Witness statement by Prof Alice Bows-Larkin for Heathrow 13 trial clearly shows CO2 problem of a new runway
Alice Bows-Larkin, a Professor in Climate Science and Energy Policy at MACE at Manchester University, gave written evidence at the trial of the Heathrow 13, for their action at Heathrow in July 2015. Her witness statement (11 pages + references) is a closely argued and highly expert assessment of the need for the emissions from aviation to be restricted. It is well worth reading. Just a few of the points she raises are that the UK has signed up to the ambition of the Paris Agreement to keep global temperature rise to below 2 degrees C. This is not consistent with an increase in the CO2 emissions from UK aviation above their capped level. There is no justification for international aviation to be excluded for global ambitions to limit CO2. Even if there is some carbon trading scheme, aviation needs to be fully included. If ‘negative emission sources’ that can remove CO2 from the air (unlikely) “do not materialise in time, ‘well below 2°C’ will only be achieved by a wholesale shift away from fossil fuel combustion. This would mean that CO2 produced by the aviation sector would also need to be reduced to near zero. This … would be largely uncontested.” Prof Larkin says in her view the Government’s intention to build a new runway, raising UK aviation CO2 emissions, “implies a misunderstanding by UK Government of the scale of CO2 mitigation that a 2°C goal relies upon – let alone a ‘well below’ 2°C target.”
Professor Alice Bows-Larkin’s Witness Statement
Below are just a few selected quotes from the (13 page) statement:
Either way, mathematically the contribution from aviation CO2 needs to be recognised in any estimate of the total reduction amount of CO2 across all sectors commensurate with a set temperature goal.
Although there are always steps being taken to improve the fuel efficiency of aircraft, given an imperative to reduce fuel costs, it is clear that to avoid an increase in CO2 production
from aviation, the growth in the industry needs to be off-set by fuel-efficiency gains or
alternative non-carbon emitting fuels. Moreover, the recent Paris Climate Agreement has a
legally binding goal of avoiding a temperature rise of ‘well below’ 2°C. There are discussions
on-going around how to achieve this – but mathematically ‘well below’ 2°C can only be
achieved by preventing CO2 production, to the extent that any sinks that can absorb CO2 are
larger than the CO2 produced, leading to net zero emissions by 2050 (Gasser et al 2015,
Anderson 2015). There is an on-going debate highlighting the limited capacity of the Earth to
absorb CO2 to the extent necessary by 2050. If it is assumed that these ‘negative emission
sources’ do not materialise in time, ‘well below 2°C’ will only be achieved by a wholesale
shift away from fossil fuel combustion. This would mean that CO2 produced by the aviation
sector would also need to be reduced to near zero. This again would be largely uncontested.
The Committee on Climate Change (CCC) recognise this, by suggesting that all other sectors would need to reduce emissions by 90% to account for aviation’s CO2 emissions in future (page 30, CCC 2009). However, this estimate assumes that other sectors are able to cut emissions by greater than 80% by 2050. To date there is limited evidence that this will be achieved, and in my view there are no policies currently in place that incentivise even 80% reductions by 2050, let alone those required to avoid a ‘well below 2°C’ goal which limits the carbon budget even further.
Moreover, others argue that emission cuts could be achieved by trading aviation
CO2 emissions with other sectors – i.e. other sectors make greater cuts and sell ‘allowances’
to the aviation sector so that it can emit. Either way, mathematically the contribution from
aviation CO2 needs to be recognised in any estimate of the total reduction amount of CO2
across all sectors commensurate with a set temperature goal. The Committee on Climate
Change (CCC) recognise this, by suggesting that all other sectors would need to reduce
emissions by 90% to account for aviation’s CO2 emissions in future (page 30, CCC 2009).
However, this estimate assumes that other sectors are able to cut emissions by greater than
80% by 2050. To date there is limited evidence that this will be achieved, and in my view
there are no policies currently in place that incentivise even 80% reductions by 2050, let
alone those required to avoid a ‘well below 2°C’ goal which limits the carbon budget even
Given that the evidence suggests that an expansion of airport capacity in general will support an increase in CO2 emissions, or at least not facilitate their reduction out to 2050, and yet the UK is supportive of the Paris Agreement, a decision to expand Heathrow suggests that CO2 is a low priority consideration in planning decisions. It is not being considered as a make or break factor. In my view, this also implies a misunderstanding by UK Government of the scale of CO2 mitigation that a 2°C goal relies upon – let alone a ‘well below’ 2°C target.
Without widespread deployment of highly speculative negative emission technologies, cutting CO2 emissions in line with ‘well below 2°C’ will require a transformation in energy systems, and will need to include all CO2 producing sectors. I am unaware of any analysis that can demonstrate how aviation could be an exception to this
9. Concluding statement
The aviation sector creates CO2 emissions through combusting kerosene. The altitude at
which aircraft fly also leads to additional warming impacts. One of the greatest challenges
for the aviation sector lies in the highly limited opportunities compared with other sectors to
reduce CO2 emissions through technical and operational measures. As a result, any increase
in growth in the sector above ~2% per year in terms of passenger-km tends to lead to an
increase in absolute CO2 emissions. Thus without any serious programme of efficiency
improvements coupled with rapid biofuel deployment for the sector, demand-side measures
(e.g. constraining airport expansion), offer an alternative but also one of the few options to
cut its CO2.
The latest Agreement from the Paris Conference of the Parties in 2015 includes text that…
“aims to strengthen the global response to the threat of climate change by holding
the increase in the global average temperature to well below 2 °C above pre-industrial
This level implies a highly constrained amount of CO2 can be released into the atmosphere in
the coming 50 years. Interpretations of what this means will vary – with assumptions around
the extent of ‘negative emission technologies’ being key to this variation. However, with
emerging widespread concern over the feasibility of these technologies operating at scale,
and within the next 35 years and beyond, the option of phasing out fossil fuels within this
period becomes a high priority. This would require all fossil fuel burning sectors to mitigate
their CO2 emissions urgently, in line with a complete phase out by around 2050.
Under less stringent climate constraints than ‘well below 2°C’, it is reasonable to assume
that some sectors will not need to significantly mitigate emissions, and aviation may be a
good candidate for being such a sector, given its limited mitigation options. However, the
‘well below 2°C’ framing of the Paris Agreement, that has been put in place to address
concerns over the extent of climate impacts associated with breaching the 2°C threshold, as
collated by the IPCC and the WHO, leads to the conclusion that the aviation sector will also
need to significantly cut its CO2 emissions by 2050. Thus, measures that support and
encourage CO2 growth, such as an expansion of airport capacity without mechanisms
enforcing increases in efficiency or carbon intensity over and above levels of passenger-km
growth, are incompatible with the goals within Paris Agreement. This interpretation would
be further underlined, were the Agreement to include an even greater recognition that for
many nations world-wide, CO2 emissions will rise in support of their development for basic
energy needs (Lamb et al 2014), leaving even more limited CO2 space for all CO2 producing
There is global agreement that the world needs to limit warming to ‘well-below 2°C above
pre-industrial levels’. Analysis regarding what this means in terms of mitigation is now being
published, with the issue of ‘negative emission technologies’ leading to the greatest area for
debate. Nevertheless, the vast majority of academics working on climate change mitigation
would agree that a rapid and significant reduction in the combustion of fossil fuels is needed
in the coming decades. Air transport is known for both its carbon intensive nature, and its
absence of viable technical mitigation options in a timeframe in keeping with avoiding a 2°C
temperature rise. As such, there is an expectation that its emissions will continue to grow, or
at least not be curbed in a similar way to other sectors, with these other sectors reducing
their emissions more to compensate. To date, and from a UK perspective, mitigation
measures targeting this sector have been less stringent than for others. However, with the
newly published Paris Agreement, most would agree that it is now crucial that targets, goals
and pledges be revisited to address the “serious concern” noted in the Agreement that there
is a …
“significant gap between the aggregate effect of Parties’ mitigation pledges in terms
of global annual emissions of greenhouse gases by 2020 and aggregate emission pathways consistent with holding the increase in the global average temperature to well below 2 °C above pre- industrial levels”.
Without widespread deployment of highly speculative negative emission technologies,
cutting CO2 emissions in line with ‘well below 2°C’ will require a transformation in energy
systems, and will need to include all CO2 producing sectors. I am unaware of any analysis
that can demonstrate how aviation could be an exception to this.
Heathrow 13: Prof Alice Bows-Larkin’s expert evidence on aviation and climate change
16.2.2016 (Carbon Brief)
Thirteen people found guilty of aggravated trespass whilst protesting against the proposed expansion of Heathrow airport are due to be sentenced next week. It could see the first custodial sentences handed down to environmental protesters in the UK in two decades.
The high-profile trial of the “Heathrow 13” has gone down the rare – but not unprecedented – route of enlisting a climate scientist as an expert witness for the defence.
Prof Alice Bows-Larkin, professor of climate science and policy at the University of Manchester, gave evidence to the court on the impact of aviation on climate change. Exclusively, Carbon Brief has her full statement, exactly as it was submitted to the judge in the trial.
The “Heathrow 13”, part of the Plane Stupid campaign group, were arrested on 13 July last year after chaining themselves to a railing on Heathrow’s northern runway for six hours to protest against the impact of aviation emissions on climate change.
The protesters were arrested and later found guilty of aggravated trespass. District Judge Deborah Wright said that while it was clear the defendants were “principled people” and committed to their cause, she didn’t accept their actions were necessary to protect people from climate change. They should be prepared for jail time, she said, because of the “astronomical” cost of disrupting more than 20 flights.
With their final sentences due to be passed at Willesden magistrates court on 24 February, the case of the “Heathrow 13” has garnered a fair amount of media coverage and high-profile political support in recent weeks. One law expert told the Independentthat custodial sentences for a peaceful, non-violent protest would be “unprecedented in modern times”.
The criminal charge of aggravated trespass came into force in 1994, following a series of road-building protests. While it can technically carry a custodial sentence “not exceeding three months”, no one has since faced jail time as a result of a non-violent environmental protest in the UK.
A statement on the Plane Stupid website says:
The “Heathrow 13” case isn’t the first time climate change has been used as a defence in a court of law. In 2008, the “Kingsnorth Six”, arrested for trying to shut down a coal-fired power plant in Kent, were acquitted after arguing what’s known in law as a “necessity defence”.
The defendants successfully argued that their actions were legally justified since they were intending to prevent the far greater harms to society posed by climate change. The nine-person jury cleared the defendants of any wrongdoing by a majority verdict.
Unlike the “Heathrow 13”, whose lesser charges of aggravated trespass warranted a trial by magistrate, the reported £30,000 damages caused by “Kingsnorth Six” meant they appeared before a jury instead.
In January 2016, a judge allowed lawyers to present climate change as a necessity defence for the first time in the US, in the case of the “Delta Five”, a group of activists accused of obstructed a train carrying coal and crude oil.
The defence was less successful that time, however, with the same judge later ruling that the evidence was insufficiently strong for the jury to take into account in its verdict. The protesters were found guilty of trespass, though not guilty of obstructing the train, and spared jail time.
On the rare occasions when climate change has been used as a criminal defence, it’s not unknown for a climate scientist to be called on to give supporting evidence.
Dr James Hansen, veteran climate scientist and former director of the NASA Goddard Institute for Space Studies, appeared as an expert witness in both the “Kingsnorth Six” and “Delta Five” cases, and again in 2010 in the trial of 20 activists accused of planning to trespass on a coal plant near Nottingham.
In the trial of the “Heathrow 13”, Prof Alice Bows Larkin, a professor of climate science and energy policy at the University of Manchester, specialising in shipping and aviation emissions, gave evidence on behalf of the defence. She did not appear in court, instead submitting a written statement to the judge, parts of which were read out as a summary in court. [The judge did not want to hear any of the defence expert witnesses in person].
Bows-Larkin’s statement begins with a general outline of the impact on climate change of carbon dioxide (CO2) and other substances present in aircraft emissions, such as nitrous oxides, soot, water vapour and sulphur dioxides. She explains:
Bows-Larkin then explains how, to be consistent with the legally-binding obligation in the Paris Agreement of limiting warming to “well-below 2C above pre-industrial levels”, emissions from the aviation sector, like all other sectors, will need to be reduced to near-zero.
The combination of growing demand and few technical options on the horizon that could dramatically reduce aircraft emissions means that the inability of the aviation industry to curb its environmental impact constitutes a public health risk, says Bows-Larkin.
Bows-Larkin acknowledges the potential for technology, such as bioenergy with carbon capture and storage, to offset greenhouse gas emissions. But there is a big question mark over whether we can assume such technologies will materialise in time to meet climate targets, she explains.
Heathrow13-evidence-from-Prof-Alice-Bows-Larkin Jan 2016 Link to Bows-Larkin’s expert witness statement to the trial of the “Heathrow 13” in full, exactly as it was submitted to the judge.
It’s a detailed account of where the aviation industry sits alongside UK domestic and international law, and is worth reading in full.
Or, for a flavour of exactly what the court heard, Raj Chada, partner at Hodge Jones & Allen and defence lawyer for four of the accused, has confirmed to Carbon Brief that sections 2.2, 2.6, 3, 8 and parts of 9 were read out in court as a summary of her testimony.