Ocean and climate - Náttúruverndarsamtök Íslands

Iceland Nature Conservation Association Ocean and climate
English summary: Climate affects all life on earth, the resources that we depend upon, the development of our
economy and society, our health and well-being. The oceans act as the world’s thermostat,
crucially regulating climate (through the transfer of heat), through carbon sequestration,
oxygen production and as a water source. Changing climate and CO2 emissions disrupt the
ability of oceanic systems to function properly. Climate change has caused sea temperatures
to rise while escalating CO2 emissions lead to increasing acidification of ocean waters. These
changes directly affect the distribution and stability of marine animal and plant communities,
sea levels will rise (as glaciers melt at an accelerated rate and as water volume increases with
temperatures) while deep ocean currents may be disrupted and thereby further destabilise
current climate patterns. Iceland is one of many countries which is economically dependent
upon the marine environment. In particular, Iceland’s territorial waters include a transition
zone where the warm waters of the North Atlantic Drift (Gulf Stream) meet with cold currents
from the Arctic Ocean; a zone upon which Iceland’s marine fishery thrives. Therefore,
disruption of existing marine systems due to climate change will result in an alteration to
Iceland’s fishery. Thus, Iceland may be one of the first countries in Europe to be severly
effected by climate change.
Introduction
The world ocean, composed of five
interconnected
geographical
entities
(Atlantic, Pacific, Indian, Arctic and
Southern Oceans), covers about 71% of the
Earth’s surface [1]. Its complex
functioning is crucial to all living
organisms on the planet [2]. For example,
the ocean is the largest net oxygen supplier
of the world [3] and plays a key role in the
complex mechanism of climatic regulation,
consequently influencing many ecosystems
[2].
Today, the changing climate is
disrupting this climatic balance, having
important consequences on the functioning
of oceanic processes, and causing major
INCA/Náttúruverndarsamtök Ísland Thorunnartun 2 105 Reykjavik unpredictable ecological changes. Despite
its crucial role in climate regulation and
ecosystem services the ocean has been
largely ignored in the debate about climate
change.
Ø To increase our understanding of
the role of the ocean and the threats
to it we will explore the following
three points:
Ø What are the key roles of the
ocean?
Ø What are the threats to the current
functioning of the oceans? And
what are the consequences?
Ø What are the solutions?
e-­‐mail: [email protected] Tel: +354 551 2279 Mobile : +354 897 2437 What are the key roles of the oceans?
The importance of the ocean
for Iceland
The ocean acts as the planet's
thermostat, playing an essential role in
climate regulation, mainly through heat
transfer, the carbon pump, oxygen
production [4] and water source:
The heat transfer function:
The heat pump function of the ocean is
mainly played by the conveyor belt. In
fact, the ocean distributes the heat
accumulated in tropical areas to the poles
through warm surface currents, thus
reducing the temperature differences
between these two areas. This is, for
example, the role of the Gulf Stream,
which allows Iceland to harbor a milder
climate in comparison with other areas at
the same latitudes. At the poles, these
warm surface currents cool down and sink
down into the depths from where they
return towards the tropics. The change of
density is due to the temperature. In fact,
the colder water is denser than warm
water. This global circulation works like a
"conveyor belt" [4].
Since the beginning of the industrial
era (19th century), global warming was
magnified by the greenhouse gas emissions
from anthropogenic activities [5]. The
moderating role of the ocean in climate
regulation has limited the effect of global
warming [6] through its heat storage
capacity and through uptake of CO2 gas. In
The ocean mechanisms (conveyor
belt, Gulf Stream) influence the
Icelandic climate and shape the
conditions for life in the country. The
ocean has always been important for
Iceland from the country's settlement to
the present time. The ocean is a mode of
transport and communication for Iceland.
Moreover, a huge part of Iceland's
economy depends upon the use of
marine resources [14]. It is at the base of
the Icelandic industry and economy [15].
For example, fisheries provide a major
share of the country’s foreign currency
earnings; in 2010, the direct and indirect
contribution to GDP was respectively
10.2% and 7.3% [15]. Several other
sectors are also concerned: fish
processing, aquaculture, tourism (whale
watching, nature expeditions, sailing,
sport
fishing...),
biotechnology,
manufacturing of gear and equipment
(for fishing and fish processing),
software production and development
(for fishing and fish processing),
shipbuilding, transport and service and
support industries [14].
fact, the ocean has a heat storage capacity
1000 times greater than that of the
atmosphere, [3]. So, since the end 1950's,
more than 80% of the accumulated heat
excess in the climatic system has been
stored in the ocean [7]. Moreover, the
ocean has a very important thermal inertia:
it heats up and cools down very slowly [3],
accentuating its moderator role.
The carbon pump function:
The ocean plays a crucial role in
regulating atmospheric carbon dioxide
(CO2) concentration. Since the industrial
2 revolution it has acted as an important sink
for CO2, via physicochemical processes
and biological activity [8 & 3]. Its carbon
storage capacity is roughly 50 times that of
the atmosphere [8]. Currently, it has
absorbed approximately 26% of total
anthropogenic CO2 emissions, roughly 120
billion tons [8 & 9].
The oxygen production function:
Between 50 to 85% of the O2 available in
the atmosphere originates from the oceans
[10]. In fact, tiny marine organisms called
phytoplankton or vegetal plankton produce
oxygen via photosynthesis.
A water source for many ecosystems:
The Ocean also contributes to the presence
of freshwater on the Earth. Indeed, the
ocean contains 97.5% of the Earths water
(whereas the continents and the
atmosphere contain respectively 2.4% and
less than 0.001%) and is the most
important reserve of water. Evaporation of
water at the sea surface provides the main
source of atmospheric water, which is
transported inland by wind and subsequent
rainfall [3].
events (such as the El Nino or the NorthAtlantic oscillation) to those on much
larger time scales (Pleistocene climatic
oscillations) [6].
Until now, the ocean has benefited
humankind by containing the rising
greenhouse gas levels and limiting the
increase of temperatures in the atmosphere,
thus reducing the impacts of global
warming so far. Fifty years ago, the
general consensus of the scientific
community was that due to the ocean's
natural buffering system, anthropogenic
addition of CO2 into the atmosphere was
unlikely to cause major changes in pH.
Today,
the
scientific
community
recognizes that this is untrue [16]. In fact,
the temperature elevation and the ocean’s
uptake of carbon dioxide are modifying the
ocean environment to the point provoking
direct consequences on marine ecosystems,
and other dependent ecosystems, as well as
on humans being.
The main concern is how much the
ocean will continue to absorb heat and CO2
excess produced by human activities? If its
absorption capacity suddenly reaches its
maximal, will the effect be accelerated
rates of global warming and ocean
acidification to a point never before
considered?
Other roles:
In addition to regulating the climate, the
ocean provides many other ecosystem
services1, such as food supply, or still
protection against natural hazards. [12].
Scientists estimate that 63% of global
ecosystem services are generated by the
ocean [13].
Conclusion:
Ocean and climate are intimately linked
and interact continuously through feedback
reactions. The ocean has an effect on
climatic phenomenon from short-term
1
The ecosystem services correspond to the benefits
people obtain from ecosystems [11]. 3 What are the threats to the current functioning
of the oceans? And what are the consequences?
The increase in CO2 has mainly two
direct effects on the ocean functioning: the
increase of water temperature and ocean
acidification, causing for example a rise in
sea levels and modifications to marine
communities. However, it remains still
difficult to predict with accuracy the
consequences of climate change on
ecosystems and humans.
Rising temperature:
Direct effects on marine species:
Studies suggest that the responses of
marine species to the ongoing increase in
sea temperature will be highly variable,
reflecting their different sensitivities. Some
species are adapting to this change, others
are migrating to colder waters and still
others will not adapt quickly enough and
will disappear [4]. In consequence, the
local abundance, the distribution and
genetic diversity of some species are
expected to change drastically. This will
also have an effect at the community level
with change in species composition and
modifications of food webs, ultimately
affecting interactions between species. The
current “balance” within communities is
changing and will certainly affect stability
of ecosystem services beneficial to human
[4].
This change of communities might also
be amplified by a localized phenomenon of
deoxygenation in seawater (anoxic
conditions). The combination of coastal
eutrophication and the increase of sea
temperature generates local areas with a
very low oxygen concentration, called
"dead zones". In fact, because the oxygen
solubility decreases with the increase of
temperature (the warmer the water the less
oxygen can be carried) dead zones are
mainly located in warmer coastal areas. In
the coastal ocean, the number of dead
zones has considerably increased since
60's, with 479 areas so far identified (such
as the Black Sea, Baltic, Kattegat, Gulf of
Mexico and the South China Sea) [3].
These modifications of marine habitats
can have direct (e.g. species extinction) or
indirect (e.g. through competition for
trophic resources or habitat…) impacts on
some species of huge economic importance
to human.
Rising sea level and melting glaciers:
Since the beginning of 20th century,
measurements have shown that the rise in
sea level increased on average to 1.7 mm
per year. The forecast for 2100 predicts a
faster rate of sea level rise than at present,
including between 25cm and 82cm,
according to the different scenarios of
greenhouse gas emission. This increase is
mainly due to thermic distention of the
4 ocean (water expands as it warms) and
melting glaciers and polar icecaps (the
additional freshwater inflows lead directly
to an increase of sea level) [3]. In Iceland,
for example, studies estimate that Iceland
has been losing about 9.5 billion tons of ice
each year since 1995 [17]. Concretely,
over the last 10 years, the glaciers have
retreated at an average rate of 25 m/year,
accelerating to 50m/year over the past 5
years. Within 150 years, all Icelandic
glaciers will disappear entirely. The
Icelandic glaciers are also sensitive to
geothermal activities but only 5% of their
melting is attributed to volcanic influences
[17]. They act as sentinels of the changes
occurring in other glaciers worldwide [18].
The melting glaciers disrupt the
ecosystems [3] by changing the
hydrographic network. In fact, the flow
rate increases and the annexed channels
disappear, to be concentrated in one bed,
engendering a loss of biodiversity by a loss
of habitats. But the most important impact
of melting glaciers might be for the oceans
[18].
Modification of deep currents
In fact, the freshwater input caused by the
melting glaciers might decrease the
seawater salinity [3] and so the density of
the seawater. The difference of density in
water layers is the engine of the conveyor
belt mechanism. When warm and
relatively saline seawater cools as it is
transported to higher latitudes, its density
increases causing the water mass to sink.
This process may be considered the driving
force behind the thermohaline circulation.
However, melting of sea-ice and glaciers
increases the flow of freshwater into the
oceans, potentially decreasing the density
of surface seawater, which may have
negative consequences for its capacity to
sink. According to some forecasts,
scientists are hypothesizing that the
conveyor belt mechanism might slow
down or even disappear. In that case,
Europe might be subjected to an important
cooling caused by the slowing down or the
stopping of Gulf Stream [18].
Acidification of the oceans:
The ocean’s uptake of carbon dioxide
modifies significantly the chemistry of
seawater, causing ocean acidification that
has direct consequences for marine
ecosystems [9]. For example, population
sizes of salmon in the North Atlantic and
North Pacific are expected to decrease
drastically in the next decades because
their main food source, the Pteropods
(planktonic mollusks), are likely to
decrease in abundance due to the effects of
ocean acidification on their shells. In fact,
the chemical reactions can lead to the
dissolving of their shells [3]. The salmon is
an important economic resource for many
people. Consequently, these modifications
of ecological communities might have
important consequences for different
economic sectors such as fisheries,
aquaculture, and tourism...
It is still difficult to predict with
accuracy the consequences of ocean
acidification, but it is certain that marine
communities will change. The organisms
that are most likely to be affected first are
those with calcium carbonate shells or
skeletons [9].
The organisms can cope with these
changes in two ways: they can acclimatize
to them or adapt. But if we continue to
emit CO2 at the present level, researchers
predict an increase of about 170% of the
ocean acidity by 2100[9]. Moreover, the
current rate of acidification is more than 10
times faster than any time in the last 55
million years. So, species that are
vulnerable to such changes must acclimate
or adapt or else they will disappear [9].
5 Consequences for Iceland
Global
warming
and
its
consequences on the ocean functioning
(rising
sea
level,
acidification,
deoxygenation, potential modification of
conveyor belt...) particularly affect coastal
and insular areas [4]. Iceland is not an
exception, even if it should not be impacted
like other islands by the rising sea level. In
fact, the melting glacier engenders an uplift
of the Icelandic crust about 35mm/year [19]
while the rising sea level is about
1.7mm/year. However, as we saw, its
economy depends strongly upon ocean
resources, so we can imagine an important
economic loss directly affecting sectors like
fisheries or tourism. Furthermore, ocean
acidification is a heterogeneous process
across the globe. The areas of greater
impact are those of cold seawater, as we can
find around Iceland [23]. Moreover, in the
case whereby the Gulf Stream might be
slowed down or stopped, the Icelandic
climatic conditions might become rougher
and colder similar to those of Greenland at
Conclusion:
It is difficult to predict with exactitude the
effect of global warming on the
functioning of the ocean but it is important
to take into account the different scenarios
in our current decision-making. Humanity
will have to cope with a changing climate
which will affect coastal populations,
industrial activities in the Arctic and the
fisheries and aquaculture [3]. Moreover,
the loss of marine biodiversity weakens the
ocean's ecosystem services, its ability to
withstand disruption, to adapt to climate
change and to play its climate regulator
role [4]. So, it is urgent to maintain the
functional quality of these ecosystems and
to restore those that are the most degraded.
In fact, although the climate machine is
already running, it is essential to reduce
our impact so as to avoid uncontrollable
global warming.
What are the solutions?
In his address to the Ban Ki-moon climate
summit held in September last year, Iceland’s
PM, Sigmundur Davíð Gunnlaugsson stated
that Recent studies, including by the Arctic
Council, suggest that climate change is the
most serious threat to Arctic biodiversity and
ecosystems, including ocean acidification as
Arctic and sub-Arctic waters can be
especially vulnerable to acidification, which
again can only be stopped by halting carbon
emissions.
This might seem obvious, the solution is
staring us in the eye and yet governments
have not risen to the challenge of halting
carbon emissions, replacing dirty energy with
clean and renewable energy.
The upcoming meeting in Paris will provide
a one off opportunity to take bring about
carbon free future.
Chloé Mathieu
6 Bibliography
[1] Website NOAA:
http://www.noaa.gov/ocean.html [2]
Website
IRD:
https://www.ird.fr/lamediatheque/expositions/expositionsdisponibles-en-pret/ocean-et-climat. [3] Océan et climat, 2015. Fiches scientifiques.
www.ocean-climate.org, 106 p.
[4] Océan et climat. Les interactions entre
l’océan et le climat, 6 fiches d’information.
www.ocean-climate.org, 12 p.
[5] Website manicore.com:
http://www.manicore.com/documentation/serre/a
nthropique.html.
[6] Website IFREMER:
http://www.ifremer.fr/lpo/cours/nao/climat.html.
[7] Michaut C., 08/2009. Les dossiers de la
recherche
n°36.
L’océan
atténue
le
réchauffement.
[8] Rhein, M., S.R. Rintoul, S. Aoki, E. Campos,
D. Chambers, R.A. Feely, S. Gulev, G.C.
Johnson, S.A. Josey, A. Kostianoy, C. Mauritzen,
D. Roemmich, L.D. Talley and F. Wang, 2013:
Observations: Ocean. In: Climate Change 2013:
The Physical Science Basis. Contribution of
Working Group I to the Fifth Assessment Report
of the Intergovernmental Panel on Climate
Change [Stocker, T.F., D. Qin, G.-K. Plattner, M.
Tignor, S.K. Allen, J. Boschung, A. Nauels, Y.
Xia, V.Bex and P.M. Midgley (eds.)]. Cambridge
University Press, Cambridge, United Kingdom
and New York, NY, USA.
[9] IGBP, IOC, SCOR (2013). Ocean
Acidification Summary for Policymakers – Third
Symposium on the Ocean in a High-CO2 World.
International Geosphere-Biosphere Programme,
Stockholm, Sweden.
[10]
Website
earthsky.org:
http://earthsky.org/earth/how-much-do-oceansadd-to-worlds-oxygen.
[11] Millennium Ecosystem Assessment (MA).
2005. Ecosystems and Human Well-Being:
Synthesis [1]. Island Press, Washington. 155p.
[12] UICN France (2013). Panorama des services
écologiques fournis par les milieux naturels en
France - volume 2.2 : les écosystèmes marins et
côtiers. Paris, France.
[13] Costanza R, d’Arge R, de Groot R, Farber S,
Grasso M, Hannon B, et al. (1997) The value of
the world’s ecosystem services and natural
capital. Nature 387:253–260.
[14] Icelandic Government Policy, 2004.Ocean,
Iceland’s policy. 46 p.
[15] Íslandsbanki. The Importance of the Ocean
Cluster for the Icelandic Economy.
[16]
Website
notreplanete.info:
http://www.notreplanete.info/actualites/actu_229
7_oceans_climat.php.
[17]
Website
livescience.com:
http://www.livescience.com/49751-icelandrising-melting-ice.html.
[18] Radio Canada.ca. Découverte - La fonte des
glaciers
islandais.
Video:
https://www.youtube.com/watch?v=SuSn8P9Rrg
o.
[19]
Website
sciencedaily.com:
http://www.sciencedaily.com/releases/2015/01/1
50129113719.htm.
[20] Website askjaenergy.org:
http://askjaenergy.org/iceland-­‐
introduction/iceland-­‐energy-­‐sector/. [21] Website ec.europa.eu:
http://ec.europa.eu/eurostat/statisticsexplained/index.php/Energy_from_renewable_so
urces.
[22] Website lemonde.fr:
http://oceanclimat.blog.lemonde.fr/2015/08/31/lo
cean-grand-absent-de-la-conference-de-paris/
[23] Website les crises.fr: http://www.lescrises.fr/climat-21-consequences-3
7 Ocean and climate
French summary: Le climat conditionne la vie sur Terre, les ressources dont nous disposons, le développement
de nos sociétés, ou encore notre santé. En fait, l'océan agit comme le thermostat de la planète, jouant
un rôle essentiel dans la régulation du climat, principalement de par ses fonctions de transfert de
chaleur, de pompe à carbone, de producteur d'oxygène et de source d'eau. Cependant, le
réchauffement climatique menace le fonctionnement actuel des océans. En effet, il entraine une
acidification et une augmentation accélérée de la température des eaux marines. La modification de
ces deux paramètres affecte directement la distribution et la stabilité des communautés marines
animales et végétales, augmente le niveau de la mer (via l’accélération de la fonte des calottes
glaciaires et la dilatation de l’eau) et pourrait ainsi modifier les grands courants océaniques
planétaires responsables du climat actuel. Certains pays comme l’Islande sont économiquement
dépendant de l'océan. Le premier secteur économique, la pêche, dépend directement de la rencontre
de courant océanique chaud (Gulf Stream) et froid dont la stabilité pourrait être remise en cause par
le réchauffement climatique global. Ainsi, L’Islande sera l’un des premiers pays impactés par ces
changements. Que pouvons-nous faire face à ce problème ? Réduire rapidement et drastiquement nos
émissions de gaz à effet de serre en 1) faisant prendre conscience à chacun la responsabilité qui lui
incombe dans l’émission de gaz à effet de serre due à son mode de vie, 2) en lançant une campagne
interventionniste des états à l’échelle internationale auprès de l’ensemble des secteurs économiques
en fixant des règles communes pour imposer l’utilisation des technologies existantes les plus efficaces,
3) en investissant massivement dans la recherche et le développement ainsi que la mise en place des
multiple formes d’énergies renouvelables prenant en compte les contextes locaux. 4) en intégrant
l'océan dans les discussions internationales comme l’acteur majeur de la régulation climatique et
socio-économiques de la planète. 5) en augmentant le budget pour le financement d’études
scientifiques indépendantes afin d'améliorer notre compréhension des conséquences de ces
changements sur le fonctionnement de l’océan et des écosystèmes dans le but de fournir des mesures
de protection / restauration adéquates.
French introduction: L’océan mondial, composé de cinq entités géographiques interconnectées (Atlantique,
Pacifique, Indien, Arctique et du Sud), couvre environ 71% de la surface de la Terre [1]. Son
fonctionnement complexe est vital pour l’ensemble des êtres vivants [2]. Par exemple, l'océan
est le plus grand fournisseur d'oxygène du monde [3]. De plus, il joue un rôle clé dans le
mécanisme complexe de la régulation climatique; influençant par conséquent de nombreux
écosystèmes et l’équilibre socio-économique actuel [2].
Aujourd’hui le réchauffement climatique global perturbe l’équilibre climatique
engendrant ainsi d’importantes conséquences sur le fonctionnement des océans, et provoquant
des changements écologiques majeurs difficilement prévisibles.
Afin de mieux comprendre le rôle de l'océan et les menaces qui pèsent sur lui, nous
développerons les trois points suivants:
Ø Quels sont les rôles clés de l'océan?
Ø Quelles sont les menaces qui pèsent sur le fonctionnement actuel des océans? Et
quelles en sont les conséquences ?
Ø Quelles sont les solutions?
8