Arctic Climate Change
4. How will the vegetation be affected by Arctic warming?
- 4.1 How will vegetation zones shift?
- 4.2 How will boreal forests be affected?
- 4.3 Will there be an increase in forest fires or insect pests?
- 4.4 Will agricultural opportunities increase in the Arctic?
Arctic vegetation zones are likely to shift, causing wide-ranging impacts.
4.1 How will vegetation zones shift?
The main vegetation zones in the Arctic are
polar deserts in the north,
boreal forests in the
south, and a wide expanse of
tundra in-between. Polar
deserts are characterized by open patches of bare ground and an
absence of even the smallest woody shrubs, whereas tundra is
characterized by low shrub vegetation.
Climate change is
expected to cause the northward expansion of forests into the
Arctic tundra, and of tundra
into polar deserts. Such
changes are likely to take place this century in areas where
suitable soils and other conditions exist. This is expected to
result in the area of tundra becoming smaller than it has ever
been during the past 21 000 years, reducing the breeding area
for many birds and the grazing areas for certain land animals.
The total number of
species in the Arctic is
projected to increase under a warmer climate due to migration of
species from the south. Many of the
adaptations that enable
plants and animals to survive in the Arctic environment also
limit their ability to compete with species that move in from
the south. Moreover, Arctic species are limited in their
northward migration by the Arctic Ocean.
Changes in the ranges of certain bird, fish, and butterfly
species have already been
observed. At present, there are more varieties of moss and
lichens in the Arctic than
anywhere else in the world. This type of vegetation is
particularly likely to decline as the Arctic warms.
The geographical spread of animals can generally shift much
faster than that of plants, and large migratory animals such as
caribou can move much more readily than small animals such as
lemmings. In addition to mobility, the availability of food
sources is another factor that influences the pace at which
different species will
shift northward. All of these differences will result in the
break-up of currently
and ecosystems and the
formation of new ones, with unknown consequences.
4.2 How will boreal forests be affected?
The projected northward expansion of
boreal forest will cause a
decrease in the amount of sunlight reflected by the surface of
the Arctic, as the newly forested areas are darker and will
absorb more solar radiation
than lighter, smoother
tundra or bare snow. In this
feedback loop warming could
thus leads to more tree-cover and, in turn, to still more
(see also Question 3.1).
However, the expanding forest will be denser and grow more
quickly than the existing tundra, and the tundra more than the
polar deserts it displaces.
This could increase the amount of carbon stored within
offsetting the projected warming linked to the increased
absorption of solar energy.
Total annual precipitation is expected to increase along with
temperatures. These changes could, nonetheless, lead to
desertification in certain land areas if evaporation increases
more rapidly than precipitation. The thawing
permafrost could also drain
moisture from soils and lead to desertification in some areas if
Almost one third of the world’s forests are located in Arctic
nations, particularly in Siberia and North America. These
forests contribute to:
- timber production providing significant export
earnings for Finland, Sweden, and Canada.
freshwater cycle in
- provision of breeding zones for migratory forest birds
and habitat for animals
such as wolves and caribou that are very important for local
After the last ice age, a warmer period for the Earth’s
climate allowed trees to grow much further north than at
present. However, whilst current warming seems likely to bring
about a similar shift, the actual northern movement of the
treeline is highly
unpredictable as various factors, including fires, floods and
human activities, can influence it.
In different areas of the
boreal forests, different
climatic conditions are favouring or limiting the extent of tree
growth. Climate change
could, thus, produce two different kinds of response:
- a simple gradual change in conditions leading to a
type of forest being replaced by another from the south,
- a more complex pattern of abrupt change in conditions
leading in some areas to the retreat of the
treeline southward and
to the formation of grasslands between
tundra and the
Either type of change may allow the formation of
ecosystems that are not
present in today’s
White spruce is the most
widespread boreal conifer, making up most of the forest near the
border of the tundra, and a
valuable timber resource, especially in North America. This
species is highly dependant
on climatic conditions and any change could hamper its
reproduction by affecting the production of cones and the
release of seeds following forest fires.
Black spruce is the
dominant tree in a large portion of the
boreal forest in Alaska. It
absorbs a lot of solar energy, thus increasing warming, and it
is a highly flammable
species that can carry fire
across the landscape. The
projected warming may affect the survival and geographic spread
of the black spruce, as this species can be influenced by
changes in permafrost, high
temperatures in early spring, and droughts.
4.3 Will there be an increase in forest fires or insect pests?
Large areas of forest are increasingly likely to be disturbed
by insect outbreaks linked to warming. Indeed, the warming will
create new opportunities for
invasive species, such as
the Spruce Bark Beetle and the Spruce Budworm, to move in from
Spruce Bark Beetle
Forest fires could become more frequent
Fire is another major disturbance factor in the
boreal forest and it has a
wide range of ecological effects. The average area of forest
burned each year in western North America has doubled over the
past thirty years, and it is expected to increase by as much as
80% over the next 100 years. The area of boreal forest burned in
Russia averaged four million hectares every year over the last
three decades. This area more than doubled in the 1990s.
Projected changes in climate would greatly increase the area
subjected to the types of weather that cause extreme fire
4.4 Will agricultural opportunities increase in the Arctic?
At present, agriculture in the north consists mostly of
raising cattle, sheep, goats, pigs, and poultry, herding
cool-season vegetables such
as turnips and spinach, and small grains such as rye and oats.
In addition to limitations imposed by climatic conditions in the
Arctic such as lack of warmth and moisture, and short growing
seasons, agriculture is also limited by the lack of
infrastructure, a small
population base, remoteness
from markets, and land ownership issues.
Climate change is
expected to increase the range of crops that can be grown in the
Arctic. As far north as the Arctic circle, it may soon be
possible to cultivate crops that currently only grow in the
warmer parts of the arctic region, for instance. Yield increases
might actually be constrained by factors such as a rapid but
shorter ripening and certain winter conditions. Water deficits
are likely to increase over the next century in most parts of
the boreal region, because evaporation is likely to increase
more rapidly than precipitation as a result of higher
temperatures. Irrigation systems will be needed in these areas
in order to minimize the effects of
water stress on crop
Insects, diseases, and weeds are likely to increase throughout
the Arctic with climate warming but, in most cases, their impact
is unlikely to offset yield increases or the potential for new
Overall, lack of infrastructure, limited local markets, and
long distances to large markets are likely to continue to limit
agricultural development in most of the Arctic during this