External Link 
You are leaving The Second State of the Carbon Cycle Report and will be redirected to a new site in 5 seconds.
A | B | C | D | E | F | G | H | I | L | M | N | O | P | R | S | T | U | V | W | Y
Adaptation
In human systems, the process of adjusting to an
actual or expected environmental change and its
effects in a way that seeks to moderate harm or exploit
beneficial opportunities. In natural systems, adaptation is the process of adjustment to an actual environmental change and its effects; human intervention
may facilitate adjustment to expected changes.
Aerosols
Fine solid particles or liquid droplets suspended in
air. They are produced by natural or human activities and can cause cooling by scattering incoming
radiation or by affecting cloud cover. Aerosols also
can cause warming by absorbing radiation.
Afforestation
The process of establishing trees on land that has
lacked forest cover for a very long period of time or
land that has never been forested (CCSP 2007).
Agriculture, Forestry, and
Other Land Use (AFOLU)
AFOLU plays a central role for food security and
sustainable development and is a key greenhouse gas
reporting category for national reports to the United
Nations Framework Convention on Climate Change.
The main carbon mitigation options within AFOLU
involve one or more of three strategies: 1) prevention of emissions to the atmosphere by conserving
existing carbon pools in soils or vegetation, or by
reducing emissions; 2) sequestration—increasing the
size of existing land carbon pools, thereby extracting
carbon dioxide from the atmosphere for long-term
storage; 3) substitution—substituting biological
products for fossil fuels or energy-intensive products,
thereby reducing carbon dioxide emissions. Demandside measures (e.g., reduction of food loss and waste,
changes in human diet, or changes in wood consumption) also may play a role (Mach et al., 2014).
(FOLU); Land Use, Land-Use Change, and Forestry (LULUCF); Greenhouse gas (GHG)
Albedo
The fraction of solar radiation reflected by a surface or object, often expressed as a percentage.
Snow-covered surfaces have a high albedo (highly
reflective). Soil albedos range from high to low, and
vegetation-covered surfaces and the ocean have a low
albedo (low reflectivity). Earth’s planetary albedo
varies mainly through changes in cloudiness, snow,
ice, leaf area, and land cover (Mach et al., 2014).
Algal bloom
A sudden, rapid growth of algae in lakes, estuaries,
and ocean waters caused by various factors including
warmer surface waters, increased nutrient levels, or
increased light levels. Some algal blooms may be
toxic or harmful to humans and ecosystems.
Anoxic
A lack of oxygen, usually referring to soils, wetlands,
lakes, estuaries, and ocean waters.
Anthropogenic
Caused or influenced by humans; human-induced
(CCSP 2007).
Atmospheric column
On average, a column of air with a cross-sectional
area of 1 cm2, measured from mean (average)
sea level to the top of Earth’s atmosphere. The
>column has a mass of about 1.03 kg and exerts a
force or “weight” of about 10.1 newtons (N) or
2.37 pounds, resulting in a pressure at sea level of
about 10.1 N/cm2 or 101 kilonewtons (kN)/m2
(101 kilopascals, kPa).
Biodiversity
The variety of life, including the number of plant
and animal species, other life forms, genetic types,
habitats, and biomes in an ecosystem.
Bioenergy
A form of renewable energy produced from plant
and animal biomass.
Bioenergy with Carbon Capture
and Storage (BECCS)
A greenhouse gas mitigation technology that
reduces carbon dioxide emissions by combining the
use of biomass with geological carbon capture and
storage (CCS).
Biofuel
Fuel produced from plant or animal matter.
Biogenic emissions
Gaseous emissions from natural sources (e.g., plants,
soils, and water bodies).
Biogeochemical cycles
Fluxes, or flows, of chemical elements between Earth’s
different carbon reservoirs, such as from living to nonliving, from atmosphere to land or ocean, from plants
to dead organic matter in soils, and from decomposition of organic matter into carbon-containing gases.
Biomass
The mass of living organisms or the material derived
from organisms.
Biome
The community of fauna and flora occupying a particular habitat (e.g., Arctic tundra and wetlands).
Biosphere
Parts of the Earth’s surface in which living organisms
reside.
Black carbon
Soot produced from incomplete combustion of
biomass-based materials, such as coal burning,
diesel engines, cooking fires, wildfires, and other
combustion sources.
Bottom-up method (for estimating
greenhouse gas emissions)
Extrapolation of measurements from a single facility
or source to larger scales (e.g., regional, national, and
global) to produce a bottom-up estimate. Bottom-up
approaches also can involve the use of activity data
and emissions factors or process-based models.
C3 plant
A plant that uses the Calvin-Benson pathway for
“fixing” carbon dioxide, such as during photosynthesis. C3 refers to the 3-carbon molecule that is the first
product of this type of carbon fixation (i.e., living
organisms changing inorganic carbon dioxide to
organic compounds).
C4 plant
A plant that uses the Hatch-Slack pathway for “fixing” carbon dioxide during photosynthesis. C4 refers
to the 4-carbon molecule that is the first product of
this type of carbon fixation.
Carbon allocation
Carbon allocation refers to the partitioning of
carbon through different parts of a plant (e.g., stem,
roots, and leaves).
Carbon capture and storage (CCS)
The process of capturing carbon and injecting it (as
carbon dioxide) into geological formations underground or in the deep ocean for long-term storage.
Carbon cycle
The series of processes by which carbon compounds flow among reservoirs in the environment,
such as the incorporation of carbon dioxide into
living tissue by photosynthesis and its return to the
atmosphere through respiration, the decay of dead
organisms, and the burning of fossil fuels. In the carbon cycle, carbon flow or output from one reservoir
transfers carbon to other reservoir(s).
Carbon dioxide (CO2)
A naturally occurring gas, also a by-product of
burning fossil fuels from fossil carbon deposits,
such as oil, natural gas, and coal; burning biomass;
land-use changes; and industrial processes (e.g.,
cement production). Carbon dioxide is the principal
anthropogenic greenhouse gas that affects Earth’s
radiative balance. As the reference gas against which
other greenhouse gases are measured, it has a global
warming potential of 1.
Carbon dioxide equivalent (CO2e)
The amount of a gas that would produce the same
effect as CO2 on the radiative balance of Earth’s climate system; applicable in this report to greenhouse
gases such as methane and nitrous oxide. Outside
this report, aerosols and black carbon also influence
global warming potential, but translating them to
CO2e values is difficult. The effect on the radiative
balance is referred to as the global warming potential, and the time frame over which it is calculated is
important because each gas or particle has a different average residence time in the atmosphere. In this
report, the time frame over which CO2e is calculated
is assumed to be 100 years, although other time
frames may be specified.
Carbon dioxide (CO2) fertilization
The enhancement of plant growth resulting from
increased atmospheric CO2 concentration (Mach
et al., 2014).
Carbon fixation
In this process, also called carbon assimilation, a
living organism converts carbon dioxide into an
organic compound, such as in photosynthesis.
Carbon flux
Refers to the direction and rate of transfer, or flows,
of carbon between pools.
stock
Carbon pool
A compartment, or reservoir, within the Earth system where carbon can be taken up, stored, and/or
released within a carbon budget.
Carbon reservoir
A compartment, or pool, within the Earth system
where carbon can be taken up, stored, and/or
released within a carbon budget.
Carbon sequestration
Storage of carbon through natural, deliberate, or
technological processes in which carbon dioxide is
diverted from emissions sources or removed from the
atmosphere and stored biologically in the ocean and
terrestrial environments (e.g., vegetation, soils, and
sediment), or in geological formations (USGS.gov).
Carbon sink
A compartment within the Earth system that acquires
carbon from the atmosphere and stores it for a specified period of time.
Carbon source
A compartment within the Earth system that releases
carbon to the atmosphere.
Carbon stock
The mass of carbon contained within a particular
compartment, or pool, within the Earth system.
Climate
Climate, in a narrow sense, is usually defined as the
average weather, or, more rigorously, as the statistical
description in terms of the mean and variability of
defining factors over a period of time ranging from
months to thousands or millions of years. The classical period for averaging these variables is 30 years, as
defined by the World Meteorological Organization.
The relevant quantities are most often surface variables such as temperature, precipitation, and wind.
Climate, in a wider sense, is the state, including a
statistical description, of the climate system (modified from Mach et al., 2014).
Climate change
Changes in average weather conditions that persist
over multiple decades or longer. Climate change
encompasses both increases and decreases in temperature, as well as shifts in precipitation, changes in
frequency and location of severe weather events, and
changes to other features of the climate system.
Climate feedback
An interaction in which a perturbation in one climate quantity causes a change in a second quantity,
with the change in this second quantity ultimately
leading to an additional change in the first. A negative feedback is one in which the initial perturbation
is weakened by the changes it causes; a positive
feedback is one in which the initial perturbation is
enhanced (Mach et al., 2014).
Climate model
A numerical representation of the climate system
based on the physical, chemical, and biological
properties of its components, their interactions, and
feedback processes and accounting for some of its
known properties. The climate system can be represented by models of varying complexity; that is, for
any one component or combination of components,
a spectrum or hierarchy of models can be identified,
differing in such aspects as the number of spatial
dimensions; the extent to which physical, chemical,
or biological processes are explicitly represented;
or the level at which empirical parameterizations
are involved. Coupled atmosphere-ocean general
circulation models provide a representation of the
climate system that is near or at the most comprehensive end of the spectrum currently available.
There is an evolution toward more complex models
with interactive chemistry and biology. Climate
models are applied as a research tool to study and
simulate the climate and for operational purposes,
including monthly, seasonal, and interannual climate
predictions (Mach et al., 2014).
Climate projection
The simulated response of the climate system to a
scenario of future emissions or concentrations of
greenhouse gases and aerosols, generally derived
using climate models. Climate projections are distinguished from climate predictions by their dependence on the emissions, concentration, or radiative
forcing scenario used, which, in turn, is based on
assumptions concerning, for example, future socioeconomic and technological developments that may
or may not be realized (Mach et al., 2014).
Climate variability
Natural changes in climate that fall within the
observed range of extremes for a particular region,
as measured by temperature, precipitation, and
frequency of events. Drivers of climate variability
include the El Niño–Southern Oscillation and other
phenomena.
Coastal ocean
The portion of the ocean that is influenced by land.
Definitions vary considerably. In this report, the
coastal ocean is defined as nonestuarine waters
within 200 nautical miles (370 km) of the coast.
Co-benefits
The positive effects that a policy or measure aimed
at one objective might have on other objectives,
irrespective of the net effect on overall social welfare.
Co-benefits are often subject to uncertainty and
depend on local circumstances and implementation
practices, among other factors. Co-benefits also are
referred to as ancillary benefits (Mach et al., 2014).
Continental shelves
The submerged margins of the continental plates,
operationally defined in this report as regions with
water depths shallower than 200 m.
Coupled Model Intercomparison
Project (CMIP)
The Coupled Model Intercomparison Project is
a standard experimental protocol for studying
the output of coupled atmosphere-ocean general
circulation models. Phases three and five (CMIP3
and CMIP5, respectively) coordinated and archived
climate model simulations based on shared model
inputs by modeling groups from around the world.
The CMIP3 multimodel dataset includes projections using the scenarios drawn from the Intergovernmental Panel on Climate Change’s Special Report
on emissions scenarios. The CMIP5 dataset includes
projections using the Representative Concentration
Pathways (edited from Mach et al., 2014).
Cryosphere
All regions on and beneath the surface of the Earth
and ocean where water is in solid form, including
sea ice, lake ice, river ice, snow cover, glaciers, ice
sheets, and frozen ground (e.g., permafrost) (Mach
et al., 2014).
Deforestation
The process of removing or clearing trees from
forested land with lasting conversion of that land to
nonforest (CCSP 2007).
Denitrification
The microbial reduction of nitrate to dinitrogen gas
and nitrous oxide.
Dissolved inorganic carbon (DIC)
The sum of inorganic oxidized carbon species in a
solution, including carbon dioxide, carbonic acid,
bicarbonate anions, and carbonate anions.
Dissolved organic carbon (DOC)
Dissolved organic carbon refers to the sum of organic
reduced carbon species in a solution (e.g., organic
and humic acids). Dissolved organic matter (DOM)
refers to the entire chemical compound, while DOC
refers only to the carbon fraction. Both DOM and
DOC typically are operationally defined as less than
0.45 micrometers and thus may include chemical
species that are colloidal and not truly dissolved.
Downscaling
A method that derives local- to regional-scale (10 to
100 km) climate information from larger-scale
models or data analyses. Two main methods exist.
Dynamical downscaling uses the output of regional
climate models, global models with variable spatial
resolution, or high-resolution global models. Empirical or statistical downscaling methods develop
statistical relationships that link the large-scale atmospheric variables with local or regional climate variables. In all cases, the quality of the driving model
remains an important limitation on the quality of the
downscaled information (Mach et al., 2014).
Drought
A period of abnormally dry weather marked by
little or no rain that lasts long enough to cause water
shortage for people and natural systems.
Earth System Model (ESM)
A coupled atmosphere-ocean general circulation
model in which a representation of the carbon cycle
is included, allowing for interactive calculation of
atmospheric carbon dioxide or compatible emissions. Additional components (e.g., atmospheric
chemistry, ice sheets, dynamic vegetation, nitrogen
cycle, and urban or crop models) may be included
(Mach et al., 2014).
Ecosystem
A functional unit consisting of living organisms,
their nonliving environment, and the interactions within and between them. The components
included in a given ecosystem and its spatial boundaries depend on the purpose for which the ecosystem is defined. In some cases, ecosystem boundaries
are relatively sharp, while in others they are diffuse,
and they can change over time. Ecosystems are
nested within other ecosystems, and their scale
can range from very small to the entire biosphere.
In the current era, most ecosystems either contain
people as key organisms, or they are influenced by
the effects of human activities in their environment
(Mach et al., 2014).
Ecosystem services
The benefits produced by ecosystems on which
people depend, including, for example, fisheries,
drinking water, fertile soils for growing crops, climate regulation, and aesthetic and cultural value.
Ecotone
A region of transition between two biological communities or biomes.
Edaphic
Produced by or influenced by the soil. Edaphic qualities may refer to characteristics of the soil itself (e.g.,
texture or chemical properties). Edaphic qualities
also may refer to other ecosystem compartments
such as microbial or plant communities that are
influenced by soil properties.
Efficiency gap
The difference between a predicted rate of an
economically attractive purchase of more efficient
technology and lower actual realized adoption rates.
El Niño–Southern Oscillation (ENSO)
A natural interaction between surface air pressure
and surface water temperature in the tropical Pacific
Ocean. ENSO has two phases: the warm oceanic
phase, El Niño, accompanies high surface air pressure in the western Pacific, while the cold phase, La
Niña, accompanies low surface air pressure in the
western Pacific. Each phase generally lasts 6 to 18
months. ENSO events occur irregularly, about every
3 to 7 years. The extremes of this climate oscillation cause extreme weather (such as floods and
droughts) in many regions of the world.
Embedded carbon
Carbon fluxes resulting from the production of
goods or services typically consumed.
Embeddedness of carbon
The condition that carbon is an integral but often
invisible part of how people lead their lives, so they
do not think of themselves as using carbon but
instead see the services and products without seeing
their embedded carbon.
Embodied carbon
Carbon residing in material typically released to
the atmosphere upon decay or disintegration (e.g.,
cardboard and construction lumber).
Emissions scenarios
Quantitative illustrations of how the release of different amounts of climate-altering gases and particles into the atmosphere from human and natural
sources will produce different future climate conditions. The Intergovernmental Panel on Climate
Change developed a Special Report on emissions
scenarios (IPCC 2000) using a wide range of
assumptions about population growth, economic
and technological development, and other factors.
An A1B emissions scenario is a medium future emissions scenario in which greenhouse gas emissions
increase, with reductions in the rate of increase in
emissions after 2070. An A2 emissions scenario is a
high future emissions scenario assuming continued
increases in greenhouse gas emissions. The B1 emissions scenario is a lower future emissions scenario
in which emissions are reduced rapidly and substantially. The B2 emissions scenario is a low future
emissions scenario in which emissions are reduced
substantially, but not as rapidly as B1.
Energy end use
Energy used for services such as transportation,
cooking, indoor thermal comfort, refrigeration, and
illumination.
Energy intensity
The ratio of energy use to economic or physical
output (Mach et al., 2014).
Energy supply
The processes for extracting energy resources and
converting them into more desirable and suitable
forms of secondary energy, and for delivering energy
to places where demand exists (Grubler et al., 2013).
Energy systems
The infrastructure and systems of electricity production, transport, storage, and consumption.
Enteric methane
Methane generated in the gastrointestinal tract;
the term is predominantly used to denote methane
originating from microbial fermentation in the
pregastric compartments of the digestive system of
ruminant animals.
Environmental justice
The fair treatment and meaningful involvement of
all people regardless of race, color, national origin,
or income with respect to the development, implementation, and enforcement of environmental laws,
regulations, and policies.
Estuary
A body of water in which river water and ocean
water mix. The landward boundary of an estuary is
defined in this report as the location (also known as
the head-of-tide) where tidal fluctuations become
very small. The seaward boundary of an estuary is
less clearly defined, but it may be determined based
on salinity, bathymetry, or coastline position.
Eutrophication
Enrichment of water by nutrients such as nitrate,
ammonia, and phosphate, and thus supporting a
dense concentration of primary producers, resulting
in an increase in primary production. It is one of the
leading causes of water quality impairment. The two
most acute symptoms of eutrophication are hypoxia
(a state of oxygen depletion) and harmful algal
blooms (Mach et al., 2014).
Evapotranspiration
Evaporation of water from soils, plants, and free
water surfaces exposed to the atmosphere.
Exclusive Economic Zone (EEZ)
A zone in the ocean typically extending 200 km or
less away from the coast of a nation. Oceanic carbon
dioxide uptake or loss is not credited to any nation
under Intergovernmental Panel on Climate Change
carbon dioxide accounting rules.
Extreme event
A weather event that is rare at a particular place and
time of year, including, for example, heatwaves, cold
waves, heavy rains, periods of drought and flooding,
and severe storms. Definitions of rare vary, but an
extreme weather event would normally be as rare
as or rarer than the 10% or 90% probability density
function estimated from observations. By definition,
the characteristics of what is called extreme weather
may vary from place to place in an absolute sense
(Mach et al., 2014).
Feedback
The process through which a system is controlled,
changed, or modulated in response to its own
output. Positive feedback results in amplification of
the system output; negative feedback reduces the
output of a system.
Energy transported and distributed to the point of
retail for delivery to final users (e.g., firms, individuals, or institutions; Grubler et al., 2013).
First Nations
Indigenous communities in Canada.
Food security
When all people always have both physical and economic access to sufficient food to meet their dietary
needs for a productive and healthy life.
Forcing
A perturbation to a factor that affects Earth’s climate.
For example, both volcanoes and humans emit
heat-trapping gases and particles through volcanic emissions and through fossil fuel combustion,
respectively, which can perturb Earth’s climate.
Forestry and Other Land Use (FOLU)
The subset of Agriculture, Forestry, and Other Land
Use (AFOLU) emissions and removals of greenhouse gases resulting from direct human-induced
land use, land-use change, and forestry activities
excluding agricultural emissions (Mach et al., 2014).
Fossil fuels
Fuels such as coal, petroleum, and natural gas
derived primarily from the chemical and physical
transformation (fossilization) of the remains of
plants and animals that lived during previous times
(CCSP 2007).
Fugitive emissions
Emissions of gases or vapors from pressurized
equipment due to leaks and other unintended or
irregular releases, typically from industrial, drilling,
or mining activities. Fugitive emissions contribute to
air pollution and climate change (e.g., methane gas
is readily lost during transport through pipelines or
during oil drilling activities), as well as the economic
cost of lost commodities.
Geoengineering
Intentional modifications of the Earth system, usually technological, to reduce future climate change.
Global change
Changes in the global environment. Global change
encompasses climate change, but it also includes
other critical drivers of environmental change that
may interact with climate change, such as land-use
change, alteration of the water cycle, changes in
biogeochemical cycles, and biodiversity loss. Global
change may alter the capacity of the Earth to sustain
life.
Global warming
The observed increase in average temperature near
Earth’s surface and in the lowest layer of the atmosphere. In common usage, global warming often
refers to the warming that has occurred because of
increased emissions of greenhouse gases from human
activities. Global warming is a type of climate change;
it also can lead to other changes in climate conditions,
such as changes in precipitation patterns.
Global warming potential (GWP)
An index, based on radiative properties of different
greenhouse gases, measuring the radiative forcing
following a pulse emission of a unit mass of a given
greenhouse gas in the present-day atmosphere
integrated over a chosen time horizon, relative to
the radiative forcing of carbon dioxide. The carbon
dioxide GWP is 1. A GWP represents the combined
effect of the differing times a given gas remains
in the atmosphere and its relative effectiveness in
causing radiative forcing over a specified time frame.
In this report, the time frame is assumed to be 100
years, but it may be specified according to other
time frames (truncated from Mach et al., 2014).
Governance
The processes and structures that steer society and
the multiplicity of actors who are involved. Institutional arrangements of governance comprise the sets
of rules, norms, and shared practices that underlie
decision making.
Greenhouse gas (GHG)
Gases that absorb heat in the atmosphere near
Earth’s surface, preventing it from escaping into
space. If the atmospheric concentrations of these
gases rise, the average temperature of the lower
atmosphere will gradually increase, a phenomenon
known as the greenhouse effect. Greenhouse gases
include, for example, carbon dioxide, nitrous oxide,
water vapor, and methane.
The gross uptake of carbon dioxide through photosynthesis.
Halocarbon
A chlorofluorocarbon or other compound in which
the hydrogen of a hydrocarbon is replaced by halogens (i.e., group VIIA of the periodic table including
fluorine, bromine, and chlorine).
Hydrocarbon
A compound composed of hydrogen and carbon
(e.g., petroleum products and fossil fuels).
Hypoxia
Deficiency of oxygen in water bodies defined as
oxygen concentrations less than 2 milligrams per
liter. Hypoxia can be a symptom of eutrophication
(nutrient overloading). Deoxygenation (the process of removing oxygen) leads to hypoxia and the
expansion of oxygen minimum zones (modified
from Mach et al., 2014).
Ionophore
Ionophores are feed additives used in cattle diets
to increase feed efficiency and body weight gain.
They are compounds that alter rumen fermentation
patterns. Ionophores can be fed to any class of cattle
and can be used in any segment of the beef cattle
industry (Hershom and Thrift 2012).
An observation or calculation that allows scientists, analysts, decision makers, and others to track
>environmental trends, understand key factors that
influence the environment, and identify effects on
ecosystems and society.
Indigenous communities
Those who, having a historical continuity with
preinvasion and precolonial societies that developed
on their territories, consider themselves distinct
from other sectors of the societies now prevailing
on those territories, or parts of them. They form at
present nondominant sectors of these societies and
are determined to preserve, develop, and transmit
to future generations their ancestral territories and
ethnic identities, as the basis of their continued
existence as peoples, in accordance with their own
cultural patterns, social institutions, and legal system
(Mach et al., 2014).
Indirect fluxes
Fluxes associated with energy used to create or
deliver electricity, products, or services consumed in
a given area or the carbon flux associated with waste
decay or removal of material to the waste stream.
Inland waters
Open-water systems of lakes, reservoirs, nontidal
rivers, and streams in noncoastal environments.
Integrated assessment
A method of analysis that combines results and models (e.g., Integrated Assessment Models) from the
physical, biological, economic, and social sciences
and the interactions among these components in a
consistent framework to evaluate the status and consequences of environmental change and the policy
responses to it (Mach et al., 2014).
La Niña
A natural interaction between surface air pressure
and surface water temperature in the tropical Pacific
Ocean. El Niño–Southern Oscillation (ENSO) has
two phases: the cold phase, La Niña, accompanies
low surface air pressure in the western Pacific, while
the warm oceanic phase, El Niño, accompanies high
surface air pressure in the western Pacific. Each
phase generally lasts 6 to 18 months. ENSO events
occur irregularly, about every 3 to 7 years. The
extremes of this climate oscillation cause extreme
weather (such as floods and droughts) in many
regions of the world.
Land cover
The physical characteristics of the land surface such
as crops, trees, or concrete.
Land use
Activities taking place on land, such as growing
food, cutting trees, or building cities.
Leakage
Can refer to leakage of methane or other gases
during drilling and storage and during transfers
through pipelines. Leakage also can refer to the situation in which a carbon sequestration activity (e.g.,
tree planting or avoided deforestation) on one piece
of land inadvertently, directly or indirectly, triggers
an activity, which in whole or in part counteracts the
carbon effects of the initial activity (modified from
CCSP 2007).
Lock-in
Occurs when a market is stuck with a standard
even though participants would be better off with
an alternative. In this report, lock-in is used more
broadly as path dependence, which is the generic
situation where decisions, events, or outcomes at
one point in time constrain adaptation, mitigation,
or other actions or options at a later point in time
(Mach et al., 2014).
Land Use, Land-Use Change, and Forestry (LULUCF)
Land Use, Land-Use Change, and Forestry
(LULUCF)—also referred to as FOLU (Forestry
and Other Land Use)—is the subset of Agriculture,
Forestry, and Other Land Use (AFOLU) emissions
and removals of greenhouse gases resulting from
direct, human-induced land use, land-use change,
and forestry activities excluding agricultural emissions (Mach et al., 2014).
Marine boundary layer
The marine atmospheric boundary layer is the part of
the atmosphere that has direct physical and material
interaction with the ocean and, hence, is directly influenced by the ocean. Thus, the marine boundary layer
is where the ocean and atmosphere exchange large
amounts of heat, moisture, and momentum, primarily
via turbulent transport (Sikora and Ufermann 2004).
Mesosphere
The layer of Earth’s atmosphere directly above the
stratosphere. Boundaries vary with season and
latitude, beginning approximately 50 to 65 km above
Earth’s surface and extending to about 85 to 100 km.
Mitigation
Measures to reduce the amount and rate of
future climate change by reducing emissions of
heat-trapping gases or removing carbon dioxide
from the atmosphere.
Monomictic lake
A lake that is mixed from top to bottom during one
mixing period per year. Monomictic lakes are found
in both warm and cold regions.
Native American
Member of an Indigenous community in the American continents.
Net ecosystem carbon balance (NECB)
The net rate of carbon accumulation in (or loss from
[negative sign]) ecosystems. NECB represents the
overall ecosystem carbon balance from all sources
and sinks—physical, biological, and anthropogenic
(Chapin et al., 2006).
Net ecosystem exchange (NEE)
The net flux of carbon dioxide to the land from the
atmosphere. Positive values refer to carbon released
to the atmosphere (i.e., a source), and negative
values refer to carbon uptake (i.e., a sink; Hayes and
Turner 2012).
Net ecosystem production (NEP)
The net carbon imbalance within an ecosystem
between uptake of carbon dioxide from gross
primary production and release of carbon dioxide
from autotrophic and heterotrophic respiration; by
convention, positive NEP values represent net carbon dioxide uptake by the ecosystem, and negative
values represent the net release of carbon dioxide
(Chapin et al., 2006).
Net primary production (NPP)
The net uptake of carbon dioxide by plants through
gross primary production in excess of losses from
plant, or autotrophic, respiration (CCSP 2007).
Nutrients
Chemicals such as nitrate, ammonium, and phosphate that plants and animals need to live and grow.
At high concentrations, particularly in water, nutrients can become pollutants.
Nutrient-use efficiency
Nutrient-use efficiency usually is measured in terms
of yield per concentration of added nutrients. The
concept is most applicable to agricultural situations
but can refer to any plant.
Ocean acidification
The process by which the pH measurement of ocean
water has moved toward more acidic levels due to
the absorption of human-produced carbon dioxide,
which interacts with ocean water to form carbonic
acid, thereby lowering the pH. Increased acidity
reduces the ability of plankton and shelled animals
to form and maintain carbonate-containing body
parts such as shells.
Ozone
A colorless gas consisting of three atoms of oxygen,
readily reacting with many other substances. Ozone
in the upper atmosphere protects Earth from harmful levels of ultraviolet radiation from the sun. In
the lower atmosphere, ozone is an air pollutant with
harmful effects on human health.
Particulate organic carbon (POC)
Colloidal particles of organic carbon in a solution,
typically operationally defined as being greater
than 0.45 micrometers. Particulate organic matter
(POM) refers to the entire chemical compound,
while POC refers only to the elemental carbon
fraction.
Pathogen
Microorganisms, such as a bacteria or viruses, that
cause disease.
Peatlands
Areas having a soil organic layer thickness of at least
40 cm (CCSP 2007).
Permafrost
Ground that remains at or below freezing (0oC) for
at least two consecutive years.
pH
A dimensionless measure of the acidity of water (or
any solution) given by its concentration of hydrogen
ions (H+). pH is measured on a logarithmic scale
where pH = –log10(H+), where the concentration
of hydrogen ions is measured in units of moles per
liter. Thus, a pH decrease of 1 unit corresponds to
a 10-fold increase in the concentration of H+, or
acidity (Mach et al., 2014).
Phenology
The pattern of seasonal life cycle events in plants
and animals, such as timing of blooming, hibernation, and migration.
Photosynthesis
The process by which green plants, algae, and other
organisms use sunlight to synthesize energy from
carbon dioxide and water. Photosynthesis in plants
generally involves the green pigment chlorophyll,
consumes carbon dioxide and water, and generates
oxygen as a by-product.
Phytoplankton
Microscopic plants that live in salt water and freshwater environments.
Planetary boundary layer
The lowest part of the atmosphere. The layer has
direct physical and material interaction with a planetary surface.
Primary energy
Energy extracted or captured directly from resources
as they exist in nature. Primary energy is typically
divided into three distinct groups: nonrenewable
energy (e.g., fossil fuels such as coal, crude oil, natural gas, and other fuels such as nuclear); renewable
energy (e.g., hydropower, biomass, solar energy,
wind, geothermal, and ocean energy); and waste. Primary energy is not used directly but is converted and
transformed into secondary energy such as electricity and fuels such as gasoline, jet fuel, or heating oils.
Priming
Priming or the “priming effect” is said to occur when
something added to soil or compost affects the rate of
microbial decomposition of soil organic matter, either
positively or negatively. Organic matter is made up
mostly of carbon and nitrogen, so adding a substrate
containing certain ratios of these nutrients to soil may
affect the microbes that are mineralizing soil organic
matter. Fertilizers, plant litter, detritus, and carbohydrate exudates from living roots potentially can
positively or negatively prime SOM decomposition.
Proven reserves (coal, oil, shale,
and natural gas)
Reserves of fossil fuels in the Earth that are economically profitable to recover using current technologies.
Proxy
Indirect measurement of climate aspects. Examples
of proxy data are biological or physical records from
ice cores, tree rings, and soil boreholes.
Radiative effects, radiative forcing
The change in the net (downward minus upward)
radiative flux (expressed in watts per m2 (W/m2) at
the tropopause or top of the atmosphere caused by a
change in an external driver of climate change, such as a
change in the concentration of carbon dioxide or in the
output of the sun (truncated from Mach et al., 2014).
Rebound effect
The case in which expected savings from technology
adoption may not be realized because of choices,
behaviors, and intervening developments not predicted by efficiency intervention planners.
Reforestation
The process of establishing a new forest by planting
or seeding trees in an area where trees have previously been removed.
Representative Concentration
Pathway (RCP)
Scenarios that include time series of emissions
scenarios and concentrations of the full suite of
greenhouse gases, aerosols, and chemically active
gases, as well as land use and land cover. The word
“representative” signifies that each RCP provides
only one of many possible scenarios that would lead
to the specific radiative forcing characteristics. The
term “pathway” emphasizes that of interest are not
only the long-term concentration levels, but also the
trajectory taken over time to reach that outcome.
RCPs usually refer to the portion of the concentration pathway extending up to the year 2100. Four
RCPs produced from Integrated Assessment Models
were selected from the published literature for use in
the Intergovernmental Panel on Climate Change Fifth
Assessment Report: RCP2.6, a pathway whereby radiative forcing peaks at approximately 3 watts per m2
(W/m2) before 2100 and then declines; RCP4.5 and
RCP6.0, two intermediate stabilization pathways in
which radiative forcing is stabilized at approximately
4.5 W/m2 and 6.0 W/m2, respectively, after 2100;
and RCP8.5, a high emissions pathway for which
radiative forcing reaches greater than 8.5 W/m2 by
2100 and continues to rise for some amount of time
(truncated and adapted from Mach et al., 2014).
Resilience
The capacity of social, economic, and environmental
systems to cope with a hazardous event, trend, or disturbance. It is measured in ways that systems respond
or reorganize to maintain their essential function,
identity, and structure, while also maintaining the
capacity for adaptation, learning, and transformation
(truncated and adapted from Mach et al., 2014).
Respiration
Metabolic pathways that break down complex
molecules to release chemically stored energy for
maintenance, growth, and reproduction, resulting in
the release of waste products such as carbon dioxide,
nitrous oxide, or methane.
Rhizosphere
The environment in soils near the root zone of
plants.
Risk
Threats to life, health, and safety; the environment;
economic well-being; and other things of value.
Risks are evaluated in terms of how likely they are
to occur (probability) and the damages that would
result if they did happen (consequences).
Rumen
The largest segment of ruminant animals’ complex
stomach, in which methanogenic archaea generate
methane (predominantly) from hydrogen and carbon dioxide.
Scenario
Set of assumptions used to help understand plausible future conditions such as population growth,
land use, and sea level rise. Scenarios are neither
predictions nor forecasts, and they are commonly
used for planning purposes.
Sink
A physical location where carbon is removed from
the atmosphere and stored, either through natural or
technological processes. Entire ecosystems, specific
ecosystem components (e.g., forest and soil), or
political boundaries may be characterized as a sink.
Snowpack
Snow that accumulates over winter and slowly melts
to release water in spring and summer.
Social network analysis
A method that maps the connections among people
who have links to one another in a common area of
concern.
Social practice theory
A perspective that focuses on activities engaged in
by people to accomplish goals as a principal way of
understanding behavior in a social context.
Socioecological systems
Nested, multilevel systems that provide essential ser- vices to society such as supply of food, fiber, energy,
and drinking water (Berkes and Folke 1998).
Sociotechnical transitions analysis
A method that includes both social and technical
aspects for understanding why technological change
occurs and whether change can be steered and
accelerated.
Soil organic carbon (SOC)
The organic carbon content of soil organic matter
(SOM). SOM and SOC in soil result from an imbalance between the supply of raw materials, such as
plant, microbial, and animal parts, and the decay of
those materials by the soil microbial community.
Soil organic matter (SOM)
Organic material (e.g., carbon and other elements
such as nitrogen in soils). SOM results from an
imbalance between the supply of raw materials such
as plant, microbial, and animal parts and the decay
of those materials by the soil microbial community.
SOM forms the basis of life on Earth, enabling persistence and growth of the entire biosphere and can
be considered in terms of its carbon content (e.g.,
soil organic carbon).
Source
A physical location from which carbon is released
to the atmosphere, either through natural or technological processes. Entire ecosystems, specific ecosystem components (e.g., forest or soil), or political
boundaries may be characterized as a source.
Stakeholder
An individual or group that is directly or indirectly
affected by or interested in the outcomes of decisions.
Stomatal conductance
The rate of passage of carbon dioxide entering, or
water vapor exiting, through the stomata (pores) of
a leaf.
Storm surge
The temporary increase, at a particular locality, in
the height of the sea due to extreme meteorological
conditions (low atmospheric pressure and/or strong
winds). The storm surge is defined as being the
excess above the level expected from the tidal variation alone at that time and place (Mach et al., 2014).
Stratification
The layering of water by temperature and salinity,
which affect the density of water. Layering can occur
in ocean waters, estuaries, lakes, and other water
bodies, and it may be long term or undergo seasonal
changes.
Stratosphere
The second major layer of Earth’s atmosphere,
residing above the troposphere and below the
mesosphere. Near the equator, the stratosphere
starts at 18 km; at midlatitudes, it starts at 10 to
13 km and ends at 50 km; at the poles, it starts at
about 8 km.
Stressor
A factor that affects people and natural, managed,
and socioeconomic systems. Multiple stressors can
have compounded effects, such as when economic
or market stress combines with drought to negatively impact farmers.
Surface energy balance
A statement of the conservation of energy applied
to a given surface. For Earth’s surface, the main
terms are the vertical fluxes into or out of the
surface due to net radiation, sensible heat, and
latent heat, as well as the net horizontal fluxes of
energy that may take place below the surface (e.g.,
due to ocean currents). Any nonzero residual flux
typically is applied as a storage term, increasing or
decreasing the internal energy below the surface
and usually resulting in an associated change of
surface temperature (AMS 2018).
Thermohaline circulation
A part of the large-scale ocean circulation that is
driven by global density gradients created by surface
heat and freshwater fluxes.
Thermokarst
The process by which characteristic landforms result
from the thawing of ice-rich permafrost or the melting of massive ground ice (Mach et al., 2014).
Threshold
The value of a parameter summarizing a system, or
a process affecting a system, at which a qualitatively
different system behavior emerges. Beyond this
value, the system may not conform to statistical
relationships that described it previously. For example, beyond a threshold level of ocean acidification,
wide-scale collapse of coral ecosystems may occur
(USGCRP 2017).
Tipping point
The point at which a change in the climate triggers
a significant environmental event, which may be
permanent, such as widespread bleaching of corals
or the melting of very large ice sheets.
Top-down method (for estimating
greenhouse gas emissions)
Approaches based on atmospheric measurements
that are directed toward estimating emissions from
regions that could include multiple facilities (Heath
et al., 2015).
Traditional knowledge
The knowledge, innovations, and practices of Indigenous and local communities around the world.
Developed from experience gained over the centuries and adapted to the local culture and environment, traditional knowledge generally is transmitted
orally from generation to generation and often is
used as a synonym for Indigenous or local knowledge (Mach et al., 2014).
Transpiration
The evaporation of water through plant leaves.
Trend
A systematic change over time (CCSP 2007).
Troposphere
The lowest region of the atmosphere, extending
from Earth’s surface to a height of about 6 to 18 km,
which is the lower boundary of the stratosphere.
The troposphere is the lowest layer of Earth’s atmosphere where nearly every weather condition takes
place. It contains approximately 75% of the atmosphere’s mass and 99% of the total mass of water
vapor and aerosols.
Tundra
A type of biome common to extreme northern
latitudes where tree growth is inhibited by low temperatures and short growing seasons.
Uncertainty
An expression of the degree to which a quantity
or process is unknown. In statistics, a term used to
describe the range of possible values around a best
estimate, sometimes expressed in terms of probability or likelihood. Uncertainty about the future
climate arises from the complexity of the climate
system and the ability of models to represent it, as
well as the inability to predict the decisions that
society will make. There also is uncertainty about
how climate change, in combination with other
stressors, will affect people and natural systems.
United Nations Framework Convention
on Climate Change (UNFCC)
An international environmental treaty adopted on
May 9, 1992, and ratified on March 21, 1994. The
objective of the UNFCC is to stabilize greenhouse
gas concentrations in the atmosphere at a level that
would prevent dangerous anthropogenic interference with the climate system.
Unproven reserves
Reserves of fossil fuels in the Earth that are economically unprofitable to recover using current
technologies.
Urban heat island effect
The tendency for higher air temperatures to persist
in urban areas because of heat absorbed and emitted by buildings and asphalt, tending to make cities
warmer than the surrounding countryside.
Urban infrastructure
Materials and organization structures and facilities
needed for the operation of urban living (e.g., roads,
buildings, public transit, and pipelines).
Validate
To establish or verify accuracy. For example, using
measurements of temperature or precipitation to
determine the accuracy of climate model results.
Value
Belief or ideal held by individuals or society about
what is important or desirable.
Value (economic)
The benefit, usually expressed in monetary terms,
gained from use or enjoyment from a good or
service.
Vector (disease)
An organism, such as an insect, that transmits
disease-causing microorganisms such as viruses or
bacteria. Vector-borne diseases include, for example,
malaria, dengue fever, and lyme disease.
Vulnerability
The degree to which physical, biological, and socio-economic systems are susceptible to and unable to
cope with adverse impacts of climate change.
Vulnerability assessment
An analysis of the degree to which a system is susceptible to or unable to cope with the adverse effects
of climate change.
Water-use efficiency
Refers to the ratio of carbon uptake through plant
productivity to water lost by the plant through
evapotranspiration.
Water stress
Water stress occurs when demand for water by people and ecosystems exceeds available supply.
Wetlands
Soils that are inundated or saturated by water at a
frequency and duration sufficient to support, and
that do support under normal circumstances, a prevalence of vegetation typically adapted for life in saturated conditions (U.S. EPA 2015). Tidal wetlands
are influenced by ocean tides and may be saturated
with salt water or freshwater. Terrestrial wetlands are
nontidal and are saturated with freshwater.
Woody encroachment
Refers to woody plants colonizing grasslands or
other nonforested ecosystems.
Yedoma
An organic-rich (about 2% carbon by mass)
Pleistocene-age permafrost sediment with ice content of 50% to 90% by volume.
AMS, 2018: Glossary of the American Meteorological Society. [URL]
Berkes, F., and C. Folke, 1998: Linking Social and Ecological Systems: Management Practices and Social Mechanisms for Building Resilience. Cambridge University Press, Cambridge, UK.
CCSP, 2007: First State of the Carbon Cycle Report (SOCCR): The North American Carbon Budget and Implications for the Global Carbon Cycle. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [A. W. King, L. Dilling, G. P. Zimmerman, D. M. Fairman, R. A. Houghton, G. Marland, A. Z. Rose, and T. J. Wilbanks (eds.)]. National Oceanic and Atmospheric Administration, National Climatic Data Center, Asheville, NC, USA, 242 pp.
Chapin, F.S., G. M. Woodwell, J. T. Randerson, E. B. Rastetter, G. M. Lovett, D. D. Baldocchi, D. A. Clark, M. E. Harmon, D. S. Schimel, R. Valentini, and C. Wirth, 2006: Reconciling carbon-cycle concepts, terminology, and methods. Ecosystems, 9(7), 1041-1050.
Grubler, A., T. B. Johansson, L. Mundaca, N. Nakicenovic, S. Pachauri, K. Riahi, H.-H. Rogner, and L. Strupeit, 2013: Energy primer. In: Global Energy Assessment. Cambridge University Press, Cambridge, UK, pp. 99-150.
Hayes, D., and D. Turner, 2012: The need for “apples‐to‐apples” comparisons of carbon dioxide source and sink estimates. Eos Transactions, 93(41), 404-405. doi: 10.1029/2012EO410007.
Heath, G., E. Warner, D. Steinberg, and A. Brandt. 2015. Estimating U.S. Methane Emissions from the Natural Gas Supply Chain: Approaches, Uncertainties, Current Estimates, and Future Studies. Joint Institute for Strategic Energy Analysis, National Renewable Energy Laboratory, Golden, CO. [URL]
Hershom, M., and T. Thrift, 2012: Application of Ionophores in Cattle Diets. University of Florida Animal Science Extension, publication AN285. [URL]
IPCC, 2000: Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. [URL]
Mach, K.J., S. Planton, and C. von Stechow, 2014: Annex II: Glossary. In: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [Core Writing Team, R. K. Pachauri and L. A. Meyer (eds.)]. Intergovernmental Panel on Climate Change, Geneva, Switzerland, pp.117-130.
Sikora, T. D., and S. Ufermann, 2004: Marine atmospheric boundary layer cellular convection and longitudinal roll vortices. In: Synthetic Aperture Radar Marine User’s Manual. [C. R. Jackson and J. R. Apel (eds.)]. U.S. Department of Commerce, National Oceanic and Atmospheric Administration. [URL]
U.S. EPA, 2015: Section 404 and swampbuster: Wetlands on agricultural lands. U.S. Environmental Protection Agency. [URL]
USGCRP, 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I. [D. J. Wuebbles, D. W. Fahey, K. A. Hibbard, D. J. Dokken, B. C. Stewart, and T. K. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, 666 pp. [URL]