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