Daily Archives: July 11, 2019

Marine ice sheet instability amplifies and skews uncertainty in projections of future sea-level rise | PNAS

Significance

The potential for collapse of the Antarctic ice sheet remains the largest single source of uncertainty in projections of future sea-level rise. This uncertainty comes from an imperfect understanding of ice sheet processes and the internal variability of climate forcing of ice sheets. Using a mathematical technique from statistical physics and large ensembles of state-of-the-art ice sheet simulations, we show that collapse of ice sheets widens the range of possible scenarios for future sea-level rise. We also find that the collapse of marine ice sheets makes worst-case scenarios of rapid sea-level rise more likely in future projections.

Abstract

Sea-level rise may accelerate significantly if marine ice sheets become unstable. If such instability occurs, there would be considerable uncertainty in future sea-level rise projections due to imperfectly modeled ice sheet processes and unpredictable climate variability. In this study, we use mathematical and computational approaches to identify the ice sheet processes that drive uncertainty in sea-level projections. Using stochastic perturbation theory from statistical physics as a tool, we show mathematically that the marine ice sheet instability greatly amplifies and skews uncertainty in sea-level projections with worst-case scenarios of rapid sea-level rise being more likely than best-case scenarios of slower sea-level rise. We also perform large ensemble simulations with a state-of-the-art ice sheet model of Thwaites Glacier, a marine-terminating glacier in West Antarctica that is thought to be unstable. These ensemble simulations indicate that the uncertainty solely related to internal climate variability can be a large fraction of the total ice loss expected from Thwaites Glacier. We conclude that internal climate variability alone can be responsible for significant uncertainty in projections of sea-level rise and that large ensembles are a necessary tool for quantifying the upper bounds of this uncertainty.

A68: World’s biggest iceberg is on the move – BBC News

By Jonathan Amos BBC Science Correspondent

  • 8 hours ago

Media captionThis movie shows A68’s progress from January 2018 to July 2019

It’s two years since the monster block of ice known as A68 broke free from Antarctica.

Satellites show the world’s biggest berg has spun around in the waters of the Weddell Sea and is now moving north along the White Continent’s peninsula.

For a while, it seemed like the 160km-long frozen mass had become stuck on a section of shallow seafloor. A68 was in danger of becoming the world’s biggest “ice island”.

But it’s since picked up the pace.

“For an object weighing around one trillion tonnes, Iceberg A68 appears to be quite nimble,” says Prof Adrian Luckman.

“Following a year of staying close to its parent ice shelf, in mid-2018 A68 became caught in the Weddell Gyre, a clockwise ocean current, which spun it through 270 degrees and carried it 250km north,” he told BBC News.

…(read more).

How Trump is building on Democrats’ militarization of the border

Democracy Now!

Published on Jul 10, 2019

John Carlos Frey, investigative journalist and author of the new book “Sand and Blood: America’s Stealth War on the Mexico Border,” talks about the history of American border militarization, and former president Bill Clinton’s key role in crafting the immigration policies that Donald Trump stands on today. “I watched all of this happen bit by bit,” Frey says. “I think it is a political construct.”

U.S. State Department Approves Potential $2.2 Billion Arms Sale to Taiwan

VOA News

Published on Jul 11, 2019

Amid a growing trade war with China, the U.S. Defense Department’s Defense Security Cooperation Agency announced, Monday, July 8, that the State Department had approved a request by Taiwan to purchase an estimated $2.2 billion worth of military equipment. The agency added that the deal would not alter the basic military balance in the region. https://www.voanews.com/usa/us-state-…

How NASA Sold Us a Trip to the Moon | Retro Report | Chasing the Moon | American Experience | PBS

AmericanExperiencePBS

Published on Jun 27, 2019

To win the space race, NASA had to develop space flight technology, train astronauts—and market the moon to the American public. Most remember the space race of the 1960s as a moment of rare national unity around the cause of scientific exploration. Public opinion polls from the 1960s show that the majority of Americans approved of Project Apollo, but the nation was deeply divided over the cost of the program. To win the space race, NASA would have to market the moon to the American public. Today NASA is using new tools to communicate its mission to the public—and private companies are marketing their plans for space exploration. Learn more in CHASING THE MOON.

Find more history, as well as where to watch the full documentary: http://www.pbs.org/wgbh/americanexper…

Trailer | Chasing the Moon | American Experience | PBS

AmericanExperiencePBS

Published on Feb 2, 2019

In 1969, we made one small step. In 2019, join American Experience and PBS to relive the journey that defined a generation in “Chasing the Moon.” “Chasing the Moon,” a film by Robert Stone, reimagines the race to the moon for a new generation, upending much of the conventional mythology surrounding the effort. The series recasts the Space Age as a fascinating stew of scientific innovation, political calculation, media spectacle, visionary impulses and personal drama. Utilizing a visual feast of previously overlooked and lost archival material — much of which has never before been seen by the public — the film features a diverse cast of characters who played key roles in these historic events.

Learn more about our documentary, CHASING THE MOON: http://www.pbs.org/wgbh/americanexper…

How NASA Sold Us a Trip to the Moon | Retro Report | Chasing the Moon | American Experience | PBS

AmericanExperiencePBS

Published on Jun 27, 2019

To win the space race, NASA had to develop space flight technology, train astronauts—and market the moon to the American public. Most remember the space race of the 1960s as a moment of rare national unity around the cause of scientific exploration. Public opinion polls from the 1960s show that the majority of Americans approved of Project Apollo, but the nation was deeply divided over the cost of the program. To win the space race, NASA would have to market the moon to the American public. Today NASA is using new tools to communicate its mission to the public—and private companies are marketing their plans for space exploration. Learn more in CHASING THE MOON.

Find more history, as well as where to watch the full documentary: http://www.pbs.org/wgbh/americanexper…

First Man on the Moon – NOVA PBS HD – 2014


Documentary Chanel
Published on Apr 26, 2015

Everyone knows Neil Armstrong was the first to set foot on the moon. But this modest and unassuming man was determined to stay out of the spotlight. Now, for the first time, NOVA presents an intimate portrait of Armstrong through interviews with his family and friends, many of whom have never spoken publicly before. Discover and relive Armstrong’s achievements before and after Apollo, from his time as a Navy combat veteran and later as a pioneer of high-speed flight to his leading role in the inquiry into the Challenger disaster and his efforts to encourage young people to take to the skies. Along the way, we learn how Armstrong’s life became the inspiring story of heroic risk-taking and humble dedication that ultimately advanced humanity’s adventure in space.