Gamle Eksamener og midterms Flashcards
What are the four main categories of ecosystem services? Explain them
-Provisioning services: Services that describe the material and energy output from an
ecosystem. Examples are food (crops, fish, wild foods), fodder, raw materials (timber,
construction materials, also energy, i.e. fuel (oils, wood etc.), or medicinal resources.
-Regulating services: Services that are provided through an ecosystem acting as a
regulator/mediator. Examples are flood mitigation (of e.g. wetlands, floodplains or
mangroves), water purification (e.g. forest soils, wetlands), pollination, erosion
prevention or carbon sequestration.
-Cultural services: Values that we as humans get from the “beauty” of an ecosystem.
Examples are recreational values (tourism, also benefits for mental and physical health
of near-by natural ecosystems), aesthetic values, spiritual/religious values.
-Supporting services: These are the really basic, underlying ecosystem services.
Sometimes they are considered too basic to be assessed on their own, and their direct
value for humans can be questioned. Examples are soil formation or nutrient cycling
and habitat provision. Soil formation alone (without a provisioning service following)
has no value for us humans. On the other hand, without soil formation there would be
no provisioning services (e.g. no growth of crops). If crops grow, people therefore
assume that the underlying supporting service must be fine too.
What is the difference between use
values and non-use values?
A use value is a value that I use, it is the utility for me for using/consuming a good or a
service. This use can take place now (actual values) or it can be a value that I may
want to have for myself in the future (option value). A non-use value is the value that
people assign to goods and services even if they never have and never will use it.
The key difference is that use values are all directed towards myself having a benefit,
while non-use values are directed to other people (including future generations) (i.e.
“everyone” except myself) that will have a benefit.
What are direct use values and bequest values and into which of the categories (use/non-use) do they fall?
Direct use values are use values. They can be consumptive (e.g. me picking berries
or mushrooms) or non-consumptive (e.g. me looking at the Grand Canyon, i.e.
recreational/cultural values).
Bequest values are non-use values. They are giving me the satisfaction of knowing
that a certain value will persist for future generations (e.g. a protected area -> cultural
value).
What is the difference between LCA and footprint analysis
A Footprinting analysis usually only deals with one issue at hand (e.g. carbon footprint,
water footprint, land footprint). For a complete LCA study we always look at multiple impact categories (e.g. climate change, water consumption, toxicants, etc).
The metrics used for footprinting are often the same like at a midpoint level in LCA (e.g. CO2-equivalents, m3 of water consumed/used, m2 of land transformed etc.)
Assessments in an LCA can take place at the midpoint or endpoint level (midpoint
level: no cross-category comparisons possible, endpoint: cross-category comparisons
facilitated because of common metrics in the Areas of Protection: PDF, DALY)
One could therefore also argue that an LCA study at midpoint level is a collection of
footprinting studies.
Also, there are different ISO standards/Technical standards that standardize footprints
and LCA
What does the chemical fate model indicate?
The chemical fate indicates the chemical behaviour/distribution in the environment. For
this we often use multimedia models.
Is the chemical fate model the same for human and
ecotoxic impacts?
Yes, fate models are the same for human toxic or ecotoxic assessments. They are
unrelated to the intake, exposure or effect and only inform us about the
distribution/concentration/residence time in the environment.
How are species
sensitivity distributions used to find the effect factor of ecotoxisity impact?
Species-sensitivity distributions (SSDs) are created using information from lab tests
(ideally at least three species from three trophic levels). We use either EC50 or LC50,
the effective concentration or lethal concentration for 50% of the population. Ranking
them from most sensitive to least sensitive we can plot them and fit a curve through
them. Where 50% are affected (y-axis), we find the HC50 (hazardous concentration
where 50% of the species are affected) value on the x-axis. With this we then calculate
the effect factor as 0.5/HC50.
What is the difference between PM10 and PM2.5? Do they have different health
implications?
PM10 refers to particles with a diameter smaller than 10 μm. PM2.5 are particles with
a diameter smaller than 2.5 μm.
Yes, they can have different health implications. Fine particulate matter (PM2.5) can
reach much deeper into the human body, particles may not only be inhalable (breathed
in and then stuck in the lungs), but respirable, which means that they can also
penetrate the alveoli in the lungs and therefore reach the bloodstream. The finer the
particle is, the larger are the potential health threats.
Note that PM10 do also include PM2.5 (per definition, but in practice often the fraction
between 2.5 and 10 is meant). If students write that health implications are the same
because PM10 include PM2.5 give half the points, because then essentially there
would need to be more health implications for PM10.
Habitat loss is one of the dominant drivers of biodiversity loss. Describe
conceptually which impacts are distinguished for land use impacts.
Land use impact assessment in general models three impacts:
-Temporary impacts
-Land occupation: This occupation impact persists during the time that the land is used.
It essentially quantifies an impact because humans hinder the recovery of the
ecosystem.
-Land transformation: After the land has been abandoned the transformation impact
starts, quantifying how long it takes until the ecosystem has again reached the “natural”
state or until it has reached a new stable state. Crucial aspect here is the recovery
time.
-Permanent impacts: If the system does not reach the natural state anymore (either
due to a permanent loss of e.g. soil quality or due to a too short time horizon
considered), we will have a permanent impact, i.e. the permanent extinction/loss of
some species.
what is the modelling approach for biodiversity loss due to habitat loss?
The basic modeling approach is the species-area relationship (SAR).
The classical SAR
assumes that species only survive in the presence of natural habitat. The now used
countryside SAR takes into account that there are species that live happily ever after
in human-modified landscapes and in the absence of natural habitat.
Why is regionalization important in many LCIA models?
There are multiple reasons!
-The natural environment varies in space (and time), such as different levels of water
scarcity, different species richness, different land systems or different population
densities.
-Impacts also vary in space, due to e.g. different vulnerabilities of species or because
the impact does not distribute far. Overusing groundwater (even in wet regions) will
only have a localized impact, not a global one, for example.
-We increasingly need to asses global value chains and therefore need models that
can deal with differences in where impacts were caused. Some of the impacts happen
in developing economies, but were caused by consumption in industrialized countries,
for example.
-The technological world varies in space: processes/substances that are allowed
somewhere, may be forbidden somewhere else; there are differences in electricity
production (clean/dirty etc), etc.
-If we use regionalization we get more detailed, and more accurate results, that may
reduce our uncertainty due to spatial variation. It also allows the identification of key
processes and gives us a better understanding of the supply chains.
In LCAs there are some decisions that can be subjective. Explain some of these
issues. The transparent reporting of all the subjective and uncertain issues is crucial.
Why?
Many subjective things are related to the goal and scope definition, such as the
definition of the functional unit, the choice of system boundaries, the in-/exclusion of
parts of the life cycle/capital goods, and the selection of which environmental impacts
to consider.
Then, related to the impact assessment phase, the choice of LCIA method is
subjective, the choice of mid-/endpoints and the importance one attributes to the different safeguard subjects (human health, ecosystem quality, resources), as well as the risk perception and perception of uncertainty (short-term impacts important or long-
term impacts important).
Transparent reporting is crucial to make these subjective choices clear and document
the thinking behind them. In this way, people can understand and compare LCAs on
an informed basis. Transparent reporting enhances the trust of decision-makers and
people into LCA results and practitioners and contributes to increasing the credibility
of results. It enables other practitioners to quickly perform data quality checks
(correctness and appropriateness of assumptions and models)
CO2-equivalents. Methane has a footprint
value of 25 kgCO2-eq/kgCH4 and nitrous oxide one of 298 kgCO2-eq/kgN2O. What
does that mean?
It means that the different greenhouse gases have different climate forcing “abilities”.
For the time horizon given (usually this is 100 years and is the case for the values here
too), methane is 25 times as active as a greenhouse gas than CO2, N2O is 298 times
as active. I.e. emitting one kg of methane equals emitting 25 kg of CO2. That changes,
when we have different time horizons that we consider
What is the difference between blue, green
and grey footprint?
Green: soil moisture, i.e. precipitation that is stored in the soil instead of running off or
recharging aquifers. Green water is only relevant for plants and crops, as they are the
only ones that can take up this water. The green water footprint, which is important for
agricultural and forestry products only, is the volume of precipitation that is consumed
(evapotranspired) and incorporated into a product during a production process.
Blue: volume of direct or indirect water that has been withdrawn from surface and
groundwater sources and is now lost to the watershed of origin. Thus, the water is
either evaporated, incorporated in a product or transferred to another watershed or the
sea. -> water consumption
Grey: required volume for diluting a certain pollution in a waterbody in such a way that
agreed water quality standards are met. While the grey water footprint takes impacts
of changes in water quality into account, both the green and the blue footprint consider
quantitative aspects.
Key is that blue is surface/groundwater and essentially
water consumption, green is soil moisture at the specific location and grey is a volume
needed for dilution.
What is the disadvantage of using the carbon and water footprint only, instead of a
full LCA?
- We cannot compare other potentially relevant impacts, e.g. the impact of the fertilizer
on freshwater eutrophication cannot be assessed. This we do not know if that impact
category would perhaps be more important. - We cannot compare the relevance of the carbon footprint to the relevance of the
water footprint, since they both use different metrics. If we would perform an LCA at
endpoint level, we could compare them against each other. If we would do it on a
midpoint level we cannot, the comparison issue would persist.
