JUDY WOODRUFF: There's troubling new research about the impact that climate change is having
on both of Earth's polar regions, and how that could affect people all over the world.
William Brangham has the latest.
WILLIAM BRANGHAM: That's right, Judy.
A warming atmosphere is creating serious problems in the Arctic Circle and on the
continent of Antarctica. The Arctic Report Card is out. High temperatures,
shrinking sea ice and extreme melting events are transforming the region.
And at the opposite pole, in Antarctica, a key ice shelf that sits in front of
the Thwaites Glacier could break up much sooner than expected, within five years.
Joining me now is David Holland.
He studies atmospheric and ocean sciences at New York University,
and is a leading researcher on the global initiative that's studying the Thwaites Glacier.
David Holland, great to have you back on the "NewsHour."
I should explain why you look so dapper tonight. You are being elected a fellow
in the American Geophysical Union at their conference in New Orleans.
Congratulations.
Viewers might remember that the last time we saw you on the "NewsHour," you
were on the Thwaites Glacier itself doing research there.
Can you help us understand what this most recent research showed?
DAVID HOLLAND, New York University: Yes.
We have been seeing for the last couple of decades a large change in Antarctica and, in particular,
on this one glacier called Thwaites in West Antarctica. And it's a very special
place here because it's marine-based. It's actually largely in the ocean.
And the ocean can, in theory, easily melt it. And so that is what actually now looks it's coming to
pass. Warm ocean waters have arrived at this glacier, and they're melting it like crazy.
WILLIAM BRANGHAM: As I was saying,
it is the ice shelf that sits in front of Thwaites that is in particular jeopardy.
Why do we care about the ice shelf, as opposed to the glacier itself?
DAVID HOLLAND: Maybe one way to think of it is like if you think of a bottle of
water with a cork, and all the water in the bottle is the water that represents
all the potential sea level rise from Thwaites. And the cork is the ice shelf.
WILLIAM BRANGHAM: I see.
And so the breakup of that ice shelf itself
would lead to Thwaites moving more quickly into the water.
DAVID HOLLAND: Exactly right. Effectively, there'd be nothing to hold it back.
WILLIAM BRANGHAM: So, if that ice shelf were to break up,
and Thwaites were to move into the ocean, what kind of impacts are we talking about?
DAVID HOLLAND: It would be absolutely massive,
on the time scale of the last century, what we'd seen.
We would see a dramatic rise of several feet of sea level. And it could be Thwaites itself perhaps
two to three feet, but Thwaites is holding back its neighbors. And they, too, could fall apart,
raising sea level by an additional maybe six feet, so, altogether, something of scale 10 feet. And
if you try to wrap your head around that, we're talking around the entire Earth, the entire ocean.
It's a massive amount of water. It's a rewriting of the global coastline in that sense.
WILLIAM BRANGHAM: I mean, we're talking about hundreds of millions of people
all over the Earth who are living on those coastlines
that are then facing inundation, flooding and having to move, having to migrate.
DAVID HOLLAND: Absolutely.
So, surely, in the past, as we look back in records, sea level at the end of the last Ice Age
was down 300 feet, or something of that scale. And it has since come up that.
So it naturally changes on the planet by big numbers. This could be a relatively
large change, but in short order, and perhaps with our fingerprint on it.
WILLIAM BRANGHAM: So I'd like to switch to the other polar region, to the Arctic Circle.
And this recent Arctic Report Card that came out referred to the disappearance of sea ice,
rising temperatures there, extreme melting events on the ice sheets of Greenland.
What stood out to you in that report?
DAVID HOLLAND: I started my Ph.D. Actually working in the north on the Arctic.
When I started in the early '90s not a human being on Earth would have said the Arctic will
ever change in our lifetime. And then, within a decade, it began to fall apart. And it's been
the largest change on the planet, perhaps, with half of the Arctic sea ice now gone.
But what really struck me in the report were the ramifications of that change,
for example, more shipping, and thus more noise in the ocean, disturbing marine mammals,
a change in the vegetation, a change in species. Now, apparently, animals like
beavers have moved into Alaska. So it's all a change and it's a disruption to what was there.
It's very significant. And it goes beyond just the melting of the ice.
WILLIAM BRANGHAM: And, broadly speaking, I know there's lots of influences in these regions,
but we're talking about changes that are being driven both in Antarctica and in the Arctic
because we burn oil and gas and coal, and it is warming the atmosphere. Is that right?
DAVID HOLLAND: I would have been the first to -- when I started my career,
I found that really difficult to believe.
And -- however, data and modeling outcomes now make it almost certain that that is the case.
WILLIAM BRANGHAM: All right, David Holland of New York University, thank you. Very good to see you.
And congratulations again on your honor today.
DAVID HOLLAND: Thank you so much, William. Have a great day.