Climate watch

I’ve studied Larsen C and its giant iceberg for years – it’s not a simple story of climate change

Enormous Antarctic icebergs are a rare but natural occurrence.

One of the largest icebergs ever recorded has just broken away from the Larsen C Ice Shelf in Antarctica. Over the past few years I’ve led a team that has been studying this ice shelf and monitoring change. We spent many weeks camped on the ice investigating melt ponds and their impact – and struggling to avoid sunburn thanks to the thin ozone layer. Our main approach, however, is to use satellites to keep an eye on things.

We’ve been surprised by the level of interest in what may simply be a rare but natural occurrence. Because, despite the media and public fascination, the Larsen C rift and iceberg “calving” is not a warning of imminent sea level rise, and any link to climate change is far from straightforward. This event is, however, a spectacular episode in the recent history of Antarctica’s ice shelves, involving forces beyond the human scale, in a place where few of us have been, and one which will fundamentally change the geography of this region.

The iceberg would barely fit inside Wales. Adrian Luckman / MIDAS, Author provided
The iceberg would barely fit inside Wales. Adrian Luckman / MIDAS, Author provided

Ice shelves are found where glaciers meet the ocean and the climate is cold enough to sustain the ice as it goes afloat. Located mostly around Antarctica, these floating platforms of ice a few hundred meters thick form natural barriers which slow the flow of glaciers into the ocean and thereby regulate sea level rise. In a warming world, ice shelves are of particular scientific interest because they are susceptible both to atmospheric warming from above and ocean warming from below.

The ice shelves of the Antarctic peninsula. Note Larsen A and B have largely disappeared.  AJ Cook & DG Vaughan, 2014, CC BY-SA
The ice shelves of the Antarctic peninsula. Note Larsen A and B have largely disappeared. AJ Cook & DG Vaughan, 2014, CC BY-SA

Back in the 1890s, a Norwegian explorer named Carl Anton Larsen sailed south down the Antarctic Peninsula, a 1,000km long branch of the continent that points towards South America. Along the east coast he discovered the huge ice shelf which took his name.

For the following century, the shelf, or what we now know to be a set of distinct shelves – Larsen A, B, C and D – remained fairly stable. However the sudden disintegrations of Larsen A and B in 1995 and 2002 respectively, and the ongoing speed-up of glaciers which fed them, focused scientific interest on their much larger neighbour, Larsen C, the fourth biggest ice shelf in Antarctica.

The author prepares to assist his colleague, Bryn Hubbard from Aberystwyth University, in drilling a borehole in Larsen C using pressurised hot water.  MIDAS, Author provided
The author prepares to assist his colleague, Bryn Hubbard from Aberystwyth University, in drilling a borehole in Larsen C using pressurised hot water. MIDAS, Author provided

This is why colleagues and I set out in 2014 to study the role of surface melt on the stability of this ice shelf. Not long into the project, the discovery by our colleague, Daniela Jansen, of a rift growing rapidly through Larsen C, immediately gave us something equally significant to investigate.

Nature at work

The development of rifts and the calving of icebergs is part of the natural cycle of an ice shelf. What makes this iceberg unusual is its size – at around 5,800 km² it’s the size of a small US state. There is also the concern that what remains of Larsen C will be susceptible to the same fate as Larsen B, and collapse almost entirely.

Our work has highlighted significant similarities between the previous behaviour of Larsen B and current developments at Larsen C, and we have shown that stability may be compromised. Others, however, are confident that Larsen C will remain stable.

What is not disputed by scientists is that it will take many years to know what will happen to the remainder of Larsen C as it begins to adapt to its new shape, and as the iceberg gradually drifts away and breaks up. There will certainly be no imminent collapse, and unquestionably no direct effect on sea level because the iceberg is already afloat and displacing its own weight in seawater.

This means that, despite much speculation, we would have to look years into the future for ice from Larsen C to contribute significantly to sea level rise. In 1995 Larsen B underwent a similar calving event. However, it took a further seven years of gradual erosion of the ice-front before the ice shelf became unstable enough to collapse, and glaciers held back by it were able to speed up, and even then the collapse process may have depended on the presence of surface melt ponds.

Even if the remaining part of Larsen C were to eventually collapse, many years into the future, the potential sea level rise is quite modest. Taking into account only the catchments of glaciers flowing into Larsen C, the total, even after decades, will probably be less than a centimetre.

Is this a climate change signal?

This event has also been widely but over-simplistically linked to climate change. This is not surprising because notable changes in the earth’s glaciers and ice sheets are normally associated with rising environmental temperatures. The collapses of Larsen A and B have previously been linked to regional warming, and the iceberg calving will leave Larsen C at its most retreated position in records going back over a hundred years.

However, in satellite images from the 1980s, the rift was already clearly a long-established feature, and there is no direct evidence to link its recent growth to either atmospheric warming, which is not felt deep enough within the ice shelf, or ocean warming, which is an unlikely source of change given that most of Larsen C has recently been thickening. It is probably too early to blame this event directly on human-generated climate change.

Adrian Luckman, Professor of Glaciology and Remote Sensing, Swansea University.

This article first appeared on The Conversation.

Support our journalism by subscribing to Scroll+ here. We welcome your comments at letters@scroll.in.
Sponsored Content BY 

The qualities of a high-performance luxury sedan

A lesson in harnessing tremendous power to deliver high performance.

Gone are the days when the rich and successful would network during a round of golf, at least in the Silicon Valley. As reported by New York Times, ‘auto-racing has become a favourite hobby for the tech elites’. However, getting together on a race track would require a machine that provides control while testing extreme limits. Enter the Mercedes-AMG range of cars.

Mercedes-AMG’s rise from a racing outfit to a manufacturer of peak performance cars is dotted with innovations that have pushed the boundaries of engineering. While the AMG series promises a smooth driving experience, its core is made up of a passion for motorsports and a spirit that can be summarized in two words – power and performance. These integral traits draw like-minded people who share and express Mercedes-AMG’s style of performance.

The cars we drive say a lot about us, it’s been said. There are several qualities of an AMG performance luxury sedan that overlap with the qualities of its distinguished owner. For instance, creating an impression comes naturally to both, so does the ambition to always deliver an exceptional performance. However, the strongest feature is that both the owner and the AMG marque continually challenge themselves in pursuit of new goals, stretching the limits of performance.

This winning quality comes alive, especially, in the latest Mercedes-AMG marque – the Mercedes-AMG E 63 S 4MATIC+. With the most powerful engine to have ever been installed in an E-class, this undisputed performance sedan promises immense power at the driver’s command. With 612 HP under its hood, the car achieves 0-100 km/h in just a few seconds - 3.4 to be precise. Moreover, the car comes with the latest driver-assistance technology that promises intelligent control and provides an agile and responsive ride.

But, the new AMG is not just about work (or traction in car lingo). One of its core features is to provide its owners a challenge on the race track. Its drift mode, which converts the vehicle into a pure rear-wheel drive, offers pure exhilaration and adds a work-play dynamic to the car. In that sense, the new AMG is a collaborator of sorts - one that partners with its owner to create an impression through performance. And on the weekends, the car pushes him/her to express absolute power using its race mode with a thunderous roar of the engine - the pure sound of adrenalin. This balance between work and play has been achieved using cutting-edge features in the car that together create an almost intuitive driver-machine relationship.

If you’re looking for a car that shares your enthusiasm for driving, you’ll find a partner in the new AMG. However, buying an AMG is not just about owning a powerhouse on wheels, it’s also about adopting a driving philosophy in which power is just the starting point - the main skill lies in how you manoeuvre that power on the road. A performance sedan in its sportiest form, Mercedes-AMG’s latest model takes vehicle performance to an unmatched level. A decade ago, this amount of speed and power in a luxury 4-door model would be un-thinkable.

Play

The new Mercedes-AMG comes with a host of individualisation options through designo, the artistic side of Mercedes’s innovation, so the car becomes an extension of the owner’s distinctive personality. An expressive design with a new radiator grille and a muscular front apron showcase its athleticism. A new-age driver environment, widescreen cockpit, the AMG performance steering wheel and sports seat delivers an intensive driving experience. With the Mercedes-AMG E 63 S 4MATIC+, AMG has created an undisputed performance sedan that can rip the race track as well as provide reliable luxury sedan-duty. To know more about the most powerful E-class of all time, see here.

This article was produced by the Scroll marketing team on behalf of Mercedes-Benz and not by the Scroll editorial team.