Case for optimism The ecosystem protecting coastlines storing carbon
mangrove forests
they are probably the weirdest ecosystem
that you may never have even heard of
they’re really unique because they’re
the only forest that
for part of the day is dry land
and then just a couple of hours later
they’re part of the sea
and this is a really stressful
environment for any forest to try and
survive in
but somehow over the last 80 million
years or so
mangrove forests have figured out how to
do it
and as well as being unique they are
critical for biodiversity
they are home to countless species of
insects
crabs fish otters
crocodiles and more even the home
of the endangered royal bengal tiger
whose last refuge is the mangrove forest
of the sunderbans
on the border between india and
bangladesh
one of the largest remaining mangrove
forests on the planet
but it’s not just biodiversity they are
also critical
for people in the coastal communities
that rely on them
they’re a really important source of
fish and shellfish
a medicinal products of construction
materials and fuel wood
they help buffer our coastlines against
storms and they help trap our pollutants
in their soil and the eco-tourism
industry around mangroves
is worth billions of dollars every year
across the tropics
so despite all of those benefits i just
described what if i told you
that this seedling here was the last
mangrove seedling on the planet the
mangroves were no longer
able to buffer our coastlines against
storms
to trap our pollutants
this would be a real problem because as
well as
all of those benefits mangroves are on
the front line
and protecting us against climate change
this graph here shows
different ecosystems and how much carbon
per hectare
they’re able to store like all plants
mangroves and rainforests and other
ecosystems absorb carbon dioxide
out of the atmosphere and they lock it
up in their leaves
and their branches and their roots and
this is the green part
of the graph and mangroves and
rainforests and other ecosystems are all
able to do this
but what’s different about mangrove
forests is that they are able to store a
lot of that carbon in their soils
which means that they can per unit area
store almost twice as much
carbon as other ecosystems
and this is what mangrove soil looks
like
so if we’re in a rainforest when those
leaves and branches fall
off the tree and onto the surface of the
forest floor
they quickly get broken down by bacteria
and fungi
and all of that carbon that was locked
up in those leaves
is put back into the atmosphere now that
doesn’t happen
with mangrove forest because their soils
are waterlogged
and so instead when those leaves fall
onto the surface
they accumulate over thousands of years
and we have this superstore
of carbon
despite all of those benefits
we were almost close to having
what was a group of world-renowned
scientists in 2007 described as a world
without mangroves
where this scene would be commonplace
across the tropics
and this is because we thought we were
losing mangrove forest at one to three
percent
per year some international
organizations said it was almost as much
as eight percent per year
and this put mangroves on par with the
amazon rainforest and the coral reefs of
the world
in being some of the world’s most
threatened habitats
and this was mostly due to conversion
for economic gain
so this is a satellite image it’s a bit
blurry it’s from 1985
but it’s a typical scene of a coastline
in indonesia
and you can see a top-down view of the
mangrove forests
now if we fast forward to the present
day this is what that scene looks like
that mangrove forest has been replaced
with all of these squares which
represent aquaculture ponds for the
production of shrimp
and fish and actually this kind of
patchwork quilt
of aquaculture has been replicated along
many of our coastlines
across the tropics but it wasn’t just
aquaculture
we’ve lost mangroves in southeast asia
due to conversion to rice paddies
in west africa due to oil pollution in
east africa
due to over-harvesting and in the
caribbean
mangroves are often converted into urban
areas and tourist resorts
but despite all of those pressures and
threats
somehow we turned the tide on mangrove
loss
rates of mangrove loss in the 21st
century
were only a fifth of the rates of loss
in the 20th century
this is a great conservation success
story
it’s something we should celebrate but
it’s actually a story that is not even
that well known
within conservation circles
so how did we save the mangroves
well first of all we got a lot better at
mapping
and monitoring them so we know where
they are
and we know how much has been lost
but it was also because we got a much
stronger understanding of all of those
benefits
that i described unfortunately
it took terrible disasters such as the
indian ocean tsunami
or typhoon haiyan in the philippines for
governments to recognize the importance
of their own mangrove forests it took
climate change negotiations
such as the paris agreement to show
governments that it’s better to keep
that carbon locked up
in the mangrove soil rather than
emitting it into the atmosphere
and as a result we’ve seen huge
conservation changes
along mangrove forests so in 2015
sri lanka announced that it would not
destroy any more mangroves and it would
protect
all of its remaining mangroves the
government of belize
has strengthened all of its mangrove
regulations and even here in singapore
in the last two years we have rapidly
expanded the number of mangrove forests
that are under protection
however despite all of these great
successes
the job isn’t done and these hard earned
gains
are not guaranteed into the future
because we know there are a lot of
threats on the horizon
mangroves still continue to be lost
around the world
and countries such as myanmar are losing
mangroves at rates
many times the global average and we’re
seeing
new deforestation frontiers open up
around southeast asia and west africa
and of course our mangroves are dealing
with the same pollution
issues that the rest of our coasts and
oceans are dealing with
the great ocean plastic crisis around
the world is also the great
mangrove plastic crisis and we’re always
thinking in the future
about the issues of climate change now
mangroves being along our coastlines
they’re really in the front line against
sea level rise
mangroves can just about tolerate some
flooding
by the coast but of course with sea
level rise we expect that flooding to
increase
and what we’re worried about is if it
increases beyond the tolerance of what
mangrove
species can survive so will mangroves be
able to keep pace with sea level rise
or are they going to drown in the future
but i’m talking a lot about the future
but actually climate change is happening
right now this devastating
image is taken from a helicopter over
the northern territory
in australia it is just a snapshot
of a one thousand kilometer stretch of
mangroves that died suddenly
in 2015 and it was due to a number of
climatic factors
there was an extended drought very high
temperatures
and actually a temporary drop in sea
level due to climatic oscillations
and what happened is they see the
mangrove dried out and died
now we expect droughts and air
temperatures
and climatic oscillations to increase
with uncertainty in the future under
climate change
the climate change isn’t a fuzzy concept
which will happen at the end of the
century
we have evidence that is happening now
so undoubtedly there are huge challenges
remaining
in the conservation of mangrove forests
yet i think
it is crucial that we remain optimistic
now we hear a lot about doom and gloom
in the global biodiversity crisis
and we’re used to seeing images that
shock us
now just close your eyes for a moment
and think about
what the global biodiversity crisis
means to you what images does it bring
up
in your mind you might be imagining
coral bleaching of the great barrier
reef or deforestation of the amazon
or the last polar bear on an ever
shrinking
piece of ice now we see these images
day in day out and they do shock
but after a while they kind of lose
their shock
and a mix unless this uh doom and gloom
you know it’s easy just to throw our
hands up and say what’s the point
whatever we do doesn’t work we’re not
changing
the world let’s just give up
when i think of biodiversity in the
global biodiversity crisis i actually
try to think of a more
inspiring and optimistic picture
and it’s this picture here called the
blue marble
taken in 1972 by the apollo 17 space
mission
it is one of the most reproduced images
in the world
and it helped galvanize the global
environmental movement in the 1970s
and it did so in part because it showed
quite how fragile
the planet is but when i see the blue
marble i actually think
of some other aspects of this photo and
particularly how much it inspires me
and it shows that there is something
beautiful still left
which is still worth fighting for
so how can we use mangroves to inspire
people in the same way
that the blue marble inspired me
well i think we have a unique
opportunity to come together
and understand how we turned the tide on
mangrove loss how did we get
mangrove deforestation rates so low and
can we use that momentum
to drive that all the way to zero
and can we come together and learn
lessons from mangrove forests
and apply them to other ecosystems
where they’re still kind of lagging
under this conservation
trajectory
amidst the global biodiversity crisis
i hope that mangrove forests provide
a bright spot a light at the end of the
tunnel
and just maybe a cause for optimism
you