Alaskan marine-terminating glacier melting 100 times faster than current models predict.

“We found that melt rates are significantly higher than expected across the whole underwater face of the glacier – in some places 100 times higher than theory would predict.” – Rebecca Jackson 

Trouble with tidewater glaciers.

The American Association for the Advancement of Science writes:

The newly observed melt rates are up to two orders of magnitude greater than those calculated by some current predictive models. The findings, published in the July 26 issue of Science, are the first based on direct subsurface measurements of a tidewater glacier and suggest that similar glaciers worldwide may be in far "hotter water" than previously known.

In Earth's Arctic region, vast rivers of ice flow slowly from the ice sheets and ice fields that blanket frozen high-latitude landscapes. Some glaciers are terrestrially bound and often sequestered among high-altitude mountain peaks from the alpine valleys below. Those that meet the sea, however, are called tidewater glaciers. As these bodies of ice push outward into the ocean, their precipitous semi-submerged fronts crumble, or calve, to release a near-constant stream of icebergs into the ocean's currents beyond.

Tidewater glaciers are most common in polar regions, like Greenland, Antarctica and coastal Alaska, where they form the literal boundary between the ocean and the planet's immense reservoirs of frozen freshwater. The nexus between ice and sea makes tidewater glaciers especially influential on the rates of overall ice mass loss and global sea level rise. Furthermore, the large quantities of fresh glacial meltwater discharged into the salty sea have the potential to destabilize or alter global ocean circulation, which is a primary driver of global climate regimes.

Like all of Earth's ice, tidewater glaciers are melting at unprecedented rates, but exact rates are a challenge to ascertain. Unlike alpine glaciers, tidewater glaciers are highly dynamic and can undergo rapid advances and retreats independent of climate changes. Much of the melt attributable to overall ice loss is difficult to measure and occurs either as increased calving or beneath the water. What is known about the dynamics of tidewater glacier melt is predicated upon sparse data and indirect inferences that inform theoretical models of subsurface melt.

Understanding the unique dynamics of tidewater glaciers, particularly as a response to the accelerated warming occurring in high-latitude environments, requires direct observations. However before the survey no direct measurements of underwater melting at tidewater glacier fronts have been made, said David Sutherland, lead author of the study and University of Oregon oceanographer

To address the need for direct submarine melt observations, Sutherland and a team of researchers conducted comprehensive field observations at LeConte Glacier in Southeast Alaska. LeConte, the southernmost tidewater glacier in the Northern Hemisphere, flows from the Stikine Icefield in Southeast Alaska for 21 miles before spilling into a narrow fjord at the edge of the Pacific Ocean. In spite of its size, LeConte's ice flows quite quickly — at a clip of nearly 25 meters per day, or three feet an hour.

Meltwater pulsing out of LeConte Glacier.

A time-lapse video taken over 8 hours from a ridge above LeConte Glacier shows the strong meltwater plume flowing away from the glacier, as well as icebergs calving and swirling in the near-glacier fjord.

Meanwhile, in west Greenland at Store Glacier, another damaged marine-terminating glacier raises alarms.

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One month of ice flow in a few seconds. Sure, the flow of the glacier is visually enhanced, but the animation nonetheless captures about a billion tonnes of ice dropped straight into the sea. In #Greenland, there are many glaciers like this. Mind-boggling #StoreGlacier#Greenlandpic.twitter.com/LgKEzzaPcB

— RESPONDER (@ERC_RESPONDER) June 22, 2019

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This week, 40 billion tons of ice will melt in Greenland as the European heat wave moves north -- enough to measurably raise global sea levels.This single heat wave will create a permanent change in our oceans that will linger for millennia.We are in a climate emergency. https://t.co/ypkH6093aU

— Eric Holthaus (@EricHolthaus) July 29, 2019

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Simulating Store #Glacier calving in response to submarine melting. #Greenland#ClimateChange@FoxGlacierMince@ERC_RESPONDERpic.twitter.com/obsZngSUZw

— StAndrews Glaciology (@StAndrewsGlacio) July 24, 2019

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Simulating Store #Glacier calving, from underwater this time. #ClimateChangepic.twitter.com/MSEgD1Gwhh

— StAndrews Glaciology (@StAndrewsGlacio) July 24, 2019

The clip below is from the Netflix documentary Our Planet. A jaw-dropping video of a Store Glacier calving event.

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The cameras catch the moment when a chunk of ice the size of a skyscraper breaks off the Store Glacier in Greenland and tumbles into the ocean. As seabirds circle in the foreground, 75 million tons of crystalline ice cascade into the water below. “Glaciers have always released ice into the ocean,” says narrator David Attenborough. “But now this is happening nearly twice as fast as it did ten years ago.

Thanks for reading.

I keep vigil. I share climate science. That fact does not make me an alarmist or a doomer.

I was asked recently in one diary that I should consider having a trigger for my stories warning readers that it is a “doomer” diary.

In my mind, they are not that, if you read what I share, you too wrestle with all of the emotions of grief and fury that I do. I feel angry with what we as a species have done to the biosphere and sadness that I can’t figure out a way to extricate myself from an economy so dependent on fossil fuels that all of us are baked into it.

For those younger than me, having a clear picture of what is coming is essential in my view. Though there will be no safe place, some places are more reliable than others at least in the short term. Picking up roots and moving won’t protect anyone from mass migration or economic collapse, unfortunately.

I’ve never felt that ignorance is bliss. I still don’ t. Knowledge can be brutal to confront, but the world is still beautiful and full of life. For me, that is enough to get myself through my life. 

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