Rising Temperatures Have Doubled Himalayan Glacier Melt—Study

The Himalayas have a powerful impact on the lives of the people who live near them: They have cultural and religious sway, they play a role in determining regional weather patterns, and they feed major rivers like the Indus, the Ganges, and the Tsangpo-Brahmaputra that millions rely on for freshwater.

A new study published in the journal Science Advances by Ph.D candidate Joshua Maurer of Columbia University’s Lamont-Doherty Earth Observatory concludes that glaciers in the Himalaya melted twice as quickly from 2000 to 2016 than they did from 1975 to 2000. “This is the clearest picture yet of how fast Himalayan glaciers are melting over this time interval, and why,” said Maurer.

Walter Immerzeel, a professor in the University of Utrecht’s department of geosciences, told GlacierHub that “the novelty lies in the fact that they go back until 1975.” He said that scientists already knew “quite well” what the mass balance rates were for the last twenty years or so, but that looking further back and over a wider area provided interesting new information.

Spiti Valley, which means “The Middle Land,” is located in the northern Indian province of Himachal Pradesh in the Himalayas. 
Source: beagle17/Creative Commons

Maurer and his co-authors examined ice loss along a 2,000-kilometer-long transect of the Himalayas, from western India eastwards to Bhutan. The study area includes 650 of the largest glaciers in the Himalaya and confirms the results of previous studies conducted by researchers who looked at the rate of mass loss in the Himalaya. 

The new study makes a major contribution by indicating that regional warming is responsible for the increase in melting. The researchers were able to determine this because mass loss rates were similar across subregions despite variations in other factors like air pollution and precipitation that can also accelerate melting.

Immerzeel agreed with the findings. “It is mostly temperature change driving the mass balances,” he said. “It can be locally enforced by black carbon or modulated by precipitation changes, but the main driving force is a rise in temperature.” 

The analysis was conducted using images from declassified KH-9 Hexagon spy satellites which were used by US intelligence agencies during the Cold War. The satellites orbited Earth between 1973 and 1980, taking 29,000 images that were kept as government secrets until relatively recently when they were declassified, creating a cornucopia of data for researchers to comb through.

Maurer and his co-authors used the images to build models showing the size of the glaciers when the images were created. The historical models were then compared to more recent satellite images to determine the changes that occurred over time. Only glaciers for which data were available during both time periods were included in the study.


A diagram of a KH-9 Hexagon satellite that was used to create the images used in Maurer’s study. 
(Source: National Reconnaissance Office)

The new study received widespread media attention. National Geographic, CNN, the New Yorker, and The Guardian, among other major publications, highlighted the study’s conclusion that mass loss in Himalayan glaciers has doubled in the last forty years.

Tobias Bolch, a glaciologist at the University of St Andrews, told GlacierHub the findings should be approached with caution. “The statement about the doubling of the mass loss after 2000 compared to the period 1975-2000 should be formulated with much more care.”

“[Scientists],” he continued, “need to be very careful presenting results about Himalayan glaciers and should communicate them correctly specifically after the IPCC AR4 error, and the wrong statement about the rapid disappearance of Himalayan glaciers.”

Bloch is referring to an error that occurred in 2007, when the IPCC included in its Fourth Assessment Report an inaccurate statement predicting that all Himalayan glaciers would be gone by 2035.

“It is a promising data set, but due to its nature there are large data gaps which need to be filled which makes the data uncertain,” Bolch said.

He added that there is “clear evidence” that mass loss has accelerated in the Himalaya.

A recent report by the International Centre for Integrated Mountain Development, a regional intergovernmental organization in Nepal working on sustainable development in mountains, predicts that the Himalayas could lose 64 percent of their ice by the year 2100.

Maurer’s study examines only past melting from 1975 to 2016.  ICIMOD’s study provides additional dimension to Maurer’s results. 

A stretch of the Indus River. 
(Source: arsalank2/ Creative Commons )

The large amount of melting that may occur in the coming decades would result in greater quantities of meltwater entering rivers. The Indus River, which millions rely on for drinking water and agriculture, receives about 40 percent of its flow from glacial melt. An increase in meltwater could augment the risk of flooding of the Indus and other rivers in the region. 

Similarly, there may be a greater number of glacial outburst floods. Outburst floods occur when the moraine, or rock wall, which acts as a dam collapses. A collapse can take place for various reasons including if a great deal of water accumulates in a lake from a phenomenon like an increase in glacial melting. Depending on the size of the lake and downstream populations, among other factors, these floods have the potential to cause substantial damage. The largest of these floods have killed thousands of people, swept away homes, and even registered on seismometers in Nepal. 

Reflections in a glacial lake in Norway. 
(Source: Peter Nijenhuis/ Flickr)

Once glaciers have lost substantial amounts of mass and no longer have large quantities of water to release, the reverse will begin to cause problems: Rivers dependent on Himalayan glacial melt will diminish and drought may become more common downstream. This will negatively affect farming and development in the Himalayan region.

In both the short and long term, according Maurer and his colleagues, glacier melt in the Himalayas will have significant impacts on the livelihoods of those dependent on its towering peaks.

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Glacier Retreat Exposes New Breeding Ground for Kelp Gulls in Antarctica

Glacier retreat caused by anthropogenic climate change is often in the news because of its impacts on sea level rise and shrinking habitats. However, a recent study published by Lee et al. in the Journal of Ethology has found that glacier retreat on King George Island could have a positive impact on kelp gulls, exposing new ground with suitable breeding sites.

Kelp gulls have a large range in the southern Hemisphere (Source: Yuri Hutflesz / Creative Commons).
Kelp gulls have a large range in the southern Hemisphere (Source: Yuri Hutflesz/Creative Commons).

The kelp gull, Larus dominicanus, breeds on coasts and islands throughout the Southern Hemisphere, as detailed on the IUCN Red List. It has a large range, from subantarctic islands and the Antarctic peninsula to coastal areas of Australia, Africa and South America. Breeding occurs between September and January, with nests usually built on bare soil, rocks or mud in well-vegetated sites.

King George Island, the largest of the South Shetland islands, is part of the kelp gull’s range. It can be found off the coast of the Antarctic peninsula and is a nesting ground for seabird species during the summer months. Numerous research stations are located on the island, and its coasts are home to a variety of wildlife, such as elephant and leopard seals, and Adelie and Gentoo penguins.

A map of Barton Peninsula on King George Island (Source: NOAA).
A map of Barton Peninsula on King George Island (Source: NOAA).

Research has shown that breeding nests of kelp gulls have been recorded in ice-free areas of King George Island since the 1970s. Studies of Gentoo penguin populations  also suggest that rapid glacier retreat could give species that favor ice-free environments a chance to expand their habitats. As such, Lee et al. used a combination of satellite photographs and field observations of kelp gull nests in newly exposed locations to study possible correlations between glacier retreat and nest distribution in the Barton Peninsula on King George Island.

Based on eight different satellite images, Lee et al. determined that glaciers on the Barton Peninsula have retreated 200-300m from the coast since 1989, exposing an area of approximately 96,000 square kilometers. Within this area, they found up to 34 kelp gull breeding nests between 2012 and 2016, along with evidence that kelp gulls have been breeding on newly exposed ground for decades.

A map of the study site showing the extent of glacier retreat and locations of kelp gull nests (Source: Lee et al.).
A map of the study site showing the extent of glacier retreat and locations of kelp gull nests (Source: Lee et al.).

As the glaciers on the Barton peninsula retreat inland, moraine surfaces made up of glacial soil and rock debris are left on the coast. Rocks within these moraines provide shelter from harsh Antarctic coastal winds, reducing the stress to the gulls arising from these winds. This makes the exposed areas more attractive for breeding.

Previous studies have suggested that kelp gulls select nest sites in favorable locations with rock and vegetation cover, and kelp gull populations are known to nest in neighboring areas like Potter Peninsula and Admiralty Bay. In this study, kelp gull nests were found between 40-50cm away from the rocks, suggesting that a combination of rocks and vegetation present on the moraines help to create favorable nesting conditions.

The rocky moraines left on the coast by retreating glaciers are suitable breeding ground for kelp gulls (Source: Acaro / Creative Commons).
The rocky moraines left on the coast by retreating glaciers are suitable breeding ground for kelp gulls (Source: Acaro/Creative Commons).

These gulls probably originated from neighboring kelp gull populations, such as those on King George Island or the Nelson Islands. Continued retreat of glaciers on King George Island could expose larger areas of suitable breeding ground, attracting more gulls from neighboring islands and increasing kelp gull populations.

Anthropogenic climate change and glacier retreat have many adverse effects, but research like this sheds light on the ways in which some species might benefit in unexpected ways.

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Roundup: Peruvian Climate, Tibetan Lakes, and Greenland’s Glaciers

Roundup: Peru, Tibet and Greenland

 

Project to Improve Climate Services in Peru

From Climate Services: “CLIMANDES is a pilot twinning project between the National Weather Services of Peru and Switzerland (SENAMHI and MeteoSwiss), developed within the Global Framework for Climate Services of the World Meteorological Organization (WMO). Split in two modules, CLIMANDES aims at improving education in meteorology and climatology in support of the WMO Regional Training Center in Peru, and introducing user-tailored climate services in two pilot regions in the Peruvian Andes… The efforts accomplished within CLIMANDES improved the quality of the climate services provided by SENAMHI.”

Read more about CLIMANDES here.

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Landscape of the Peruvian Andes from behind walls of Machu Piccu (Source: Mariano Mantel/Creative Commons).

 

Monitoring Lake Levels on the Tibetan Plateau

From Journal of Hydrology: “Lakes on the Tibetan Plateau (TP) are of great interest due to their value as water resources but also as an important indicator of climate change. However, in situ data in this region are extremely scarce and only a few lakes have gauge measurements… In this study, Cryosat-2 SARIn mode data over the period 2010–2015 are used to investigate recent lake level variations… Lakes in the northern part of the TP experienced pronounced rising (avg. 0.37 ± 0.10 m/yr), while lakes in southern part were steady or decreasing even in glaciated basins with high precipitation… These results demonstrate that lakes on the TP are still rapidly changing under climate change, especially in northern part of the TP, but the driving factors are variable and more research is needed.”

Learn more about climate change on the Tibetan Plateau here.

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Aerial view of lakes of the Tibetan Plateau (Source: Stuart Rankin/Creative Commons).

 

Data Portal to Study Greenland’s Ice Sheet

From Eos: “A new web-based data portal gives scientists access to more than 40 years of satellite imagery, providing seasonal to long-term insights into outflows from Greenland’s ice sheet… This portal harnesses more than 37,000 images from Landsat archives, dating back to the early 1970s, to track changes in outlet glaciers over time… Through analyzing data from this portal, we can see in great detail how several outlet glaciers are speeding up their treks to the sea. What’s more, any user can access the data to conduct their own studies of glacier behavior at Greenland’s coasts through time.”

Read more about Greenland’s retreating glaciers here:

Aerial view of coastal Greenland glacier (Source: Terry Feuerborn/Creative Commons).
Aerial view of a coastal Greenland glacier (Source: Terry Feuerborn/Creative Commons).

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