Eight days since leaving Bluff we’ve at last entered the Ross Sea and so in the final stretch to get down to McMurdo and Scott Bases. Along the way we’ve had a few milestones which brings home just how remote this part of Antarctica is. Indeed these days there are 25,000 tourists visiting per year, yet fewer than 100 will come into the Ross Sea this year. All the rest come via South America and after a quick one day crossing of the Drake Passage, cruise along the Antarctic Peninsula – certainly not quite so arduous as 6 to 8 days being tossed around in the Southern Ocean – but without the unique attractions of the sub-Antarctic islands or the historic explorer huts that are dotted on Ross Island and indeed the bulk of visitors don’t even get lower than the Antarctic Circle as the cruise ships ply their passage north of where the midnight sun is still visible.
The upside of going to Antarctica via South America is accessibility, something we are learning is somewhat tenuous for those of us trying to get in via sea, via the Ross Sea. On Day Six of our voyage we crossed latitude 60 degrees south, as far north as the sea ice extends during winter. Yet McMurdo is at 77 degrees south – so we still had 1,000 miles to go. It’s hard to imagine that the extent of the annual sea ice expansion is that far but now we can appreciate that this cycle doubles the size of Antarctica each winter.
Perhaps more daunting though is that when this annual expansion of Antarctica’s ice apron, formed because winds bring the winter low temperatures of the interior of Antarctica when it’s at it furthest point from the sun to the surrounding sea, that the pump room of the great ocean conveyor is cranked into action. Fresh water sea ice leaves a salty brine below it that, being denser than sea water, sinks to the bottom of the Southern Ocean. Once it’s had a spin around the continent it heads north up New Zealand’s east coast where it warms as it approaches the equator and rises to the surface some of it being pushed west across the Indian Ocean to continue its northern journey around The Cape of Good Hope and up the Atlantic as the Gulf Stream just in time to meet the winter conditions of the Arctic where the process begins again as sea ice formation again sends salty brine deep and this time it heads south where it rises as it warms, to eventually hit another Antarctic winter. Antarctica being colder than the Arctic we can think of it being the primary pump that drives the global ocean conveyor, and the Arctic being the auxiliary engine. The ocean conveyor redistributes heat from the equator to the poles.
As we’ve headed south it’s been the westerly winds that have been on our beam for much of the time, but that has changed now we’re in the vicinity of the great Continent. This is where those westerly spinning cyclones that frequent the Southern latitudes come together and spin around the Continent. So the winds close to the centre are in fact the easterly rotations of these cyclones.
And the sea conditions we’ve had are what you’d expect of the Southern Ocean – 5 metre swells breaking over the ships rails at times, and now as we’ve broken through the pack ice that this year has stubbornly remained at the north edge of the Ross Sea, we are at last in the Ross Sea proper although temperatures have plunged and we’ve gone from snow covered decks to ice-covered ones, as the wind from the south builds. And the temperature is now well down from that one-out-of-the-box balmy sun-drenched day just a few days ago that we spent sitting amongst the albatross nests high up on the ridges of Campbell Island.
Today was the first contact with others as we rendezvoused with the Argos Georgia, the fishing boat that before Christmas was on TV News, having broken down in the pack ice. An aircraft dropped the emergency engine parts for it, and today we delivered to it the rest of the machinery needed for it to be able to make the voyage back to New Zealand.
And so from 72 degrees south, it’s onward through the icebergs of the Ross Sea to the historic huts on Ross Island and our final landing point at the south end of McMurdo Sound.