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