January 25 Brownson Islands

 

We've spent many quiet moments contemplating amazing vistas like this.

Brownson Islands and our passage around B22A (satellite image)

A month ago today while on our Antarctic Peninsula and subantarctic islands expedition, we sailed alongside A76A a massive iceberg drifting in the Scotia sea. Then a couple of days ago we passed another mammoth iceberg half its size but still humongous - the fourth largest iceberg in the world, the B22A.  This iceberg broke off the Thwaites Ice Tongue which is a huge ice outflow projecting into Pine Island Bay from Thwaites Glacier. Thwaites glacier is nicknamed the Doomsday glacier because it is at risk of collapsing. The timing of that can only be estimated from modelling but rising sea temperatures will increase the melt rate of that component of the glacier which projects out beyond the land to which it is bound onto the sea surface. It's so hard to imagine - 3 km thick and the size of Texas draining into Pine Island bay and on out into the Amundsen Sea. I know that many people are alarmed at what will happen to Antarctica with ‘global warming’.  It is mainly western or Lesser Antarctica that’s at most 'immanent' risk because a considerable amount of that is ice over water.  A 2022 assessment of tipping points in the climate system indicated that the entire West Antarctic Ice Sheet would most likely take 2,000 years to disintegrate entirely once it crosses its tipping point, and the minimum timescale they suggest is 500 years. In regard to Thwaites glacier, scientists are concerned that only part of Thwaites - specifically its Eastern Ice Shelf, the part of its body that floats above the ocean - may collapse within 10 years. Take that in whatever way you can understand it – it baffles me. Many of the icebergs that break off these huge glaciers run aground and refreeze into surrounding ice. Incidentally, Western/Lesser Antarctica joins Eastern/Greater Antarctica at the Transantarctic Mountains which run pretty much from the east side of the Ross Sea (which lies due south from New Zealand) to the Weddell Sea on the opposite side of the continent (confusing I know but the Weddell Sea is that big scooped out bit above the sign for Thwaites Glacier on the pic below - I hope I haven't confused you more!).

Western/Lesser Antarctica joins Eastern/Greater Antarctica at the Transantarctic Mountains

The hikers gathering to walk to the summit

So back to our travels! This afternoon we headed for a place where few tourist vessels venture – the Brownson Islands. This is an important breeding region for penguins and we saw many. Our bunch of polar hikers landed on one of the islands with the aim of climbing to the top. Rock samples have been taken from the particular island but the rest of the group have not been well explored. Driving our zodiac is Marilia one of our guides, a marine mammals specialist who was just a powerhouse of enthusiasm. An absolutely delight.

Have you ever walked on ice and icy rocks? It's a bit challenging!

While the hikers were trudging to the top of their island, the rest of us headed for another snow and ice covered island. They believe no-one has ever set foot on this island so people were quite excited - me included. The landing spot looked rather precarious to me with lots of assistance required – slippery rocks and ice so I stayed on the zodiac and cruised around some of the 20 islands in this grouping. 

Unsurprisingly, these islands provide a safe breeding place for penguins.

The shimmering icicles captured my imagination

So too the carvings in icy cliffs of other islands

Just as an aside, Antarctica is the best place in the world for finding meteorites so not only is the continent and its islands an important place to study earth’s geological history, it also provides a window into the geology of the solar system.