Faster Glacier Melting Mechanism Could Cause Huge Sea Level Rises

When it comes to the issue of climate change, naysayers often contend that we have an incomplete understanding of the Earth’s systems. While humanity is yet to uncover all the secrets of the world, that doesn’t mean we can’t act on what we know. In many cases, as climate scientists delve deeper, they find yet more supporting evidence of the potential turmoil to come.

In the stark landscapes of Greenland, a team of intrepid researchers from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory have unearthed a hidden facet of ice-ocean interaction. Their discovery could potentially flip our understanding of sea level rise on its head.

The Tide Is High

Scientists have been studying the Petermann glacier for some time. This photo was taken in 2013 about a year after a large iceberg broke away, pushing the glacier’s front significantly upstream. Credit: NASA, public domain

As we grapple with the accelerating impacts of climate change, one of the greatest looming threats is that of rising sea levels. Melting sea ice is no threat, as it doesn’t cause sea levels to rise. Instead, the real problem is land ice, with the vast ice sheets of Greenland and Antarctica acting as colossal water reservoirs.

As our planet heats up, these ice sheets melt into the ocean, causing sea levels to rise. This naturally comes with implications for humans. The greatest threat is to coastal communities, where increased flooding or total inundation could make some areas uninhabitable. There’s also the threat that sea level rises could render some agricultural land unusable due to increased salinity, affecting even those who live inland due to food scarcity.

Predicting the extent of sea level rise is a complex puzzle, with many interconnected mechanisms at play. Researchers have to consider factors such as air temperatures, ocean currents, and the physical characteristics of the ice sheets themselves. But as this new research reveals, there might be more to the story.

A large iceberg was spotted calving away from Petermann Glacier in 2012. Glaciers lose mass by melt, sublimation, and by iceberg calving into the sea. Credit: NASA, public domain

The scientists focused their study on the Petermann Glacier in northwest Greenland. Using satellite radar data, they found that the glacier’s “grounding line” – the point where the glacier detaches from the bedrock and begins to float in the ocean – moves substantially with the tidal cycles. This movement, significantly larger than expected, allows warm seawater to seep far underneath the glacier, accelerating ice melt. Data collected by researchers suggests that the grounding line is more of a “grounding zone” which migrates from 2 to 6 kilometers as the tide goes in and out.

In essence, the researchers discovered that warm seawater carves channels beneath the ice, particularly at the “grounding zone,” leading to increased melt rates. The team observed a dramatic example of this between 2016 and 2022, when the glacier’s grounding line retreated by 4 kilometers. In the process, a 670-foot-tall cavity formed underneath the glacier, carved out by retreating warm water.

This revelation defies the traditional understanding that these grounding lines remain static during tidal cycles and are immune to melt. The implications of these findings could be significant. The team suggests that if these overlooked ice-ocean dynamics were accounted for in models, estimates of future sea level rise could double. This isn’t just limited to Petermann Glacier – the same could apply to any glacier ending in the ocean. This includes glaciers across most of northern Greenland, as well as Antarctica in its entirety.

Warmer water tends to get under glaciers and melt them out from underneath. Now, researchers have discovered that the grounding line where melting occurs may actually move significantly with the tides, which would drastically accelerate sea level rises.

This suggests that the already serious problem of sea level rise may be even more urgent than we thought. We’re already aware that the Greenland ice sheet has lost billions of tons of ice over recent decades, largely due to warming subsurface ocean waters. The interactions between this warm water and the ice speed up glacier movement towards the sea, leading to more rapid ice loss.

As our understanding of the intricacies of climate change continues to grow, the Greenland research is a sobering reminder that some variables might remain hidden beneath the ice, so to speak. It’s a classic case of science in action: our models and predictions are only as good as our understanding of the systems involved. As we continue to investigate the depths of climate change, let this be a reminder that there’s always more to learn and that the quest for knowledge is never over, especially when the stakes are so high.

It would be a beautiful moment to find out that some previously-unknown mechanism meant that we would all be safe from the expected dangers of climate change. Sadly, though, most new research seems to confirm we’re in for a bad time, much of it saying the peril is on a more advanced timetable than previously thought.

2023-05-19 17:00:00