Greenland loses 4 trillion pounds of ice in one day

Normally, the landscape in this photo would be a white ice sheet.

Melting Greenland Ice
  • Climate scientists say that Greenland is experiencing ice losses that are unusually early and heavy.
  • Two main weather factors are fueling the losses: a high-pressure system and the resulting low cloud cover.
  • Greenland is a major contributor to sea-level rise.


Four trillion pounds of ice melted in Greenland on June 13 due to unusually warm and sunny weather, scientists report. Although it's normal for ice to melt during Greenland's "melt season," the ice this year is melting earlier than expected and at an alarmingly fast rate.

"It's very unusual to have this much melt so early in the season," William Colgan, senior researcher at the Geological Survey of Denmark and Greenland, told the BBC. "It takes very rare conditions but they're becoming increasingly common."

Greenland's current ice loss is on track to break records. In 2012, the island nation saw similarly severe losses, which, like current melting, was fueled by two main weather factors: a high-pressure system that carried warm air from the Central Atlantic to the skies over Greenland, causing warmer temperatures, and the resulting low cloud cover and snowfall, which allowed sunlight to hit the vast ice sheets.

Frozen white ice reflects most sunlight back into the sky. But melting ice turns into darker colors, which absorb more light and heat. This creates a positive feedback loop that speeds up melting.

"You've experienced this if you've walked down the road barefoot on a hot summer day," geologist Trevor Nace wrote for Forbes.

"The black asphalt is much hotter than the white concrete sidewalk. This is due to the difference in how much solar radiation white versus black reflects. Hence, as Greenland melts more of its ice, the surface is converted from a high albedo white to darker colors. This, in turn, causes more melting and adds to the positive feedback loop."

Albedo

This figure depicts how radiation from the sun is reflected or absorbed by different terrains. More radiation is reflected by white snow and ice, while more radiation is absorbed by dark surfaces, such as water.

Arctic Monitoring and Assessment Programme/https://amap.no

Steffen Olsen, a scientist with the Danish Meteorological Institute, got an eerie up-close look at the changing ice sheets last week. Olsen was on a routine mission to pick up weather monitoring tools on sea ice in northwest Greenland when he saw meltwater pooled up on the sheet's surface, making it look like his sled dogs were walking on water.

Greenland's rapidly melting ice could raise global sea levels.

"Greenland has been an increasing contributor to global sea level rise over the past two decades," Thomas Mote, a research scientist at the University of Georgia who studies Greenland's climate, told CNN. "And surface melting and runoff is a large portion of that."

This is what aliens would 'hear' if they flew by Earth

A Mercury-bound spacecraft's noisy flyby of our home planet.

Image source: sdecoret on Shutterstock/ESA/Big Think
Surprising Science
  • There is no sound in space, but if there was, this is what it might sound like passing by Earth.
  • A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
  • Yes, in space no one can hear you scream, but this is still some chill stuff.

First off, let's be clear what we mean by "hear" here. (Here, here!)

Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.

All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.

BepiColombo

Image source: European Space Agency

The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.

Into and out of Earth's shadow

In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.

The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."

In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."

When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.

Magentosphere melody

The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.

BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.

MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.

Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.

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Photo by Reinhart Julian on Unsplash
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