2°C - Village Magazine

68 March 2015

ENVIRONMENT CLIMATE CHANGE

N 2009, signatories to the UNFCCC

met to agree new legally binding

greenhouse-gas emission targets.

The outcome, known as the Copenhagen

Accord, singularly failed to meet high

expectations for a legally-binding agree-

ment but the Accord did specify for the

ﬁrst time that the objective of the inter-

national community was to “hold the

increase in global temperature below 2

degrees Celsius”.

In the lead-up to the next big oppor-

tunity for a global climate agreement in

Paris this December (COP-21), 2 degrees

is repeatedly used as a reference point

to frame a political deal. The 2 degree

warming limit is essentially a political

construct with a scientiﬁc basis for cli-

mate policy – but it is a tragically ﬂawed

approach.

In principle, the 2 degree threshold

made sense back in 2009: it seemed to

be a politically realistic target but the

politics changed as it became clear that

change would be too slow, and – even

more importantly – the received science

changed too.

As recently as 2007, scientists rea-

soned that CO2 concentrations could

be safely allowed to reach 550 parts per

million (ppm), but more recent research

produces a scientiﬁc consensus that

“urges the world to reduce atmospheric

carbon dioxide concentration CO2 to

about 300ppm by volume” to keep below

2 degrees warming.

But crucially and shockingly it is

already over 400ppm. The National

Geographic noted that the concentra-

tion of carbon dioxide in the atmosphere

is this high “for the ﬁrst time in 55 years

of measurement – and probably more

than 3 million [others say 20 million]

years of Earth history”.

In any event, the risks associated

with even 2 degrees of warming have

been vastly underestimated. The likes

of former NASA climate scientist James

Hansen are now saying that even 1

degree is not safe. Tyndall Centre sci-

entists Kevin Anderson and Alice

Bows-Larkin stated as far back as 2011

that the latest evidence suggested that 2

degrees “...now represents a threshold,

not between acceptable and dangerous

climate change, but between danger-

ous and ‘extremely dangerous’ climate

change: in which the importance of low

probabilities of exceeding 2 degrees Cel-

sius increases substantially”.

The scientists argued that any assess-

ment of climate policies should be framed

in light of the likelihood of adhering to

an emissions pathway that would stick

to the 2-degree carbon budget. Yet they

found that many of the models used to

map out emissions-reductions scenar-

ios showed that there was in fact a high

probability of the 2-degree warming

threshold being breached.

For one thing, the global climate

regime requires an acceptance of a global

carbon budget instead of future-ori-

ented mitigation targets. It is cumulative

global emissions that count; not just

good intentions to reduce emissions in

the future. According to one recent pub-

lication [Brad Plumer ‘2 degrees: How

the world failed on climate change’ Vox,

22nd April 2014], one tenth of the total

carbon budget allowable under a 2-de-

gree warming scenario was emitted in

2012 alone. Moreover emissions are

still rising: the only year since the base

year of 1990 to report a global emissions

reduction is 2008, when economies

around the world ground to a halt in the

grip of a global recession. That decrease

only amounted to 1% and only for one

year. Overall, since 1990 global emis-

sions have risen by 57% and show no

signs of abating. Even the IPCC has

warned that the narrow window of

opportunity to take action on reduc-

ing emissions gradually has probably

passed, and eﬀective measures will now

require drastic and sustained cuts by

Annex I [ie rich] countries.

In 2011 and in more recent papers,

Tyndall Centre scientists Kevin Ander-

son and Alice Bows-Larkin have looked

at the realistic emission pathways

required both to meet a 2-degree warm-

ing limit and fairly share the carbon

budget between Annex I and non-Annex

I countries, and conclude that developed

nations are likely, based on ‘business as

usual’ scenarios, to use up the remain-

ing budget since they are ‘locked-in’

to fossil fuel and growth-dependent

economies. Furthermore, the various

emission pathway scenarios developed

by Annex I countries to project a peak

to their emissions and then reduce them

whilst adapting to already-embedded

climate change do not adequately assess

the risks and probabilities of reaching

or exceeding the 2-degree warming

target.

If the international community is seri-

ous about backing up any limit to global

warming with credible but fair policies,

then scenarios will have to be devel-

oped that explicitly construct pathways

for developing countries to grow, peak

and then reduce their emissions, along-

side radical cuts in emissions by Annex

I countries. But eﬀective climate policies

need to be measured against scientiﬁc

evidence and their likelihood of suc-

ceeding: not against wishful or magical

thinking. •

Too much to avoid catastrophic

possibly runaway climate change

yet unrealistic as a target.

By Sadhbh O’Neill

2°C

In 2007,

scientists

reasoned

that CO2

concentrations

would be safe

at 550 ppm.

Now they say

300 ppm –

and we’ve

shockingly

already

reached

400ppm

“