Looking over the tongue of Mawson Glacier.
Rocks: collected (300 kg). Weather: warm (-3 to +5 °C). Incidents: sprained ankle, thawing camp site, moisturiser mistaken for toothpaste, poor facial hair growth.
The aim of our expedition was simple – to collect rocks deposited by Mawson Glacier as it thinned in the recent geological past (since the last ice age). This would provide insight into the potential rates and magnitudes of ice loss in Antarctica and, ultimately, how such glaciers can respond to a changing climate.
For this we visited a series of nunataks – essentially, mountains surrounded by glacier ice. One of these, Mt Murray, was the location of our camp for the duration of the expedition.
Arriving by helicopter, we targeted a large snow patch to set up camp. Soon after the helicopter had departed us, we realised that the snow was only tens of centimetres (a few inches) deep, which, for the most part, capped solid ice. To make matters worse, melting snow and ice had formed slushy ponds in some places.
It didn’t take long for us to decide that we needed to camp elsewhere, and a nearby rocky area was the only candidate. Luckily we had foam pads and sheepskins – intended to insulate us from the cold ground – which provided some comfort against the rough floor of the tent.
Perhaps the most disappointing aspect about this camp site was that we couldn’t build an igloo-like toilet, and instead had to perch our poo bucket behind an insufficiently-sized boulder.
Over the next several days, we explored this area by foot, collecting cobbles at various elevations above the glacier margin.
While glacier-deposited cobbles were not abundant, our largest limitation was how much rock we could haul the several kilometres back to camp. A 35 kg (nearly 80 lb) backpack was definitely our limit, as proved on Day 2. Travel across snow patches was made harder by melt ponds, streams and penitentes.
Further signs of relatively warm air temperatures could be seen during helicopter flights over Mawson Glacier to other nunataks.
Mawson Glacier (76°13′ S, 162°5′ E) flows out into the Ross Sea, where it forms the Nordenskjöld Ice Tongue – a floating shelf of ice that projects out from the coast. The ice tongue is one of the largest in the Ross Sea region, stretching over 35 km out from where the grounded glacier meets the sea, and about 8 km wide – that’s about 5 times larger than Manhattan in New York.
Unexpectedly, we saw large melt ponds on the surface of the ice tongue, reminiscent of the Greenland Ice Sheet margin. In 2002, a build up of melt ponds in the relatively warmer Antarctic Peninsula caused the weakening and collapse of the Larsen-B Ice Shelf, and the subsequent acceleration of glaciers into the sea.
Meltwater stream and lake on Mawson Glacier surface.
Melt ponds on ice surface.
While such melt ponds make for nice photos, it is worrying to see them this far south, where the air temperature reaches above freezing point for less than a few weeks of the year.
One positive of these mild summer temperatures was the ease of getting drinking water. Instead of spending hours melting snow on stoves, we were able to melt pots of snow in our tent porches during the day – it reached over 30 °C (86 °F) in my mountain tent one day! – or we could simply collect water from a nearby melt pond.
So, what did I take from this expedition?
Firstly, and most importantly, lots of rocks to process in the lab over the next few months.
Secondly, a lesson to be prepared for thawing conditions; parts of Antarctica are not always cold and frozen.
Thirdly, a swollen ankle; looking at your notes while walking over rocky terrain is not advised.