Download Quantifying climate change induced effects upon glaciers and their

Quantifying climate change induced effects upon glaciers and their
impact on ecosystem services
C. Battistuzzi, S. Buenrostro Mazon, N. Edwards, G. Gostlow, I. Jeba Raj
It is understood that current climate change is causing glaciers to retreat globally in various
areas, such as the Alps, the Himalayas and the Andes. This rate is estimated to be on average 10 metres
y¯¹. In this report, we will be analysing the rate of glacier retreat and some of its impacts by reviewing
literature and the associated effects and costs toward ecosystem services. A variety of methods can
be used to analyse retreats and changes to the extent and mass of glaciers, which can also contribute
to the creation of models which help in predicting future impacts. Despite the amount of studies, it
remains difficult to assign reasons and predictions for glaciers worldwide due to variability of retreat
rates. Impacts include changes to water quality and quantity, the frequency of outburst floods, and
changes in the landscape which all affect the value of ecosystem services.
The increase in solute concentration in melt-water can be traced to a higher rate of melting
of adjacent glaciers due to regional temperature increases that affect services connected to water
quality. Furthermore, these temperature increases can be associated with higher frequency of glacial
outburst floods contributing to landscape change and threatening human welfare. The potential to
utilise hydropower energy, another ecosystem service, is being diminished by the future risk of
reduced glacial runoff. We will assess these impacts by quantifying the change in the valuation of
ecosystem services. It is therefore evident that there are many multifaceted impacts of climate change
upon glaciers, and a range of costs upon ecosystem services.
Contents
1. Introduction
2. Relationship between glacial retreat and climate change
3. Quantifying the impact of climate change upon the physical retreat of glaciers
4. Analysis of Impacts
a. Water Quality
b. Outburst Floods
c. Hydropower
5. Economic ecosystem services assessment
6. Conclusion
1. Introduction
Glaciers are increasingly proving to be effective evidence and susceptible barometers of
climate change, responding to changes in temperature and precipitation among other factors (Benn
& Evans, 2014). The way mountain glaciers have been viewed by populations has morphed over
centuries; not too long ago, glaciers would have been viewed destructive forces, engulfing farms and
land, of which would have been of great importance to communities. Increasingly, we are seeing them
as ‘endangered species’, first hand victims of climate change (Pachauri, 2014). Glaciers have become
one of the key resources in teaching us how sensitive the earth is to human impacts. Already, our
outputs into our environment, largely the amounts of greenhouse gases such as methane and CO2
emitted into the atmosphere, have contributed towards the fact that the past three decades have
each been successively warmer at the surface of the Earth than any decade since 1850 (Pachauri,
2014). This warming has meant that future glaciation will likely be delayed by tens or hundreds of
thousands of years (Orlove et al., 2008). It is also vital to recognise that the response of glaciers to
climate change is not solely to retreat, although the global average is a loss of 10 m yr¯¹ (IPCC, 2014),
two to three times more than the correlating average for the whole of the 20th century (Radford,
2015). Some glaciers are actually advancing due to climate change causing an increase in snowfall and
precipitation, and there are some cases, such as the Hubbard Glacier, Alaska, which experiences
unrelated advance due to the fact they are calving glaciers. The Hubbard Glacier has infact been
advancing for over 100 years (Trabant et al, 2003). It is therefore evident that the effects of climate
change are variable and it is important not to over-generalise impacts. This report will focus on the
impacts from retreating glaciers, as this is the predominant global glacial trend, and one with a wide
range of impacts.
The glacial retreat that is being witnessed has had many impacts on both the physical and
human environments, directly and indirectly. One of the impacts that could potentially be the most
damaging is the rise in the global sea level, of which melting glacial ice contributes to (Pachauri et al,
2014). The total volume of what Dyurgerov and Meier (2005) class as ‘small glaciers’, which are ice
masses excluding the Greenland and Antarctica ice sheets (mountain glaciers, ice fields, ice caps and
glaciers surrounding but independent of the ice sheets), is 260 ± 65 x 10³ km³ and if fully melted would
contribute 0.65 ± 0.16 m to global sea-level rise. This per year rate has increased due to climate
warming, since glacier retreat caused sea level to rise by 0.51 mm yr¯¹ between 1961 and 2003, yet
increased to 0.93 mm yr¯¹ between 1994 and 2003. Even small increases in sea level can pose problems
to coastal communities, coral reefs and coastal farmland. Other impacts glacier wastage has on the
earth include the hydrology of mountain-fed streams and rivers, regional land uplift, the freshwater
balance in oceans and even the rotation and oblateness of the Earth (Dyurgerov & Meier, 2005).
However, the scope of these impacts requires a large amount of further global study. This report seeks
to identify and investigate some specific local impacts, specifically affecting the physical environment,
human welfare and various ecosystem services in relation to glacial retreat experienced in mountain
glaciers in the Alps, the Andes and the Himalayas.
Over half of the world’s population resides inside the watershed of vital rivers which originate
in mountains inhabited by glaciers (Kaltenborn et al, 2010). These glaciers therefore have influence
over livelihoods, cultures, food production, and in the modern day also power and industry. The costs
of mountain glacier retreat can have varying impacts on ecosystem services, having huge economic
and social impacts. This essay will first evaluate the physical evidence of climate change's impact upon
mountain glaciers, before investigating three specific impacts upon them: water quality, outburst
floods and hydropower production. The knock-on impacts and costs towards ecosystem services from
these three themes will then be discussed.
2. Relation between glacial retreat and climate change
The worldwide response of glaciers to climate change is often mentioned as a distinct and
unambiguous signal of warming (Oerlemans, 2005). Glaciers have actually shown a general retreat
pattern since the end of the Little Ice Age 150 years ago, approximately 1870 when temperatures
reached so low that many farms and villages were engulfed in the Swiss Alps. The rate of retreat since
the Little Ice Age passed has substantially increased in many areas since the beginning of the 1980s,
which is parallel with a rise in global mean air temperature (Kaltenborn, 2010). Some highlight the
question that the global temperature increase could be a natural forcing, however the Fourth
Assessment Report of the IPCC (IPCC, 2007) stated that there is a greater than 90% certainty that
greenhouse gases which trap heat inside the atmosphere, largely emitted from human activities, have
been the main cause of the observed increase in average global temperatures since 1950. This
certainty was also repeated in the latest IPCC report (IPCC, 2014). Therefore, it can be said that the
increasing rate of retreat of glaciers is largely due to human-emitted heat-trapping gases.
Human-influenced climate change affects the
mass balance of glaciers. The mass balance is the
difference between the accumulation of snow and ice on
the glacier, and the ablations (melting and mass loss)
(Kaltenborn, 2010). It is also highly dependant on the
summer temperature, as this is when the ablation period
occurs. The response of a glacier to climate change also
hinges on its geometry and climate setting (Oerlemans,
2005).
Glaciers are also important records of past
climate change, and long-term records can be identified
by extracting drilled ice-cores from glaciers and ice
sheets (nsidc.org, 2016). These layers of ice also trap
bubbles of gas inside, therefore showing historical levels
of greenhouse gases. By studying them we can see how
current levels relate to past levels, and how at points in
history when there were high levels of CO2 in the
atmosphere due to land-atmosphere feedbacks, glacial
extent was reduced.
Mountain glaciers have been evolving in a
complex way since not all glaciers have been in recession,
not at least at the same rate. For the last decade, Patagonian, European and the North American
glaciers have been losing more ice mass per unit area compared to the other regions. With current
melting rates, some glaciers will have disappeared by the end of the 21st century (Kaser et al., 2006,
Lemke et al., 2007, Arendt et al., 2009).
Among many glaciated mountain ranges, we will consider the Alpine regions among other
study areas. The glaciers in the Alps have lost more than a third of their glacial mass since 1850, more
than half of which were lost since 1980 when the rate of recession was 20%. This steep increase in
recession has been due to the increase in Alpine temperatures which increased by 1⁰C during that
time. The Hindu Kush Himalayan range meanwhile has had a mixed period where some glaciers have
increased in size (The Karakoram), while the others have seen both increase and decrease, however
the overall glacial mass has decreased in the Himalayas at a steady rate. It is therefore evident that
quantifying the physical impact is important, despite the variating reactions, as there is significant
change.
3. Quantifying the impact of climate change upon the physical retreat of glaciers
Many studies have been undertaken to quantify the rate of glacier retreat, how this has
changed over recent history and how this change relates to observed changes in climate. Calculating
mass balance remains the primary quantitative measure to identify the effect of climate change on
glaciers (Kaltenborn, 2010). Figure 1 shows this increasing retreat, and it can be seen that most regions
have seen a dramatic cumulative mass balance loss, where mass balance is described as the difference
between the accumulation and ablation (melting) on the glacier. The European region does appear to
be growing up to approximately 1995, however has vastly declined since then. By analysing studies
quantifying glacier retreat in the three regions of Europe (the Alps), the Andes and the Asian High
Mountains (the Himalayas) the retreat can be analysed for its consistency with climatological data.
Studies on the relationship between glacier fluctuations in inputs and outputs and variations
in climate began with the formation of the International Commission on Glaciers in 1894 (Dyurgerov
& Meier, 2000), and measures in short term glacier mass balance fluctuations were first carried out in
the late 19th and early 20th century, beginning with the Alps. Before 1957, less than 10 glaciers were
analysed for their glacier mass balance values; today, this figure has jumped to more than 260 glaciers
that have been measured. Thorarinsson (1940) was the first to attempt a global-scale analysis of
glaciological changes in accordance to their glacier mass balance values, and attempted also to
calculate glacier volume changes’ contribute to sea level rise. Alongside mass balance studies, GIS and
remote sensing techniques are also frequently used, and dynamic models can be created to identify
how future climate change can affect glacier extent.
Oerlemans et al (2005) conducted a study extracting a climate signal from 169 glacier records
around the world, relating changes in length to changes in temperature. Although his report doesn’t
specifically discuss human-induced climate change, it does highlight how closely linked glacier retreat
and temperature are.
An example of a study which looked at mass balance is Huss et al’s (2008) report on the
seasonal mass balance of four Alpine glaciers between 1865 and 2006. Here they created a mass
balance model which required only temperature and precipitation data inputs, which are widely
available in the alpine region. By calibrating this data with ice volume changes detected from high
resolution elevation models, discharge data and in-situ measurements of mass balance, the
cumulative mass balance over the 142 years period was calculated. They found that the balances had
changed between -35 and -97 m, revealing considerable mass loss, mainly due to fluctuations in the
summer balance. It appeared that the summer temperature had the most influence in glacier mass
balance, therefore as summers become much warmer there will be even greater shifting in balance,
and the ablation period will be lengthened into the Autumn.
Other methods such as remote sensing are being increasingly used as measuring the area of
glaciation and change requires much effort and time. Satellite data is widely becoming more effective
in large scale detection and analysis of glacier changes. Bolch (2007) analysed the relation between
precipitation and temperature trends and glacier changes in the northern region of Tien Shan in the
Himalayas. Tien Shan is a good place to conduct a study such as this, because there exists a dense
network of climate stations at differing altitudes, allowing for detailed results. In fact, most of the
Himalayas offers good data and plenty of past studies, as it remains to be an area still heavily glaciated,
but equally heavily populated. Bolch conducted in support of the climatic data a GIS remotely sensed
extent analysis, using Landsat ETM scene images from 1999 in comparison to glaciers in the 1955
Soviet Glacier Inventory, which represented the approximate study area. He found the climate data
to have shown a strong temperature increase, pronounced since the 1950s, and generally staying at
high levels since the 1980s. Northern Tien Shan temperature increase was shown to be two times
higher than the global average from 1950 to 2000, which was the most likely factor towards the glacier
extent decrease being more than 32% between 1955 and 1999. However, Bolch does highlight the
fact that glacier retreat was non-homogenous, and different glaciers reacted differently depending on
their location, size and climate regime. We can then assume that the response of glaciers to climate
change in the Alps will not necessarily be the same response as in the Himalayas, or the Andes. This is
something which is important to consider when impacts from glaciers are discussed later in this report.
Scherler et al (2011) also discuss the spatial variability of Himalayan glacier’s response to
climate change. They note how 65% of the monsoon influenced glaciers were retreating between 2000
and 2008, however those that were debris covered had largely stagnant and stable fronts. 50% of the
glaciers in the Karakoram region, influenced by westerly-winds, were actually advancing or stable.
Therefore it can be concluded again that there is no uniform response to climate change.
Salzmann et al (2013) brought together multiple
sources to identify glacier changes in the Cordillera
Vilcanota region, Peruvian Andes. They found that while
there was only a marginal change for between 1962 and
1985, there has been considerable loss since 1985 (30%
area, 45% volume), in corroboration with other studied
areas in Peru. To calculate these losses, aerial photos
from glacier inventories were used, alongside LandsatTM5 images and climate data.
Guglielmina et al (2011) documented 50 years of
glacial retreat in the Italian Alps with the help of aerial
and historical photos, such as those in Figure 2. It is
clearly visible to see the difference in retreat between
1932 and 2007. In conclusion, between 1954 and 2003, there was a 51%
reduction in the area coverage.
It is therefore evident that many techniques can be used to analyse glacier response to climate
change. The resulting retreat in the mountain glaciers that are affected can have many differing
impacts upon ecosystem services. Continuing on from this, the rest of this report will identify three
impacts that glaciers experience due to human-induced climate change: changes in water quality, the
frequency of outburst floods and the availability of hydropower, before discussing the costs to
ecosystem services because of these impacts.
4a. Analysis of Impacts: Water Quality
Water quality is a relative concept; it is based on the physical, chemical and biological
characteristics defined as suitable for a particular use. Limits for a range of variables are set as
standards and there are, in fact, different quality standards for the safe use of water as applied to
human health and activities (e.g. drinking water, agriculture, industrial use, fisheries), and to the
environment (aquatic ecosystems) (UNEP/WHO, 1996). The importance of the assessment of water
quality is therefore established by the need of the end-user; given the projections up to 2050 that
alpine glaciers will be shrinking (Beniston et al., 2014), it is vital to find a predictive model where the
use of water by different services that often have competing interests will have to be decided.
Global mountain glaciers provide 50% of the freshwater supply, essential for human needs. In addition
to that, glacial meltwater has not only an effect on local lake and river ecosystems, but also on
freshwater balance in the ocean (Slemmons et al., 2013).
A number of reasons call for water quality analysis of glacier meltwater as observed in
mountain lakes. Alpine lakes are considered to be indicators of even small changes in environmental
conditions due to natural processes and human action, given their location, harshness of conditions
and isolation from human activity (Beniston et al., 2014). Water quality is also a window on subglacial
hydro-chemical and hydrological process from an otherwise inaccessible environment. In addition, it
can possibly be an indicator of the rate of alpine glacial melting through different models applied to
the measurements of a series of variables, (the variation in the contribution of glacial meltwater to
water downstream, as compared to snow meltwater and the rain contribution.) Furthermore, glacial
meltwaters may have a role in long term atmospheric CO2 sequestration (Brown et al., 2002).
Persistent organic pollutants (POP) have been found in alpine lakes, and their concentration and
influence on the ecosystem is dependent on bulk meltwater (Morselli et al., 2014).
Water transiting through the hydroglacial system controls chemical weathering reactions
occurring within the system. The assumption is, therefore, that the ionic content of the meltwaters is
a reflection of the type and speed of the reactions. There are many factors affecting subglacial
chemical weathering, some of which are not yet understood because of the complexity of the system
and the possible variations due to individual environments and seasonal variations, just to mention
two examples (Brown et al., 2002) However, a change of variables such as the concentration of solutes
in the water and the pH may be important indicators, as illustrated in the three case studies of alpine
glacial meltwater in the Alps, the Andes, and the Himalayas.
The monitoring of electrical conductivity of the water of two alpine lakes in the Alps between
Austria and Italy, Rasass See (RAS) and Schwarzsee ob Sölden (SOS) (Fig.2), as a measure of the
concentration of ions in solution, was performed from 1985 to 2005. Remarkably, comparing the initial
values to the final values of the conductivity, there was an 18 fold increase in RAS, with also a
concentration of nickel above safe drinking water standards. In SOS, the increase was 3 fold (Fig. 4).
Figure 3. Conductivity and ion concentrations in RAS (black triangles) and SOS (open circles)
These values were found to be directly related to an increase in glacial meltwater at the sites, due to
increased temperatures, and also weathering and the presence of active rock glaciers. (Thies et al.,
2007).
Individual concentration of ions including Ca2+, Na+, SO42- , was used to calculate in a model,
the contribution of glacial meltwater to stream discharge in Callejon de Huaylas, Peru. The study
found consistent glacier mass loss of the Yanamarey Glacier at a higher rate when comparing 19981999 to the period between December 2001 and July 2004, with glacial meltwater contribution to the
annual mean discharge increasing from 35% to 58% (Mark et al., 2005).
The ionic content of the water of two lakes in the Kumbhu Valley in Nepal, at 5200 and 5400
m a.s.l. was monitored starting in 1990 for a period of about 20 years. The study found an increasing
concentration of ions in the water of both lakes, and linked the trend to global warming (Figs 4 and 5).
Lake sediment was also analysed for algal abundance in an attempt to correlate it to known changes
in climate systems in the last 3500 years. The study found that there is a correlation between past
warmer periods and the present data, concluding that this particular area of the Himalayas is
susceptible to changes in Northern hemisphere climate dynamics (Lami et al., 2010).
The generalized tendency of alpine glaciers to retreat as measured this century and the second
half of last century has clear consequences on the quality of glacial meltwater as also exemplified in
the three case studies presented. Here, I have described the information that the monitoring of water
quality can give in relation to global warming. Water quality changes may have an impact on natural
water ecosystems (Slemmoms et al., 2013) and on human activities. The kind of impacts more
specifically on human activities, i.e. on water dependent ecosystem services, might vary according to
the measured changes in relation to water quality standards for safe use.
Figure 4: Annual mean air temperature at
Kathmandu Airport and the AWS Pyramid
(weather stations)
Figure 5: Trends in selected ions and
conductivity, time period 1990-2008
4b. Analysis of Impacts: Glacial Lake Outburst Floods
A Glacial Lake Outburst Flood (GLOF) is a specific type of outburst flood which occurs when
the dam containing a glacial lake fails. An event similar to the description of the GLOF when a water
body contained by a glacier melts or overflows from the glacier is called Jökulhlaup (Icelandic term for
glacial outburst floods). The dam can be made of glacial ice or a terminal moraine. Glacial dam failure
can happen due to many reasons like erosion, buildup of water pressure, avalanche or rockslides,
earthquake or volcanic eruption under the ice are some of the many reasons which can cause the
GLOF events (Clague & Evans, 1994; Tweed & Russell, 1999).
GLOFs are of many types and are caused by different reasons. To keep this study relevant to
the overall point of the report, which is about the effects of climate change, I will solely focus upon
GLOF events caused by climate changes. Climate change is causing a significant mass loss in high
mountain glaciers worldwide. Although glaciers in high mountains show complexity and variation in
how they develop, their overall trend indicate glacial recession which have been accelerated in the
past few decades. Impacts of this shrinkage in glacial mass include changes in how the glacial fed rivers
flow, glacial lake outburst floods (GLOF), increase in the frequency and severity of floods. There is an
increasing concern about these impacts as the effects of glacial recession on sea level rise, natural
hazards and vanishing water resources for the downstream communities.
Mountain glaciers have been evolving in a complex way since not all glaciers have been in
recession, not at least at the same rate. For the last decade, Patagonian, European and the North
American glaciers have been losing more ice mass per unit area compared to the other regions. With
current melting rates, some glaciers will have disappeared by the end of the 21st century. (Kaser et al.,
2006, Lemke et al., 2007, Arendt et al., 2009).
Among many glaciated mountain ranges, we will consider the Alpine and the Hindu Kush
Himalayas for this study. The glaciers in the Alps have lost more than a third of their glacial mass since
1850, more than half of which were lost since 1980 when the rate of recession was 20%. This steep
increase in recession has been due to the increase in Alpine temperatures which increased by 1°C
during that time. The Hindu Kush Himalayan range meanwhile has had a mixed period where some
glaciers have increased in size (The Karakoram), while the others have seen both increase and
decrease, but the overall glacial mass has decreased in the Himalayas at a steady rate.
Unlike the Alps however, the Peruvian Andes and The Himalayas are in lower altitudes. Low
latitude glaciers behave differently to their high latitude counterparts (Bradley et al., 2006). While high
latitude glaciers experience an accumulation season and a melt season based on the time of the year,
the glaciers in the Andes are tropical and are significantly different and are characterized by a constant
temperature all through which results in colliding melt and accumulation season which is during the
summer rainy (Kaser, 2001). The Hindu Kush Himalayas, however, is subtropical and there is a big
difference in temperature between the summer and the winter months. The Himalayas are also
affected by the monsoon which brings most of the accumulation in the summer months, which also is
the time when most of the melting happens. This simultaneous melt and accumulation differentiates
the Himalayan glaciers from their higher latitude counterparts.
Glacial lakes
Glacial lakes are lakes that are formed when a glacier starts melting. They are formed where
the glacier erodes the land, then melts fill a hole or space in the ice (If it’s a very deep glacier) that it
is created. Glaciers have been retreating since their maximum extent 10,000 years ago and in general
retreat since the Little Ice Age 150 years ago (Oerlemans, 2005) and lakes have been formed and
disappeared. However, the present climate change cycle means the glaciers are melting faster than
ever creating glacial lakes in high mountain glaciers which are very vulnerable to breakage. These
catastrophic glacial lake outbursts have happened all through history as the ice retreated.
Glacial lakes, may vary in volume and may hold millions to hundreds of millions in cubic meters
of water. Failure of the ice or glacial sediment to contain this volume of water can release it over a
period of days or even minutes. Flows have been as high as 15,000 cubic meters per second in such
catastrophic events (Martini et al., 2002; Korup & Tweed 2007). Such GLOF events are often
compounded by massive erosion of the river bed in the moraine valleys and as a result they get far
more dangerous as they flow downstream. On the downstream floodplain, the scenario can be a
significant threat to life, property and infrastructure.
In the European Alps, Scandinavia and Iceland, there have been many recorded events over
the past hundred years that have have been disastrous and catastrophic. Events of greater magnitude
have happened in other mountain ranges which were either not recorded or took place in areas that
were uninhibited. Many studies have been systematically conducted on different glaciers to see how
they change annually till the present day. As a result of these studies it has been suggested that the
mountain glaciers are thinning and retreating at an alarming rate and the associated meltwater lakes
are increasing in size and new lakes are created. These glacial lakes however are different from the
ice-dammed lakes which gather plenty of scientific attention. These lakes are predominantly moraine
dammed rather than being dammed by advancing glaciers (Benn & Evans, 1998).
Glaciers in the tropics and the sub-tropics will be the focus of this study. In the tropics,
especially in the Peruvian Andes, moraine dammed glaciers occur in the Cordillera Blanca (Ames,
1998). The smaller, clean-ice glaciers have shrunk rapidly over the past few decades since they are
subject to all season melt regimes (Kaser & Osmaston, 2012). Some of the most devastating GLOF
events of the 20th century have occurred in this region (Carey, 2005; Vilímek et al., 2005). Surprisingly,
the Glacial lakes are mostly absent in the inner tropics. A further distribution of such moraine dammed
lakes are in the subtropical Himalayan countries of Nepal, China, India and Bhutan.
The Environmental Program of the United Nations (UNEP) and the International Centre of
Integrated Mountain Development (ICIMOD) have monitored 2,323 glacial lakes in Nepal (Mool et al.,
2002a, b) out of which 20 were potential threats. On the contrary, the glaciers in the Karakoram range
to the north west have seen increased glacial mass but also an increase in glacial lakes which are
moraine dammed by an advancing glacier which is tributary (Hewitt, 1982; Iturrizaga, 2005a, b, c).
Very high magnitude glacial floods happened at the end of the little ice age but to a very little extent
at present.
Mid latitude glaciers such as the European Alps which have a relatively smaller glaciarized area
and smaller glaciers in general have started developing moraine dammed lakes and numerous other
cirque lakes in over deepened rocks and sediment basins (Triff Glacier, Swiss Alps). The ice dammed
Alpine glaciers have all but melted except for the icefalls close to high altitude regions in the range
(Russell, 2007).
Ice-dammed lakes according to literature (Blachut & Ballantyne, 1976; Tweed &Russell, 1999)
are lakes which may be blocked by a tributary glacier or small ice lobes. This kind of damming is
different from the type of damming found in the subtropical region. Glacier barriers here have a high
number of debris incorporated in the supraglacial and lateral moraines. The debris are vital to glacial
dynamics and the mechanics of the GLOF and the hydrodynamics of the flow. The initial flood may be
a water flood with a highly concentrated flow with debris. These glacial dammed lakes are relatively
short lived (several months or a few years) and end with a catastrophic event. With an increasing
monsoon in the sub tropics due to climate change, glacier dammed lakes overflow and destroy the
dam that has been holding them and run downstream. This is usually the case of floods in the subtropical river basins which are flooded often due to such events (Bajracharya &Mool, 2009).
Glacial dammed lakes are usually impounded by the tributary glacier of different
constellations or by smaller glacial ice lobes. They are also known as ice-dammed lakes in the literature
(Blachut & Ballantyne, 1976; Tweed & Russell, 1999). However, glacier moraines of the subtropical
mountainous regions have a high content of debris mixed with the supraglacial and moraine that is
lateral to the tongue. This debris material plays a vital role in the mechanics of the glacier lake
outbursts and during the subsequent flood events.
It is easy to draw conclusions from this that the low latitude glacier dammed lakes are far
more dangerous when they occur and they can occur due to many reasons which are accelerated by
climate change. The drainage which is catastrophic has occurred several times in the twentieth century
and it has only been getting worse at a steady rate.
Figure 6: Top: Imja glacier ca.1955 (photo E. Schneider): Bottom: Imja lake in 2007 (photo: Alton Beyers). Imja Lake has formed where
the glacier used to be, and as the glacier retreats the lake continues to grow.
Nepal has over 2,000 glacial lakes of which 20 are considered to be potentially catastrophic. The
biggest lakes are the Tso Rolpa, Lower Barun, Imja and the Thulagi lakes. These lakes are at an altitude
between 4,000-5,200m. Tso Rolpa, the biggest lake has a depth of 130m and a width of 500m and is
located at 4,580 m at the head of the Rolwaling valley. It is a relatively young lake which has formed
over the last 40 years at the tongue of the Trakarding Glacier (Yamada, 1998; Renolds 1999). The
Rolwaling valley is steep where the altitude decreases from 4500m to 1700m over a vertical
Figure 7: Tso Rolpa lake formation from 1957 till 2003. The lake has formed where the glacier used to be.
distance of just 20 km and a moraine dam failure of the Tso Rolpa would mean that the erosional flow
velocities would be very high.
What is concerning however is the prominence of such glacial lakes in Nepal. There have been
a number of lakes which have formed over the past few decades including Imja. When Sir Edmund
Hillary made his legendary expedition to the top of Mt. Everest in 1953, Imja did not exist. However,
it is the fastest growing of some 1600 glacial lakes in Nepal. The lake stretches down from the glacier
for 2 miles and grows at a rate of 50m a year (Yamada, 1998), which is nearly three times faster than
most glacial lakes in the Himalayas.
Figure 8:Arteson Glacier and its system of three glacial lakes (a) Arteson glacier and the new glacial lake forming at the terminus; (b) Lake
Artesonraju; (c) Lake Paron, the lowest and the largest of the three lakes (photos: Daene Mckinney)
The glaciers in the Peruvian Andes have a similar pattern to that of the subtropical Hindu KushHimalayan ranges. Their accumulation and melt periods are different from the high latitude glaciers.
A number of GLOF events have occurred in the Andes resulting in great loss of life and property. The
catastrophic floods that destroyed the city of Huaraz and killed 7000 people in 1941 was a GLOF event
in the upstream glaciers in the Cordillera Blanca (Mark and Seltzer, 2005), which is the home to most
of the highest peaks in the Americas. We will look at the Arteson glacier that has in recent years
formed a new lake at its base, which is a series of three lakes linked together (Coudrain, Francou,
Kundzewicz, 2005). In Peru, the growth of these glacial lakes is deeply linked to the recession of the
nearby glaciers. By knowing how fast the glaciers retreat, It is easier to know the future size of the
glacial lake. This is one of the important differences between the glaciers in the tropics and the sub
tropics. Peru has more people living in the direct impact zone if there was to be a GLOF event.
As discussed above, glacial lakes are directly and indirectly a result of changing climate and it
is expressed by the fluctuation in glacier dynamics. Glacial lakes are short lived however during the
history of our planet, GLOF events have had profound impacts in shaping the landscape. The types of
lakes that seem concerning might change from time to time from moraine dammed lakes to ice
dammed lakes in different situations based on their topographic setting. Only a few glacial systems
are prone to form moraine dammed lakes. These lakes are often smaller than the ice dammed ones.
However, when they break, they are usually more devastating than the ice dammed ones due to the
debris and the altitude. In general overview, as the climate changes, and in a period of deglaciation,
the number of glacial lakes increase. To avoid catastrophic events of the past, there have been efforts
taken to reduce the risks the GLOFs create.
4c. Analysis of Impacts: Hydropower
In an effort to mitigate climate warming, there is a focus on alternative energy sources away
from fossil fuel sources. Today, hydropower is one of the most widely used clean, renewable energy
sources. Harnessing the energy of water has been historically used to generate power, grind crops,
etc. And for a green future, it is one of the most viable options for countries with topographies that
allow for it. However, studies across various glaciers worldwide agree that most glaciers are retreating
due to warming (IPCC 2007, Lemke et al. 2007, Gardner et al. 2013) and will jeopardize the water
availability, and with it, the supply for hydropower generation, such as territories in India and Nepal
(Himalayas), parts of Andean South America (Soruco 2008, Chevallier et al. 2011), and Alpine Europe.
Decreasing glacier area, or the ‘ablation zone’, will provide a temporary enhanced streamflow, which
will eventually lead to a shortage of runoff, and hence, hydropower source. This is particularly
problematic for countries that already depend on glacier-derived hydropower, and which additionally
are economically constrained in making the appropriate adaptation plans to relocate hydropower
plants or turn to alternative, more expensive renewable sources, such as the case in Nepal (Laghari
2013, Sharma & Awal 2013). Furthermore, modelling studies have attempted to predict the extent of
glacier retreat impact of water runoff in terms of amount and timing, and importantly, where and
when the peak of runoff from increase melting will shift to decreasing meltwater volumes no longer
sustainable for hydropower generation. In this paper, we turn to 3 case studies to identify the regional
impacts that melting glaciers could have from the Andean cities in South American, to politically and
economically strained Nepali Himalayas, and lastly, to the affluent Alps.
Hydropower in South America: The Andes
What is particularly important about Andean glaciers is the geographical location. These glaciers are
tropical glaciers covering the Central Andes, positioned at high altitudes above 4,000 m. Modelled
studies (from the WCRP CMIP3) have shown that elevated territories will face a higher warming than
the same latitude counterparts at ground level (Raymond et al. 2004, 2006) (fig.8). Tropical glaciers
are already exposed to warmer temperatures than glaciers at higher latitudes, making these glaciers
most vulnerable to climate warming. Detailed studies of Andean glaciers, where over 99% of tropical
glaciers are located (Chevalliers et al. 2011), have depicted the urgency that the South American cities
of Peru, Bolivia, Ecuador and Columbia are facing in order to deal with the water shortage facing them
from a decreased glacier runoff. Their capital cities, particularly Peru’s Lima, already employs a large
fraction of electricity generation to hydropower fed from glacier water. Ongoing and planned projects
aim to make hydropower over 50% of Peru’s energy source (International Hydropower Association
2015 Report). However, simulations have shown by 2100, managing of glacial water lakes might not
provide enough meltwater to run current hydropower plants (Chevalliers et al. 2011) at low risk areas.
What is more, already in La Paz, Bolivia, almost 30% of water reservoirs during the dry season are
already being used for hydropower, at quantities which will not be available in current modelled
predictions. The urgency in planification of water resources in South America stems also from the
step-like journey from the glaciers and melt water reservoirs, to hydropower plants, to downhill
irrigation and fresh water supply to mountain communities that depend on this runoff as their source
of water at these high altitudes; alternatively, there will be competition of how to allocate water when
it becomes scarce.
Figure 9: Global warming in the American
Cordillera, extracted from Raymond et al.
(2006). Modelled air temperatures following
the A2 scenario with 8 general circulation
models (GCMs) covering Alaska to Chile from
North to South of the Cordillera. Black
triangles: highest mountains.
Hydropower in South Asia: Himalayas
The Himalayan glaciers are not only a crucial water sources for millions of people, but provide
a currently substantial energy source for the area, with ongoing massive constructions for a future or
hydropower, particularly from China and India (International Hydropower Association 2015 Report).
China’s plan is to double its hydropower generation from its current ~18% of energy production (IHA
2015). India’s plans for hydropower facilities and dams are also numerous. However, in addition to
climate change impacts of water resources, it has
geopolitical issues to consider, such as the Indus
Waters Treaty with Pakistan, among other Himalayanfed water bodies shared with neighbouring countries.
Earthquakes and floods affecting this area further
increase the pressure of the Himalayan region to
establish ties to face the impending water shortages in
the most efficient way (Laghari 2013). Nepal, while
dependant on India or now China for fossil fuel, subject
to a political play as was seen after the oil blockade of
2015, could become self-sufficient in alternative green
energies, including hydropower. Already it’s electricity
supply mainly in hydroelectric plants. It is an unreliable
Figure 10. Figure extracted from (Sharma & Awal 2013).
source, nonetheless, with fluctuations in energy supply River discharge from 9 rivers displaying the variability
in predicting an estimate of available water sources for
from a lack of storage opportunities, with run-of-river
hydropower. There is a need for further research of
sources, and leaks in its structure (Hydroelectricity
Nepali river discharge flows in order to assess
Investment & Development Company, Nepal), and
hydropower capacity and plan infrastructures
studies are needed to understand the risk zones for
accordingly.
future hydroelectric plants (Sharma & Awal 2013), particularly to build smaller, local dams for
hydropower (Orlove 2009). Further planning is crucial for Nepal in making a transition towards a more
independent, sustainable future.
Hydropower in Europe: the Alps
Several recent studies have reviewed the physical and economic impact on the hydropower
and electricity sector from retreating glaciers in the Swiss Alps (Gabbi et al. 2012, Gaudard et al. 2013,
2014a, 2014b, 2016). They take into consideration the hydrology from various rivers, multiple models
projecting changes in energy prices as well as the difference in electricity usage and overall socioeconomic environments from these areas in the Alps. The research consensus lies in the importance
of planning regionally, as decrease of glacier runoff will occur, but at different rates, some offering a
possibility of storage, and ultimately heavily dependant on the communities energy demand.
Switzerland's energy comes from 56% hydropower sources, with almost half of those being
storage power plants (SFOE 2016). It is thus obvious that the future of hydropower generation is very
important not only nationally, but for the European electricity grid. Model studies coupling hydrology
and economy (electricity prices and usage) applied to IPCC future scenarios for the Alp region predict
an initial increase in hydropower generation until mid-21st century, only to decrease by over 15% by
2100 (Gaudner et al. 2013), considering hydropower making use of other non-glacial water supplies
and enhanced reservoir management (Gabbi et al. 2012).
Table 1: Hydropower stations considered
in the hydrology-economic study of
Gaudner et al. (2014). Hydropower
accounts for over 50% of Switzerland
energy source. Notice the number of
hydropower stations, including the high
number of run-of-river plants.
Figure 11: Extracted from Gabbi et al. (2012). The
availability in historical glacial runoff compared to
predicted modelled runoff (blue shaded area, with 95%
confidence interval). Grey: ice covered catchment area.
In conclusion, hydropower faces an unclear future, mainly subject to individual case scenarios
for specific regions and down to specific hydropower plants. It is nevertheless the biggest renewable
energy source at the moment, with ongoing projects to expand and maximize the hydropower
capacity around the world (International Hydropower Association, www.hydropower.org/). The
studies we have presented here agree in that it is crucial to invest research and modelling to identify
risk zones and the fate or glacial river runoffs. By mapping safe zones for hydropower infrastructure,
free from possible flooding and land instability, and identifying longer lasting glacial water reservoirs,
hydropower plant projects can be implemented to maximize sustainable clean energy that in cases,
such as Nepal, can secure energy independence, and even a possible source of export. As is clearly
seen from Fig. 1, the majority of glaciers are retreating, so long term plans from hydropower suffer
from this physical downfall.
Nonetheless, as has been seen from economic and market studies on the future of
hydropower (Gaudard et al. 2014, 2016), it is not only - or to even a lesser extent - the negative climate
effect, but a significant source of uncertainty comes from the future of energy prices and the transition
into a renewable energy laden future, where the choice of energy sources will play a market role
determining where the investments are placed, and what is given a priority. What is clear is further
scientific and economic research is needed, and at the moment, from our case studies regions, it is
lagging behind in the Andean and Himalayan, areas where communities are at risk from energy and
water scarcity, as well as flooding from unmanaged water reservoirs. Lastly, the Paris Agreement is
likely to favour hydropower as a renewable source, as it is an immediately applicable clean energy
that could help maint the intended goal of under 2C, with the aim of 1.5C. Water reservoirs containing
decaying organic material, particularly in the Tropics, have been shown to emit methane, a
greenhouse gas (Beaulieu et al. 2014). So while a working hydropower plant is generating clean
energy, it is still important to consider the carbon footprint of building a plant, of those already
working, and the impact of damming rivers on the river ecosystem (eg. fish) (EIA) in order to make
hydropower plants more sustainable (Jager & Smith, 2008).
5. Economic Ecosystem Services Assessment
Introduction to valuation and ecosystem services
The physical processes discussed previously allow for adaptation and mitigation plans to be
created to help humans manage climate change and its effect on glaciers. However, considerable
concern has been raised about the integration of environmental knowledge into economic systems –
particularly the current pricing system (Costanza, 1997). This dilemma highlights the infancy of the
interdisciplinary field of environmental economics. Indeed, the problem of valuing nature fits nicely
within our framework because we wish to establish quantifiable impacts of climate change. If we are
able to quantify, in monetary terms, the impacts of climate-change-induced glacial retreat, then we
can provide another dimension to understanding environmental vulnerabilities. This section will be
structured in the following way. An introduction to valuation will precede a discussion on methods
used to value ecosystems. Next, estimations of the change in the value of ecosystems will be made
for the case studies that have been discussed previously. These include insights into water quality in
the Alps, outburst floods in the Himalayas and hydropower in the Alps and Andes.
The first, pioneering attempt to conservatively value nature was made by the Millennium
Ecosystem Assessment (MEA). This work, commissioned by the United Nations, focuses upon
ecosystem services (MEA, 2005). Ecosystem services can be defined as the benefits that humans
obtain from ecosystems and are divided into four broad categories. These include supporting services
(the basis of all other services; given by nutrient recycling, soil formation etc.), provisioning services
(food, water and general products from nature), regulating services (carbon sequestration,
decomposition and purification, for example) and cultural services (recreation, spirituality, reflection
and aesthetics). Whilst the majority of the MEA focuses on understanding the services we receive from
ecosystems, a partial analysis was attempted to value the contribution of these services. Overall, it
was deemed that ecosystem services provide humans with benefits worth $46tn each year, far more
than the global Gross Domestic Product ($37tn) at the time of the estimation (MEA, 2005; Costanza,
1997, in 2007$US). In 2011, ecosystem service benefits were estimated to be worth $125tn per year
(GDP: $72tn per year). This phenomenon is unlikely to have changed since (Costanza et al., 2014). In
fact, various calculations have been made on ecosystem services. The value of global ecosystem
services ranges from $16tn – $125tn/year (Costanza et al., 2014; TEEB, 2010).
Methods for valuation
Valuation is important for three main reasons (MEA, 2005, p.34): to ‘assess the total
contribution that ecosystems make to human wellbeing’, to understand the incentives that individuals
face when managing ecosystems and to ‘evaluate the consequences of alternative courses of action’.
The MEA understands valuation as the latter reason – to evaluate alternative actions. This means that
the value of an ecosystem is measured so that the most efficient use of resources, natural or
manmade, can be utilised. The process of valuation starts with following the physical change in an
ecosystem service and then by ‘following the causality chain’ until it reaches a change to human
welfare (MEA, 2005). This is shown schematically in Fig. 12.
Figure 12: Schematic of the Analytical Approach for Assessing Ecosystem Service Changes (adapted from MEA,
2005, p. 57)
Pearce (1993) offers a theory of Total Economic Value where ecosystem services are valued
in a cost-benefit-analysis approach. Pagiola et al. (2004) also offers a summary of other known
valuation techniques (see Table 2).
Table 2: Economic Valuation Techniques (adapted from Pagiola et al. 2004)
Methodology
Approach
Production function
The effect of a change in ecosystem services on produced goods
Cost of illness
The effect of a change in ecosystem services on mortality rates
Replenishment cost
Cost of replacing the service
Hedonic pricing
Effect of environmental factors on the price of a good
Contingent valuation
The willingness to pay for an ecosystem service
Choice modelling
Ask participants to choose their preferred option from a set of alternatives
This report will seek to predominantly use the valuation method offered by the Millennium
Ecosystem Assessment – which is most closely aligned to the production function methodology
(Pagiola et al. 2004). However, at times it may be beneficial to refer to the other valuation methods
such as replenishment costs.
Valuation of ecosystem service change in case study areas
Before discussing specific valuations for water quality, outburst floods and hydropower it is
useful to appreciate important global economic valuations. In 1997 global GDP was $37tn which
equates to $17.3 per person per day (World Bank, 2016). Ecosystem services for 1997 were
consequently valued at $21.5 per person per day (Costanza et al., 1997). In 2011, global GDP increased
to $54tn (World Bank, 2016) which is equal to $21.2 per person per day. Ecosystem services in 2011
provided humans with $57 of benefits per day (Costanza et al., 2014).
Water Quality
The Indus Delta in Pakistan is a large irrigation system that connects to over 15m ha of
farmland. Almost 90% of the water for this system comes from glaciers in the Himalayas. Despite the
system's benefits, it is deemed economically and ecologically inefficient (Emerton, 2005). The loss of
freshwater, reinforced by retreating glaciers, causes saltwater intrusion and consequently reduces the
value of ecosystem services. Aggregate crop production and fish yield has declined and led to a loss of
$70,000 and $45,000 respectively. Similarly, $1.8m is lost a year from the ecosystem services provided
by mangroves – such as fuelwood and regulatory services. Export earnings for fish, a provisional
service, have declined by almost $125m in recent years (Emerton, 2005).
Despite these estimations, general knowledge and valuations of water quality remain limited.
It would beneficial for future research to attempt a valuation of water quality and its different
components. However, I believe that this area suffers from the same methodological errors as the
valuation technique. That is, water is either priceless or infinitely valuable.
Outburst Floods
The analysis on outburst floods described the physical and human impacts of an increase in
glacial lake outburst floods (GLOFs). This section, however, shows that there are various economic
impacts from these events. It is difficult to specify which particular ecosystem service is being altered
and by what amount, but generalised valuations and impacts can be quantified in order to understand
environmental vulnerabilities more fully.
For example, the continuing retreat of the Hindu Kush-Himalaya glacier is linked to climate
change (Shrestha et al., 2010). The potential glacial outburst flood risks impacting 950 ha of land and
human infrastructure whilst also having an economic replenishment cost of between $159m - $197m.
Furthermore, Nepal has had estimated replenishment costs of $60m in 2009, $27m in 1987 and $200m
in 1993 as a result of glacial lake outburst floods. These figures do not cover the cost to non-market
benefits either. Consequently, on average these costs represent 1.5% of Nepalese GDP and assets that
are currently at risk of further damage are estimated to be worth between $2m - $9m (Shrestha et al.,
2010).
Contingent valuation and replenishment costs within Pakistan are valued at $7.5m – mostly
via a United Nations Development Programme initiative to protect vulnerable Pakistani communities.
The contingent costs involve monitoring systems to prepare for future glacial floods. Consequently,
most losses in ecosystem services concern replenishment values of failed services – but production
values, such as fish revenue, also exist.
Finally, further research attempts to understand individual preferences for flood zones,
especially in areas where the risk of floods is increasing due to climate change, has been conducted.
Birol et al (2007) found that, out of 192 households, nearly half of the households would want to be
compensated if biodiversity initiatives were increased in the study area. This is because the
participants were given a choice model whereby they chose whether to accept a tax increase for
increased biodiversity or flood mitigation. The study highlights key issues with valuation methods,
whereby individuals are not necessarily keen to pay for the protection of ecosystem services even if
they understand the risks involved.
Hydropower
As mentioned in the discussion on the physical impacts of climate change on hydropower,
many economies around the world are increasingly utilising water energy whether because of
availability or for renewability purposes. The impact of retreating glaciers, however, should also be
understood economically to help quantify the change in the ecosystem services related to
hydropower.
The European Union generates 10% of its electricity from hydropower (GSE, 2010-11).
Switzerland, situated partly within the Alps, generates 56%. According to Gaudard et al (2013), the
main system that operates to harness hydropower will lose around 21% of its annual inflow in 20312050 compared to 1991-2010. This impact is likely to be caused by retreating glaciers and reinforced
by climate change. The revenue received in royalties from hydropower companies’ amounts to
€440m/year although this figure is unlikely to be relatable to other hydropower operations in
neighbouring countries.
Furthermore, glacial retreat in the Andes was assessed for its economic impact by Vergara et
al. (2007). They used figures from Peru’s power system to estimate a yearly output drop for the Cañon
del Pato hydropower plant of 10.9%, caused by a 50% reduction in effective glacier runoff, and an
estimated future reduction of 14.2% if the nearby glacier completely disappears. Such estimates can
be effective in calculating the provisional ecosystem service cost of climate change. The barometers
for the calculation include assuming producer fees of $20 per megawatt-hour, long-run average cost
for electricity of $35 per megawatt-hour and the cost of rationing energy at $250 per megawatt-hour.
With this in mind, the cost of glacier runoff was estimated (Table 3).
Table 3. Cost of Glacier Retreat for Energy Sector, Peru ($ million/year) (Vergara et al. 2007)
Furthermore, regulatory services such as water purification will cause an added cost of $100m
for the Peruvian government to replace the purification service with man-made alternatives demonstrating a clear replenishment cost for the degradation of an ecosystem service. The reduction
in potential energy as a result of glacial runoff will lead to more investment in other sources of energy.
Most likely to be thermal, this is estimated to cost $1bn per gigawatt installed. The cost of changing
ecosystem services for Peru is therefore quite severe. The replicability of the study, however, is not
clear cut as energy prices vary greatly depending on market structure and demand in other countries.
In Nepal, a country that relies heavily on hydropower for electricity generation despite
seasonal flooding, outburst floods have increased in frequency due to climate change and affected
provisional ecosystem services (Shrestha et al., 2010). The Dig Tsho glacial lake outburst flood in
Khumbu Himal in 1985 had an estimated replenishment cost of approximately $500m – mostly used
to rebuild the hydropower plant. Furthermore, an adaptation cost to dig a channel that lowers a glacial
lake in Nepal cost $3m in 2002. It is known that further reductions would be much more expensive. It
seems, therefore, that government forces are needed for individuals to pay for renewal of ecosystem
services which demonstrates clear market failure (Orlove, 2010).
Further Research
Whilst Costanza et al (1997 & 2014) provide global valuations for specific biomes; the
generalised ecosystem reports (MEA, 2005; TEEB, 2010) either focus on too narrow a field or do not
tackle the valuation problem adequately. For example, the TEEB (2010) report only values forests and
wetlands. The MEA (2005) discusses methodological issues and physical ecosystem services, but does
not go far enough to value specific services or indeed to provide a global value of ecosystems. Indeed,
the MEA (2005) and TEEB (2010) discuss production costs as a key proponent of valuation but then
predominantly use replenishment costs to assess the impact of ecosystem service changes. This lack
of clarity makes any assessment difficult. The lack of research on the economic impact climate change
and glaciers is troublesome, but more so is the perceived difficulty in gaining the information.
6. Conclusion
In conclusion, climate change induced glacial retreat has wide-ranging and predominantly
negative impacts on ecosystems. A rising average annual global temperature will continue to pose
challenges for vulnerable communities and for physical landscapes. In particular, we have sought to
highlight more details about the complex nature of glacial retreat upon water quality, outburst floods
and hydropower. Climate change seems to directly impact water quality, increase the number of glacial
lakes and affect the potential energy from hydropower in varying degrees over the short and long term.
These areas can then be collectively assessed using various economic tools, although this field needs
more research in the future.
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