http://www.sciencedaily.com/releases/2009/05/090525173542.htm
Rapid Climate Change Forces Scientists To Evaluate 'Extreme'
Conservation Strategies
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A tortoise on the edge of Athens, Greece. (Credit: Dov Sax)
ScienceDaily (May 26, 2009) — Scientists are, for the first time,
objectively evaluating ways to help species adapt to rapid climate
change and other environmental threats via strategies that were
considered too radical for serious consideration as recently as five
or 10 years ago. Among these radical strategies currently being
considered is so-called "managed relocation." Managed relocation,
which is also known as "assisted migration," involves manually moving
species into more accommodating habitats where they are not currently
found.
A new, ground-breaking tool to help decision-makers determine if, when
and how to use managed relocation is described in the May 25, 2009
issue of the Proceedings of the National Academy of Sciences (PNAS) by
a multi-disciplinary working group.
Partially funded by the National Science Foundation (NSF), the working
group is co-led by Jessica Hellmann and Jason McLachlan of the
University of Notre Dame, Dov Sax of Brown University, and Mark
Schwartz of the University of California at Davis. David Richardson of
Stellenbosch University in South Africa led the writing of the paper.
The researchers' tool is ground-breaking because managed relocation
has been categorically eschewed by some scientists for fear that
relocated species would overpopulate their new habitats, cause
extinctions of local species, or clog water pipes as invasive zebra
muscles have done in the Great Lakes. Nevertheless, some
conservationists and groups have already used managed relocation or
are currently considering doing so.
Do Something or Do Nothing?
So why is managed relocation, a once-taboo and potentially harmful
strategy, now being seriously considered? "Because," says Hellmann,
"it is becomingly overwhelmingly evident that climate change is a
reality; and it is fast and large. Consequences will arise within
decades, not centuries." So action seems much more important now than
it did even five or 10 years ago when atmospheric concentrations of
greenhouse gases were lower. Now, we are committed to greater degrees
of climate change."
What's more, a "do nothing" response to climate change involves
significant risks. Hellman says, "We have previously been able to say,
'let nature run its course.' But because humans have already changed
the world, there is no letting nature run its course anymore. Now,
action, like inaction, has potential negative consequences." So, adds
Richardson, "we must develop new tools and new ways to balance the
risks of inaction vs. action."
Managed relocation is not the only controversial adaptation strategy
currently being considered by scientists. Other such strategies
include fertilizing the oceans to increase their absorption of
greenhouse gases and thereby reduce climate change, conserving huge
migratory corridors that may extend thousands of kilometers, and
preserving the genetic diversity of threatened species in seed banks.
Speed Kills
Many species have survived previous, slower periods of climate change
by evolving or by moving to more hospitable habitats via their own
power. But such survival strategies are now often precluded by: 1) the
presence of cities and by other unnatural obstacles that prevent
organisms from reaching new destinations; and 2) the speed of climate
change, which may raise the Earth's average temperature by as much as
6 degrees Celsius in the next 100 years--a large, rapid change by
nature's standards.
As temperatures increase, significant percentages of the Earth's
species may become trapped--like fish out of water--in habitats that
have become too hot, too dry, or too something else for them. They may
therefore go extinct or lose genetically important segments of their
populations. Such losses may disrupt large ecosystems and damage
agricultural, cultural and economic systems.
Risky Business
The working group's consideration of managed relocation has not ended
the controversies surrounding this strategy's use, which sometimes
still even pit members of the working group against one another. Why
is managed relocation so controversial? Because it begs the question:
Do we really know enough to predict how organisms will behave in new
locations and whether they will harm receiving habitats?
"The results of intentional and accidental introductions of species
into new habitats have taught us a great deal about the implications
of moving organisms to new habitats," says Richardson. Nevertheless,
predictions of whether introduced species will 'take' in new areas and
their likely impacts will always involve uncertainty. But we can make
informed predictions with stated bounds of uncertainty."
To this end, the researchers' tool is designed to help expose managed
relocation's risks, trade-offs and costs--considerations that are
often absent from decision-making on natural resources. Specifically,
it provides stakeholders with a system for individually scoring a
proposed relocation based on multi-disciplinary criteria. These multi-
disciplinary criteria include the probability of the success of a
proposed relocation, its potential for harming receiving ecosystems,
its costs, its potential for triggering violations of the Endangered
Species Act, and the social and cultural importance of impacted
species.
Comparisons of stakeholders' scores should help stakeholders identify
the sources of their disagreements so that they may be resolved.
However, the tool does not, by itself produce management
recommendations.
"The tool takes advantage of the fact that, although science can't
tell us exactly what will happen in the future, it can tell us how
likely a favorable result is--useful information for decision-makers,"
says NSF Program Director Nancy Huntly.
Not Just Applicable to Endangered Species
In addition to addressing managed relocations of endangered species,
the researchers' tool may also address:
* Managed relocations of species that are not endangered. For
example, the working group's PNAS paper applies the tool to the debate
over whether certain species of North American hardwood trees should
be planted beyond their northern range boundaries into coniferous
forests. This application suggests that such relocations may be
supported by commercial foresters who value their high potential for
producing economic returns as well as their high feasibility and low
risk of harming recipient ecosystems. By contrast, conservationists
who value the natural heritage of recipient ecosystems may perceive
fewer benefits and greater risks.
* Controversial climate-related adaptation strategies besides
managed relocation that are currently being considered by scientists.
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