BMJ Draft (2)> >.


In the past few weeks, it has been hard to miss the impact that Greta Thunberg, a Swedish schoolgirl, has had on the global politics of climate change. She has inspired millions of people to join the global climate strikes and addressed world leaders at the UN General Assembly. She has attracted a huge amount of praise and support, but she has also faced a noticeable amount of criticism. Her way of dealing with this has been to say that her message is simple. She has called for people to unite behind the science which shows the danger that we are all in from the rates at which climate is already changing. She points to the fact that it will be her and her peers who are going to be directly affected by the impact of climate change. What we all do now, or fail to do, to control the climate emergency we're in will have a huge impact on younger generations.

Extinction Rebellion (XR), a civil disobedience group campaigning to prompt action on the climate emergency, and co-founded by Roger Hallam, Gail Bradbrook and others in the UK, has also had a major impact on the global politics of climate change. The response to XR has been similar— much praise and support, but also a noticeable amount of criticism. XR’s way of dealing with this has been to say that their message is to speak the truth and encourage others to understand the dangers that we are all in from the rate at which the climate is already changing. They also say, let us all act together to prevent as much of this as is still possible.

Together these movements are strong and support for their message is growing rapidly. Moreover, they are achieving a level of public participation that many of us veterans have hoped for and worked towards for the past thirty years. What they are saying is exactly what the science is at last saying. Some may ask, why at last? Hasn't the science always said this? The answer is no it hasn't, though even from early days some key players have stressed the ‘feedback-issue’.

Since the UK Climate Act was agreed in 2008, it had been asserted (wrongly) that its upper limit of 2.0° C was safe against the threats of runaway rates of climate change taking hold. Seven years of preparing the subsequent IPCC 5th Assessment Report (AR5 published in 2015) were based on that assumption. It was the result of the largely feedback-free Representative Concentration Pathway (RCP) policy-scenarios which dominated the output of AR5 in its Summary for Policy Makers with this aspirational limit for global temperature rise of 2.0° C.

The omission of feedback-effects is very serious, as climate models under-estimate the rates of climate change and the risks we face as a result. These omissions were flatly denied by the UKMO in an Enquiry by the Environmental Audit Select Committee in 2013. However, these omissions were finally confirmed by DECC in 2016. This has been and remains a substantive issue, as does the contentious issue of the base year for temperature rise.

At the same time as the publication of AR5, the political ‘Paris Agreement’ on Climate Change of 2015 occurred. It included the lower limit of 1.5° C. This was largely the result of enormous political pressure brought in the negotiations by the nations of the Climate Vulnerable Forum.

This resulted in a Special Report being commissioned from the IPCC to establish what would be necessary to limit global temperature rise to 1.5° C and it was published in August 2018 [see here]. In this and for the first time in thirty years of IPCC Assessments, it focused solely on: -

[a] the projection of only 1.5° C above pre-industrial as a lower but safer maximum upper limit on temperature rise
[b] details of climate and climate-feedback modelling and then, most importantly
[c] the inclusion of remainder-global-carbon-budgeting (see table 2.2, page 108, Chapter 2) to support this new temperature limit of 1.5° C,
[d] where 33%, 50% & 66% odds of success require progressively smaller and smaller carbon budgets,

[e] a web-page detailing the IPCC table referred to and the conversions used for charting as below is here.

It is behind this scientific reckoning that Greta Thunberg and XR are now calling for us all to unite. Preventing the global temperature rise from going above 1.5° C above pre-industrial levels with a 66% chance of success requires us to achieve zero emissions globally by 2034. This is much faster than zero emissions globally by 2075, the rate put forward in RCP 2.5 for 2.0° C as put forward in IPCC AR5. It's even much faster than zero emissions globally by 2050, the new 'consensus' i.e. 33% odds for limiting temperature rise to 1.5° C. And as scientists at observed, "Professions such as doctors wouldn't take such a punt (33%) on preserving life if better odds (66%) were available," i.e. zero emissions globally by 2030 as shown in the chart above.

Simply put, to resolve the accelerating problem of CO2 accumulation in the global atmosphere (at around 50% of emissions), means acting faster to prevent it than we're still acting to create it. It means we need to be removing our CO2 emissions to the atmosphere at two times or three times or even four times the rate of emissions at which we are currently adding them (see here) if we are serious about 66% chances for 1.5° C. Unless such steep cuts in CO2 emissions start now, the danger is that the still rising rates of emissions, concentrations, temperature and positive feedbacks to changing climate, potentially accelerate completely beyond our ability to control them in any way whatsoever.

As things stand our emissions levels are above those projected in RCP 8.5. Nature magazine pointed out that the RCP 8.5 emissions path equals Permian Extinction levels of atmospheric CO2 concentration & temperature in the 21st Century. In the Permian Extinction Event, it is estimated by Professor Michael Benton in When Life Nearly Died that 95% of all life forms were made extinct.

The bad news is that with the increasingly rapid rates of ocean warming, cryo-melt, sea-level rise and climate emergency related forest fires, the rates of overall climate change are now starting to accelerate potentially beyond any human ability to control, and this is now increasingly obvious to more and more people around the world.

The methodology of the Contraction and Convergence (C&C) Principle can yet be the basis on which internationally we can organize to be UNFCCC-Compliant. C&C was introduced at COP-2 in 1996. It was largely agreed at COP-3 in 1997, peer-reviewed in Springer Verlag in 2000. Thereafter, C&C gained significant international support with the UNFCCC Executive saying that C&C was inevitably required for UNFCCC-Compliance.

C&C became the basis of the UK Climate Change Act of 2008 and Lord Adair Turner, the then chair of the Climate Change Committee created by the Act, confirmed this to the Environmental Audit Committee in 2009. He also subsequently confirmed to the Energy and Climate Change Committee that if for reasons of urgency the global rate at which contracting greenhouse gas emissions had to be increased, then for reasons of equity the rate of convergence had to be accelerated relative to that (see here & here).

The issue couldn't be more urgent, climate-inequity and mortality is increasing and the moment for organizing on the C&C basis is now. The UN Secretary General recently warned again forcefully that the race against the climate crisis is a race we are all losing & that to win it demands urgent action.

A strategy for UNFCCC-Compliance needs a structure, not the rolling programme of climate-triage that will occur in the absence of that strategy. Amongst others, the medical profession particularly due to the remarkable and enduring efforts of people like Dr Robin Stott, has expressed a remarkable degree of support for this.


Aubrey Meyer is one of the co-founders of the Global Commons Institute (GCI).
He has campaigned for thirty years on GCI's campaign for UNFCCC-Compliance.

No Competing interest.