 ♪ ♪ 804 00:42:09,766 --> 00:42:11,376 NARRATOR: If only a tiny fraction 805 00:42:11,400 --> 00:42:14,542 {\an1}of the fossil reservoirs were to reach the atmosphere, 806 00:42:14,566 --> 00:42:16,942 {\an1}it could intensify warming, 807 00:42:16,966 --> 00:42:21,442 {\an1}putting even more pressure on human emissions targets. 808 00:42:21,466 --> 00:42:23,176 How fast that's going to happen 809 00:42:23,200 --> 00:42:27,000 {\an1}and just how much methane will come out, we don't know. 810 00:42:30,833 --> 00:42:33,209 NARRATOR: Scientists don't currently understand 811 00:42:33,233 --> 00:42:35,876 {\an1}how fast such a cycle might occur, 812 00:42:35,900 --> 00:42:38,533 {\an1}or what it would look like. 813 00:42:40,733 --> 00:42:41,976 {\an1}But there's one place on Earth 814 00:42:42,000 --> 00:42:43,642 that gives a chilling example 815 00:42:43,666 --> 00:42:48,733 {\an1}of how a human-made permafrost feedback cycle actually works. 816 00:42:50,500 --> 00:42:55,066 {\an1}Northeast Siberia is home to the Chersky Mountains. 817 00:42:57,033 --> 00:43:00,376 In the 1960s, in a place called Batagaika, 818 00:43:00,400 --> 00:43:04,609 a stretch of forest was cleared to make a road. 819 00:43:04,633 --> 00:43:07,909 {\an1}Stripped of its tree cover, 820 00:43:07,933 --> 00:43:11,676 {\an1}the permafrost was exposed to the warming sun. 821 00:43:11,700 --> 00:43:13,209 As it thawed, the ground sank, 822 00:43:13,233 --> 00:43:19,509 {\an1}pulling down trees at its edge and exposing more permafrost: 823 00:43:19,533 --> 00:43:21,476 {\an1}a positive feedback cycle. 824 00:43:21,500 --> 00:43:24,309 ♪ ♪ 825 00:43:24,333 --> 00:43:26,476 Today, the strip of cleared forest 826 00:43:26,500 --> 00:43:30,042 is a depression nearly 300 feet deep 827 00:43:30,066 --> 00:43:32,042 {\an1}and over half a mile wide. 828 00:43:32,066 --> 00:43:33,809 And it's growing. 829 00:43:33,833 --> 00:43:36,742 Scientists call it a megaslump. 830 00:43:36,766 --> 00:43:38,876 LEIBMAN: Batagaika, 831 00:43:38,900 --> 00:43:40,442 {\an8}it is very big, 832 00:43:40,466 --> 00:43:46,176 {\an7}but this, the size is because of the initial human impact. 833 00:43:46,200 --> 00:43:48,876 {\an1}And this one is already more than one kilometer, 834 00:43:48,900 --> 00:43:51,066 {\an1}and growing every summer. 835 00:43:54,700 --> 00:43:57,909 NARRATOR: Batagaika reveals how a small human impact 836 00:43:57,933 --> 00:44:02,366 {\an1}can start a devastating feedback cycle in permafrost. 837 00:44:03,633 --> 00:44:05,909 (birds chirping) 838 00:44:05,933 --> 00:44:07,676 Scientists are now trying to discover 839 00:44:07,700 --> 00:44:08,876 {\an1}what a feedback cycle 840 00:44:08,900 --> 00:44:11,609 could mean for the entire permafrost region 841 00:44:11,633 --> 00:44:15,342 and whether it could reach a point where it becomes 842 00:44:15,366 --> 00:44:17,976 irreversible. 843 00:44:18,000 --> 00:44:20,842 Such a phenomenon is called a tipping point. 844 00:44:20,866 --> 00:44:22,342 SULLIVAN: A tipping point is 845 00:44:22,366 --> 00:44:26,276 the proverbial straw that broke the camel's back. 846 00:44:26,300 --> 00:44:28,776 {\an1}You can get away with adding straw for so long, 847 00:44:28,800 --> 00:44:31,042 and then you can't. 848 00:44:31,066 --> 00:44:34,976 {\an1}And the tipping point is the point of no return. 849 00:44:35,000 --> 00:44:37,309 ♪ ♪ 850 00:44:37,333 --> 00:44:40,842 {\an8}NARRATOR: It's a controversial idea among climate scientists. 851 00:44:40,866 --> 00:44:42,409 {\an8}But the prospect of a tipping point 852 00:44:42,433 --> 00:44:45,709 {\an7}has been raised for a number of global climate systems, 853 00:44:45,733 --> 00:44:48,242 {\an1}including Arctic sea ice 854 00:44:48,266 --> 00:44:51,442 and deforestation in the Amazon. 855 00:44:51,466 --> 00:44:53,676 So far, there's no conclusive evidence 856 00:44:53,700 --> 00:44:58,376 that a tipping point is near for permafrost. 857 00:44:58,400 --> 00:45:02,042 {\an1}However, some scientists believe aspects of the thaw 858 00:45:02,066 --> 00:45:04,409 {\an1}are now irreversible. 859 00:45:04,433 --> 00:45:05,976 (ground squelching) 860 00:45:06,000 --> 00:45:10,009 Vladimir Romanovsky has spent decades studying 861 00:45:10,033 --> 00:45:12,133 {\an1}the changing permafrost. 862 00:45:14,200 --> 00:45:16,442 Near Utqiagvik in Northern Alaska, 863 00:45:16,466 --> 00:45:17,642 he investigates 864 00:45:17,666 --> 00:45:20,076 {\an1}what happens as large wedges of ice in the ground 865 00:45:20,100 --> 00:45:22,242 start to melt. 866 00:45:22,266 --> 00:45:23,210 ROMANOVSKY: Before, 867 00:45:23,234 --> 00:45:25,409 it was more or less flat area, 868 00:45:25,433 --> 00:45:27,576 but then ice melts 869 00:45:27,600 --> 00:45:29,766 {\an1}and surface subsides. 870 00:45:31,700 --> 00:45:32,809 NARRATOR: Romanovsky believes 871 00:45:32,833 --> 00:45:35,376 lakes formed by melting permafrost ice 872 00:45:35,400 --> 00:45:39,309 have passed a point of no return. 873 00:45:39,333 --> 00:45:41,842 ROMANOVSKY: It took tens of thousands of years 874 00:45:41,866 --> 00:45:43,809 {\an7}to put this ice into the ground. 875 00:45:43,833 --> 00:45:45,009 {\an7}Now, it's, it's melting. 876 00:45:45,033 --> 00:45:47,709 To put all this ice into the ground back, 877 00:45:47,733 --> 00:45:50,342 {\an1}you will need several tens of thousands of years. 878 00:45:50,366 --> 00:45:54,109 {\an1}So that's, for humans, definitely irreversible process. 879 00:45:54,133 --> 00:45:58,109 It is tipping point. 880 00:45:58,133 --> 00:46:02,142 NARRATOR: While melting ice forms lakes in the wilderness, 881 00:46:02,166 --> 00:46:06,142 {\an1}just a few miles away, it's causing very different problems 882 00:46:06,166 --> 00:46:08,776 {\an1}for the local community. 883 00:46:08,800 --> 00:46:12,942 In the roads outside Utqiagvik, 884 00:46:12,966 --> 00:46:14,409 the effects of rising Arctic temperatures 885 00:46:14,433 --> 00:46:16,042 are easy to see. 886 00:46:16,066 --> 00:46:19,376 NELSON: Just from observation, growing up here, 887 00:46:19,400 --> 00:46:22,209 {\an8}coming out here since I was a kid, 888 00:46:22,233 --> 00:46:26,633 {\an7}the roads were a lot higher than they are now. 889 00:46:28,500 --> 00:46:31,776 {\an1}It is literally sinking. 890 00:46:31,800 --> 00:46:33,809 {\an1}His bumper might get wet. 891 00:46:33,833 --> 00:46:36,776 NARRATOR: Native Alaskan Inupiaq Lars Nelson 892 00:46:36,800 --> 00:46:38,442 {\an1}is an infrastructure consultant. 893 00:46:38,466 --> 00:46:40,109 He knows firsthand 894 00:46:40,133 --> 00:46:44,042 what permafrost thaw is doing to his community. 895 00:46:44,066 --> 00:46:47,442 {\an8}NELSON: This road is for subsistence use; 896 00:46:47,466 --> 00:46:50,642 {\an8}we come out here and stage our hunts. 897 00:46:50,666 --> 00:46:54,842 {\an7}It's a big part of our history, and it's important that 898 00:46:54,866 --> 00:46:57,233 {\an1}we're able to access it in case of an emergency. 899 00:46:58,633 --> 00:47:01,876 NARRATOR: And it's not just the roads that are sinking. 900 00:47:01,900 --> 00:47:04,009 {\an1}In downtown Utqiagvik, 901 00:47:04,033 --> 00:47:07,742 Nelson meets Inupiaq Anthony Edwardsen. 902 00:47:07,766 --> 00:47:09,576 {\an1}These ones are subsiding, too. 903 00:47:09,600 --> 00:47:10,942 Yeah. 904 00:47:10,966 --> 00:47:13,209 NARRATOR: He's an expert on the Inupiaq community 905 00:47:13,233 --> 00:47:16,509 {\an1}with four decades' experience in the construction industry. 906 00:47:16,533 --> 00:47:18,209 Yeah, look at... This one is really messed up. 907 00:47:18,233 --> 00:47:19,442 Look at how it's just... 908 00:47:19,466 --> 00:47:23,376 {\an1}EDWARDSEN: That's where the houses are sinking. 909 00:47:23,400 --> 00:47:27,442 {\an8}NARRATOR: Local houses are built on wooden pilings. 910 00:47:27,466 --> 00:47:28,476 {\an8}If they were built on the ground, 911 00:47:28,500 --> 00:47:30,842 {\an8}the heat used to warm the homes 912 00:47:30,866 --> 00:47:32,642 {\an8}would thaw the permafrost below. 913 00:47:32,666 --> 00:47:36,242 {\an7}But now the permafrost is thawing by itself, 914 00:47:36,266 --> 00:47:40,976 {\an8}and the pilings are starting to sink. 915 00:47:41,000 --> 00:47:44,009 {\an8}EDWARDSEN: When the piling is a very small base, 916 00:47:44,033 --> 00:47:46,676 {\an1}it doesn't hold its structure. 917 00:47:46,700 --> 00:47:48,442 {\an1}The communities, 918 00:47:48,466 --> 00:47:50,609 {\an1}they need the house leveling, 919 00:47:50,633 --> 00:47:53,409 move houses, houses need to be torn down. 920 00:47:53,433 --> 00:47:56,133 We're in the middle of a housing crisis. 921 00:47:57,566 --> 00:47:59,609 NARRATOR: Nelson believes 922 00:47:59,633 --> 00:48:01,976 strategic building is the answer. 923 00:48:02,000 --> 00:48:03,442 We're on to it right now, 924 00:48:03,466 --> 00:48:04,709 and we're refining it right now. 925 00:48:04,733 --> 00:48:06,809 We can build nice, good, healthy homes. 926 00:48:06,833 --> 00:48:09,809 We just got to pay attention to our foundation, 927 00:48:09,833 --> 00:48:12,976 {\an1}pay attention to the tundra we're building on more closely. 928 00:48:13,000 --> 00:48:16,309 Because it's such an awesome spot, you know? 929 00:48:16,333 --> 00:48:17,776 {\an1}It's the top of the world. 930 00:48:17,800 --> 00:48:21,709 ♪ ♪ 931 00:48:21,733 --> 00:48:24,476 NARRATOR: But as the permafrost continues to thaw, 932 00:48:24,500 --> 00:48:28,376 {\an1}others in Alaska are looking at more drastic solutions. 933 00:48:28,400 --> 00:48:32,742 GRIFFIN HAGLE: So this is our portable, adjustable, 934 00:48:32,766 --> 00:48:34,276 sled-base home. 935 00:48:34,300 --> 00:48:37,809 {\an1}It is on a giant steel sled, 936 00:48:37,833 --> 00:48:41,076 as opposed to the pilings. 937 00:48:41,100 --> 00:48:45,309 NARRATOR: C.E.O. of the regional housing authority Griffin Hagle 938 00:48:45,333 --> 00:48:47,766 {\an1}has a more radical plan for sinking homes. 939 00:48:49,366 --> 00:48:52,676 HAGLE: What we would do if we needed to, to move this, 940 00:48:52,700 --> 00:48:55,409 {\an1}we would be hooking up our tow chains 941 00:48:55,433 --> 00:48:57,409 {\an1}to these two attachment points. 942 00:48:57,433 --> 00:48:58,742 {\an1}We've got one on this side 943 00:48:58,766 --> 00:49:01,309 {\an1}and one on that corner of the building over there. 944 00:49:01,333 --> 00:49:04,142 {\an1}Hook that up to a piece of heavy equipment, Caterpillar, 945 00:49:04,166 --> 00:49:07,242 {\an1}and then drop it off the pads 946 00:49:07,266 --> 00:49:09,176 and basically tow it across the snow 947 00:49:09,200 --> 00:49:10,809 in the wintertime. 948 00:49:10,833 --> 00:49:14,133 ♪ ♪ 949 00:49:16,500 --> 00:49:17,942 NARRATOR: As temperatures rise, 950 00:49:17,966 --> 00:49:19,942 {\an1}Hagle is searching for ways 951 00:49:19,966 --> 00:49:22,376 {\an1}to protect some of the most isolated communities 952 00:49:22,400 --> 00:49:24,576 {\an1}in the United States. 953 00:49:24,600 --> 00:49:25,876 HAGLE: This is the largest 954 00:49:25,900 --> 00:49:27,909 {\an1}municipality in the world, I think, by land area. 955 00:49:27,933 --> 00:49:30,509 {\an1}We provide affordable housing 956 00:49:30,533 --> 00:49:34,109 {\an1}in eight villages across an area the size of Minnesota, 957 00:49:34,133 --> 00:49:35,833 {\an1}only without any roads. 958 00:49:37,300 --> 00:49:39,842 NARRATOR: No Alaskan homes have been sledded away, 959 00:49:39,866 --> 00:49:41,676 yet. 960 00:49:41,700 --> 00:49:45,909 {\an1}But Arctic warming has forced some towns to relocate. 961 00:49:45,933 --> 00:49:50,509 {\an1}And Hagle thinks houses will soon be on the move. 962 00:49:50,533 --> 00:49:52,242 {\an1}And there are several, you know, communities, 963 00:49:52,266 --> 00:49:54,409 {\an1}especially in rural Alaska, Native communities, 964 00:49:54,433 --> 00:49:57,109 {\an1}that are increasingly at risk of relocation 965 00:49:57,133 --> 00:49:59,176 {\an1}due to global warming. 966 00:49:59,200 --> 00:50:00,942 And so this gives us an advantage 967 00:50:00,966 --> 00:50:03,876 {\an1}in having the option, the adaptability, 968 00:50:03,900 --> 00:50:08,042 {\an1}to move that, that structure if it becomes necessary. 969 00:50:08,066 --> 00:50:10,876 Native people, the Indigenous communities 970 00:50:10,900 --> 00:50:13,042 {\an1}that have called this place home for thousands of years, 971 00:50:13,066 --> 00:50:14,842 have come up with all sorts of innovations 972 00:50:14,866 --> 00:50:16,309 {\an1}to make life work here. 973 00:50:16,333 --> 00:50:18,442 {\an7}So we draw a lot of inspiration from that, 974 00:50:18,466 --> 00:50:19,609 {\an8}and we see that as kind of the continuation 975 00:50:19,633 --> 00:50:23,200 {\an1}of a long, long tradition of innovation. 976 00:50:25,466 --> 00:50:28,700 ♪ ♪ 977 00:50:29,900 --> 00:50:32,409 NARRATOR: As inhabitants across the Arctic 978 00:50:32,433 --> 00:50:34,776 adapt to their changing world, 979 00:50:34,800 --> 00:50:38,342 scientists strive to build a better picture 980 00:50:38,366 --> 00:50:40,842 {\an1}of our climate future. 981 00:50:40,866 --> 00:50:44,309 {\an7}The methane craters are just one sign of 982 00:50:44,333 --> 00:50:46,666 {\an8}a region undergoing unprecedented changes... 983 00:50:49,333 --> 00:50:52,242 {\an1}...placing communities with deep ties to this land 984 00:50:52,266 --> 00:50:53,842 at risk. 985 00:50:53,866 --> 00:50:55,976 BROWER: We've been whaling here 986 00:50:56,000 --> 00:50:57,676 {\an1}well over 4,000 years. 987 00:50:57,700 --> 00:50:59,909 (birds cawing) 988 00:50:59,933 --> 00:51:04,176 We've adapted time and time again. 989 00:51:04,200 --> 00:51:06,566 {\an1}Today, we might not be able to do it by ourselves. 990 00:51:07,900 --> 00:51:12,509 NARRATOR: But the big thaw is not just a regional problem. 991 00:51:12,533 --> 00:51:15,676 {\an1}What's happening in the Arctic could really affect 992 00:51:15,700 --> 00:51:18,109 everyone on Earth. 993 00:51:18,133 --> 00:51:19,709 NARRATOR: Arctic greenhouse gases 994 00:51:19,733 --> 00:51:21,776 will intensify future global warming. 995 00:51:21,800 --> 00:51:26,509 How quickly is difficult to predict. 996 00:51:26,533 --> 00:51:28,609 {\an1}And positive feedback cycles 997 00:51:28,633 --> 00:51:31,142 could accelerate beyond human control, 998 00:51:31,166 --> 00:51:35,642 {\an1}making our choices today even more urgent. 999 00:51:35,666 --> 00:51:39,042 LEE: Because it's very difficult to take control 1000 00:51:39,066 --> 00:51:42,542 {\an1}over the natural systems, 1001 00:51:42,566 --> 00:51:46,500 {\an1}it's even more important for us to lower our emissions. 1002 00:51:48,266 --> 00:51:49,742 NATALI: These craters are 1003 00:51:49,766 --> 00:51:52,442 a really important and concerning indicator 1004 00:51:52,466 --> 00:51:55,542 {\an1}that things are changing, and the Arctic is melting, 1005 00:51:55,566 --> 00:51:56,976 {\an1}and the Arctic is thawing. 1006 00:51:57,000 --> 00:51:58,742 {\an1}And the future of the Arctic 1007 00:51:58,766 --> 00:52:00,876 {\an1}is a very different place than it was 1008 00:52:00,900 --> 00:52:02,376 several decades ago. 1009 00:52:02,400 --> 00:52:05,566 ♪ ♪ 1010 00:52:28,800 --> 00:52:33,700 ♪ ♪ 1011 00:52:45,000 --> 00:52:48,709 ANNOUNCER: Episodes of "NOVA" are available with Passport. 1012 00:52:48,733 --> 00:52:52,242 {\an1}This program is also available on Amazon Prime Video. 1013 00:52:52,266 --> 00:52:57,400 ♪ ♪ 1014 00:53:09,100 --> 00:53:14,966 {\an8}♪ ♪