Latest / DEEP INSIGHT / Despite setback, researchers uncover new findings at Antarcticas Thwaites Glacier

Transcript

Despite setback, researchers uncover new findings at Antarcticas Thwaites Glacier · DEEP INSIGHT

• 0:00
  Speaker 1: As the Trump administration pulls back from regulations on climate change,
• 0:04
  Speaker 1: many scientists remain worried about the warming of the oceans, glaciers,
• 0:08
  Speaker 1: and sea level rise. Our science correspondent Miles O'Brien has
• 0:12
  Speaker 1: been reporting from Antarctica on a major mission to understand
• 0:15
  Speaker 1: what's happening there. In his latest report from the Thwaits Glacier,
• 0:19
  Speaker 1: he looks at other key research projects that have been
• 0:22
  Speaker 1: part of that trip.
• 0:25
  Speaker 2: The timing was awkward. New York University glaciologist David Holland
• 0:30
  Speaker 2: and I landed on the Thwaits Glacier almost precisely when
• 0:35
  Speaker 2: the valiant effort to bore through it and install a
• 0:38
  Speaker 2: suite of censors in the ocean beneath reached an unceremonious
• 0:43
  Speaker 2: dead end.
• 0:45
  Speaker 3: Who ambre stock. We did not succeed in doing. What
• 0:48
  Speaker 3: we wanted to do was to put a weather station
• 0:50
  Speaker 3: in the ocean out there to begin to monitor it.
• 0:53
  Speaker 3: What we achieved there was nothing. That's absolutely nothing, a
• 0:57
  Speaker 3: little bit Shakespearean.
• 1:01
  Speaker 2: The tragedy became comedy when doctor Holland asked me to
• 1:05
  Speaker 2: give him a hand, which, as an arm amputee, is
• 1:09
  Speaker 2: literally all I had to off. Yeah, all right, but
• 1:13
  Speaker 2: I have a hard time saying no, okay, these are
• 1:16
  Speaker 2: empty just my speed. All right, let's go.
• 1:25
  Speaker 4: How you doing your end?
• 1:26
  Speaker 2: It was all right, so we started setting up the
• 1:29
  Speaker 2: distributed temperature sensor, the last instrument slated to go down
• 1:33
  Speaker 2: the hole. The heavy gear connects to a fiber optic
• 1:37
  Speaker 2: cable that provides continuous temperature readings from the surface to
• 1:41
  Speaker 2: the seafloor. But now it will come up about six
• 1:45
  Speaker 2: hundred and fifty feet short. Once the hole closed up,
• 1:49
  Speaker 2: you could have closed up shop and just come back
• 1:51
  Speaker 2: to the ship, but you didn't.
• 1:52
  Speaker 3: Why So it shows the possibility of what we can
• 1:55
  Speaker 3: do in terms of remote instrumentation. So it would be
• 1:58
  Speaker 3: sugarcoating to say, you know, that's really great. I would
• 2:01
  Speaker 3: say that's better than nothing.
• 2:03
  Speaker 2: The drill project was the marquee event of a month
• 2:06
  Speaker 2: long scientific campaign launched from the deck of the icebreaker
• 2:10
  Speaker 2: our own, owned by the Korea Polar Research Institute or COPRI.
• 2:17
  Speaker 2: Despite the drilling failure, they notched some success. One of
• 2:22
  Speaker 2: the helicopters flew for several days over the ice.
• 2:25
  Speaker 5: A little bit of a hate for the left of us.
• 2:27
  Speaker 2: To surveying with a powerful radar able to peer through
• 2:31
  Speaker 2: the thick ice to measure it and see what the
• 2:34
  Speaker 2: lay of the land is below. Now in its sixth year,
• 2:39
  Speaker 2: the research campaign is a partnership between COPRI, the University
• 2:43
  Speaker 2: of Texas, and Montana State University.
• 2:46
  Speaker 4: So they've been out for what six hours now, a
• 2:49
  Speaker 4: little over six hours.
• 2:51
  Speaker 2: The field team leader is glaciologist Chris Pearce. They logged
• 2:55
  Speaker 2: more than eighteen hundred miles of straight lines up, down,
• 2:59
  Speaker 2: and acrosss the glacier over six flight days. The trio
• 3:04
  Speaker 2: of long booms contains the radar antennas, they said, long
• 3:08
  Speaker 2: wavelength radio signals downward and then listen for the echoes.
• 3:12
  Speaker 2: The lapse time of their return defines details beneath the surface.
• 3:17
  Speaker 4: We've got really good quality data and we've got really
• 3:20
  Speaker 4: good coverage coming out of this.
• 3:22
  Speaker 2: He showed me one of their radar grams. It's a
• 3:25
  Speaker 2: two dimensional slice of the ice like an MRI or
• 3:29
  Speaker 2: X ray. Understanding the terrain beneath the ice is a
• 3:33
  Speaker 2: priority for researchers developing models to predict how fast the
• 3:38
  Speaker 2: glacier might retreat.
• 3:40
  Speaker 4: Once you get past a certain point, you're going to
• 3:42
  Speaker 4: have a really low friction surface on which the glacier
• 3:47
  Speaker 4: can slide, so that's one of the reasons that people
• 3:50
  Speaker 4: believe that twaits is particularly susceptible to instabilities.
• 3:55
  Speaker 2: To help calibrate his radar, Pierce turns to c ice
• 3:59
  Speaker 2: scientist Chavone Johnson of the British Antarctic Survey to get
• 4:04
  Speaker 2: a precise read on the density of fern snow that
• 4:08
  Speaker 2: is transitioning to ice. She is an expert in ice coring.
• 4:13
  Speaker 2: We were on top of Thwaites when she showed me
• 4:16
  Speaker 2: how it's done. So it's a little easier than doing
• 4:18
  Speaker 2: a manually. So let's give it. Let's give it a
• 4:20
  Speaker 2: try and see how it goes. She uses a coreing
• 4:26
  Speaker 2: device attached to a cordless drill, easy pasy. This core
• 4:32
  Speaker 2: represents about six months of fern. It tells a story
• 4:37
  Speaker 2: if you know how to read it. Clear ice means
• 4:40
  Speaker 2: a warm spell. Oh, actually, you see a little here
• 4:43
  Speaker 2: and there's not some melt layer you see? I do
• 4:45
  Speaker 2: I do? When she cores sea ice, she cuts a
• 4:48
  Speaker 2: precise section, then weighs it to determine its density. In
• 4:52
  Speaker 2: twenty sixteen, sea ice here began a sharp and unexpected
• 4:55
  Speaker 2: drop as the climate crisis changes, wind and ocean currents.
• 5:00
  Speaker 2: Melting sea ice does not directly raised sea level, since
• 5:04
  Speaker 2: it's already floated, but its loss can indirectly accelerate the
• 5:08
  Speaker 2: melting of land dice glaciers like Thwaites.
• 5:12
  Speaker 1: The cover of the sea ice in this area is
• 5:15
  Speaker 1: quite important for ocean heat transport, which will melt the
• 5:19
  Speaker 1: underside of Thwaites.
• 5:20
  Speaker 2: The role of sea ice in glacier melt forecasts is
• 5:24
  Speaker 2: one of a myriad of uncertainties. This expedition was designed
• 5:28
  Speaker 2: to help unravel. The team deployed and recovered moorings that
• 5:33
  Speaker 2: collect underwater data profiles over multi year periods. They made
• 5:38
  Speaker 2: frequent stops to measure the ocean's salinity, temperature, depth, currents,
• 5:42
  Speaker 2: and chemical composition. And they launched and retrieved an autonomous
• 5:47
  Speaker 2: underwater glider carrying profiling instruments on a multi day mission.
• 5:53
  Speaker 2: But perhaps the most novel approach was this a device
• 5:57
  Speaker 2: called rift ox. Polar geophysicist this Jamin Greenbaum of the
• 6:01
  Speaker 2: Script's Institution of Oceanography at UC San Diego teamed up
• 6:06
  Speaker 2: with helicopter Maestro Dominic o'rouric to fly into ice canyons
• 6:11
  Speaker 2: on a series of daring missions.
• 6:14
  Speaker 5: Sir at swaits. We can take advantage of the fact
• 6:16
  Speaker 5: that it's collapsing and producing these rifts that allow you
• 6:19
  Speaker 5: to get to places that you know in other glaciers
• 6:22
  Speaker 5: you just can't get to.
• 6:23
  Speaker 2: Riftdocks is lifted by helicopter and flown to a fractured rift.
• 6:29
  Speaker 2: It breaks through thin ice and lowers a rosette of
• 6:32
  Speaker 2: canisters as deep as twenty eight hundred feet. They capture
• 6:36
  Speaker 2: water samples that prescribe depths. They're looking for telltale signs
• 6:41
  Speaker 2: of subglacial discharge formed under the glacier by geo thermal
• 6:46
  Speaker 2: heat and friction. As the ice slides over the rock,
• 6:50
  Speaker 2: it squirts into the sea, where it mixes with warm
• 6:54
  Speaker 2: ocean water.
• 6:55
  Speaker 5: You know, I like to think of the warm ocean
• 6:57
  Speaker 5: as like the fire, and this subglacial discharge. I like
• 7:00
  Speaker 5: to think of it like lighter fluid. It's getting sprayed
• 7:02
  Speaker 5: into the fire and it just just blows the whole
• 7:04
  Speaker 5: thing up.
• 7:05
  Speaker 2: His early data have confirmed this hypothesis.
• 7:09
  Speaker 5: And Lo and Behold in area three, we see direct
• 7:12
  Speaker 5: evidence of some glacious discharge. So it really is exactly
• 7:14
  Speaker 5: where we thought it might be.
• 7:16
  Speaker 2: It's all hard won data. Kopri is vowing to return
• 7:20
  Speaker 2: in two years. The puzzle pieces are elusive, and the
• 7:25
  Speaker 2: hard work here moves at the pace of a glacier.
• 7:29
  Speaker 2: But this one, the most consequential of them all, is
• 7:32
  Speaker 2: moving faster than efforts to understand it. For the PBS
• 7:38
  Speaker 2: News Hour, I'm Miles O'Brien at the Thwaites Glacier.
• 7:53
  Speaker 1: Support journalism you trust. Support PBS News. Donate now, or
• 7:58
  Speaker 1: even better, start a monthly cotribution today