The Economist - UK (2022-04-09)

The Economist April 9th 2022 Science&technology 71

before  2030,  compared  with  2019  levels.
Yet  human  societies  emit  more  green­
house  gases  with  every  passing  decade,
and  the  last  one  saw  the  largest  rise  in
emissions in human history. While the re­
port’s  socioeconomic  simulations  of  the
coming decades show that it is theoretical­
ly  possible  to  cut  emissions  by  the
amounts needed, the political realities and
inherent  inertia  of  economies  that  are
largely structured around fossil fuels make
the  transition  challenging,  particularly  at
the speed that is now required.
Achieving  the  1.5°C  Paris  goal  means
that global use of coal must decline by 95%
by 2050, relative to 2019. Oil use must drop
by 60% and gas by 45% in that period. The
decreases  needed  to  limit  warming  to  be­
low 2°C are not much lower. Under all sce­
narios, there is no room for new unabated
fossil­fuel projects (such as power plants),
and  most  existing  ones  will  have  to  be
wound  down  faster  than  they  would  have
otherwise. “Estimated emissions from the
current  [fossil­fuel]  infrastructure  over
planned lifetimes are roughly what we can
emit  for  a  2°C  scenario,”  said  Michael
Grubb of University College London, one of
the ipccreport’s authors. 
Keeping  warming  to  less  than  2°C
would  therefore  mean  shortening  the
lifespans of existing fossil­fuel power sta­
tions and refineries. These could be retro­
fitted  with  installations  that  capture
warming gases before they escape into the
atmosphere in order to store them under­
ground  or  beneath  the  oceans.  But,  as  the
report’s  authors  note,  governments  and
business  have  promised  to  develop  such
an  industry  (dubbed  “carbon  capture  and
storage”) for decades, but failed to do so.
Among  the  darker  warnings,  there  are
some shafts of light. The cost of solar ener­
gy  dropped  by  85%  during  the  2010s,  and
wind power by 55%. During the same per­
iod, the market for electric vehicles grew a
hundredfold. The ipccreport notes that at
least  24  countries  have  consistently  cut
emissions  for  at  least  a  decade.  Despite
worrying  trends  in  the  Brazilian  Amazon,
there is more forest cover and less defores­
tation  today  than  in  2010.  In  2020  more
than 20% of global emissions were covered
by  carbon  taxes  or  trading  schemes.  And
also  in  2020,  more  than  50  countries,  ac­
counting for more than half of global emis­
sions,  had  enacted  climate  laws  intended
to reduce emissions.
The energy intensity of the global econ­
omy  (a  measure  of  the  amount  of  energy
expended to generate one unit of gdp) de­
creased  by  2%  per  year  between  2010  and

2019. At the same time, the amount of car­
bon dioxide emitted for each unit of energy
produced  (known  as  “carbon  intensity”)
decreased—an  indication  that,  globally,
energy is becoming greener.
But these gains are nowhere near what

modelssaywillbeneededtostabilisethe

climatebeforeit istoolate.Carbonintensi­

ty,forinstance,declinedby0.3%peryear

inthe2010s,a fractionofthe3.5%peryear

thatthemodelssayisneededtogivea good

chanceoflimitingwarmingto2°C.Fora

1.5°Cgoal,theannualimprovementwould

havetobe7.7%.

Onecommonthreadrunningthrough

the Paris­compliant scenarios presented

bytheipccistheinclusionofoptionsfor

removinggreenhousegasesfromtheat­

mosphere.Thatisbecauseallscenariosas­

sumethattherewillberesidualemissions

fromsomeeconomicsectorscomemid­

century,evenunderthemostoptimistic

assumptions.Viableoptionsforeliminat­

ingfossilfuelsfromaviationandheavyin­

dustryarecurrentlylacking,andfewen­

visagea sufficientchangeinthisoverthe

comingdecades.

Options for removing these residual

emissionsbroadlycomeintwotypes:the

ecological(reforestation,ecosystemresto­

ration,schemestoincreasetheamountof

carbonsequesteredinagriculturalsoils)

andthechemical (usingmineralsorre­

agentsthatselectivelybindtoatmospheric

CO 2 andallowittobestoredunderground,

underwaterorinsolidform).

Theformerappearseasyandcheapbut

ispotentiallyunreliable.Forestsburnand

releasegreenhousegasesastheydo;ina

warmer,drierworld,theywillburnmore.

To be long­term stores of carbon, trees

mustbe managed andprotected,some­

thingthathumansingeneraldonotalways

dowell.Ecologicalsolutionscanalsocom­

peteforlandwithagriculture,particularly

atthekindsofscalesrequiredbythecli­

matemodels.

Suckit up

Ontheotherhand,technologicalsolutions

forremovingcarbondioxidefromtheat­

mosphere are in their infancy and ex­

tremely expensive. The two companies

thathavecommercialoperationsofferto

removeonetonneofcarbondioxideforbe­

tween$300and$1,000.Forcomparison,a

singleeconomyseatona returnflightfrom

LondontoSanFranciscoisresponsiblefor

justunderonetonneofemissions.

These carbon­removal technologies

mayseea rapiddropincosts.Proponents

pointtotherecentsuccessesofsolar­and

wind­energyprojects—all threetechnol­

ogiesinvolvesmallmodularcomponents,

makingthemrelativelyeasytoscaleup,

andfansofthe“directaircapture”industry

haveusedthesimilaritiestosuggestthat

theirtechnologywillalsotakeoffquickly.

Still,it isworthnotingthatevensolarener­

gy,a modern­daydarlingofthegreen­en­

ergy world, took several decades to get

whereit istoday.

Tosome,thecallstoendtheageoffos­

silfuelsorfacetheconsequencesofletting

theworldburnmayseemdivorcedfrom

immediate reality, particularly as Euro­

pean countries desperately seek gas to

replaceRussiansuppliesandstaveofffuel

shortagesandcripplingpricesduringthe

nextwinter.

Buttherearesomesynergiesbetween

thetwocrises.Inthelonglistofoptionsfor

reducingemissions,improvingenergyef­

ficiencyintransport,buildingsandindus­

tryislow­hangingfruit,asarebehavioural

changessuchasswitchingfromprivateve­

hicles to public transport. Encouraging

consumerstodecreaseenergydemandin

Drop, and fast

Future global greenhouse-gas emissions

for Paris targets, gigatonnes of CO2 equivalent

Source:IPCC

60

50

40

30

20

10

0

20504540353025202015

2°C(>67%chance)

or1.5°Cafterhigh

overshoot(>5%)*

2°C(>67%)†

1.5°C(>5%), no or limited overshoot

Implied by

current policies

Limit warming to:

Government climate

pledges for 200

*With current government pledges

†With increased government pledges

Mitigation menu

Options to cut global emissions by 2030*,

gigatonnes of CO2 equivalent per year

Source:IPCC

Colour=lifetime cost compared

with current options, $ per

tonne of CO2 equivalent

*Selectionamong 45 publishedoptions

Fuelswitchinginindustry

Greaterenergyefficiency

inindustry

Greaterenergyefficiency

inaviation

Shifttopublictransport

Fuel-efficientcarsandvans

Newbuildingswithhigh-

energyperformance

Ecosystemrestoration,

afforestation,reforestation

Reducedlossof

forests/otherecosystems

Boostedcarbon

sequestrationonfarmland

ReduceCH4emissions

fromoilandgas

Nuclearenergy

Hydropower

Solar energy

Wind energy

20 50 100 200

Greater reduction →

0

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