I take issue with the central proposition of the paper, that “Key climate/earth system parameters that need to be restored to safe levels are:
ocean heat content
global surface temperature
|Geopiracy by ETC Group|
The climate science that I've seen referred to over the years on this topic suggests that ocean temperature rise is basically irreversible on human lifetimes. If we stop adding greenhouse gases and stop adding heat to the atmosphere, it may gradually cool back to where it was, but over centuries. In the meantime, warmer oceans means warmer climate and there's not much can be done to change it. Warmer oceans and climate also drive sea level rise.
I haven't seen research on how fast ocean acidification may be reversed, but I suspect it's similar if not slower.
I'm very happy to hear of research which contradicts me on either of these points, of course. But in the meantime, there is only one crucial parameter that we know for sure we can control: the excess greenhouse gases being added to the atmosphere every day, month and year.
(You could add that we can also stop destroying the biodiversity that gives ecosystems some stability and/or adaptability in the face of climate change. Indeed, biodiversity loss is a close second to climate change on the scale of major ecological threats to human civilisation. We will have to work to reverse this, too.)
Backcasting vs wishful thinkingThe paper goes on to use the methodology of “backcasting”: if we aim to protect people and species, then “backcasting” from assuming we achieve that aim, what actions do we need to take to get there? The goal set – 'restoring a safe climate' – leads to the conclusion that we must actively remove CO2 and heat. But as I pointed out above, it may not be feasible to do remove heat. Removing CO2 is also a big task, although seeing limited progress in this may be more feasible via revegetation.
A nasty complication is that ending fossil fuel use will end the emissions of sulphate aerosols that partially cool the earth by reflecting some sunlight (“global dimming”). They only last in the atmosphere very briefly, unlike CO2, so we will probably get a sudden jump in warming if we stop emitting sulphates from our coal power stations and so on.
“Solar radiation management” is Phil's proposal for active cooling, and this geoengineering concept is hypothetically possible by deliberately putting more sulphate aerosols into the atmosphere – perhaps into the stratosphere, where they will last for a bit longer. We're already doing a version of this already, by burning coal, right?
But such geoengineering techniques are hypothetical and fraught with problems. There is no way to trial them, other than at scale with the Earth as a laboratory. Geoengineering is often promoted like “clean coal”, an excuse for not cutting emissions. In reality, its various hypothetical methods are untested and not known to work safely or even at all in many cases. They are, however, expected to cause climatic chaos (yes, more) especially for tropical areas dependent on monsoon rainfall. Where a large part of the world's population lives.
The notion that clumsily meddling further with the climate systems is a good idea is silly in any case. There are too many unknowns. It may make a neat sounding policy proposal to square the circle of “restoring a safe climate”, but in reality it's a dangerous distraction.
Working backwards from an impossible goalBeyond Zero Emissions (BZE) also started from a backcasting approach in designing the groundbreaking Zero Carbon Australia 100% renewable energy plan in 2010: assuming that we needed to reach zero emissions as fast as possible (choosing ten years as the timeframe), they researched the technology and systems that could achieve that. The thing that BZE had in their favour was that engineering an energy supply system (or energy efficienct buildings) is a relatively simple task, and as it turned out available technologies are up to the task. The Earth's climate system is at the far other end of the complexity spectrum.
Carbon draw down is the other dubious concept in the paper. It is unlikely for agriculture and forestry to go beyond zero emissions in the long term, and draw down significant amounts of CO2 from historic fossil fuel combustion. Vegetation regrowth and soil building is unlikely to draw down more CO2 than was released when it was cleared and ploughed previously: once soils hit their natural peak amount of stored carbon, any excess organic matter tends to decompose to CO2 fairly rapidly.
Other mechanisms for carbon draw-down are hypothetical, pie-in-the-sky: industrial (artificial) methods for removing CO2 from the air, for example.
Backcasting approaches can be a useful thought exercise for exploring a problem, but not necessarily for solving it. Factoring in complex systems, including politics, makes it like planning a game of chess backward from the checkmate: it's impossible. Equally, it's not a very useful process if the desired outcome turns out to be unachievable. Backcasting from an unachievable aim won't provide meaningful guidance.
Is a “safe climate” a realistic goal?All this leaves us with the unpleasant fact that greenhouse emissions have (already) done massive damage to the stability of our planet's climate system, and that the only way we know that it may return to a more stable balance is by natural processes that take a lot of time: at least centuries, in most cases.
The first challenge, logically, is to stop doing damage. We have to move to zero emissions. “Beyond zero” is only hypothetical. In fact, BZE adopted the approach of only advocating technology that is proven and commercially available. By that practical measure, artificial carbon draw-down and solar radiation management are not worth advocating.
So this unfortunate back-casting exercise leads us to a lot of dubious, hypothetical, and possibly dangerous technology, that we should not be spending our time advocating for when there are real practical things we can get done like moving to zero emissions.
I think the “restore a safe climate” proposition should be abandoned. If it becomes apparent in future that it is a realistic proposition, then we could revisit the discussion. Right now, though, we need to admit the fact that our coal-burning capitalist economy has done apparently irreversible damage. We need to firstly stop it, and secondly, deal with the consequences to prevent suffering and (as much as possible) see that ecosystems are protected and/or allowed to adapt to a changed climate. That's a big work for a lot of people on the ground. It's a people power solution, not a technocratic solution enacted from on high.
For Pacific nations or Bangladeshi farmers faced with sinking beneath the waves, threatened by a future of disposession and living as refugees, and for all the other people who will suffer in various ways: this doesn't mean we have to write them off as though we're saying “too bad, it's too late for you lot” from our comfy first-world situation. We have to fight with them to save their lands by artificial means if possible, or to rehouse and resettle. But first and foremost to stop the deepening of climatic instability by our ongoing fossil fuel use.
In support of this, it would be good if we could meet one important challenge that the paper sets. I'm not sure the world will, but certainly it would be good to advocate for it and explore what it would take.
“To prevent severe climate and ocean acidification impacts expected by 2030, net global greenhouse gas emissions should reach zero...”
But it seems a fantasy to think we can make the remainder of this sentence happen safely:
“... and temperatures start to fall before then.”
It's certainly true we need to take the fight against climate change to a new level. I agree with the paper's sharp insight from its introduction:
“Over those last 27 years, while all the research, activism and negotiation has been going on, the climate has actually become dangerous. So, the key goal now must be to provide, at the 11th hour, real protection for the vulnerable people, species and ecosystems of the world.
“The principal struggle must shift, from the clash between no action and some action, to the crucial struggle between those who want to constrain reform to levels that are not too disruptive and those who want action that will provide highly effective and timely protection.”
But exploring geoengineering and “safe climate restoration” really doesn't provide the answers that we need to resolve that struggle. It sets impossible targets, obscuring the achievable targets that we urgently need to fight for. It's a recipe for missing the point, not striking the target.