Heading Home

Highlights of Gary’s progress on the

Our Far South Expedition

March 7, 2012

Minke Whale

Where next?

As we now steam towards Lyttleton after a brief visit to the Antipodes and Bounty Islands region, it’s time to pause and think about what comes next. What is striking about New Zealand’s subantarctic is that the amount of effort being put into research and understanding of this region is miniscule in proportion to both the size of the region as well as the importance of this region to New Zealand. New Zealand is home to one of the biggest exclusive economic regions in the world, yet what do we know about that portion of New Zealand that is underwater? Or for that matter within the water? 

 The Auckland Islands sit in an ideal place to address the issues – they lie at the northern boundary of the Antarctic Circumpolar Current, they are a biodiversity hotspot, and they are surrounded by fishing grounds. The Islands themselves also house a number of natural environments that have recorded past change – fiord basins, peat swamps, and locations to record present change – natural harbours, channels between the Islands and home to whales, sea lions and other plant, animal and bird species, many that are endemic. The challenge is to improve access and support for scientific and conservation efforts on the Islands and take advantage of their position as the canary in coalmine for the changing oceanic, climatic and biological realms.

Campbell Island

Highlights of Gary’s progress on the

Our Far South Expedition

March 4, 2012

Gary Wilson positioning the piston corer

Campbell Island

How nice it is to be at anchor again, even if it is in a howling sou’westerly and the ship is swinging 60 on it’s anchor. We have two anchors out just to be sure. Unfortunately, in only 22 m of water, we can’t risk deploying the corer as it would quickly turn into an anchor as the ship swung away from it, so we wait in the hope that the wind dies down. We managed to spend a few hours at Duris Point at the Head of Perseverance Harbour and collect some samples that I have been wanting for some time to date the last glaciation of Campbell Island. 

While we wait for the wind to die down, we were able to hike up to Col Lyall and spend a few hours watching Royal Albatross as they nested, gammed and flew – they really are enormous birds, with a 3 metre wingspan, a body more than twice the size of a turkey and an enormous hooked beak – truly beautiful. Since the removal of introduced animals and the eradication of rats on Campbell Island by the Department of Conservation, the birdlife and mega-herbs that Campbell Island is so well know for are flourishing once more.

Still coming up …. Questions, questions… where will we find answers

Global warming and CO2

Highlights of Gary’s progress on the

Our Far South Expedition

March 2, 2012

 Global warming and CO₂

Ice core records show that atmospheric CO₂ levels and temperature are intimately linked and that both have varied cyclically over a 100 thousand year timescale between about 180 and 280 parts per million, with low CO₂ levels representing past glaciations and high CO₂ levels representing interglacial or warm periods.

 The warm up phase has been rapid and the cooling phase has taken much longer. Peak warmth generally lasted a few thousand to 10,000 years. Our current position in the natural cycle would imply that we should now see reducing CO₂ and cooling. But we are not. In fact, CO₂ levels are now above 380 parts per million and the last time the earth saw those levels was several million years ago. And, Antarctic geological research indicates that at those times, the Ross Ice Shelf collapsed and linked climate and ice sheet models tell us that the West Antarctic Ice Sheet also melted driven primarily by warmer waters underneath floating parts of the ice sheets and shelves. Such melting would result in a rise of global sea level of between 3 and 7 metres once you put that ice back into the ocean (this is not even considering what would happen in Greenland). How fast would that happen? Maybe as quickly as 400 years, but more work is required here to determine that rate as well as quite whether the rate is uniform over that time period. 

Crabeater Seal

One thing we do know is that man is continuing to pump CO₂ into the atmosphere at unconstrained rates, and that we are seeing signs consistent with the predicted warming: warming oceans, melting ice shelves – a relatively new lesson is that it is warming faster at the poles than the equator (a concept known as polar amplification), which is a little frightening as those are the regions most vulnerable to warming. And, what of all that additional CO₂ in the atmosphere, well a lot of it is being absorbed by the southern ocean and measurements show that this is making the ocean more acidic. What are the side effects of that? Can we stop the rise in atmospheric CO₂? That’s a hard one, given our fossil fuel addiction, but, another thing we do know is that even if we stopped tomorrow, we would still see the effects for a hundred or more years, so some degree of adaptation is going to be required. And, that begs the questions of what are the wider effects on sea-level, climate, fisheries…? And, how much? How fast? And especially what might we expect in “our own backyard”?

Still coming up …. Campbell Island

Wind

Highlights of Gary’s progress on the

Our Far South Expedition

March 1, 2012

Giant Petrol

Wind

At, 62° South, we appear to have no wind. Most unusual, but long may it continue. It means we get a bit of sea fog and can’t see very far, but what’s to see down here anyway but ocean and more ocean. In the South Island of New Zealand we’d be forgiven for thinking that the wind only ever blew from the West, sometimes a warm nor’west and sometimes a cold sou’west… but why is that? Well, atmosphere circulates around the globe and like the oceans it is driven by the temperature gradient from the poles to the equator and the fact the earth is spinning on it’s polar axis naturally subdivides the atmosphere into smaller cells of different temperature air circulating in opposing directions. Wind speed is greater at the boundaries of these air masses and in New Zealand this results in the Westerly Winds that we know so well in the south, in fact they were relied on by the big clipper ships that plied the southern oceans at the turn of the last century. In the Northern Hemisphere we have the Trade Winds. That’s great, but what will happen with a warming planet? Will the warm atmospheric cell over the tropic expand and push the westerlies south, resulting in a significant change to New Zealand’s climate? (there does seem to be some evidence of this already), or will the temperature gradient from equator to pole reduce and result in a weakening of the westerly system we know so well?

Still coming up …. global warming and CO₂ 

Oceanography

 Highlights of Gary’s progress on the

Our Far South Expedition

February 29, 2012

So what have we learnt? 

Oceanography

At 68° South, we have just crossed through the Antarctic Divergence and left most of the floating icebergs behind on our way north to Campbell Island. With a few days of steaming ahead, it is time to take stock and assess what we have learnt along the way. 

Oceanographically, this is a very unique part of the world. Because Antarctica is separated from all the other Southern Hemisphere continents by ocean, it allows a circum Antarctic ocean current to develop between the Antarctic Divergence and the Subantarctic Front buffering the Antarctic Continent from external influences. This current, known as the Antarctic Circumpolar Current or ACC washes along the southern margin of New Zealand’s subantarctic and then sweeps up past Dunedin to the Chatham Rise before heading east, which explains why Dunedin was witness to those ice-bergs a few years ago. The ACC effectively regulates temperatures at the southern end of New Zealand. Closer to Antarctica, and within the Antarctic Divergence, cold and saline water sinks to the ocean floor and also flows along the bottom of the ocean past the eastern seaboard of New Zealand, effectively driving global ocean circulation. Together, these two ocean currents form the main engine room of the global ocean system transferring heat around the planet and New Zealand’s subantarctic is in the firing line so to speak. 

So, what? Well the recent evidence is that Antarctica is warming up and with the melting and loss of ice shelves, a major concern is how will these major currents respond and what will be the effect on New Zealand? Changing temperature gradients across New Zealand? Different storm and rainfall patterns? A move in fishing grounds? Sea level rise? How much? How fast? It’s clear that our back yard does not end at Stewart Island, in fact one of the most significant part of the country is further south yet.

Coming up …. global warming and CO₂

Ice

Highlights of Gary’s progress on the

Our Far South Expedition

February 27, 2012

Ice

Well we’ve now spent 3 days trying to get into places on the Mainland of Antarctica – Terra Nova Bay, Cape Hallet, Cape Adare… to no avail. Even though the Ross Sea itself is fairly open, sea ice and ice bergs are clustered along the bays and inlets along the northern Victoria Land coastline. We pushed through in several places but still did not manage to reach the coastline. Cape Adare was interesting as the current is about 2 knots and as we sat attempting to take samples, the floating ice was banking up against the ship. Needless to stay, we didn’t hang around. We’re now tracking east around the ice that has accumulated in the Ross Gyre and then tomorrow morning, it should be north to Campbell Island

Coming up….. So what have we learnt? 

Historic Huts and the Ross Ice Shelf

Our Far South Expedition

February 25, 2012

Historic Huts

Ross Island is home to three historic huts from the Heroic Era of Antarctic exploration: Scott’s 1901 Discovery Expedition Hut at Hut Point, Shackleton’s 1907 Nimrod Expedition Hut at Cape Royds and Scott’s 1910 Terra Nova Hut Expedition Hut at Cape Evans. The Discovery Hut now lies in the shadow of McMurdo Station, but when constructed from an Australian kitset, it shared Winterquarters Bay only with the Discovery, which was moored nearby. The Hut itself proved too cold and difficult to heat for Scott’s men to live in it, so they used it mainly for stores and slept aboard the ship. 

Shackleton's Nimrod Hut at Cape Royds

In contrast, and 40 km to the north, Shackleton’s Hut at Cape Royds was home for 15 men. It was smaller with a large stove at one end and built in a hollow providing protection from the weather on all sides. This hut has recently been restored by the Antarctic Heritage Trust and should now withstand its next century on the flanks of Mount Erebus – sea level rise permitting. Only about 10 km to the south and across the Barne Glacier, the beach at Cape Evans is home to Scott’s Terra Nova Hut. Far larger and warmer than Discovery Hutt inside, but fairly exposed to the wind, as we discovered yesterday afternoon. Visiting the Hut is a dream for any Antarctic Geologist. To see the geologists quarters in the Hut and remember the feats of Frank Debenham, Edgeworth David, Raymond Priestley, and Griffith Taylor who all contributed to the mapping of the Dry Valleys and the Ice free areas of Victoria Land to the west of Ross Island.

Officers Table

Ross Ice Shelf

Ross Ice Shelf

Named the Ice Barrier in 1841 by Ross, when he found that he could not sail his ships Terror and Erebus further south, the leading edge of the Ross Shelf ends in a 30 m cliff. At 3.30 am, the light was not ideal, but for the first time I was able to see this great floating ice shelf in perspective. Stretching for hundreds of kilometers to the east, the ice cliff is the mere tip of the ice berg – the shelf is actually closer to 300 m thick, with much of it floating below sea level and in, on average, about 600 m of water. We saw the ice shelf from east of Cape Crozier, where the ANDRILL project are planning to use it as a floating platform to drill into the Eocene, 40 million year old, rocks on Coulman High to recover, amongst other things, a record of Antarctica in the high carbon dioxide greenhouse world. The drilling is only possible because of the ice shelf but the ice shelf also provides the biggest challenges for drilling. Ten years ago, a large ice berg broke off allowing a ship in to survey the sea floor and subsequently the ice has advanced back over the site at a kilometer a year, thereby re-establishing the platform for the drill rig over the site. But that 2.5-m a day ice advance limits the time that the drilling operation can continue before there is too much bend in the pipe. So, the technology will either have to enable us to drill faster than previous efforts or allow us to move the drill rig back along the ice shelf and then re-enter the drill hole and continue drilling deeper.

Ross Sea at midnight

Coming up….. the Antarctic Mainland