TL: GREENPEACE BRIEFING: THE THREAT OF CLIMATE CHANGE TO BOREAL
FORESTS
SO: GREENPEACE INTERNATIONAL, (GP)
DT: JULY 1997

 "...these forests of trees -- so enchain the senses of the
grand and so enchant the sense of the beautiful that I linger on
the theme and am loathe to depart -- surpassing the woods of all
the rest of the globe..." (1)

 -- Samuel Wilkeson, on North America's forests, 1869

 "Living systems are vulnerable to change.  They have limits,
that, if exceeded, cause them  to decline and collapse." (2)

 -- Elliott A. Norse, Ancient Forests of the Pacific Northwest

The northern boreal forests comprise almost one third of the
Earth's forest systems, covering 3.7 billion acres. Along with
the temperate forest of the mid-latitudes, and tropical forest
near the equator, it is one of the three great forest ecosystems
of the world, supporting a unique assemblage of wildlife,
endangered species, as well as human needs. 

Unfortunately, over half of the existing boreal forest may
disappear, due to the effects of climate change. Over the next
30 to 50 years, atmospheric levels of human-induced greenhouse
gases are expected to double, creating significant changes in
the Earth's climate. Conditions may become too severe for boreal
forest health and survival of its species, and up to 65 percent
of the forest may be lost. (3) 

THE CHANGING CLIMATE

The United Nations' Intergovernmental Panel on Climate Change
(IPCC), reflecting consensus of 2,500 of the world's leading
scientists, recently conveyed its finding that human activities
have begun to modify global climate. The global average surface
temperature has increased approximately 1 degree F over the past
century, and IPCC projections indicate that the Earth will warm
by 1.8 to 6.1 degrees F by the year 2100, with a middle estimate
of 3.6 degrees F. Even at the low end of these projections, the
anticipated rate of warming over the coming years will be,
according to the IPCC, "greater than any seen in the past 10,000
years." (4)

A variety of human activities produce greenhouse gases, like
carbon dioxide (CO2), nitrous oxide (N20), and
hydrofluorocarbons (CFCs, HCFCs, and HFCs), methane (CH4), and
sulfur hexafluoride (SF6), increasing their atmospheric
concentrations. Acting as a blanket, these human-induced
emissions trap the sun's heat and warm the planet. In the U.S.,
fossil fuel combustion is the most significant cause of
greenhouse gas emissions, and has contributed to dramatic
increases in CO2 levels. Since pre-industrial times, atmospheric
CO2 concentrations have gone up 30 percent, from 280 parts per
million to more than 360 parts per million; in the last 35 years
alone, CO2 levels increased over 12 percent. If this trend
continues, CO2 concentrations will double by the end of the next
century. IPCC scientists clearly warn that humans will continue
to drive future climate change, with potentially catastrophic
and irreversible consequences, if action is not taken now to
reduce greenhouse gases. (5)

CLIMATE AND BOREAL ECOLOGY

The northern boreal forest, also called the taiga, is a vast
ecosystem encircling the Northern Hemisphere. The forest covers
17 percent of the world's surface area, stretching from Alaska
through most of Canada, to Northern Europe and parts of Northern
Asia. Small fragments of the boreal forest also thrive in
mountainous areas south of the northern system, as in America's
Rocky Mountains, where they are called "oroboreal," from the
Greek word "oro," or mountain. 

Boreal forest species are uniquely adapted to grow in very cold
climates: conifers, including spruce, pine, and fir; and
broadleaves, including birch, poplar, alder and willow. Like all
forests, boreal forests are highly dependent on climate in their
function and species composition. Species distribution is thus
limited primarily by temperature, each forest thriving in a very
narrow temperature "niche." Trees are also vulnerable to
extremes of water availability, especially in areas like
interior Alaska, where annual precipitation is extremely low
(one-tenth to two-tenths of an inch).

THE POLAR MELTDOWN: CLIMATE CHANGE AT THE HIGHER LATITUDES

To understand how climate change threatens northern boreal
forests, it is important to understand where, and how, the
impacts will be felt first. On a global scale, climate change
will have its first and most severe impact at higher latitudes
of the Northern Hemisphere, where tundra, boreal forest and
polar desert zones will face the greatest ecological change. (6)
Modeling confirms that ice-covered areas of the polar sea and
polar land areas will experience the greatest temperature
increases on Earth. (7) The Arctic is expected to warm up by as
much as 9 to 18 degrees F, causing widespread changes in
evaporation rates, cloudiness, and precipitation. (8)

ARCTIC SIGNS OF CHANGE: INDICATIONS FOR NORTH AMERICA

The Arctic region is already shows signs of change. Arctic
temperatures are rising three to five times faster than the
global average. Summer temperatures on Ellesmere Island, in the
eastern Canadian Arctic, are higher than they have been in 1,000
years. (9) Arctic sea ice is thinning, and permafrost -- or
frozen ground material -- is melting along Alaska's North Slope.
Glaciers in Greenland and Sweden, for example, have retreated
significantly throughout the century. (10) If greenhouse gas
emissions continue unabated and global temperatures continue to
climb, the physical and biological impacts on the Arctic could
be tremendous. Melting glaciers will elevate global sea levels,
and the entire Arctic food web -- from marine algae to polar
bears -- could suffer. 

The Arctic is a crucial indicator of how climate change may
affect the rest of North America. As the Arctic heats up, we can
anticipate warmer temperatures through much of the U.S.,
increased chances of drought and other extreme weather events,
rising sea levels around coastal areas, and loss of precious
natural habitat -- including our forests. 

According to projections, climate change is likely to create
unsuitable conditions for many tree species, and boreal forests
will be especially hard hit. (11) Because we have already
clearcut so much of our forested areas -- and altered what
remains -- most forests now exist as patches and remnants. The
few, extensive continuous tracts that remain lie primarily in
the boreal region. And they are the most threatened. (12)

THE MOST VULNERABLE FOREST

There is general consensus that climatic changes will have the
greatest impact on boreal forests; their unique adaptation makes
them more sensitive to temperature fluctuations than temperate
or even tropical forests. (13) Even a slight increase in mean
annual temperature is enough to affect many species' growth and
regeneration.

Climate change will affect boreal ecosystems in a number of
ways: air temperature will increase by around 1.8 to 3.6 degrees
F in summer and 3.6 to 5.4 degrees F in winter; rainfall and
humidity will change; soils will become drier. As climate warms,
conditions suitable for the growth of many boreal species are
likely to shift dramatically, and the trees' ecological niches
may move northward ten times faster than the trees themselves
can migrate. Overall, the boreal forest is likely to decrease in
area, biomass, and carbon stock, with a significant disruption
at its southern boundary. Taken all together, these impacts
could add up to an alarming 65 percent loss of boreal forests.
(14)

TWO DEADLY PLAGUES: FIRE AND INSECTS

In addition to temperature, precipitation and soil fluctuation,
altered disturbance regimes -- especially fire and pest
outbreaks -- will cause the most rapid and extensive biotic
changes in boreal forests. Both disturbances are, in part,
driven by climate, and both are potentially catastrophic. 

Fire contributes to the overall health and distribution of
boreal forests by removing weakened trees and sparking seed
release during reproduction. Fire, however, is more common
during warm, dry weather, and as climate alters forest
environments, the frequency of fire may increase, as well. (15)
This threat has already become a reality in North America.
Recent Canadian forest fire rates far exceed the century trend,
resulting in the worst fires on record, which together burned
western Canada and areas east of James Bay in Quebec in 1989.
Fire frequency has increased since 1975 in Alaska, as well. (16)
In the next century, Canadian researchers predict a 40 to 50
percent increase in area burned in Canada annually, under a
doubling of carbon dioxide. There are similar projections for
boreal forests in Russia over the next 50 years. (17)

Insects also play a role in boreal ecology: they decompose
litter, supply food for birds and small animals, and eliminate
diseased trees. But insect attacks are likely to increase in
frequency and intensity, as established forest stands succumb to
the physiological stress associated with warmer, drier
conditions. This could prove deadly to boreal species, because
even under stable climate conditions, pest outbreaks usually
occur when host species are under stress. (18)

A notorious pest is the spruce budworm, found throughout the
southern boreal forest in North America. Encouraged by warm
temperatures, the budworm defoliated 55 million hectares of fir
trees -- an area larger than France -- during its most recent
North American outbreak from 1978 to 1985. (19) The budworm has
also devastated Canadian forests in recent years, dramatically
slowing growth of coniferous trees. (20) According to IPCC
predictions, such outbreaks will likely increase and expand
northward, along with additional pest and disease problems. (21)

Since 1989, more than 25 million trees have been killed and over
1.2 million acres of forest infested by the worst spruce bark
beetle outbreak in Alaskan history. Spreading rapidly on the
Kenai Peninsula, the outbreak has now reached Anchorage. The
vast numbers of dead and dying trees have also created a major
forest fire hazard.

Although bark beetles are indigenous to the Alaskan boreal
forest, the unprecedented size of this outbreak has been linked
to climate change by U.S. Forest Service scientists. Climate
change has increased forest water stress, improved conditions
for beetle brood development, reduced winter mortality, created
a larger dispersal period, and allowed beetles to reach sexual
maturity in one year rather than two.

RAPID CHANGE VS. HISTORIC MIGRATION RATES

The rate of climate change -- and not the change itself -- is
perhaps the biggest threat to the boreal forest. Unlike past
fluctuations, which occurred over thousands of years, future
climatic changes of about the same magnitude are expected to
take place over 100 years or less -- a remarkably short time
span. With rapid change, conditions may become unsuitable for
trees to complete their life cycle. (22) Seedlings are
especially sensitive to short-term drought, saplings to varying
levels of sunlight, and mature trees to soil moisture during the
growing season. Thus, in a kind of "arrested development,"
healthy-looking tree populations may not ever mature to the
point of reproduction. Entire remnant stands of forest may no
longer sustain themselves, or their resident animal and plant
communities. (23) A temperature rise of only 3.6 degrees F
could, for example, eliminate up to half of the animals
currently inhabiting boreal mountain ranges from the Rocky
Mountains to the Sierra Nevada. (24)

Forests have historically migrated or shifted in response to
past climate fluctuations: spruce generally migrated 240 to
1,500 feet per year in response to past climate variations, fir
60 to 900 feet, and pine 4,500 feet. These rates are fairly
slow. By contrast, climate models indicate that the boreal
forest range may have to shift 15,000 feet per year or more to
follow suitable climate conditions -- more than 10 times the
historic migration rates of most boreal species. Vast areas of
forest, unable to adapt to rapidly changing climatic conditions,
will die. (25)

AN ALTERED LANDSCAPE

This potentially rapid change will occur on a landscape already
greatly altered by human activities. Forests that once spread
over great areas, interrupted only by lakes and rivers, have now
been reduced to small, isolated patches due to logging and
deforestation. This fragmentation will worsen the effects of
climate change, since the previous means of forest adjustment --
through the slow spread of seeds through the landscape -- is now
impossible over much of North America. (26) 

CASE STUDY: NORTHERN MINNESOTA FORESTS

Scientists at the University of California examined the
potential effects of climate change on Northern Minnesota's
Boundary Waters Canoe Area (BWCA), a million-acre designated
wilderness in the Superior National Forest. Their results are
alarming. According to projections, the southern portion of the
BWCA and adjacent National Forest may change dramatically, from
boreal evergreen forest to northern hardwoods. The changes may
appear in as soon as 15 years, between 2010 and 2040. Their
research concluded that "Forests of Minnesota and Michigan may
undergo rapid, dramatic changes as a result of climate changes
due to the greenhouse effect." (27)

CONCLUSION

The threats that global climate change present to northern
boreal forests are numerous and real. Yet they reflect only a
portion of a larger, bleaker picture of the Earth in a
dramatically changing climate. These potentially drastic changes
in the forest serve as a wake up call to governments and
individuals alike to take action now. Greenpeace fully supports
deep reductions in greenhouse gas emissions, and a shift away
from a fossil fuel-based economy to one based on clean,
renewable energy sources. Solar and wind power and energy
efficiency measures are available now. These alternatives have
the potential to meet the world's energy needs, create jobs,
encourage world trade in clean technologies, and reduce energy
costs while protecting the planet. The barriers to these
solutions are not technical, but political. As nations seek ways
to cut greenhouse gases, Greenpeace calls on world leaders to
invest in, and implement, renewable energies and efficiency now,
for a sustainable planet tomorrow.

ENDNOTES  

1 cited in Elliott A. Norse, Ancient Forests of the Pacific
Northwest, Island Press, Washington, D.C., 1990, p.12.

2 Ibid, p. xiii.

3 Intergovernmental Panel on Climate Change, Working Group II
Report, Impacts, Adaptations and Mitigation of Climate Change:
Scientific - Technical Analyses, Climate Change Impacts on
Forests (chapter 1), 1996.

4 Intergovernmental Panel on Climate Change, Working Group I
Report, The Science of Climate Change, 1996.

5 Ibid.

6 Barrie Maxwell, Arctic Climate: Potential for Change under
Global Warming, in F. Stuart Chapin, Robert Jefferies, James
Reynolds, Gaius Shaver and Josef Svoboda, Arctic Ecosystems in
a Changing Climate: an Ecophysiological Perspective, Academic
Press, Inc., San Diego, 1992, p. 29. Original source of data
found in W.J. Tegart, G.W. Sheldon and D.C. Griffiths (eds.),
"Climate Change: the IPCC Impacts Assessment," Australian
Government Printing Service, Canberra, 1990.

7 Vera Alexander, Arctic Marine Ecosystems, in Robert L. Peters
and Thomas E. Lovejoy, Global Warming and Biological Diversity,
Yale University Press, New Haven, 1992, p. 222. Original data
taken from J. Hansen, et al, Global climate changes as forecast
by Goddard Institute for Space Studies three-dimensional model,
in Journal of Geophysical Research 93 (D8): 9341.

8 F. Stuart Chapin, et al, Arctic Plant Physiological Ecology:
A Challenge for the Future, in Arctic Ecosystems in a Changing
Climate, op. cit., p. 6. Original data taken from Allen M.
Solomon, et al, The global cycle of carbon, in "Atmospheric
Carbon Dioxide and the Global Carbon Cycle," (J.R. Trabalka,
ed.), DOE/ER-0239, Natl. Tech. Info. Service, 1985, pp 1-13.

9 Allen M. Solomon and Wolfgang Cramer, Biospheric implications
of global environmental change, in Allen M. Solomon and Herman
H. Shugart (eds.), Vegetation Dynamics and Global Change,
Chapman and Hall, New York, 1993, p. 41.

10 W. Dwight Billings and Kim Moreau Peterson, Some Possible
Effects of Climate Warming on Arctic Tundra Ecosystems of the
Alaskan North Slope, in Global Warming and Biological Diversity
1992, op. cit., pp. 240-242. See also Intergovernmental Panel on
Climate Change, Working Group II Report, The Cryosphere: Changes
and their Impacts (chapter 7), 1996.

11 IPCC II 1996, op. cit., chapter 1. See also Adam Markham,
Nigel Dudley and Sue Stolton, Climate Change, Biodiversity and
the Survival of Species, World Wildlife Fund publication, Gland,
Switzerland, 1993, pp. 54-56.

12 Daniel B. Botkin and Robert A. Nisbit, Projecting the Effects
of Climate Change on Biological Diversity in Forests, in Global
Warming and Biological Diversity 1992, op. cit., p. 278.

13 IPCC II 1996, op. cit., chapter 1.

14 Ibid.

15 Ibid.

16 Brian J. Stocks, The extend and impact of forest fires in
northern circumpolar countries, in Joel S. Levine (ed.), Global
Biomass Burning: Atmospheric, Climatic and Biospheric
Implications, The MIT Press, Cambridge, 1991, pp. 197-202.

17 IPCC II 1996, op. cit., chapter 1.

18 Jerry Franklin, et al, Effects of Global Climatic Change on
Forests in Northwestern North America, in Global Warming and
Biological Diversity 1992, op. cit., p. 253.

19 J.R. Blais, The ecology of the eastern spruce budworm: a
review and discussion, in recent advances in spruce budworm
research: proceedings of the CANUSA spruce budworm research
symposium, Bangor, Maine, September 16-20, 1984.

20 "Severe Drop in Tree Growth Found," Toronto Star, January 30,
1987.

21 IPCC II 1996, op. cit., chapter 1.

22 Ibid.

23 Daniel B. Botkin and Robert A. Nisbit, in Global Warming and
Biological Diversity 1992, op. cit., p. 283.

24 IPCC II 1996, op. cit., chapter 1.

25 Ibid.

26 Daniel B. Botkin and Robert A. Nisbit, in Global Warming and
Biological Diversity 1992, op. cit., pp. 287-291.

27 Ibid.