According to paragraphs 9 and 10 (lines 60-78), PIOMAS is a model intended to
The Arctic Ocean has lost 95 percent of its oldest ice
— a startling sign of what’s to come
By Chris Mooney
December 11, 2018
Over the past three decades of global warming, the oldest and thickest ice in the Arctic has declined by a stunning 95 percent, according the National Oceanic and Atmospheric Administration’s annual Arctic Report Card. The finding suggests that the sea at the top of the world has already morphed into a new and very different state, with major implications not only for creatures such as walruses and polar bears but, in the long term, perhaps for the pace of global warming itself.
The oldest ice can be thought of as a kind of glue that holds the Arctic together and, through its relative permanence, helps keep the Arctic cold even in long summers. “The younger the ice, the thinner the ice, the easier it is to go away,” said Don Perovich, a scientist at Dartmouth who coordinated the sea ice section of the yearly report.
If the Arctic begins to experience entirely ice-free summers, scientists say, the planet will warm even more, as the dark ocean water absorbs large amounts of solar heating that used to be deflected by the cover of ice. The new findings were published as climate negotiators in Poland are trying to reach a global consensus on how to address climate change.
In March, NASA scientists with the Operation IceBridge mission, which surveys the polar regions using research aircraft, witnessed a dramatic instance of the ongoing changes. Flying over the seas north of Greenland, in a region that usually features some of the oldest, thickest ice in the Arctic, they instead saw smooth, thin strips binding together the thicker, ridged pieces.
“I was just shocked by how different it was,” said NASA’s Nathan Kurtz, who has flown over the area multiple times. The floating sea ice had broken up entirely the previous month — very unusual for this location — and now was feebly freezing back together again.
Scientists think a strange wind event caused the breakup in this region just a few hundred miles south of the North Pole — so it’s unclear whether it is directly linked to climate change. Still, the breakup could be just one more sign of the growing fragility of the oldest ice.
The new findings about the decreasing age of ice in the Arctic point to a less noticed aspect of the dramatic changes occurring there. When it comes to the icy cap atop the Arctic Ocean, we tend to talk most often about its surface area — how much total ocean is covered by ice, rather than by open water. That’s easily visible — it can be glimpsed directly by satellite — and the area is, indeed, in clear decline.
But the loss of old and thick ice, and the simultaneous decline in the total ice volume, is even larger — and arguably a much bigger deal. Young and thin ice can regrow relatively quickly once the dark and cold winter sets in. But it may not add much stability or permanence to the Arctic sea ice system if it just melts out again the next summer.
The total volume of ice in September, the lowest ice month, declined by 78 percent between 1979 and 2012, the record low year. That’s according to an analysis by scientists at the University of Washington in Seattle called PIOMAS, or the Pan-Arctic Ice Ocean Modeling and Assimilation System — a top source for tracking ice volume.
In fairness, the ice volume has rebounded somewhat since 2012. And PIOMAS is only a model, cautioned the University of Washington’s Axel Schweiger, who runs the analysis. (The model draws upon direct measurements of ice thickness taken from submarines, satellites and other sources.) Still, Schweiger agreed that when you think about the total volume of the ice, rather than its mere surface extent, you realize that far more has been lost. “We’ve lost about half of the extent, we’ve lost half of the thickness, and if you multiply these two things, we’ve lost 75 percent of the September sea ice,” he said.
Going by PIOMAS’s numbers, the losses represent more than 10 trillion tons of ice. While the Arctic Ocean contained over 15 trillion tons of floating ice in 1979 during the month of September, in the same month in 2012, it averaged just under 3.5 trillion tons. This year, it averaged just 4.66 trillion tons in September.
“The Arctic is an indication of what’s coming to the rest of the globe,” said Walt Meier, a sea ice expert at the National Snow and Ice Data Center. “In the Arctic Ocean, a difference of 2 degrees can be huge. If it goes from 31 Fahrenheit to 33 Fahrenheit, you’re going from ice skating to swimming. … the Arctic is an early warning system for the climate.”
Available at: <https://www.washingtonpost.com/energy-environment/2018/12/11/arctic-is-even-worse-shape-than-you-realize/?noredirect=on&utm_term=.508085a17318>.
Retrieved on: July 2, 2019. Adapted.
PUC RJ 2020 - QUESTÃO 09
According to paragraphs 9 and 10 (lines 60-78), PIOMAS is a model intended to
(A) keep track of the melting of young and thin ice in the Arctic.
(B) gather information about variations in ice volume in the Arctic.
(C) evaluate how the change of seasons affects ice extent in the Arctic.
(D) investigate how submarines and satellites affect ice volume in the Arctic.
(E) study the stability of the Arctic sea ice system during the summer months.
QUESTÃO ANTERIOR:
GABARITO:
(B) gather information about variations in ice volume in the Arctic.
RESOLUÇÃO:
Para acertar esta questão de compreensão localizada dos parágrafos 9 e 10, o candidato deverá ser capaz de identificar o propósito do modelo PIOMAS (Sistema Pan-Ártico de Modelagem e Assimilação do Oceano Gelado). O gabarito é (B), que significa que tal modelo tem por objetivo coletar informações sobre a variação do volume de gelo no Ártico. Tal afirmativa encontra respaldo nas linhas 62-66: “Isso é de acordo com uma análise feita por cientistas da Universidade de Washington em Seattle chamada PIOMAS, ou o Sistema Pan Ártico de Modelagem e Assimilação do Oceano Gelado - uma fonte importante para monitorar o volume de gelo.”
As demais opções devem ser descartadas, pois não explicam corretamente a intenção do modelo PIOMAS ao afirmar que ele teria por objetivo
- “monitorar o derretimento do gelo jovem e fino no Ártico”, como em (A);
- “avaliar como a mudança das estações afetam a extensão do gelo no Ártico”, como em (C);
- “investigar como os submarinos e satélites afetam o volume de gelo no Ártico.”, como em (D);
- “estudar a estabilidade do sistema de gelo do mar Ártico durante os meses de verão”, com o em (E).
PRÓXIMA QUESTÃO:
QUESTÃO DISPONÍVEL EM:
