Technical ReportPDF Available

Blue Carbon - The Role of Healthy Oceans in Binding Carbon

Authors:
  • RHIPTO Rapid Response - Norwegian Center for Global Analyses
  • Independent

Abstract

The objective of this report is to highlight the critical role of the oceans and ocean ecosys­ tems in maintaining our climate and in assisting policy makers to mainstream an oceans agenda into national and international climate change initiatives. While emissions’ re­ ductions are currently at the centre of the climate change discussions, the critical role of the oceans and ocean ecosystems has been vastly overlooked. Out of all the biological carbon (or green carbon) captured in the world, over half (55%) is captured by marine living organ- isms – not on land – hence it is called blue carbon. Continu- ally increasing carbon dioxide (CO2) and other greenhouse gas emissions are contributing to climate change. Many countries, including those going through periods of rapid growth, are increasing their emissions of brown and black carbon (such as CO2 and soot) as a result of rapid economic development. Along with increased emissions, natural ecosystems are being degraded, reducing their ability to absorb CO2. This loss of ca- pacity is equivalent to one to two times that of the annual emis- sions from the entire global transport sector. Rising greenhouse gases emissions are producing increasing impacts and changes worldwide on weather patterns, food pro- duction, human lives and livelihoods. Food security, social, eco- nomic and human development will all become increasingly jeopardized in the coming decades. Maintaining or improving the ability of forests and oceans to absorb and bury CO2 is a crucial aspect of climate change mitigation. The contribution of forests in sequestering carbon is well known and is supported by relevant financial mecha- nisms. In contrast, the critical role of the oceans has been over- looked. The aim of this report is to highlight the vital contribu- tion of the oceans in reducing atmospheric CO2 levels through 6 sequestration and also through reducing the rate of marine and coastal ecosystem degradation. It also explores the options for developing a financial structure for managing the contribution oceans make to reducing CO2 levels, including the effective- ness of an ocean based CO2 reduction scheme. Oceans play a significant role in the global carbon cycle. Not only do they represent the largest long-term sink for carbon but they also store and redistribute CO2. Some 93% of the earth’s CO2 (40 Tt) is stored and cycled through the oceans. The ocean’s vegetated habitats, in particular mangroves, salt marshes and seagrasses, cover <0.5% of the sea bed. These form earth’s blue carbon sinks and account for more than 50%, perhaps as much as 71%, of all carbon storage in ocean sediments. They comprise only 0.05% of the plant biomass on land, but store a comparable amount of carbon per year, and thus rank among the most intense carbon sinks on the planet. Blue carbon sinks and estuaries capture and store between 235–450 Tg C every year – or the equivalent of up to half of the emissions from the entire global transport sector, estimated at around 1,000 Tg C yr–1. By preventing the further loss and degradation of these ecosystems and catalyzing their recovery, we can contribute to offsetting 3–7% of current fossil fuel emis- sions (totaling 7,200 Tg C yr–1) in two decades – over half of that projected for reducing rainforest deforestation. The effect would be equivalent to at least 10% of the reductions needed to keep concentrations of CO2 in the atmosphere below 450 ppm. If managed properly, blue carbon sinks, therefore, have the po- tential to play an important role in mitigating climate change. The rate of loss of these marine ecosystems is much higher than any other ecosystem on the planet – in some instances up to four times that of rainforests. Currently, on average, be- tween 2–7% of our blue carbon sinks are lost annually, a sev- en-fold increase compared to only half a century ago. If more action is not taken to sustain these vital ecosystems, most may be lost within two decades. Halting degradation and restoring both the lost marine carbon sinks in the oceans and slowing deforestation of the tropical forests on land could result in mitigating emissions by up to 25%. Sustaining blue carbon sinks will be crucial for ecosystem- based adaptation strategies that reduce vulnerability of hu- man coastal communities to climate change. Halting the de- cline of ocean and coastal ecosystems would also generate economic revenue, food security and improve livelihoods in the coastal zone. It would also provide major economic and development opportunities for coastal communities around the world, including extremely vulnerable Small Island De- veloping States (SIDS). Coastal waters account for just 7% of the total area of the ocean. However the productivity of ecosystems such as coral reefs, and these blue carbon sinks mean that this small area forms the basis of the world’s primary fishing grounds, sup- plying an estimated 50% of the world’s fisheries. They provide vital nutrition for close to 3 billion people, as well as 50% of animal protein and minerals to 400 million people of the least developed countries in the world. The coastal zones, of which these blue carbon sinks are cen- tral for productivity, deliver a wide range of benefits to hu- man society: filtering water, reducing effects of coastal pol- lution, nutrient loading, sedimentation, protecting the coast from erosion and buffering the effects of extreme weather events. Coastal ecosystem services have been estimated to be worth over US$25,000 billion annually, ranking among the most economically valuable of all ecosystems. Much of the degradation of these ecosystems not only comes from unsus- tainable natural resource use practices, but also from poor watershed management, poor coastal development practices and poor waste management. The protection and restoration of coastal zones, through coordinated integrated manage- ment would also have significant and multiple benefits for health, labour productivity and food security of communities in these areas. The loss of these carbon sinks, and their crucial role in man- aging climate, health, food security and economic develop- ment in the coastal zones, is therefore an imminent threat. It is one of the biggest current gaps to address under climate change mitigation efforts. Ecosystem based management and adaptation options that can both reduce and mitigate climate change, increase food security, benefit health and subsequent productivity and generate jobs and business are of major importance. This is contrary to the perception that mitigation and emission reduction is seen as a cost and not an investment. Improved integrated management of the coastal and marine environments, including protection and restoration of our ocean’s blue carbon sinks, provides one of the strongest win-win mitigation efforts known today, as it may provide value-added benefits well in excess of its costs, but has not yet been recognized in the global protocols and carbon trading systems
1
A RAPID RESPONSE ASSESSMENT
THE ROLE OF HEALTHY OCEANS IN BINDING CARBON
BLUE CARBON
Disclaimer
The contents of this report do not necessarily reflect the views or policies of UNEP or con-
tributory organisations. The designations employed and the presentations do not imply the
expressions of any opinion whatsoever on the part of UNEP or contributory organisations
concerning the legal status of any country, territory, city, company or area or its authority, or
concerning the delimitation of its frontiers or boundaries.
UNEP promotes
environmentally sound practices
globally and in its own activities. This
report is printed on 100% recycled paper,
using vegetable-based inks and other eco-
friendly practices. Our distribution policy aims to
reduce UNEPs carbon footprint.
This report is produced as an inter-agency collaboration between UNEP, FAO and IOC/
UNESCO, with special invited contribution of Dr. Carlos M. Duarte, Institut Mediter-
ráni d’Estudis Avançats, Spain.
Nellemann, C., Corcoran, E., Duarte, C. M., Valdés, L., De Young, C.,
Fonseca, L., Grimsditch, G. (Eds). 2009. Blue Carbon. A Rapid Response
Assessment. United Nations Environment Programme, GRID-Arendal,
www.grida.no
ISBN: 978-82-7701-060-1
Printed by Birkeland Trykkeri AS, Norway
Christian Nellemann (Editor in chief)
Emily Corcoran
Carlos M. Duarte
Luis Valdés
Cassandra De Young
Luciano Fonseca
Gabriel Grimsditch
A RAPID RESPONSE ASSESSMENT
THE ROLE OF HEALTHY OCEANS IN BINDING CARBON
BLUE CARBON
4
5
The burning of fossil fuels is generating levels of what one
might term ‘brownand ‘black’ carbon in the atmosphere and
unless checked may take global temperatures above a threshold
of 2˚C. Dramatic reductions are possible by accelerating energy
efficiency measures and boosting the deployment of cleaner
energy generation and renewables such as solar, wind and geo-
thermal. Over the past few years science has been illuminating
other sources of emissions and other opportunities for action.
Deforestation for example now accounts for close to 20% of
global greenhouse gas emissions.
In a matter of weeks, governments will meet in Copenhagen
where there is an urgency to Seal the Deal on a new and forward-
looking agreement. Part of that package of measures needs to
include ‘green’ carbon – the carbon stored in the globe’s forests
and their soils and especially in the tropics. Financing a part-
nership for Reduced Emissions from Deforestation and forest
Degradation (REDD) can play an important role in keeping that
green carbon where it belongs while also assisting the develop-
ment and employment objectives of developing economies by
giving an economic value to these vital ecosystem services.
Science is now also telling us that we need to urgently address
the question of ‘blue’ carbon. An estimated 50% of the carbon in
the atmosphere that becomes bound or ‘sequesteredin natural
systems is cycled into the seas and oceans another example of
nature’s ingenuity for carbon capture and storage’. However, as
with forests we are rapidly turning that blue carbon into brown
carbon by clearing and damaging the very marine ecosystems
that are absorbing and storing greenhouse gases in the first place.
This in turn will accelerate climate change, putting at risk com-
munities including coastal ones along with other economically-
important assets such as coral reefs; freshwater systems and
marine biodiversity as well as ‘hardinfrastructure from ports
to power-stations. Targeted investments in the sustainable
management of coastal and marine ecosystems the natural
infrastructure alongside the rehabilitation and restoration of
damaged and degraded ones, could prove a very wise transac-
tion with inordinate returns.
This report, produced by some of the world’s leading scientists
and in collaboration with the FAO and IOC-UNESCO, finds
that the most crucial, climate-combating coastal ecosystems
cover less than 0.5% of the sea bed. But they are disappearing
faster than anything on land and much may be lost in a couple
of decades. These areas, covering features such as mangroves,
salt marshes and seagrasses, are responsible for capturing and
storing up to some 70% of the carbon permanenty stored in the
marine realm.
If we are to tackle climate change and make a transition to a re-
source efficient, Green Economy, we need to recognize the role
and the contribution of all the colours of carbon. Blue carbon,
found and stored away in the seas and oceans, is emerging as
yet another option on the palette of promising opportunities
and actions, one that can assist in delivering a bright rather
than a dark brown and ultimately black future.
Achim Steiner
UN Under-Secretary General and Executive Director, UNEP
PREFACE
The most crucial, climate-
combating coastal ecosystems
are disappearing faster than
anything on land and much may
be lost in a couple of decades.
If the world is to decisively deal with climate change, every source of emissions and every
option for reducing these should be scientifically evaluated and brought to the interna-
tional community’s attention.
6
EXECUTIVE SUMMARY
The objective of this report is to highlight the critical role of the oceans and ocean ecosys-
tems in maintaining our climate and in assisting policy makers to mainstream an oceans
agenda into national and international climate change initiatives. While emissionsre-
ductions are currently at the centre of the climate change discussions, the critical role of
the oceans and ocean ecosystems has been vastly overlooked.
Out of all the biological carbon (or green carbon) captured in
the world, over half (55%) is captured by marine living organ-
isms not on land hence it is called blue carbon. Continu-
ally increasing carbon dioxide (CO
2
) and other greenhouse gas
emissions are contributing to climate change. Many countries,
including those going through periods of rapid growth, are
increasing their emissions of brown and black carbon (such
as CO
2
and soot) as a result of rapid economic development.
Along with increased emissions, natural ecosystems are being
degraded, reducing their ability to absorb CO
2
. This loss of ca-
pacity is equivalent to one to two times that of the annual emis-
sions from the entire global transport sector.
Rising greenhouse gases emissions are producing increasing
impacts and changes worldwide on weather patterns, food pro-
duction, human lives and livelihoods. Food security, social, eco-
nomic and human development will all become increasingly
jeopardized in the coming decades.
Maintaining or improving the ability of forests and oceans
to absorb and bury CO
2
is a crucial aspect of climate change
mitigation. The contribution of forests in sequestering carbon
is well known and is supported by relevant financial mecha-
nisms. In contrast, the critical role of the oceans has been over-
looked. The aim of this report is to highlight the vital contribu-
tion of the oceans in reducing atmospheric CO
2
levels through
sequestration and also through reducing the rate of marine and
coastal ecosystem degradation. It also explores the options for
developing a financial structure for managing the contribution
oceans make to reducing CO
2
levels, including the effective-
ness of an ocean based CO
2
reduction scheme.
Oceans play a significant role in the global carbon cycle. Not
only do they represent the largest long-term sink for carbon but
they also store and redistribute CO
2
. Some 93% of the earth’s
CO
2
(40 Tt) is stored and cycled through the oceans.
The ocean’s vegetated habitats, in particular mangroves, salt
marshes and seagrasses, cover <0.5% of the sea bed. These
form earth’s blue carbon sinks and account for more than
50%, perhaps as much as 71%, of all carbon storage in ocean
sediments. They comprise only 0.05% of the plant biomass on
land, but store a comparable amount of carbon per year, and
thus rank among the most intense carbon sinks on the planet.
Blue carbon sinks and estuaries capture and store between
235–450 Tg C every year or the equivalent of up to half of
the emissions from the entire global transport sector, estimated
at around 1,000 Tg C yr
–1
. By preventing the further loss and
degradation of these ecosystems and catalyzing their recovery,
we can contribute to offsetting 3–7% of current fossil fuel emis-
sions (totaling 7,200 Tg C yr
–1
) in two decades over half of
that projected for reducing rainforest deforestation. The effect
7
would be equivalent to at least 10% of the reductions needed to
keep concentrations of CO
2
in the atmosphere below 450 ppm.
If managed properly, blue carbon sinks, therefore, have the po-
tential to play an important role in mitigating climate change.
The rate of loss of these marine ecosystems is much higher
than any other ecosystem on the planet in some instances
up to four times that of rainforests. Currently, on average, be-
tween 2–7% of our blue carbon sinks are lost annually, a sev-
en-fold increase compared to only half a century ago. If more
action is not taken to sustain these vital ecosystems, most may
be lost within two decades. Halting degradation and restoring
both the lost marine carbon sinks in the oceans and slowing
deforestation of the tropical forests on land could result in
mitigating emissions by up to 25%.
Sustaining blue carbon sinks will be crucial for ecosystem-
based adaptation strategies that reduce vulnerability of hu-
man coastal communities to climate change. Halting the de-
cline of ocean and coastal ecosystems would also generate
economic revenue, food security and improve livelihoods in
the coastal zone. It would also provide major economic and
development opportunities for coastal communities around
the world, including extremely vulnerable Small Island De-
veloping States (SIDS).
Coastal waters account for just 7% of the total area of the
ocean. However the productivity of ecosystems such as coral
reefs, and these blue carbon sinks mean that this small area
forms the basis of the world’s primary fishing grounds, sup-
plying an estimated 50% of the world’s fisheries. They provide
vital nutrition for close to 3 billion people, as well as 50% of
animal protein and minerals to 400 million people of the least
developed countries in the world.
The coastal zones, of which these blue carbon sinks are cen-
tral for productivity, deliver a wide range of benefits to hu-
man society: filtering water, reducing effects of coastal pol-
lution, nutrient loading, sedimentation, protecting the coast
from erosion and buffering the effects of extreme weather
events. Coastal ecosystem services have been estimated to be
worth over US$25,000 billion annually, ranking among the
most economically valuable of all ecosystems. Much of the
degradation of these ecosystems not only comes from unsus-
tainable natural resource use practices, but also from poor
watershed management, poor coastal development practices
and poor waste management. The protection and restoration
of coastal zones, through coordinated integrated manage-
ment would also have significant and multiple benefits for
health, labour productivity and food security of communities
in these areas.
The loss of these carbon sinks, and their crucial role in man-
aging climate, health, food security and economic develop-
ment in the coastal zones, is therefore an imminent threat.
It is one of the biggest current gaps to address under climate
change mitigation efforts. Ecosystem based management
and adaptation options that can both reduce and mitigate
climate change, increase food security, benefit health and
subsequent productivity and generate jobs and business are
of major importance. This is contrary to the perception that
mitigation and emission reduction is seen as a cost and not
an investment. Improved integrated management of the
coastal and marine environments, including protection and
restoration of our oceans blue carbon sinks, provides one of
the strongest win-win mitigation efforts known today, as it
may provide value-added benefits well in excess of its costs,
but has not yet been recognized in the global protocols and
carbon trading systems
8
Establish a global blue carbon fund for protection
and management of coastal and marine ecosys-
tems and ocean carbon sequestration.
a. Within international climate change policy instruments, cre-
ate mechanisms to allow the future use of carbon credits for
marine and coastal ecosystem carbon capture and effective stor-
age as acceptable metrics become available. Blue carbon could
be traded and handled in a similar way to green carbon – such
as rainforests – and entered into emission and climate mitiga-
tion protocols along with other carbon-binding ecosystems;
b. Establish baselines and metrics for future environmentally
sound ocean carbon capture and sequestration;
c. Consider the establishment of enhanced coordination and
funding mechanisms;
d. Upscale and prioritize sustainable, integrated and ecosys-
tem-based coastal zone planning and management, especially
in hotspots within the vicinity of blue carbon sinks to increase
the resilience of these natural systems and maintain food and
livelihood security from the oceans.
Immediately and urgently protect at least 80% of
remaining seagrass meadows, salt marshes and
mangrove forests, through effective management.
Future funds for carbon sequestration can contribute to main-
taining management and enforcement.
Initiate management practices that reduce and re-
move threats, and which support the robust recovery
potential inherent in blue carbon sink communities.
Maintain food and livelihood security from the
oceans by implementing comprehensive and inte-
grated ecosystem approaches aiming to increase
the resilience of human and natural systems to change.
Implement win-win mitigation strategies in the
ocean-based sectors, including to:
a. Improve energy efficiency in marine transport, sh-
ing and aquaculture sectors as well as marine-based tourism;
b. Encourage sustainable, environmentally sound ocean based
energy production, including algae and seaweed;
c. Curtail activities that negatively impact the ocean’s ability to
absorb carbon;
d. Ensure that investment for restoring and protecting the ca-
pacity of ocean’s blue carbon sinks to bind carbon and provide
food and incomes is prioritized in a manner that also promotes
business, jobs and coastal development opportunities;
e. Catalyze the natural capacity of blue carbon sinks to regener-
ate by managing coastal ecosystems for conditions conducive
to rapid growth and expansion of seagrass, mangroves, and salt
marshes.
1
5
4
3
2
In order to implement a process and manage the necessary funds for the protection,
management and restoration of these crucial ocean carbon sinks, the following options
are proposed:
KEY OPTIONS:
9
PREFACE
EXECUTIVE SUMMARY
INTRODUCTION
EMISSIONS AND SEQUESTRATION
– THE BINDING OF CARBON
BLUE PLANET: OCEANS AND CLIMATE
BLUE CARBON – THE ROLE OF OCEANS
AS CARBON SINKS
THE WORLD’S OCEAN CARBON SINKS
IN RAPID DECLINE
OCEANS’ BLUE CARBON SINKS AND
HUMAN WELLBEING
ECOSYSTEM BASED ADAPTATION AND
MITIGATION
POLICY OPTIONS
GLOSSARY
ACRONYMS
CONTRIBUTORS
REFERENCES
CONTENTS
5
6
11
15
23
35
45
51
61
65
70
72
73
74
10
11
Of all the Green carbon captured annually in the world, that is the carbon captured by
photosynthetic activity, over half (55%) is captured by marine living organisms (Falkow-
ski et al., 2004; Arrigo, 2005; González, et al., 2008; Bowler, 2009; Simon et al., 2009).
This oceanic carbon cycle is dominated by micro-, nano-, and picoplankton, including
bacteria and archaea (Burkill, 2002). Even though plant biomass in the oceans is only
a fraction of that on land, just 0.05%, it cycles almost the same amount of carbon each
year (Bouillon et al., 2008; Houghton, 2007); therefore representing extremely efficient
carbon sinks. However, while increasing efforts are being made to slow degradation on
land, such as through protection of rainforests as a means to mitigate climate change, the
role of marine ecosystems has to date been largely ignored.
INTRODUCTION
Knowledge of the role of natural ecosystems in capturing CO
2
is an increasingly important component in developing strate-
gies to mitigate climate change. Losses and degradation of
natural ecosystems comprise at least 20–30% of our total emis-
sions (UNEP, 2008a; 2009). While overall emissions from the
burning of fossil fuels needs to be severely reduced, mitigating
climate change can also be achieved by protecting and restoring
natural ecosystems (Trumper et al., 2009). Even from a nar-
row perspective of emission reductions alone, they can play a
significant role. As steep reduction of fossil fuel emissions may
compromise the development potential of some countries, it is
critical that options are identified that can help mitigate climate
change with neutral or even positive impacts on development.
It is therefore absolutely critical to identify those natural ecosys-
tems that contribute most to binding our increasing emissions
of carbon or CO
2
and enhance this natural capacity (Trumper et
al., 2009). Some of these are in the oceans.
Some 93% of the earth’s carbon dioxide – 40Tt CO
2
– is stored
in the oceans. In addition, oceans cycle about 90 Gt of CO
2
yr
–1
(González et al., 2008), and remove over 30% of the carbon
released to the atmosphere.
Resilient aquatic ecosystems not only play a crucial role in bind-
ing carbon, they are also important to economic development,
food security, social wellbeing and provide important buffers
against pollution, and extreme weather events. Coastal zones
are of particular importance, with obvious relations and impor-
tance to fisheries, aquaculture, livelihoods and settlements (Kay
and Alder, 2005) over 60% of the world’s population is settled
in the coastal zone (UNEP, 2006, 2008b). For many coastal
developing countries, the coastal zone is not only crucial for
the wellbeing of their populations, it could also, as documented
in this report, provide a highly valuable global resource for cli-
mate change mitigation if supported adequately.
This report explores the potential for mitigating the impacts
of climate change by improved management and protection of
marine ecosystems and especially the vegetated coastal habitat,
or blue carbon sinks.
12
Carbon cycle
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150
1 020
750
1 580
1 020
610
38 100
650
50
Deep ocean
Dissolved organic C
Labile
dissolved
organic C
Sediments
Coal fields
Oil and gas
fields
Ocean surface
Atmosphere
Soil
Biosphere
Land use change
Rivers
Marine
biota
0.8
3
4
6
6
0.2
40
50
100
90
92
121
60
60
1.5
0.5
8
96.1
Source: IPCC.
3 000
300
Carbon fluxes and stocks
Fluxes: Gigatonnes of C per year
Storage: Gigatonnes of C
1 020
8
13
Carbon cycle
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150
1 020
750
1 580
1 020
610
38 100
650
50
Deep ocean
Dissolved organic C
Labile
dissolved
organic C
Sediments
Coal fields
Oil and gas
fields
Ocean surface
Atmosphere
Soil
Biosphere
Land use change
Rivers
Marine
biota
0.8
3
4
6
6
0.2
40
50
100
90
92
121
60
60
1.5
0.5
8
96.1
Source: IPCC.
3 000
300
Carbon fluxes and stocks
Fluxes: Gigatonnes of C per year
Storage: Gigatonnes of C
1 020
8
Figure 1: Carbon Cycle. Oceans are crucial in the global
carbon cycle. It was here where life first evolved; they are
the source of our wealth and development. The living
oceans capture over half of all the Green carbon – the car-
bon bound by living organisms through photosynthesis.
Units of Carbon used. This report will use Tg C, but read-
ers will also see values for C and CO
2
, provided in a wide
range of formats. The following information may assist
in wider reading.
Definition: Measuring Carbon
1km
2
= 100ha
1 ton = 2,240lbs
1 (metric) ton = 1,000kg or 1x10
6
g
Blue carbon sinks capture CO
2
through photosynthesis
from the air and water and store it as carbon.
The rate of converting C to CO
2
is 44/12; i.e. 1 aton of C
is equivalent to 3.67t CO
2
Name
One thousand
One million
One billion
One trillion
Factor
10
3
10
6
10
9
10
12
10
15
Symbol
k (Kilo)
M (Mega)
G (Giga)
T (Tera)
P (Peta)
14
15
Anthropogenic climate change is caused by the rising content of greenhouse gases and
particles in the atmosphere. Firstly by the burning of fossil fuels, releasing greenhouse
gases such as CO
2
, (“brown carbon”) and dust particles (part of “black carbon”); secondly
by emissions from clearing natural vegetation, forest fires and agricultural emissions, in-
cluding those from livestock; and thirdly by the reduced ability of natural ecosystems to
bind carbon through photosynthesis and store it – so called green carbon (Trumper et al.,
2009). The uptake of CO
2
into a reservoir over long (several decades or centuries) time
scales, whether natural or artificial is called carbon sequestration (Trumper et al., 2009).
EMISSIONS AND SEQUESTRATION
THE BINDING OF CARBON
Climate Change has driven widespread appreciation of atmo-
spheric CO
2
as the main greenhouse gas and of the role of an-
thropogenic CO
2
emissions from energy use and industry in
affecting temperatures and the climate we refer to these emis-
sions as “brown carbon” for greenhouse gases and “black car-
bon” for particles resulting from impure combustion, such as
soot and dust. The Emissions Trading System of the European
Union (EU-ETS) is a “black-brown carbon” system as it does not
incorporate forestry credits. The Kyoto Protocol’s Clean Devel-
opment Mechanism (CDM) does in principle include forestry
credits, but demand (in the absence of a linking directive and
demand from the EU-ETS) and prices have always been too low
to encourage success, so CDM has also become, for all practical
purposes, another “black carbon” mechanism.
Terrestrial carbon stored in plant biomass and soils in forest land,
plantations, agricultural land and pasture land is often called “green
carbon”. The importance of “green carbon is being recognized
through anticipated agreement at the United Nations Framework
Convention on Climate Change Conference of the Parties (COP)
in Copenhagen, December 2009, which includes forest carbon
through various mechanisms, be they REDD and afforestation,
REDD-Plus, and/or others (e.g. ‘Forest Carbon for Mitigation’). The
world’s oceans bind an estimated 55% of all carbon in living or-
ganisms. The ocean’s blue carbon sinks – particularly mangroves,
marshes and seagrasses capture and store most of the carbon
buried in marine sediments. This is called “blue carbon”. These
ecosystems, however, are being degraded and disappear at rates
5–10 times faster than rainforests. Together, by halting degradation
of “green” and “blue” carbon binding ecosystems, they represent
an emission reduction equivalent to 1–2 times that of the entire
global transport sector – or at least 25% of the total global carbon
emission reductions needed, with additional benefits for biodiver-
sity, food security and livelihoods. It is becoming increasingly clear
that an effective regime to control emissions must control the en-
tire “spectrum” of carbon, not just one “colour”.
In the absence of “Green Carbon”, biofuel cropping can become
incentivized, and can lead to carbon emissions if it is not done cor-
rectly. The conversion of forests, peatlands, savannas and grass-
lands to produce food-crop based biofuels in Brazil, Southeast Asia
and the United States creates a biofuel carbon debt by emitting 14
to 420 times more CO
2
than the annual reductions in greenhouse
gases these biofuels provide by replacing fossil fuels. In contrast,
biofuels produced from waste biomass and crops grown on de-
graded agricultural land do not accrue any such carbon debt.
Fact box 1. The colours of carbon: Brown, Black, Blue and Green
16
BROWN, BLACK, GREEN AND BLUE CARBON
global warming over the past century. Black carbon tends to
remain in the atmosphere for days-weeks (Hansen and Naza-
rento, 2004) whereas CO
2
remains in the atmosphere for ap-
prox 100 years (IGSD, 2009).
The total CO
2
emissions of are estimated to be between 7,200
Tg C yr
–1
, and 10,000 Tg C yr
–1
(Trumper et al., 2009), and
the amount of carbon in the atmosphere is increasing by ap-
proximately 2,000 Tg C yr
–1
(Houghton, 2007).
GREEN CARBON
Green carbon is carbon removed by photosynthesis and stored
in the plants and soil of natural ecosystems and is a vital part of
the global carbon cycle. Sofar, however, it has mainly been con-
sidered in the climate debate in terrestrial ecosystems, though
the issue of marine carbon sequestration has been known for
at least 30 years.
A sink is any process, activity or mechanism that removes a
greenhouse gas, an aerosol or a precursor of a greenhouse gas
or aerosol from the atmosphere. Natural sinks for CO
2
are for
example forests, soils and oceans.
Unlike many plants and most crops, which have short lives or
release much of their carbon at the end of each season, forest bio-
mass accumulates carbon over decades and centuries. Further-
more, forests can accumulate large amounts of CO
2
in relatively
short periods, typically several decades. Afforestation and refores-
tation are measures that can be taken to enhance biological car-
bon sequestration. The IPCC calculated that a global programme
involving reduced deforestation, enhanced natural regeneration
of tropical forests and worldwide re-afforestation could seques-
Figure 3: World greenhouse emission by sector. All transport
accounts for approximately 13.5% of the total emissions, while
deforestation accounts for approximately 18%. However, esti-
mates of the loss of marine carbon-binding ecosystems have
previously not been included.
Figure 2: Projected growth in energy demand in coming decades.
Brown and black carbon emissions from fossil fuels, biofuels
and wood burning are major contributors to global warming.
Black carbon emissions have a large effect on radiation trans-
mission in the troposphere, both directly and indirectly via
clouds, and also reduce the snow and ice albedo.
Black carbon is thought to be the second largest contributor to
global warming, next to brown carbon (the gases). Thus, reduc-
ing black carbon emission represents one of the most efficient
ways for mitigating global warming that we know today.
Black carbon enters the ocean through aerosol and river deposi-
tion. Black carbon can comprise up to 30% of the sedimentary
organic carbon (SOC) in some areas of the deep sea (Masiello
and Druffel, 1998) and may be responsible for 25% of observed
Other
renewables
1980 1990 2000 2010 2020 2030
3
6
9
0
Oil
Actual and projected energy demand
Gigatonnes of oil equivalent
Hydropower
Note: All statistics refer to energy in its original form (such as coal) before being
transformed into more convenient energy (such as electrical energy).
Source: International Energy Agency (IEA), World Energy Outlook 2008.
Projections
Gas
Coal
Biomass
Nuclear
15
12
17
Land use change
Agriculture
Waste
Transportation
Electricity & heat
Industry
Fugitive emissions
Other fuel
combustion
Carbon dioxide
(CO
2
)
77%
(CH
4
)
14%
(N
2
O)
8%
Methane
Nitrous oxide
HFCs,
PFCs,
SF
6
1%
Agriculture soils
Livestock & manure
Rice cultivation
Other agriculture
Landfills
Wastewater, other waste
Agricultural energy use
T&D losses
Coal mining
Oil/gas extraction,
Refining & processing
Deforestation
Afforestation
Reforestation
Harvest/Management
Other
Cement
Other industry
Chemicals
Aluminium/Non-ferrous metals
Food & tobacco
Pulp, paper & printing
Machinery
Road
Air
Rail, ship
& other transport
Unallocated
fuel combustion
Commercial buildings
Residential buildings
Iron & steel
Sector End use/activity Gas
All data is for 2000. All calculations are based on CO
2
equivalents, using 100-year global warming potentials from the IPCC
(1996), based on a total global estimate of 41 755 MtCO
2
equivalent. Land use change includes both emissions and absorptions.
Dotted lines represent flows of less than 0.1% percent of total GHG emissions.
Source: World Resources Institute, Climate Analysis Indicator Tool (CAIT), Navigating the Numbers: Greenhouse Gas Data and
International Climate Policy, December 2005; Intergovernmental Panel on Climate Change, 1996 (data for 2000).
Industrial processes
E N E R G Y
World greenhouse gas emissions by sector
18.2%
13.5%
3.6%
3.4%
13.5%
24.6%
10.4%
3.9%
9%
6%
5.1%
1.5%
0.9%
2%
1.6%
1.4%
1,9%
1,4%
6.3%
18.3%
-1.5%
-0.5%
2.5%
-0.6%
3,8%
5,0%
4.8%
1%
1%
1.4%
1%
9.9%
1.6%
2.3%
3.5%
5.4%
9,9%
3.2%
18
ter 60–87 Gt of atmospheric carbon by 2050, equivalent
to some 12–15% of projected CO
2
emissions from fossil
fuel burning for that period (Trumper et al., 2009).
It is becoming better understood that there are critical
thresholds of anthropogenic climate change, beyond
which dangerous thresholds will be passed (IPCC,
2007a). For example, to keep average temperature rises
to less than 2°C, global emissions have to be reduced
by up to 85% from 2000 levels by 2050 and to peak
no later than 2015, according to the IPCC (Trumper et
al., 2009).
But while the loss of green carbon ecosystems have at-
tracted much interest, for example by combating the
East Asia
South America
Western Africa
Southern Asia
South-East Asia
East Africa
Middle East
Northern Africa
East Europe
Central America
Oceania
Japan
Canada
Former USSR
USA
Southern Africa
Black Carbon emissions
Teragrams per year (2000)
1570
800
380
200
120
42%
18%
14%
10%
10%
6%
Open biomass
Residential - coal and others
Transport - non road
Transport - road
Industry and power generation
Residential - biofuel
Black Carbon emissions
Sources: Bond et al., 2000.
Share by sector and geographic
distribution
Figure 4: Combustion sources of black carbon.
(Source: Dennis Clare, State of the World 2009, www.
worldwatch.org).
19
loss of tropical rainforests, the fact that near 55% of all
green carbon is captured by living organisms not on land,
but in oceans, has been widely ignored, possibly our great-
est deficit in mitigating climate change. The carbon cap-
tured by marine organisms is herein called “blue carbon”.
BLUE CARBON
Blue carbon is the carbon captured by the world’s oceans
and represents more than 55% of the green carbon. The
carbon captured by living organisms in oceans is stored in
the form of sediments from mangroves, salt marshes and
seagrasses. It does not remain stored for decades or centu-
ries (like for example rainforests), but rather for millennia.
In this report, the prospects and opportunities of binding
carbon in oceans is explored.
Source: UNEP-WCMC, 2009.
Green Carbon
Tonnes of C stored per hectare
Tropical,
Subtropical,
Savannas,
Shrublands
Tropical,
Subtropical
Forests
Deserts and
Dry Shrubland
Temperate
Grasslands,
Savannas
Shrublands
Temperate
Forest
Boreal
Forest
Tundra
547.8
285.3
178.0
183.7
314.9
384.2
155.4
50
130
325
Gigatonnes
of C stored in
terrestrial
biomes
Figure 5: 45% of green carbon stored in natural terrestrial
ecosystems and the remaining 55% is captured by living or-
ganisms in oceans by plankton and ocean’s blue carbon sinks.
20
21
22
That’s here. That’s home. That’s us.
On it everyone you love, everyone you know, everyone
you ever heard of, every human being who ever was,
lived out their lives. The aggregate of our joy and
suffering, thousands of confident religions, ideologies,
and economic doctrines, every hunter and forager,
every hero and coward, every creator and destroyer of
civilization, every king and peasant, every young couple
in love, every mother and father, hopeful child, inventor
and explorer, every teacher of morals, every corrupt
politician, every ‘superstar’, every ‘supreme leader,’
every saint and sinner in the history of our species lived
there – on a mote of dust suspended in a sunbeam.
Look again at that dot.
Carl Sagan 1997.
Image from the solar system taken by the Voyager 1 spacecraft (NASA/JPL).
23
The existence of the vast ocean is the main defining characteristic of our planet, mak-
ing earth unique in the solar system and the only Blue Planet. Although water is not
uncommon in the universe, oceans are probably extremely rare. Other planets in the so-
lar system have evidence of ice, ancient water
basins and valleys, or even subsurface liquid
water, but planet earth is the only one which
has liquid surface water; probably due to our
privileged position in respect to the sun: not close enough to evaporate and escape, nor
far enough to freeze. Water is also linked to the origin of life, in which early organic
molecules rested protected from temperature swings and from the sun’s destructive
ultraviolet radiation, and where they could move freely to combine and evolve. This
successful combination of water and life changed the composition of the atmosphere
by releasing oxygen and extra water vapour, and shaped our landscape, through ero-
sion, weathering and sedimentation, in a continuous interchange of water between the
ocean, the land and the atmosphere.
BLUE PLANET:
OCEANS AND CLIMATE
How inappropriate to call this planet earth
when it is quite clearly Ocean.
Arthur C. Clarke
Water moves in a continuous cycle that begins and ends in
the ocean. This hydrologic cycle is powered by solar radiation,
which provides energy for evaporation. Then precipitation,
transpiration from plants, runoff into streams and infiltration
to ground water reservoirs complete the cycle, which will start
over again when most of the initial evaporated water reaches
the ocean. Although during the cycle, water can be present in
different states as ice, liquid or vapor, the total water content
of the ocean has remained fairly constant since its formation,
with an average residence time of approximately 3,000 years.
At the moment, 97.25% of the water in planet earth is in the
form of liquid salty water in the oceans, with only 2.05%
forming ice covers and glaciers, 0.68% groundwater, 0.01%
rivers and lakes, and 0.001% in the atmosphere (Campy and
MaCaire, 2003).
Oceans have been influencing the climate and the ecology of
the planet since the very beginning of life on earth. Over time,
both the physical oceans and living organisms have contrib-
uted to the cycling of carbon. Plankton in marine ecosystems
produces more organic material than is needed to maintain
the food chain. The excess carbon slowly accumulates on the
sea bed during geological time (biological pump) (Longhurst,
1991; Siegenthaler and Sarmiento, 1993; Raven and Falkowski,
1999). With that process, sediment and fossilized carbonate
plankton have changed the shape of our coasts.
24
PHYSICAL PUMP
Transport of CO
2
by Vertical
Mixing and Deep
Water Masses
Primary
Production
Organic Carbon
Oxygen
Respiration
Egestion
Food Web
Decomposition
Nutrients
(Nitrate)
Particulate Carbon
(Organic and Inorganic)
Nutrients
CO
2
CO
2
CO
2
CO
2
CO
2
CO
2
Nutrients
(Ammonia)
CO
2
CO
2
CO
2
CO
2
CO
2
Bacteria
Oxidation
Bacteria
Remineralization
Carbon Deposition
Carbon Burial
SOLUBILITY PUMP
Transport of CO
2
through the
air-sea interface
Phytoplankton
High
Latitudes
Low
Latitudes
Vertical Mixing
Local Action
Short-time
Scale
Long-time
Scale
Global Action
Deep Water Masses
Formation
AIR-SEA INTERFACE CO
2
EXCHANGES
ATMOSPHERIC CIRCULATION PATTERNS
Sinking
BIOLOGICAL PUMP
Vertical gravitational
settlings of
biogenic debris
Nutrients
(Nitrate)
Sources:
R. Chester, 2003; H. Elderfield, 2006; R.A. Houghton, 2007; T.J.
Lueker et al, 2000;J.A. Raven and P.G. Falkowski, 1999.
25
Figure 7: Carbon fluxes in the oceans. (Source: adapted from Takahashi et al., 2009).
Oceans are absorbing both heat and carbon from the atmosphere,
therefore alleviating the impacts of global warming in the environ-
ment. Covering more than two-thirds of the earth’s surface, the
oceans store the sun’s energy that reaches earth’s surface in the
form of heat, redistribute it, from the coast to the mid-ocean, shal-
low to deep waters, polar to tropical, and then slowly release it back
to the atmosphere. These storage and circulation processes prevent
abrupt changes in temperature, making coastal weather mild and
some high latitude areas of the globe habitable. However this huge
heat storage capacity can have undesirable consequences with the
advent of climate change. With global warming, the ocean is ab-
sorbing a large portion of the excess heat present in the atmosphere
(almost 90%), resulting in a measurable increase of surface water
temperatures (an average of approximately 0.64
o
C over the last 50
years) (Levitus et al., 2000; IPCC, 2007b). As water warms, it ex-
Figure 6: Carbon cycling in the world’s oceans. The
flow of carbon dioxide across the air-sea interface is
a function of CO
2
solubility in sea water (Solubility
Pump). The amount of CO
2
dissolved in sea water
is mainly influenced by physico-chemical conditions
(sea water temperature, salinity, total alkalinity) and
biological processes, e.g. primary production. The
solubility pump and the biological pump enhance the
uptake of CO
2
by the surface ocean influencing its val-
ues for dissolved CO
2
and transferring carbon to deep
waters. All these mechanisms are strongly connected,
subtly balanced and influential to the ocean’s capacity
to sink carbon. The net effect of the biological pump
in itself is to keep the atmosphere concentration of
CO
2
around 30% of what it would be in its absence
(Siegenthaler and Sarmiento, 1993).
Mol of carbon per square metre
Oceans carbon fluxes
-1
0.5
-0.5
1
Source: Marine Institute, Ireland, 2009.
Net carbon
release
Net carbon
uptake
26
31 34
Practical salinity unit
Deep water formation
Surface
current
Deep current
Deep water formation
Deep water formation
Pacific
Ocean
Pacific
Ocean
Atlantic
Ocean
Indian
Ocean
36 39
(1 psu = 1 gram of salt per kilogram of water)
Thermohaline circulation
Source : NASA, 2009.
Figure 8: Thermohaline circulation is a 3-dimensional flow involving surface and deep ocean waters, which
is driven by differences in water temperature and salinity. (Image source: NOAA/NCDC).
pands causing the ocean surface to rise (UNEP, 2008b). Over
time, this heat will descend to greater ocean depths, increasing
expansion and triggering further changes in sea level.
Melting of sea ice in the Arctic, inland glaciers and continen-
tal ice sheets of Greenland and Antarctica is changing the sa-
linity of sea water and in some cases also contributing to sea
level rise (UNEP, 2008b). So, melting and warming will have
further consequences on ocean circulation, as ocean currents
are driven by the interactions between water masses through a
balance with temperature and salinity, which controls the den-
sity. Changes in oceanic currents could expose local climates
to abrupt changes in temperature. Higher water temperatures
also lead to increased evaporation, making more energy avail-
able for the atmosphere. This has direct consequences on
extreme weather events, as warming sea temperatures boost
the destructive energy of hurricanes, typhoons, etc. Tropical
sea-surface temperatures have warmed by only half a degree
Celsius, while a 40% increase in the energy of hurricanes has
been observed (Saunders and Lea, 2008).
Warmer, low salinity surface waters together with the annual sea-
sonal heating are extending and strengthening the seasonal lay-
ers in the water-column (stratification), limiting the vertical move-
ment of water masses. This phenomenon together with changes
in wind regimes has implications for some of the most produc-
tive parts of earth’s oceans (Le Quéré et al., 2007), where upwell-
ing of deep waters and nutrients enhances primary production,
supporting massively abundant surface ecosystems. If reduction
of upwelling occurs to any degree, marine ecosystems, fisheries
27
and communities will be negatively affected. It is important to
highlight that enhanced stratification is already a fact in temper-
ate seas at mid-latitudes, where stratification is diminishing the
total annual primary production as a result of the reduction in the
supply of nutrients to the surface layers (Cushing, 1989; Valdés
and Moral, 1998; Valdés et al., 2007). Warming temperatures are
also changing the geographical ranges of marine species. Chang-
es in depth range are occurring, as species shift down in the
water column to escape from warming surface waters. There is
also evidence that the distribution of zooplankton, fish and other
marine fauna has shifted hundreds of kilometers towards higher
latitudes, especially in the North Atlantic, the Arctic Ocean, and
the Southwest Pacific Ocean (Cheung et al., 2009)
Another important role played by the ocean is the storage and
exchange of CO
2
with the atmosphere, and its diffusion toward
deeper layers (solubility pump) (Fact box 2) (Siegenthaler and
Sarmiento, 1993). The ocean has absorbed approximately one-
third of the total anthropogenic CO
2
emissions since the begin-
ning of the industrial era (Sabine and Feely, 2007). In so doing,
the ocean acted as a buffer for earth’s climate, as this absorption
of CO
2
mitigates the effect of global warming by reducing its
concentration in the atmosphere. However, this continual intake
of CO
2
and heat is changing the ocean in ways that will have
potentially dangerous consequences for marine ecology and bio-
diversity. Dissolved CO
2
in sea water lowers the oceanspH level,
causing acidification, and changing the biogeochemical car-
bonate balance (Gattuso and Buddemeier, 2000; Pörtner et al.,
2004). Levels of pH have declined at an unprecedented rate in
surface sea water over the last 25 years and will undergo a further
substantial reduction by the end of this century as anthropogenic
sources of CO
2
continue to increase (Feely et al., 2004).
As the ocean continues to absorb further heat and CO
2
, its ability
to buffer changes to the atmosphere decreases, so that atmosphere
and terrestrial ecosystems will face the full consequences of cli-
mate change. At high latitudes, dense waters sink, transferring
carbon to the deep ocean. Warming of the ocean surface inhibits
this sinking process and therefore reduces the efficiency of CO
2
transport and storage. Furthermore, as water warms up, the solu-
bility of CO
2
declines, therefore less gas can be stored in the sea
water. With acidification, warming, reduced circulation and mix-
ing, there has been a significant change in plankton productivity
in the ocean, reducing the portion of the carbon budget that would
be carried down to the deep seafloor and stored in sediments.
So, the ocean system is being threatened by the anthropogenic
activities which are causing global warming and ocean acidifica-
tion. As waters warm up and the chemical composition of the
ocean changes, the fragile equilibrium that sustains marine bio-
diversity is being disturbed with serious consequences for the
marine ecology and for earth’s climate. There is already some
clear evidence that the global warming trend and increasing
emissions of CO
2
and other greenhouse gases are affecting en-
vironmental conditions and biota in the oceans on a global scale.
However, we neither fully appreciate nor do we understand how
significant these effects will be in the near and more distant fu-
ture. Furthermore, we do not understand the mechanisms and
processes that link the responses of individuals of a given spe-
cies with shifts in the functioning of marine ecosystems (Valdés
et al., 2009). Marine scientists need urgently to address climate
change issues, particularly to aid our understanding of climate
change effects on ecosystem structure, function, biodiversity,
and how human and natural systems adapt to these changes.
The solubility pump: CO
2
is soluble in water. Through a gas-
exchange process CO
2
is transferred from the air to the ocean,
where it forms of dissolved inorganic carbon (DIC). This is a
continuous process, as sea water is under-saturated with CO
2
compared to the atmosphere. The CO
2
is subsequently distrib-
uted by mixing and ocean currents. The process is more effi-
cient at higher latitudes as the uptake of CO
2
as DIC increases
at lower temperatures since the solubility of CO
2
is higher in
cold water. By this process, large quantities of CO
2
are removed
from the atmosphere and stored where they cannot contribute
immediately to the greenhouse effect.
The biological pump: CO
2
is used by phytoplankton to grow.
The excess of primary production sinks from the ocean sur-
face to the deep sea. In the very long term, part of this carbon
is stored in sediments and rocks and trapped for periods of
decades to centuries. In order to predict future CO
2
concentra-
tions in the atmosphere, it is necessary to understand the way
that the biological pump varies both geographically and tem-
porally. Changes in temperature, acidification, nutrient avail-
ability, circulation, and mixing all have the potential to change
plankton productivity and are expected to reduce the trade-off
of CO
2
towards the sea bed.
Fact box 2. The ocean – a giant carbon pump
28
Free living marine microorganisms (plankton, bacteria and vi-
ruses) are hardly visible to the human eye, but account for up to
90% of living biomass in the sea (Sogin et al., 2006; Suttle, 2007).
These microscopic factories are responsible for >95% of primary
production in oceans, producing and respiring a major part of the
reduced carbon or organic matter (Pomeroy et al., 2007).
Plankton
More than 36.5Gt of CO
2
is captured each year by planktonic
algae through photosynthesis in the oceans (Gonzalez, et al.
(2008). Zooplankton dynamics are a major controlling factor in
the sedimentation of particulate carbon in open oceans (Bishop
and Wood, 2009). Of the captured CO
2
, and an estimated 0.5Gt
C yr
–1
is stored at the sea bed (Seiter et al., 2005).
Marine viruses and bacteria significant in the carbon budget
Marine viruses require other organic life to exist, but in them-
selves have a biomass equivalent to 75 million blue whales
(11.25Gt). The estimated 1x10
30
viruses in the ocean, if stretched
end to end, would span farther than the nearest 60 galaxies (Sut-
tle, 2007). Although the story of marine viruses is still emerging,
it is becoming increasingly clear that we need to incorporate vi-
ruses and virus-mediated processes into our understanding of
ocean biology and biogeochemistry (Suttle, 2007).
Interactions between viruses and their hosts impact several impor-
tant biological processes in the world’s oceans including biogeo-
chemical cycling. They can control carbon cycling due to cell lysis
and microbial diversity (by selecting for various hosts) (Wiggington,
2008). Every second, approximately 1x10
23
viral infections occur in
the ocean and cause infection of 20–40% surface water prokaryotes
every day resulting in the release of 108–109 tonnes of carbon per
day from the biological pool within the oceans (Suttle, 2007). It is
thought that up to 25% of all living carbon in the oceans is made
available through the action of viruses (Hoyle and Robinson, 2003).
There is still a critical question as to whether viruses hinder or
stimulate biological production (Gobler et al., 1997). There is an
ongoing debate whether viruses (1) shortcircuit the biological
pump by releasing elements back to the dissolved phase (Poor-
vin et al., 2004), (2) prime the biological pump by accelerating
host export from the euphotic zone (Lawrence and Suttle, 2004)
or (3) drive particle aggregation and transfer of carbon into the
deep sea through the release of sticky colloidal cellular compo-
nents during viral lysis (Mari et al., 2005).
Bacteria
Ocean bacteria are capable of taking up CO
2
with the help of
sunlight and a unique light-capturing pigment, proteorhodopsin,
which was first discovered in 2000 (Beja et al., 2001). Proteorho-
dopsin can be found in nearly half of the sea bacteria. Knowledge
of marine bacteria may come to be of major importance to our
understanding of what the climate impact of rising CO
2
emis-
sions means for the oceans.
Life deep below the sea bed
Life has been shown to exist in the deep biosphere, even 800m
below the sea floor. It is estimated that 90 Gt of microbial organ-
isms (in terms of carbon mass) are living in the sediments and
rocks of the sea bed, with bacteria dominating the top 10 cm, but
more than 87% made up by a group of single cell microorganisms
known as Archaea. It is still not clear what their ecological func-
tions are, or even how they survive in such a low flux environment,
living on previously digested fossil remains (Lipp et al., 2008).
Fact box 3. The role of ocean viruses and bacteria in the carbon cycle
29
SEVEN DETRIMENTAL WAYS IN WHICH THE
OCEANS THEMSELVES WILL BE AFFECTED
BY CLIMATE CHANGE
MELTING OF
ARCTIC SEA ICE
Arctic sea-ice reductions have significant impacts on climate,
wildlife and communities. The opening of open water across
the Arctic ocean will have unknown consequences in terms of
changes in water circulation and redistribution of species from
the Atlantic and Pacific oceans. As sea ice coverage declines, albe-
do diminishes and more radiation is absorbed by the sea water, in
a feed-back process that enhances warming and melting sea ice.
The ecology of the planet is closely linked to different ocean processes, most of which are
directly affected by climate change.
Figure 9: Loss of the ice sheet.
1
Sea ice anomaly in Northern Hemisphere
Million square kilometres, from 1978-2000 average
Source : NOAA, 2009.
2000
2001
2003 2005
2007
2009
20102002 2004 2006 2008
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
0.5
30
OCEAN CIRCULATION AND
THERMAL EXPANSION
Melting and warming will have consequences on ocean cir-
culation, as ocean currents are driven by the interactions
between water masses though balance in temperature and
salinity, in other words, their density. Additionally melting of
inland glaciers and continental ice sheets on Greenland and
Antarctica, and the thermal expansion of ocean waters are
causing sea level rise.
Source: IPCC, 2007.
Sea level anomalies
(Metres)
0 0.05 0.10 0.15 0.20 0.25 and more-0.05-0.10-0.15-0.20-0.25
INCREASED FREQUENCY AND
SEVERITY OF STORM EVENTS
Higher water temperatures lead to increased evaporation,
making more energy available for the atmosphere, which
boosts the destructive force of extreme weather events like
hurricanes, typhoons etc.
32
Figure 10. Sea level anomalies (see text).
31
Sea-level rise
Metres
1.000.750.500.250
1000
100
10
1
0.1
no additional efforts undetaken
strong efforts to protect coastal populations against floods
Source: H. Ahlenius, GEO Ice and Snow, 2007, based on Nicholls, R.J. and
Lowe, J.A., 2006.
more protection efforts than today
Note: The upper margin of each band shows the amount of
people affected in the A2 scenario according to which global
population will reach 14 thousand million by 2080 with the
lowest GDP of all IPCC scenarios. Therefore little capacity
exists to adapt, and more people will be affected by floods.
The lower end of each curve shows