Tasman Glacier and its terminal lake with icebergs and icy debris after massive terminal face calving in 2010 under sunset, Mt. Cook National Park, Mackenzie Country, World Heritage Area, New Zealand

Glaciers around the world are melting and disappearing from World Maps. We are not immune to it as this sad reality is hitting New Zealand as well, and it’s not a nice sight.
The Southern Alps are becoming more and more unstable for alpine activities with increased rock avalanches as the warmer temperatures are melting rock binding ice in lower altitudes then in past.
All this rock avalanche debris falls on the shrinking and narrowing glaciers in valleys below, covering their gasping for breath remnants under layers of rocks.

In case of Tasman Glacier, this is even more evident, as with it’s lengths of 27km now, it is New Zealand’s longest and mightiest glacier…but how long for when its retreat is today estimated to be close to 1 km each year.
In 2010 massive calving event occurred, littering Tasman Glacier terminal lake, non-existent 40 years ago, with tons of ice debris and icebergs.

It’s not every day when event like this happens so I went to check it out myself. When I arrived at the terminal lake near sunset time, the sky suddenly closed up, clouds rolled over my head and it started to snow. The light of the setting sun was penetrating this gentle snowfall, and all Tasman Valley got dressed up in this beautiful pinkish pastel colours…very eerie, moody scene with all the icebergs in the lake…how lucky I was to witness this alone…

Tasman Glacier with its terminal lake after calving at sunset, Mt. Cook National Park, Mackenzie Country, World Heritage Area, New Zealand

Taken with Nikon D300 and Nikkor 24-70mm f2.8 lens

Beautiful shapes of deep, freshly snowed up crevasses on Franz Josef Glacier, Westland National Park, West Coast, New Zealand

On this day, it was these turquoise fringes of the crevasses which caught my attention, as they were shining from a distance at me.
I love these ice colours but it is not easy to get around locations like this, especially in winter when every crack, deep crevasse or whole is covered with snow. These adventures can truly be deadly if you don’t know what you’re doing. I’ve been tip toeing around these crevasses, poking the ground in front of me before I put my next step down. I wanted to get as close as I could to get a nice wide angle shot with a lot of detail.

Standing on the slippery edge of the crevasse I made this exposure with my 12-24 mm wide angle lens at 12mm and with +1.3 EV exposure compensation.
Only very little of touch up on this RAW file in Lightroom was required to finalize the frame.
I hope you’ll like it as I do.

Enjoy!

Ice Climbing Franz Josef Glacier - Westland National Park, West Coast, New Zealand

Franz Josef Glacier is hugely popular to all kinds of visitors. And that’s no wonder, when one realizes the facets this stunning piece of Mother Nature’s work has on offer.
Besides its pure, mesmerizing blue, translucent beauty hitting us from every direction, Franz Josef Glacier has also its rough face, challenging many people with its ice climbing opportunities.

The characteristics of this icy beast, combined with comfortable access, make this very easily possible. The steep and narrow valley works as a funnel into which Franz Josef slides from almost 3.000m above sea level. Once the body of ice gets into lower, steep and uneven valley floor, massive waves of ice are formed. These waves can be as high as 15-20 m and just scream to be climbed…and there is always plenty of those who can hear the call!

Fox Glacier under highest peaks in New Zealand - Mt. Tasman 3,497m and Mt Cook 3,754m

When do we call a chunk of ice a glacier? Usually, the ice mass has to be at least 100m x 100m in size and needs to show some signs of a present or past movement.
Generally, glaciers are divided into two main groups – Ice Sheets and Valley Glaciers, each with several sub-types.
Ice Sheets or Continental Glaciers are the largest masses of ice on Earth spreading over 50,000 square kilometres with the depth of ice sometimes more than 4,200m. They are only found in Antarctica and Greenland. Ice Shelves are floating extensions of Ice Sheets and surround most of Antarctica. Ice masses smaller than 50,000km2, with a dome-shaped accumulation of ice and snow completely covering mountainous areas, are called Ice Caps and are found in high elevations of polar and sub-polar regions. Similar but smaller than Ice Caps are Ice Fields which can cover low-relief mountain plateaus providing a source of ice for Mountain or Valley Glaciers. Relatively smaller than its originating ice source are Outlet Glaciers, these are rapidly moving frozen streams flowing out of larger bodies of ice.

Beautiful pastel colours of the sunset above Franz Josef Glacier photographed from Centennial Hut toward the Tasman Sea visible on a horizon. Tusk Rocks in a foreground, Chamberlin Snowfield right, Agassiz Glacier left - Westland National Park, West Coast, New Zealand

The most destructive and powerful hand of Mother Nature lies, arguably, in the cryosphere. We may not see it doing much immediate damage, but by observing the landscape we can see enormous changes in our environment caused by glaciers. One of the very typical and most visible footprints glaciers leave behind are our, often ice free, valleys. Entire mountainsides were remodeled by

glacial action leaving only steep valley walls behind. In the upper reaches of the Franz Josef Glacier there is massive pressure from the build up of up to 300m of ice and snow. Associated erosional forces combine to create a bowl shaped depression in the underlying rock called a Cirque, with the snow and ice field contained in the cirque being called the Neve. As gravity encourages ice down the valley the weight of the ice presses downwards and outwards scouring the valleys into a distinctive glaciated U-shape. These are much broader and flatter floored than the V-shaped valleys carved by rivers.

As with all the rest of the glaciated world, New Zealand is also losing ice mass at a rapid rate, with 61% lost since 1850 (Hoelzle et al. 2007), and 11% in the last 30 years (T. Chinn, pers. comm.).

Most of this loss is from the large glaciers calving into pro-glacial lakes, such as the Tasman Glacier. This lake formation is the result of glacier thinning in response to climatic warming in the 20^th century. As well as these large dynamic changes in glacier volume, there are smaller annual changes in volume due to changes in the amount of snow accumulation and snow and ice melt. An idea of how much mass is lost or gained each year throughout the Southern Alps is given by measurements of the end-of-summer snowlines since 1977. These measurement indicate that there have been positive mass balances at times during this period balance (Chinn et al. 2008) and the very sensitive and responsive Franz Josef and Fox Glaciers have advanced as a result.

The advance of Ka Roimata o Hine Hukatere Franz Josef Glacier since 1984 has been extraordinary given the global pattern of receeding glaciers during this period. Recent work has confirmed the very sensitive nature of this glacier – that is it advances or retreats a large amount for a small change in climate (Anderson et al. 2006; Anderson et al. 2008). Combined with its very short response time this explains the large variations in glacier length observed in the last decade.

All of the indications are that Franz Josef Glacier has lost mass in recent years, particularly in 2008, and 2010. We do not have enough measurements to calculate an annual mass balance, but the combination of thinning in the accumulation area and lower amounts of net accumulation observed indicate a negative mass balance. This makes it likely that the recently-started retreat will continue.

This is an excerpt from a full report researched and written by one of the leading New Zealand glaciologists Brian Anderson/Victoria University Wellington.

Text ©Brian Anderson

The ice flow of a glacier is divided into two types, internal deformation and basal sliding. Internal deformation is movement of parts of the glacier relative to itself. Throughout the descent of the glacier, the ice at the sides and bottom side of the glacier are subject to more friction from the valley floor and walls, and therefore forced to move at a slower rate than the ice in the centre of the glacier. As a result the ice deforms within itself. Basal sliding occurs as water, either rain or melt passes underneath the glacier and acts as a lubricant between the ice and the bedrock. This is the main source of terminal velocity of temperate glaciers.

The bottom layers of the glacier flow deform plastically under the pressure allowing the glacier as a whole to slide down the valley like a huge toffee. It is the upper layer of around 30metres where the glacier is more brittle, therefore the ice here cracks and breaks into crevasses and seracs in order to bend over uneven bedrock.

]]> http://nzicescapes.com/blog/2010/05/weather-on-the-west-coast/feed/ 0 http://nzicescapes.com/blog/2010/05/glacial-erosion/ http://nzicescapes.com/blog/2010/05/glacial-erosion/#comments Mon, 10 May 2010 04:45:30 +0000 admin http://nzicescapes.com/blog/?p=32 One of the most striking forms of evidence of glacial erosion is the colour of rivers like the Waiho River in Franz Josef. The melt water of the river gains a characteristic greyish colour, sometimes known as glacier milk. This is the result of the suspension of very fine grains of rock <0.002mm in size. These particles are called glacial flour and are the result of a type of glacial erosion known as abrasion. The abrasion occurs where the glacier slides over bedrock and works much like sandpaper, as rock fragments meet at the boundary of rock and ice they grind and smooth the surface below. If a large rock is trapped, large grooves or glacial striations are engraved into valley walls and bedrock.

Another major type of erosion is known as plucking. When the ice slides over the downstream side of the bedrock, it can freeze loosened rocks from the bottom into itself and rips the rocks out from the valley floor and walls, changing its shape forever.