A response to Victor & Kennel’s commentary “Ditch the 2°C warming goal”

Published in Nature Climate Change. 2nd Oct. 2014

In preparation for an article a broadsheet journalist was writing, I was asked to respond to a series of questions related to Victor and Kennel’s proposition. Below is a tidied up version of the notes I forwarded.

For a more detailed examination of the global climate change framework, see Going beyond two degrees? The risks and opportunities of alternative options – a paper colleagues and I co-authored in 2013 and was subsequently published in Climate Policy.

See also a response on the Real Climate site Limiting global warming to 2 °C – why Victor and Kennel are wrong 


Is it time to ditch the target of keeping temperature rises to 2ºC?

No. It is time to take the international community’s commitment on 2°C seriously, not “ditch” it just because the necessary changes are proving difficult.

2°C is the best (or perhaps the least worst) proxy we have for a range of impacts that, through the messy process of international negotiations, has been defined as the appropriate threshold between acceptable and dangerous climate change. Though science informed the discussions, delineating between acceptable and dangerous was rightly the responsibility of policy makers and civil society. By contrast, Victor and Kennel’s paper hints at it being the role of scientists to define dangerous, a role they anyway suggest is inevitably “fruitless”. This important misunderstanding of roles undermines the cogency of some of their arguments.

From an energy perspective, the central concern in terms of mitigation is carbon dioxide emissions. Through a suite of transparent assumptions the 2°C target can be readily translated into carbon budgets and emission pathways, languages accessible to policy makers and wider civil society. That the international community has, thus far, chosen not to act is, to a degree, the responsibility of us as scientists and experts failing to be brutally honest about the policy implications of the small and rapidly dwindling 2°C carbon budget. We have run scared of our paymasters and repeatedly adjusted our responses to fit within their particular Zeitgeist. But now, facing the problem of accumulating emissions, the remaining 2°C carbon budget demands changes that beg fundamental questions of the dominant economic and growth paradigm – and woe betide anyone who suggests that physics trumps economics, or more accurately short-term finance. The current political stasis on mitigation, is not therefore an inevitable outcome of the 2°C framing of climate change, but rather stems from the systemic inertia of the current socio-economic worldview.

So whilst 2°C is far from perfect, it is probably the best proxy we have. Complemented with a range of vital signs it offers an appropriate and robust framework meaningful to scientists and, once translated into carbon budgets, understandable by policy makers, the business community and wider civil society.

It is worth emphasising that whilst on aggregate 2°C may have been defined as ‘globally’ acceptable (as distinct from desirable), such rises will undoubtedly have severe repercussions for many poorer and climatically more vulnerable communities.


Do you agree with Victor & Kennel that 2ºC is now “effectively unachievable”?

Certainly no, but I think it very likely we will choose to fail, but this is a choice – not a fait accompli.

To start, 2°C is not a categorical position; it has to be interpreted terms of probabilities, uncertainties and risks. This is important terrain for scientists and social scientists, quantifying the language, arguments, statements and commitments of policy makers in terms of probabilities and finally carbon budgets. From here on science, engineering and academia can only outline the necessary rates of change and the options for governments, institutions and individuals – they cannot define the ‘correct’ way forward. That said, the remaining 2°C carbon budgets require that whatever the mix of technological, social, policy and economic options, they need to deliver on two fronts. First a deep and almost immediate cut in absolute energy demand (and hence emissions) by those whose energy consumption is far above the average level. Guarding for issues of rebound, this would deliver almost immediate reductions in emissions within wealthy nations and a much-reduced rate of emission growth in poorer countries (delivered through a combination of, behaviours, routines and end-use technologies). Second, implement a Marshall-style construction plan of low/zero carbon energy supply accompanied with high levels of electrification.

Such proposals will inevitably face the usual cackles that they are too costly etc. But we are not short of resources to deliver such timely change only the innovative capacity and courage to think and act differently. The UK, almost overnight, conjured up over £350b to bail out the banks and stimulate the economy – but it has earmarked just £3.8b for its Green investment bank! Finance trumps not only physics but also our and the planets future wellbeing. Again Victor and Kennel’s belief that it is the targets that are at fault is misplaced. As before, the failure to deliver relates much more to political inertia buttressed by powerful vested interests in maintaining the status quo, set against a relatively compliant academia and an indifferent public.


What do you think of Victor and Kennel’s suggestion of having a suite of ‘vital signs’ instead; including ocean heat content, high latitude temperature and CO2 concentrations in the atmosphere?

I think there is significant merit in including a suite of vital signs alongside a temperature target (2°C by 2100). But these are complementary and not substitutes. In reality this is what is happening anyway. Much of science centres its analyses on more specific impacts and criteria – so formalising vital signs, as the paper suggests, is an approach worthy of serious consideration.


Are Victor & Kennel right that by mainly measuring our progress on surface temperature risks allowing us to miss the other stresses we are putting on the climate system, e.g. the oceans?

There is certainly a risk of this. But rather than reject the current target, I would suggest a somewhat more inclusive approach, factoring in more specific and geographically well defined criteria – alongside 2°C; this is, in many respect, already occurring.


Would agreement at the Paris 2015 COP to work towards a new set of ‘vital signs’ as Victor & Kennel suggest, be a good idea or a distraction from the main negotiating efforts on a climate pact?

Again this is a complementary rather than a replacement issue. Whilst I see considerable merit in the vital signs approach, I suggest it is wiser that those developing such proposals do so alongside the 2°C framing. Scientists infighting on the nuanced differences play into the hands of both the sceptics and our natural tendency for procrastination. For Paris (and really well before then) the 2°C framework needs to be quantitatively, robustly and starkly laid out for policy makers to understand; this could certainly be complemented with a suite of vital signs.


By all working towards a 2ºC goal, which many say is now unrealistic, with 3ºC to 4ºC much more realistic, do we risk being unprepared in our adaptation efforts, i.e. not building flood defences to the right height, not planting the right crops that can cope with higher temperatures, etc.

This is an important issue and underpinned my 2007 suggestion that we should “aim for 2°C but plan for 4°C”.

Describing visions of the future as realistic or unrealistic simply misses the point that the future will be radically different from today. Either we’ll make the necessary changes to our energy and agricultural systems and broadly hold to the 2°C carbon budget, or we’ll continue to make hay while the sun shines and witness the increasingly dangerous repercussions of a rapidly changing climate. These will likely play out initially amongst the poor and vulnerable and then later across every level of our own communities. In today’s terms neither delivering radical mitigation nor living with dangerous levels of climate change would commonly be described as realistic. Our ongoing and abject failure to respond to the climate challenge leaves us now facing a radically different future – whatever we do.

My other concern is that in thinking through the impacts and adaptation agenda for a 3°C to 6°C future, we tend to focus narrowly on people like us. Many of the worlds seven billion population are maladapted to the current climate let alone one with increasingly destructive and unpredictable impacts. If we consider we have the moral calibre, wherewithal and sufficient insight to implement a global 4°C adaptation plan for nine or more billion people, surely it would be wise to put similar if not more effort into reducing emissions now, so as to lessen the likelihood of facing such uncertain futures.


In the end I remain convinced that pulling out all stops to avoid going above 2°C whilst planning infrastructure and institutions etc. for 4°C is the most appropriate policy framework. Vital signs are a potentially important and helpful complement to such an approach; but they are not an alternative.