Elements for Life

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Glaciers and ice caps in the Nordic countries have retreated

and advanced during historical times in response to climate

changes, which are believed to have been much smaller than

the greenhouse-induced climate changes that are expected

during the next 100–200 years. These changes have in many

cases left clear marks on the landscape in the neighbourhood

of the glaciers.

Simulated changes in ice volume and glacial runoff

Several ice caps and glaciers in the Nordic countries were

studied within the CE project using mass balance and dynamic

models to project future changes in ice volume and glacial

runoff based on scenarios for future climate change.

In simulated ice wastage for the modelled glaciers, simula-

tions with a 2D ice flow model are run to 2200, but the

Norwegian and Swedish glaciers are only run to 2100 because

of limitations in a simplified dynamic model used for these

glaciers. The time evolution of ice volume has a similar char-

acter for the modelled glaciers, except for Engabreen in Norway

and Mårmaglaciären in Sweden. The modelled ice volume is

reduced by more than half within the next 100 years, and the

glaciers essentially disappear in 100–200 years after the start

of the simulations, given that the rate of warming with time

remains the same. One of the Norwegian glaciers retreats more

slowly because of a substantial increase in precipitation, which

is projected by the CE scenario for the area where this glacier

is located.

The projected change in the mass balance of the glaciers

leads to a marked increase in runoff from the area covered by

ice at the start of the simulations. Due to the large amplitude

of the projected changes, the changes with respect to the

runoff at the start of the simulations are similar to changes

with respect to a 1961–1990 baseline, which was not explic-

itly modelled for most of the glaciers. By around 2030, annual

average runoff is projected to have increased by approxi-

mately 0.4–0.7 m

w.e

-1

for the Norwegian and Swedish

glaciers, and 1.5–2.5 m

w.e

-1

for the Icelandic ice caps. The

runoff increase reaches a comparatively flat maximum

between 2025 and 2075 (except for Engabreen in Norway)

when the increasing contribution from the negative mass

balance is nearly balanced by the counteracting effect due to

the diminishing area of the glacier. For all the glaciers, this

maximum in relative runoff increase is over 50 per cent with

respect to the current runoff from the area presently covered

with ice.

For the Icelandic ice caps, the specification of a compara-

tively large change in climate during the initial decades of the

simulation, based on the observed climate of recent years, and

the seasonality of the climate change with the largest warming

in spring and fall, leads to a rapid increase in runoff with time.

The simulated runoff changes may be compared to average

runoff from these ice caps between 1981 and 2000, which is in

the range 2.4–4.1 m

w.e

-1

. In model results for Engabreen in

Norway, although the precipitation increase for the other glac-

iers is of much smaller importance than the temperature

change, the assumed precipitation change can significantly

alter the simulation results in cases where substantial precip-

itation changes take place. The fact that this only happens for

one of the glaciers highlights the uncertainty of the climate

change scenario.

These results clearly suggest large changes in runoff from

glaciated areas, which are projected to have reached quite

Location of the glaciers and ice caps studied in the CE project

significant levels compared with current runoff, well before

2030. The associated changes that may be expected in diurnal

and seasonal characteristics of glacial runoff will come on top

of the changes in the annual average.

Hydropower is the most important renewable source of elec-

tricity in Iceland and it is the renewable energy source most

strongly affected by climate. The results from the CE project

and the related national research programmes show that this

impact can be quite strong. Global warming will shorten the

winter season, make it less stable and lengthen the ablation

season on glaciers and ice caps. This leads to a more evenly

distributed river flow over the year, which is a profitable situ-

ation for the industry.

There is also potential for increased hydropower production

as the highest modelled increase in river flow is simulated in

highland areas that are most important for hydropower. This

implies that the projected hydrological changes may be

expected to have practical implications for the design and oper-

ation of many hydroelectric power plants, and also for other

use of water, especially from glaciated highland areas.

One negative aspect is that the new annual rhythm in runoff

indicated in the simulations will put more stress on the spill-

ways. They will probably have to be operated more often in

winter, as the unstable winter climate will generate more

frequent sudden inflows when reservoirs may be full. This

will also have an impact on the infrastructure with more

frequent flooding problems downstream at the reservoirs.

These areas are normally adapted to the present-day climate

with stable winters and without high flows from autumn to

spring.

In summary, the power industry needs to develop a new

strategy characterized by flexibility because it must be possi-

ble to adapt the operation and even the design of power plants

as climate change leads to changes in the discharge and season-

ality and other hydrological characteristics. Continued research

on climate change is essential to address the added uncertainty

with which the industry is faced due to this situation and in

order to supply the necessary information for proper adapta-

tion to the evolving climate.

Image: Fenger (2007)