Maybe it’s because it’s summer (in the northern hemisphere, obviously) or maybe it’s just coincidence, but the stream of fascinating research papers seems to have dried up. But there’s still ongoing activity around the planet — and one piece of research which caught my eye did provide a fascinating illustration of the complex feedback mechanisms which operate in our Earth system.
Surprise Consequences of Antarctic Ice Melting
Maybe it’s because it’s so hot where I am (all right, not hot for most people but hot in terms of what I’m used to) that my interest was caught this week by something cold. On this Earth, it doesn’t get much colder than the Antarctic, where satellites recorded a temperature of -94.7C (that’s -138.46F) in 2010.
I’ve talked before about how the Earth functions as a system, so that change in one area invariably causes change in another. The Antarctic ice sheet contains a vast quantity of ice — approximately 7.2 million cubic miles — and it is a fundamental control on many elements of the Earth as we know it. Ocean currents, world climate and global sea levels are all closely linked to what happens in the Antarctic.
As the global climate warms, scientists have expressed widespread concerns about the future of the ice sheet, the western part in particular. The collapse, or melting, of the ice sheet would have profound implications and the evidence suggests that the ice is melting rapidly.
But the relationship between ice, land and sea is a complicated one, and this week I saw an article about a piece of research which illustrates just how complex they can be.
Large volumes of ice depress the land surface, and when the ice melts, the land rises in a process known as isostatic rebound. With large volumes of ice melting in West Antarctica isostatic rebound is taking place — but new research indicates that this is happening unusually quickly, something attributed to the characteristics of the underlying mantle rock.
And one discovery means that we have to rethink our understanding of all those things that are dependent up on it. In this case the implications of this are twofold and contradictory. On the one hand, the amount of ice that’s lost is likely to have been higher than previously thought, and on the other, the uplift may counteract further ice loss by altering topographical features which contribute to melting and, in the words of the report: “the ice sheet may stabilize against catastrophic collapse.”
Is Anything Happening in Iceland?
The world has stopped watching Kilauea (though there’s a report below on what’s going on) but, as I keep mentioning, there are other things happening volcanically speaking. And there are other things that might happen.
I have a particular interest in Icelandic volcanism and so I keep a close eye on what’s happening there. Iceland’s volcanic setting generates a range of volcanic types, both effusive and explosive and eruptions are a regular feature. The often-quoted rule of thumb is an average of around every five years and the last, at Holohraun, was four years ago, so we shouldn’t be surprised if another eruption occurs.
Recently I’ve seen one or two reports in the Icelandic local press that suggest another volcanic eruption may be on the cards — most notably the warning that; ““The Glacier of the Wastes” stirs: Earthquake swarm in Iceland’s 2nd deadliest volcano”.
The volcano in question is Öraefajökull, which has erupted twice in Iceland’s recorded history, in 1728 and 1362, both times with considerable vigour and producing a large amount of erupted material. It has potential for a disruptive and possibly deadly eruption in the future.
Since the autumn of last year there’s been unrest in Öraefajökull and it’s been closely monitored by the authorities. In fact, over recent weeks, seismicity has decreased, and the last official bulletin from Iceland’s Meteorological Office (dated May) indicated no imminent eruption.
The latest reports seem to be based on an earthquake which occurred on 29 June, 2018, which was described by IMO in its regular earthquake bulletin as: “the third largest event ever measured by the SIL system in Öræfajökull”.
Something is obviously happening beneath the volcano, though that doesn’t necessarily mean an eruption is imminent. Nevertheless, it’s it’s worth watching.
Kilauea Eruption Continues
The eruption of Kilauea is well into its second month and seems to have established a pattern. There’s a significant distance — a matter of tens of kilometres — between the crater and the main location of the eruption and so they may seem to be separate, but they aren’t. Activity at the crater is linked to deflation of the magma chamber, and that deflation is caused by the channelling of magma to the eruption zone.
As a scientist I should be wary of anthropomorphising Earth processes, but it seems to me helpful to visualise the system as an organism’s chest rising and falling, as lungs inflate and deflate during the process of breathing.
In the rift zone, lava flows continue from two of the 22 fissures which opened up during the original phase of the eruptions, with Fissure 8 the most active and feeding the stream of lava entering the ocean.
Levels of volcanic gases continue to be high — and so, hazardous — and the USGS warns of the possibility of further ground cracking and fissuring. Meanwhile, at the crater, another in a series of explosive eruptions. It’s a pattern we can expect to see repeated for a while yet.