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Climate Change and Pest Risk
Analysis – Discussion and Position
Papers
Prepared by a small TAG and support
from IS and PRA Panel members
NAPPO 2012
Assignment

Prepare a discussion document on
the potential for climate change to
affect the ability of pests to spread
and establish in new areas,
including the implications for the
current PRA process.
Process
Review of climate change literature
 Review of WTO disputes regarding
pest risk assessment and technical
justification for phytosanitary
measures
 Document sent for peer review by
EPPO and Quads

An Overview of Climate Change
“Warming of the climate system is unequivocal,
as is now evident from observations of increases
in global average air and ocean temperatures,
widespread melting of snow and ice, and rising
global average sea level” (IPCC)
 According to model projections, global and
regional climate change in this century will be
characterized by higher temperatures, altered
precipitation regimes and increases in the
frequency of extreme events
 These will directly affect both human and
biological systems, including the ability of pests
and invasive species to establish and spread in
new ecosystems

Some Findings
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Global surface
temperature increases
in 11 of last 12 years
Rising sea levels decreases in snow
and ice
Observed increases in
anthropogenic
greenhouse gas
emissions
Temperature Change in North America

In the US, the average temperature has
risen more than 1 C over the last 50 years.
 In Canada, the average temperature has
increased by 1.3 C in the last century with
the northwest experiencing the most
pronounced increases.
 In Mexico, the trend over the last 10 years
indicates warming of 0.7 C.
 Increases predicted in next 100 years
between 1.8-6 C, depending on
greenhouse gas emissions.
Precipitation Change in North America

In the US, precipitation has increased an
average of about five percent in the last 50
years.
 In Canada, wet areas are generally getting
wetter, dry areas drier, and the
probabilities of both heavy rainfall and
drought have increased.
 Rising sea levels in all of North America.
Global sea levels continue to rise, causing
flooding and coastal erosion (IPCC 2007).
Climate change might affect …

Biodiversity - changes in phenology,
population dynamics of native species,
geographic ranges, and functioning of
ecosystems
 Invasive species, causing them to expand
into new ranges and affecting the risk
associated with them
– Warmer temperatures usually increase
virulence by promoting growth, reproduction,
and higher transmission rates
The challenge lies in …

Examining how the changes in climate variables
such as temperature, precipitation and increase
of atmospheric CO2, as well as extreme events,
may impact weeds, insect pests, pathogens and
host plants; and

Linking the consequences of climate change for
invasive species to the sequential stages of an
invasion process: introduction (entry +
establishment) and spread.
Climate Change Impacts on IS
Entry, establishment, spread
 Global change stressors
 Uncertainty in climatic and
bioclimatic models
 Climate change models and PRA –
issues of spatial and temporal scale
 Fit for purpose: PRA as a decision
support tool

Climate Change Effects on Entry


Invasive insects or
pathogens could be blown
into North America via
hurricanes from Africa,
South America and the
Caribbean
Other extreme events such
as floods may might result
in the ability of previously
confined aquatic species
to migrate to new areas
Larvae of Cactoblastis cactorum
Source: Ignacio Baez, USDA
The cactus moth (Cactoblastis
cactorum) provides an example of
facilitated movement by extreme
weather events for Mexico. The
arrival of the cactus moth is likely
attributable to strong winds during
the 2005 hurricane season, which
transported the insect from host
islands in the Caribbean to Mexico
Climate Change Effects on
Establishment
May lead to an increased likelihood of
pest establishment through
different mechanisms:


Species currently constrained by
short growing seasons might be
able to set fruit or compete with
resident species.
Rising winter temperature may
decrease the mortality rate of
pathogen populations, increase
the pathogen load and
consequently increase their range
and distribution.
Kudzu (Pueraria montana) is an
example of an invasive alien
plant predicted to undergo
range expansion as a result
of climate change in North
America. It is known in the
U.S. as the “plant that ate the
south”.
Climate Change Effects on Spread
Climate change might affect the
ability of pests to spread in a
variety of ways. For example:


Accelerated spread of vectors,
pests and diseases towards
the north is predicted for
temperate species, as former
climate barriers are no longer
effective
In a warming climate pests
lowland pests may move
upwards and threaten
mountain ecosystems
Tree mortality caused by Mountain pine beetle in Yellowstone
National Park.
John W. Schwandt, USDA Forest
The
mountain
pine
beetle
(Dendroctonus ponderosae)
provides an example of a
native forest pest that has
undergone range expansion
due to climate warming, in
particular due to less frequent
and
less
extreme
cold
weather events.
Fit for Purpose

Intended to help countries decide if a
particular organism is a pest, and whether
phytosanitary measures should be taken
 Process should be transparent, based on
sound science, not intended to be an
extensive exercise in scientific research
for its own sake
 Climate and bioclimatic modeling are
complex, resource- and time-intensive
Legal Considerations

To date, 5 disputes interpreting the role of
PRA to justify sanitary and phytosanitary
measures have traveled through the WTO
dispute settlement process
 In each case phytosanitary measures were
challenged and were ultimately judged to
be in violation of the SPS agreement
because of the inadequacy of the risk
analysis
Dispute Findings





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Measures chosen must be based on sufficient scientific evidence that
verify necessity
Requirement of rational relationship between the measure and the
scientific evidence means such a relationship can only be determined on a
case by case basis
Factors to be considered are not intended to be a closed list, so where
appropriate, climate change can be taken into consideration with the
caveat that there must be an ascertainable risk identified; “theoretical
uncertainty is not the kind of risk which is to be assessed”
A PRA must evaluate what is likely or probable – not what is possible
The precautionary principle is not recognized in the SPS Agreement as
grounds for justifying measures, precautionary measures can be adopted
under certain circumstances as long as these can not be considered
arbitrary or unjustified, and accordingly, a disguised barrier to trade
The “rational relationship” requirement means that a decision to include
climate change will also be done on a case by case basis, again – based
on the sufficiency of the scientific evidence.
An important, but outstanding issue is what constitutes “sufficient”
Conclusions

Climate change is occurring and could have significant effects on
both biological and human systems, and could impact the ability
of IS to spread and establish - possibly resulting in an increased
number and severity of invasions
 The interaction of climate change with the other pressures
involved in global change including trade patterns will increase
the need for PRA
 A decision to consider climate change scenarios or incorporate
complex models into a PRA will depend on feasibility, fit-forpurpose, and the rigor of the associated scientific support
 International agreements and jurisprudence indicate that PRA is
intended to provide sufficient evidence that a chosen measure(s)
is not arbitrary, unjustified, or a disguised barrier to trade
 Therefore, climate change projections within a PRA must be
sufficiently robust to meet these requirements so the role of
climate change in the conduct of PRA will need to be considered
on a case-by-case basis
Recommendations

The working group recommends that NAPPO:
– take a “fit-for-purpose” approach
– take into consideration the time and resources available,
complexity of the issue, relevance of climate to the
phytosanitary issue at hand, and whether or not there is
sufficient scientific evidence to show a causal link
– consider if the time frame for which the PRA is
considered to be “current” should be specified in the
document, with an update after a specified amount of
time
– Include a statement in the PRA about whether or not
climate change was considered along with a brief
explanation as to why or why not