Rebalancing our climate the future starts today

[Music]

earth’s climate is out of balance

we have heard this many times from

climate researchers

including myself but we rarely hear what

can be done about it

in this talk i summarize our options

based on

my book the future climate starts today

which will be released

in oxford university press in 2021

we are talking here about the balance

between incoming shortwave radiation

which we all know as sunlight and

outgoing long-wave radiation or heat

we understand very well that we are in

this situation

because of the human caused increase in

the planet’s natural greenhouse effect

mainly but not only because of carbon

dioxide or co2

emissions from fossil fuel burning now

how do we know this

well there are three independent lines

of argument

first fossil fuel carbon is millions of

years old

and as a result its radioactive carbon

component

has completely decayed away because this

takes only about 50 000 years

so when we radiocarbon date three rings

from the industrial revolution to the

present we find

ages that appear too old and this is

because of vast amounts of carbon

old dead fossil fuel carbon that have

been added to the atmosphere

second fossil fuel has a characteristic

very negative

stable carbon isotope ratio when we

measure changes

in this ratio since the industrial

revolution we find

a distinct trend to more negative values

which are caused by the fossil fuel

carbon addition

and third fossil fuels are an economic

resource

they get sold and account books are kept

of the quantities that are sold

and this way we know for sure that we

have burned double the amount of carbon

that we find in the atmosphere today one

half of the total has caused atmospheric

co2 rise

and the other half has been absorbed in

the ocean and in vegetation

now co2 and other greenhouse gases

reduce the amount of outgoing heat

meanwhile incoming solar radiation is

relatively constant

and as a result we are causing a shift

in the climate

think of it as a bathtub in which

the filling tap stays the same but the

outflow gets partially blocked

because the balance between inflow and

outflow is disturbed

the water level in the bath rises now in

a similar way

constant incoming radiation and partial

blocking of outgoing radiation

causes an increase in the global average

temperature

now we get to the big question what can

we do to repair this imbalance in the

climate

well global climate change proves that

we do

have the power to change the earth

system this beyond question we’ve done

it

so what we now need to do is to take

responsibility

use that power and restore the climate

first we could try to make the planet

more reflective

to sunlight there are some suggestions

on how to do this

and these fall often under the name of

geoengineering

there are many open questions about this

and especially about the safety of this

approach

so i will not further delve into this

topic

second we can reduce greenhouse gas

levels

there is a lot of activity around

emissions reduction already

including a move to electric cars to

more eco-friendly houses

a development of renewable energy

sources and so on

but at best this might bring about

emissions to zero but nations

are aiming at net zero emissions at some

point in the future

will that be enough well unfortunately

the answer there has to be no

we’ve already emitted too much co2 and

other greenhouse gases

and they have already caused more than

1.1 degrees c

of global average warming and what’s

worse

some of the components of our climate

system take many centuries to

fully respond and key examples of this

for example

are ocean warming and continental ice

sheet melting

so these systems are not yet fully

adjusted to our emissions up to now

and once they play out fully warming

will reach one and a half to two and a

half degrees c

clearly we are already at or above the

warming limits of the paris climate

agreement

if we consider things from a long long

term perspective that is

and this is a very important message in

this

it is that even if we completely stop

the missions from today

this delayed warming would still

continue while the slow systems are

catching up with what has been omitted

already until today and because we won’t

stop

emissions from today it will only get

worse

most nations are talking of reaching net

zero emissions as late as

2030 or 20 20 50.

so in short there is no doubt

we must stop emissions as soon as

possible and we must find

ways to actively remove greenhouse gases

from the climate system

most importantly the main one co2

co2 removal is possible on small scales

we do it already in space capsules and

space stations and in submarines

remember that improvised co2 scrubber in

the film

apollo 13 well that’s exactly what we’re

talking about but then on

truly massive scales we need to remove

between 70 and 280 billion tons of

carbon by 2100

you need to multiply that by about four

to get the mass of co2

this means almost 10 to 35 billion tons

of carbon removal per year

and for scale our emissions are about 10

billion tons of carbon per year

i’m not gonna lie to you it’s a gigantic

task

to have a chance of success we must

activate

every single reasonable process that can

contribute

and we must do so while making dramatic

emissions reductions at the same time

otherwise we’d have to remove even more

carbon

this is arguably humanity’s greatest

challenge yet

but humanity has excelled before at

facing massive challenges

it will be costly but the costs of

climate change

impacts if we do nothing are actually

projected to be higher

so what are our options there are three

main streams of possibilities

first we have the earth system-based

methods on land

earth system methods employ processes

of carbon removal that exist already in

natural form

and then artificially speed them up

here we find such approaches

as the more familiar ones massive tree

planting or reforestation

restoring carbon levels in degraded

soils all around the world

burial of charcoal-like products called

biochar

artificially accelerated weathering of

rocks which consume co2

or they use of captured carbon to make

long-lasting products such as building

materials

second there are marine earth

system methods so and and among these

are a bit more unfamiliar but we have

artificial fertilization of ocean areas

to trigger algal blooms

which then sink into the deep sea when

they die and

there at least theoretically the carbon

is locked away for thousands of years

then there’s restoration and enrichment

of coastal ecosystems which can hold

vast quantities of carbon

and we could add lime to the oceans or

other

so-called alkaline products to combat

ocean acidification

and this might be done together with

seawater electrolysis

to drive a hydrogen fuel-based economy

third

then we have the land-based technologies

to remove carbon from the atmosphere

here examples include biofuel based

energy generation with co2 capture at

the smokestack

and subsequent burial of that co2 or

direct capture of co2 from the open air

linked with burial of that co2 there are

also marine

technological approaches being

investigated but it’s still too early to

get into those they’re very immature

still

if you add the potential of all these

methods together then it reaches between

4

and 40 billion tons of potential carbon

removal per year

and as we saw before the target is 10 to

35 billion tons of carbon removal per

year

so we might just about be able to meet

the challenge

but only if we put our shoulders under

it

critically it will only be enough if we

massively reduce

emissions at the same time to press that

point a little

we can only succeed if we follow a

combined approach of drastic emission

reductions

and rapid development of all reasonable

carbon drawdown methods

and we need to keep an open mind

and we need to be ready to optimize and

include any new ideas that may come

along

and finally i emphasize that many of the

carbon drawdown methods

are particularly interesting because

they have good potential to pay for

themselves

and this is because there are there are

additional benefits and

for example these include improvements

in soil quality

and therefore food production and

associated food security

or improvements in coastal ecosystems

which benefit

with benefits for fisheries and for

protection against coastal erosion and

flooding

or availability of next generation

building materials

or even driving a more sustainable

circular economy that’s based on

recycling

so to conclude it is still possible to

avert the worst of climate change not

everything but the worst of it and the

time to act if we want to accomplish it

is now you know that future that people

always talk about

about when they’re discussing climate

action well that future starts today

right here right now otherwise we are

too late

together we can still make it happen

thank you