The term El Niño (Spanish for “the Child Christ”) was initially used by Peruvian fishermen to describe a warmwater current that periodically flows along the coast
of Ecuador and Perú about Christmas time. It is an
oscillation associated with the unusually large basinwide warmings of the eastern tropical Pacific Ocean
that occur every few years (about 2–7 years) and
change the local and regional ecology and have global
impacts. The oceanic event is connected to the atmospheric component termed “Southern Oscillation.” The
coupled atmosphere-ocean phenomenon is collectively
known as the El Niño-Southern Oscillation (ENSO).
While El Niño refers to the warm phase of ENSO, La Niña
(Spanish for “the girl”) refers to the cold phase of ENSO. See Trenberth (1997) for a review on definitions of El
Niño.
An initial positive sea surface temperature (SST) anomaly intensifies due to a positive feedback first hypothesized by Bjerknes (1969). The anomaly reduces the
east-west SST gradient, which leads to reduced equatorial
westerlies of the Walker circulation and inherent
weakening of equatorial upwelling. This reinforces the
positive SST anomaly. To explain the determination of
an El Niño event and its quasiperiodic reoccurrence, two
mechanisms are still discussed. ENSO is explained by
either a self-sustained, naturally oscillatory mode of the
coupled ocean atmosphere system or a stable mode triggered by stochastic forcing. See Wang and Fiedler
(2007) and Wang et al. (2012) for a review of these
mechanisms.
There are two types of El Niño that differ with respect
to their spatial structure, evolution, underlying mechanisms, and their global impacts. The eastern-Pacific type
is characterized by SST anomalies centered in the eastern
Pacific cold tongue region. The SST anomalies of the
central-Pacific type, also referred to as date line El Niño
or warm pool El Niño, are centered near the International
Date Line (Wang et al., 2012).
Bibliography
Bjerknes, J., 1969. Atmospheric teleconnections from the equatorial
pacific. Monthly Weather Review, 97, 163–172.
Trenberth, K. E., 1997. The definition of El Niño. Bulletin of the
American Meteorological Society, 78, 2771–2777.
Wang, C., and Picaut, J., 2004. Understanding ENSO physics – a
review. In Wang, C., Xie, S. P., and Carton, J. A. (eds.), Earth’s
Climate: The Ocean-Atmosphere Interaction. Washington, DC:
AGU, pp. 21–48.
Wang, C., Deser, C., Yu, J.-Y., DiNezio, P., Clement, A., 2012. El
Niño and Southern Oscillation (ENSO): a review. In Glymn, P.,
Manzello, D., Enochs, I. (eds.), Coral Reefs of the Eastern
Pacific. Springer.
Cross-references
Coasts
Currents
Sea-Level
ENERGY RESOURCES
Dieter Franke and Christoph Gaedicke
Federal Institute for Geosciences and Natural Resources,
Hannover, Germany
Definition
Energy resources. Energy resources are used to satisfy the
energy consumption of the global economy. Energy in
general is the capacity of a system to perform work. The
unit for measurement of this scalar physical quantity is
the joule. A resource is defined as a source of supply or
support that is ready to use if or when it is needed. Energy
derived directly from a natural resource is called primary
energy, i.e., burning coal for heating or collecting solar
energy with solar cells to generate electricity. When primary energy is transferred into another form of energy,
i.e., burning coal in a power plant to generate electric
power, this energy is called secondary energy.
Energy resources are generally divided into (1) renewable energy sources and (2) fossil energy resources. The
renewable sources are continually replenished from sunlight, wind, rain, water, waves, tides, geothermal heat,
and biomass. Fossil energy resources consist of coal, uranium, natural gas, and oil. The most important offshore
energy resources are oil and gas. Renewable offshore
energy is mainly derived from wind, waves, and tides.
Introduction
Energy resources from offshore areas are of increasing
importance. This is valid for both renewable and fossil
energy resources: On the one hand, new exploration
methods and technical innovations enlarge the volumes
and accessible areas for the exploitation of fossil energy
resources. On the other hand, technological advancements
and the increasing efficiency in using the renewable
energy resources, combined with the benefits of mass production and market competition, are continuously improving the competitiveness of renewable technologies.
World primary energy consumption grew by more than
40 % over the past 20 years and is likely to grow by a similar amount over the next decades. The world’s most
important energy resource is oil. With an annual worldwide consumption of about 34 billion (10
9
) barrels, it
accounts for more than 30 % of the world’s primary
energy consumption. The global oil supply is continuously growing and rose to up to 90 million barrels/day in
2011, but further growth is uncertain. In fact there is considerable controversy about the date when the maximum
rate of oil production is reached. Without doubt the
amount of oil on earth is limited. However, there is an
ongoing discussion about the percentage that has already
been extracted and mainly about the date when a further
increase in production will no longer be possible (“peak
oil”). Peak oil must not be confused with oil depletion.
Even when reaching the point of maximum production,
there will be continuous oil supply on high levels; only
ENERGY RESOURCES
217
of Ecuador and Perú about Christmas time. It is an
oscillation associated with the unusually large basinwide warmings of the eastern tropical Pacific Ocean
that occur every few years (about 2–7 years) and
change the local and regional ecology and have global
impacts. The oceanic event is connected to the atmospheric component termed “Southern Oscillation.” The
coupled atmosphere-ocean phenomenon is collectively
known as the El Niño-Southern Oscillation (ENSO).
While El Niño refers to the warm phase of ENSO, La Niña
(Spanish for “the girl”) refers to the cold phase of ENSO. See Trenberth (1997) for a review on definitions of El
Niño.
An initial positive sea surface temperature (SST) anomaly intensifies due to a positive feedback first hypothesized by Bjerknes (1969). The anomaly reduces the
east-west SST gradient, which leads to reduced equatorial
westerlies of the Walker circulation and inherent
weakening of equatorial upwelling. This reinforces the
positive SST anomaly. To explain the determination of
an El Niño event and its quasiperiodic reoccurrence, two
mechanisms are still discussed. ENSO is explained by
either a self-sustained, naturally oscillatory mode of the
coupled ocean atmosphere system or a stable mode triggered by stochastic forcing. See Wang and Fiedler
(2007) and Wang et al. (2012) for a review of these
mechanisms.
There are two types of El Niño that differ with respect
to their spatial structure, evolution, underlying mechanisms, and their global impacts. The eastern-Pacific type
is characterized by SST anomalies centered in the eastern
Pacific cold tongue region. The SST anomalies of the
central-Pacific type, also referred to as date line El Niño
or warm pool El Niño, are centered near the International
Date Line (Wang et al., 2012).
Bibliography
Bjerknes, J., 1969. Atmospheric teleconnections from the equatorial
pacific. Monthly Weather Review, 97, 163–172.
Trenberth, K. E., 1997. The definition of El Niño. Bulletin of the
American Meteorological Society, 78, 2771–2777.
Wang, C., and Picaut, J., 2004. Understanding ENSO physics – a
review. In Wang, C., Xie, S. P., and Carton, J. A. (eds.), Earth’s
Climate: The Ocean-Atmosphere Interaction. Washington, DC:
AGU, pp. 21–48.
Wang, C., Deser, C., Yu, J.-Y., DiNezio, P., Clement, A., 2012. El
Niño and Southern Oscillation (ENSO): a review. In Glymn, P.,
Manzello, D., Enochs, I. (eds.), Coral Reefs of the Eastern
Pacific. Springer.
Cross-references
Coasts
Currents
Sea-Level
ENERGY RESOURCES
Dieter Franke and Christoph Gaedicke
Federal Institute for Geosciences and Natural Resources,
Hannover, Germany
Definition
Energy resources. Energy resources are used to satisfy the
energy consumption of the global economy. Energy in
general is the capacity of a system to perform work. The
unit for measurement of this scalar physical quantity is
the joule. A resource is defined as a source of supply or
support that is ready to use if or when it is needed. Energy
derived directly from a natural resource is called primary
energy, i.e., burning coal for heating or collecting solar
energy with solar cells to generate electricity. When primary energy is transferred into another form of energy,
i.e., burning coal in a power plant to generate electric
power, this energy is called secondary energy.
Energy resources are generally divided into (1) renewable energy sources and (2) fossil energy resources. The
renewable sources are continually replenished from sunlight, wind, rain, water, waves, tides, geothermal heat,
and biomass. Fossil energy resources consist of coal, uranium, natural gas, and oil. The most important offshore
energy resources are oil and gas. Renewable offshore
energy is mainly derived from wind, waves, and tides.
Introduction
Energy resources from offshore areas are of increasing
importance. This is valid for both renewable and fossil
energy resources: On the one hand, new exploration
methods and technical innovations enlarge the volumes
and accessible areas for the exploitation of fossil energy
resources. On the other hand, technological advancements
and the increasing efficiency in using the renewable
energy resources, combined with the benefits of mass production and market competition, are continuously improving the competitiveness of renewable technologies.
World primary energy consumption grew by more than
40 % over the past 20 years and is likely to grow by a similar amount over the next decades. The world’s most
important energy resource is oil. With an annual worldwide consumption of about 34 billion (10
9
) barrels, it
accounts for more than 30 % of the world’s primary
energy consumption. The global oil supply is continuously growing and rose to up to 90 million barrels/day in
2011, but further growth is uncertain. In fact there is considerable controversy about the date when the maximum
rate of oil production is reached. Without doubt the
amount of oil on earth is limited. However, there is an
ongoing discussion about the percentage that has already
been extracted and mainly about the date when a further
increase in production will no longer be possible (“peak
oil”). Peak oil must not be confused with oil depletion.
Even when reaching the point of maximum production,
there will be continuous oil supply on high levels; only
ENERGY RESOURCES
217