Glacier Retreat Drives 400% Lake Expansion Southern Alps, New Zealand 1990-2020

Glaciers of the Southern Alps of New Zealand have been losing ice volume since 1978, with an increasing rate in the last decade (Pelto, 2016).  Gjermundsen et al (2011) examined glacier area change in the central Southern Alps and found a 17 percent reduction in area mainly from large valley glaciers such as Hooker, Mueller, Tasman and Murchison Glacier. The NIWA glacier monitoring program noted that 30 percent of New Zealand’s ice that was existed in the late 1970’s has been lost in the past 40 years as snowlines have been rising. The retreat has been driven by a series of  increasingly warm summers (NIWA, 2019). The NIWA and University of Wellington 2020 snowline survey indicated improvement in 2020.  Lauren Vargo and Andrew Lorrey reported there was more retained snowcover compared to the very high snowlines in 2018 and 2019, despite the presence of ash/dust from Australian fires (NIWA, 2020).

Landsat images  from 1990 and 2020 of the Mueller (M), Hooker (H), Tasman (T) and Murchison (Mn) Glacier.  Red arrows indicate the 1990 terminus location, yellow arrows the 2020 terminus location and pink arrows the upglacier extent of debris cover in 1990.

If we look back to the 1972 Mount Cook map, see below, no lakes are evident at the terminus of Hooker (H), Mueller (M), Tasman Glacier (T), or Murchison Glacier that all drain into Lake Pukaki, pink dots indicate terminus location. In 1990 four lakes had developed one in front of each retreating glacier with a combined area of 2.5 km2.  By 2020 the combined lake area is 12.9 km2.

1972 Map of region when Tasman, Mueller and Hooker Glacier lacked proglacial lakes.

Mueller Glacier has had a 2,300 meters retreat from 1990-2020, which will continue in the future as the lower 1.2 kilometer section of the glacier is stagnant. Mueller Lake area was under 0.2 square kilometers in 1990, expanding to 1.9 square kilometers by 2020. Mueller Glacier’s lower section is not a typical convex valley glacier, but a concave reach of debris covered ice with significant melt valleys and hollows indicating stagnation in the lowest 1.6 kilometer.  In 1990 a fringing discontinuous area of water along the southern glacier margin existed. By 2004 the Mueller Glacier Lake had expanded to a length of 700 meters.  Mueller Lake in 2010 had a surface area of 0.87 square kilometers and a maximum depth of 83 meters (Robertson et al, 2012). By 2015 the lake had reached 1,800 meters in length. From 2015-2020 the terminus collapsed into the lake with icebergs and other attached ice remnants.  Terminus images from 2018, taken by Jill Pelto, indicate the high turbidity of the lake, which is expected from a debris covered ablation zone.

Mueller Glacier terminus collapse in 2018, image from Jill Pelto.

Hooker Glacier retreated 1,350 m from 1990 to 2020 with the retreat enhanced by calving in Hooker Lake. The lake had an area of 0.5 square kilometers in 1990, expanding to 1.5 square kilometers by 2020. The retreat was faster during the earlier part of this period with lake area reaching 1.22 square kilometers by 2011 (Robertson et al.,2013). Hooker Glacier has a low gradient which helps reduce its overall velocity and a debris covered ablation zone reducing ablation, both factors increasing response time to climate change  (Quincey and Glasser 2009). Hooker Lake which the glacier ends in began to form around 1982 (Kirkbride, 1993). The peak lake depth is over 130 meters, with the terminus moving into shallow water after 2006 leading to declining retreat rates (Robertson et al, 2012). The debris cover now extends ~2 kilometers further upglacier than in 1990.

Tasman Glacier retreated 4,900 meters from 1990 to 2020 primarily through calving into the expanding proglacial lake. In 1990 Tasman Lake had an area of 1.7 square kilometers, expanding to 7.1 square kilometers by 2020.  Dykes et al (2011) note a maximum depth of 240 meters, and an annual growth rate of 0.34 square kilometers. The proglacial lake at the terminus continues to expand as the glacier retreats upvalley. The lake is deep with most of the lake exceeding 100 meters in depth, and the valley has little gradient, thus the retreat will continue. It has been noted by researchers at Massey University that the lake can expand in this low elevation valley another 9 kilometers, and that at the current rate this could occur over two decades. The debris cover now extends ~1.5 kilometers further upglacier than in 1990.

Canals draining from Lake Tekapo to Lake Pukaki then upriver of Lake Benmore

Murchison Glacier has retreated 2,700 meters From 1990 to 2020.  In 1990 the lake had an area of under 0.2 square kilometers, expanding to 2.5 square kilometers by 2020. The rapid retreat will continue as 2010, 2013 and 2015 imagery indicate other proglacial lakes have now developed 3.5 km above the actual terminus. The debris cover now extends ~2 kilometers further upglacier than in 1990.

For each glacier debris cover now extends further upglacier which along with rising snowlines highlights the expansion of the ablation area, that also drives volume loss, retreat and lake expansion.

Canal at Ohau hydropower, image from Jill Pelto.

Glacier runoff is a key hydropower water resource. Water from Lake Pukaki is sent through a canal into the Lake Ohau watershed and then through six hydropower plants of the Waitaki hydro scheme: Ohau A, B and C. Benmore, Aviemore and Waitaki with a combined output of 1,340 megawatts.  Meridian owns and operates all six hydro stations located from Lake Pūkaki to Waitaki.  Interestingly salmon have been introduced into the Waitaki River system for fishing near its mouth, though Lake Pukaki itself has limited fish.

This post by Mauri Pelto originally appeared on his blog From a Glacier’s Perspective, published by the American Geophysical Union.

Read More on GlacierHub:

Video of the Week: “Return to Natural––Documenting the Tasman Glacier”

Request for Submissions to the Global Report of Indigenous Knowledge and Local Knowledge on Climate Change 2020

Roundup: COVID-19 in Glacier Regions

Video of the Week: “Return to Natural––Documenting the Tasman Glacier”

This week’s Video of the Week is a short film featuring award-winning photographer and natural progressive, Chris Burkard, on a quest to take a single photograph that represents humans’ relationship with nature. The film, Return to Natural, was produced by New Zealand outdoor apparel brand, Icebreaker, who invited Burkard to the Tasman Glacier to seek and capture the photo. In that search for the right image, the film was created.

The 12-minute movie follows Burkard and his team over the course of five days as they hike, ski, boat, and fly above the Tasman, becoming increasingly intimate with the glacier. On the final day Burkard found the image he was looking for––one that would challenge peoples’ perspective of nature. “It hit me when I was taking the photo of the lake,” Burkard said.

“It was the literal open wound of a melting glacier,” Burkard said of the glacial lake, which is younger than the 34-year old photographer himself. “The lake was in fact new, only 30 years old. Created from the run-off from the ever melting glacier.”

About a year after Return to Natural was filmed, the Tasman Glacier was the site of a heartbreaking video that went viral in January when ash and soot from the Australia bushfires turned the sky orange and darkened the ice. The fallout will accelerate the melt of Tasman, which the docu-film reported is already receding 477-822 meters each year. The dire forecast for Tasman is underscored by a recent study that showed fires in the Amazon in 2010 caused a 4.5 percent increase in water runoff from Zongo Glacier in Bolivia alone.

Earlier this year GlacierHub reported on Burkard’s new book At Glacier’s End in which he and author Matt McDonald documented Iceland’s glacial rivers by air to advocate for their protection as part of a new national park covering most of the country’s interior. In the book, as with the short film, Burkard’s ‘it’s not the photo––it’s what you have to say about it’ mantra is unmistakably consistent.

“We have the potential to reduce our impact, but it starts with changing our perspective and moving to natural alternatives,” Burkard said. “We need people to re-examine their perceptions and individual choices…particularly the things that might not be so obvious.”

Read More on GlacierHub:

At Glacier’s End: Protecting Glacial Rivers in Iceland

Video of the Week: Smoke and Ash Choke Tasman Glacier in New Zealand

Photo Friday: New Zealand’s Tasman Glacier

Photo Friday: New Zealand’s Fox Glacier

This week’s Photo Friday features Fox Glacier, one of New Zealand’s most famous glaciers. It is located in the Westland Tai Poutini National Park, among the Southern Alps on the South Island.

Fox Glacier begins at an elevation of over 3000 meters, and descends to a final elevation of just 300 meters above sea level. On its journey from the mountains of the Southern Alps into a temperate rainforest climate right on the coast, Fox Glacier stretches a total length of 13.1 kilometers.

Fox Glacier is a temperate maritime, or “warm glacier,” meaning its ice exists at its melting point of 0°C. This, along with the wide snow accumulation area and steep, narrow tongue of Fox Glacier, makes it extremely responsive to small temperature and mass balance changes.

From 1983 to 2008, New Zealand experienced a cluster of cold years, influenced by short-term natural climate variability. Of New Zealand’s 3,000+ glaciers, Fox Glacier was one of 58 that advanced in this time period.

From 2009 to the present, however, Fox Glacier––along with a majority of New Zealand’s glaciers––has entered a period of significant retreat. In 2017, the glacier’s length was the shortest it had ever been in recorded history, and this trend is expected to continue for the foreseeable future.

Fox Glacier, along with neighboring Franz Josef Glacier, is one of the world’s most easily accessible glaciers, and is a popular tourist attraction. Both Fox and Franz Josef feature iconic, magnificently sculpted blue ice caves.

As a result of massive retreat in recent years, Fox Glacier now is directly accessible only by helicopter––some 150,000 people a year take these scenic flight tours. On foot, visitors can hike to a scenic overlook, but logistics have limited guided walks to around 80,000 people a year, less than half of what it used to be.

In March 2019, a massive landslide blocked the Fox Glacier access road to both vehicles and pedestrians. In the months following, the small town of Fox Glacier has suffered immensely from the lack of tourism, its primary source of revenue. As of June 21, 2019, access to the road was still closed off.

Read more on GlacierHub:

Measuring the Rise and Fall of New Zealand’s Small and Medium Glaciers

Photo Friday: New Zealand’s Tasman Glacier

The Curious Case of New Zealand’s Shrinking Glaciers

From Sea to Summit: the Māori and the Crown

New Zealand’s tallest mountain, Aoraki, at sunset (Source: Andrea Schaffer/Creative Commons).

Typically, the stones that have made their way through faraway moraines down to the mouths of glacier-fed rivers never return to their high-altitude origins. But on the 150th anniversary of the signing of the Treaty of Waitingi between the British Crown and the indigenous Māori people of New Zealand, Māori and Crown representatives came together to usher two stones from the mouth of the Waitiki river to the base of the Tasman Glacier, New Zealand’s longest glacier. A recent article in Te Kaharoa documents the lifework of an indigenous Māori activist, Anne Sissie Pate Titaha Te Maihāroa Dodds, and her efforts to build peaceful relations between Māori and non-indigenous communities.

The colony of New South Wales was founded by Britain in 1788, and while its territory technically included much of what is now New Zealand, Britain didn’t become involved politically on the islands until the 1820s, in response to reports about European lawlessness. Ultimately, the Treaty of Waitingi was signed in 1840, with the Crown and Māori chiefs coming to a contractual agreement over New Zealand’s relationship to settler colonialism. The treaty has been the source of longstanding dispute because of conflicting political agendas and issues of translation that continue to plague relations between sovereign states and indigenous communities worldwide.

In short, notions of rights over property and land emerge within individual cosmological systems, and when these systems are forced to confront one another, it is nearly impossible for each side to understand the other. The article’s author, Kelli Te Maihāroa, explained in an interview with GlacierHub that for the Māori, Papatūānuku (Earth Mother) is considered sacred and does not belong to human beings, although human beings derive from and return to her. This understanding is the complete inverse of that held by the British, for whom land could be possessed and parceled. Any treaty that offered permanent control over the land and its resources was incoherent in traditional Māori culture.

One of the lakes that feeds into the Waitaki (Source: TimN NZ/Creative Commons).

Though Te Maihāroa Dodds recognizes these disputes, she has chosen to dedicate her life to community-building across boundaries, bringing indigenous and non-indigenous parties together in pursuit of a more equitable future. The article is a life-history of Te Maihāroa Dodds that elucidates the many corners of New Zealand life, indigenous and not, that she has touched. A steadfast promoter of Māori tino rakatirataka (self-determination), she has advocated for environmental awareness in keeping with Māori traditional practices.

On December 31, 1989, Te Maihāroa Dodds and others organized an Ocean to Alps celebration (New Zealand’s mountains are known as the ‘Southern Alps’) to mark the 150th anniversary of the signing of the Treaty of Waitingi. To commemorate the event, two stones were chosen from the mouth of the Waitiki river by a Māori tribal chief. According to the author, the chief was a deeply spiritual man, and was probably drawn to the Mauri (life force) of the stones. “As we would say, it was speaking or calling to him,” she stated. The two stones were then transported via boat by a group of Māori and Crown representatives up the river, and ultimately placed at two locations: the Tasman Glacier’s moraine and its visitor center (to commemorate the event).

The Waitaki River as it rolls out to sea (Source: grumpylumixuser/Creative Commons).

For Te Maihāroa Dodds, it runs in the family. She is a direct descendant of Te Maihāroa, a Māori priest who in the late 19th century unified Māori living on New Zealand’s South Island against the influx of Western encroachment. Like her great-grandfather, she has a commitment to the land as it was traditionally understood— not belonging to human beings, but acting as the bearer of mankind.

In an interview with GlacierHub, Te Maihāroa emphasized that solidarity lay at the heart of the event— honoring different histories and celebrating a shared vision for the future. Since the Crown and Māori represent the two partners of the Treaty of Waitangi, both parties saw the event as a celebration of the two peoples. Though not all iwi (Māori tribes) agree about the nature of the treaty, the commemoration was widely supported by both Māori and non-Māori.

According to the author, the journey from sea to summit— from Waitiki river to Aoraki glacier— marked a return of a living object to its source. Similarly, the participants were marking a return to the spirit, if not intent, of the treaty: the funds came from the New Zealand government, while the ceremonial objects were provided by Māori chiefs. “The transportation of the kohatu (stone) from the mouth of the Waitaki River to the Tasman Glacier was about honoring the source from where the kohatu came from and the journey down the river. The return of objects to their natural place of origin is often undertaken by the Māori,” Te Maihāroa stated.

The Tasman Glacier lake (Source: ginny russell/Creative Commons).

The river and the glacier are both sacred ancestors of the Māori, and non-indigenous participants were involved in order to celebrate past agreements and forgive transgressions in the name of mutual progress. “The celebration was a return to the spirit of partnership in which the treaty was signed. Unfortunately, it was broken after only a few years by the Crown. This in essence was another extension of goodwill, generosity of spirit and partnership, an opportunity to reset the relationship again after 150 years. The Waitaha people welcomed first North Island tribes and then colonial settlers,” Te Maihāroa said. “It is encompassed in our extension of ‘manaakitanga‘— caring, hospitality, hosting, looking after visitors,” she added. Through marriages, the visitors have become a part of Māori whakapapa (geneology), and they share a future— one that activists like Te Maihāroa Dodds help to facilitate for the well-being of all New Zealanders.

Photo Friday: The Kerguelen Islands

The Kerguelen Islands, part of the French Southern and Antarctic lands, are located in the southern Indian Ocean.The islands are among the most isolated places on Earth, over 3200 km away from the nearest populated area. The largest island is Grand Terre (120 by 150 km). It contains the capital city of Port-aux-Francais. On the islands, there are only around 100 people, mostly scientists, sheepherders and fishers. The local people use only ships for travel and transport. The Kerguelen Islands also have a nickname,  the Desolation Islands.

The climate on the island is incessant with howling winds as well as rain almost every day throughout the year. The wind, whipping at about 49 degrees South in the Southern Hemisphere, places Kerguelen through the path of the belt of westerly winds, called “Furious Fifties.” The frigid temperatures have provided  conditions for the creation of multiple glaciers which are scattered across the island. The largest, Cook Glacier, located on the southwest section of the island, looks like a white cap decorated with ice. Mount Ross, covered with snow in the southeast, is one of the youngest volcanic mountain in the world.

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