25
© The Author(s) 2018
S. Jungblut et al. (eds.), YOUMARES 8 – Oceans Across Boundaries: Learning from each other,
https://doi.org/10.1007/978-3-319-93284-2_3
The Physical System of the Arctic Ocean
and Subarctic Seas in a Changing
Climate
Camila Campos and Myriel Horn
Abstract
The Earth’s climate is changing and the poles are particularly sensitive to the global warming, with most evident
implications over the Arctic. While summer sea ice
reduced significantly compared to the previous decades,
and the atmospheric warming is amplified over the Arctic,
changes in the ocean are less obvious due to its higher
inertia. Still, impacts of the changing climate on highlatitude and polar oceans are already observable and
expected to further increase. The northern seas are essential regions for the maintenance of the Atlantic Meridional
Overturning Circulation, which in turn is a key aspect of
the maritime climate. Alterations in heat and freshwater/
salinity content in the Arctic Ocean and adjacent seas
impact and are closely linked to buoyancy flux distributions, which control the vertical and horizontal motion of
water masses, thus impacting the climate system on a longer time scale. In this context, we set our focus on the
Arctic Ocean and Atlantic subarctic seas, review some of
the contemporary knowledge and speculations on the
complex coupling between atmosphere, sea ice, and
ocean, and describe the important elements of its physical
oceanography. This assessment is an attempt to raise
awareness that investigating the pathways and timescales
of oceanic responses and contributions is fundamental to
better understand the current climate change.
Introduction
The Arctic region (Fig. 1) is a relative small fraction of the
globe’s surface, but plays a crucial role in determining global
climate dynamics due to the intimate and complex couplings
between cryosphere, atmosphere, ocean, and land (Serreze
et al. 2007). Currently, the Arctic is undergoing remarkable
environmental changes and has been in focus of the climate
sciences community (Winton 2008; Overland 2016).
The Arctic near surface air temperature is warming twice
as fast as the global average (Serreze and Francis 2006). This
accelerated response is known as the Arctic amplification
(Winton 2008; Serreze and Barry 2011; Cohen et al. 2014),
and one of the most dramatic indicators of the Arctic warming has been the decline in the sea ice cover. Satellite observations reveal that the area of the Arctic sea ice during
summer has steadily decreased by more than 40% in recent
decades (Fig. 2) (Comiso et al. 2008; Pistone et al. 2014).
Notwithstanding, observations further show a year-round
loss of sea ice extent and thickness (Lindsay and Schweiger
2015; Rothrock et al. 2008), which suggest that from year to
year more melt and less recovery is taking place.
The observed rate of sea ice extent reduction during the
last three to four decades has occurred faster than anticipated
by models participating on the Intergovernmental Panel on
Climate Change Fourth Assessment Report: the observed
trend for the September sea ice extent was −9.12 ± 1.54%
per decade for the period 1979–2006, while the mean decline
trend of all the models participating in the report was
−4.3 ± 0.3% per decade (Stroeve et al. 2007). The accelerated sea ice decline has likely occurred due to a combination
of decadal-scale variability in the coupled ice-oceanatmosphere- land system and radiative greenhouse gas forcing (e.g., Serreze and Barry 2011; IPCC 2014; Zhang 2015).
According to model studies, the Arctic sea ice will continue
shrinking and thinning year-round in the course of the
twenty-first century as the global mean surface temperature
rises, with projections of summer ice free Arctic in the near
C. Campos · M. Horn (*)
Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and
Marine Research, Bremerhaven, Germany
e-mail: camila.campos@awi.de; myriel.horn@awi.de
Both authors contributed equally.
© The Author(s) 2018
S. Jungblut et al. (eds.), YOUMARES 8 – Oceans Across Boundaries: Learning from each other,
https://doi.org/10.1007/978-3-319-93284-2_3
The Physical System of the Arctic Ocean
and Subarctic Seas in a Changing
Climate
Camila Campos and Myriel Horn
Abstract
The Earth’s climate is changing and the poles are particularly sensitive to the global warming, with most evident
implications over the Arctic. While summer sea ice
reduced significantly compared to the previous decades,
and the atmospheric warming is amplified over the Arctic,
changes in the ocean are less obvious due to its higher
inertia. Still, impacts of the changing climate on highlatitude and polar oceans are already observable and
expected to further increase. The northern seas are essential regions for the maintenance of the Atlantic Meridional
Overturning Circulation, which in turn is a key aspect of
the maritime climate. Alterations in heat and freshwater/
salinity content in the Arctic Ocean and adjacent seas
impact and are closely linked to buoyancy flux distributions, which control the vertical and horizontal motion of
water masses, thus impacting the climate system on a longer time scale. In this context, we set our focus on the
Arctic Ocean and Atlantic subarctic seas, review some of
the contemporary knowledge and speculations on the
complex coupling between atmosphere, sea ice, and
ocean, and describe the important elements of its physical
oceanography. This assessment is an attempt to raise
awareness that investigating the pathways and timescales
of oceanic responses and contributions is fundamental to
better understand the current climate change.
Introduction
The Arctic region (Fig. 1) is a relative small fraction of the
globe’s surface, but plays a crucial role in determining global
climate dynamics due to the intimate and complex couplings
between cryosphere, atmosphere, ocean, and land (Serreze
et al. 2007). Currently, the Arctic is undergoing remarkable
environmental changes and has been in focus of the climate
sciences community (Winton 2008; Overland 2016).
The Arctic near surface air temperature is warming twice
as fast as the global average (Serreze and Francis 2006). This
accelerated response is known as the Arctic amplification
(Winton 2008; Serreze and Barry 2011; Cohen et al. 2014),
and one of the most dramatic indicators of the Arctic warming has been the decline in the sea ice cover. Satellite observations reveal that the area of the Arctic sea ice during
summer has steadily decreased by more than 40% in recent
decades (Fig. 2) (Comiso et al. 2008; Pistone et al. 2014).
Notwithstanding, observations further show a year-round
loss of sea ice extent and thickness (Lindsay and Schweiger
2015; Rothrock et al. 2008), which suggest that from year to
year more melt and less recovery is taking place.
The observed rate of sea ice extent reduction during the
last three to four decades has occurred faster than anticipated
by models participating on the Intergovernmental Panel on
Climate Change Fourth Assessment Report: the observed
trend for the September sea ice extent was −9.12 ± 1.54%
per decade for the period 1979–2006, while the mean decline
trend of all the models participating in the report was
−4.3 ± 0.3% per decade (Stroeve et al. 2007). The accelerated sea ice decline has likely occurred due to a combination
of decadal-scale variability in the coupled ice-oceanatmosphere- land system and radiative greenhouse gas forcing (e.g., Serreze and Barry 2011; IPCC 2014; Zhang 2015).
According to model studies, the Arctic sea ice will continue
shrinking and thinning year-round in the course of the
twenty-first century as the global mean surface temperature
rises, with projections of summer ice free Arctic in the near
C. Campos · M. Horn (*)
Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and
Marine Research, Bremerhaven, Germany
e-mail: camila.campos@awi.de; myriel.horn@awi.de
Both authors contributed equally.