Current proposals for geoengineering, measures to directly influence parts of system Earth, like the global climate system, seem overestimated – with respect to their proclaimed beneficial outcomes. Last month science magazine PNAS published an overview of some of the better established suggestions – and reached the conclusion geoengineering would be no more than another piece of the pie (like renewables, CCS or energy efficiency) in curbing climate change – or halting/preventing sea level rise, to be more precise.

Problem with climate change in general, and with sea level rise specifically, is the delayed start of the process and the irreversible nature once it gets going [see for instance NOAA research in other PNAS publication].

Thermal expansion of ocean waters is a chemical characteristic of water, immediately taking place with any increase in temperature [water is an odd substance in that it also expands when reaching solid state – one would expect ice to sink].

Over the depth of the oceans it is estimated that sea levels will rise about a meter per degree, due to expansion only, so without the added effects of melting icecaps. However, it takes a long time for atmospheric temperature increases to average out with our deep, bulky oceans.

It is quite the same with big glaciers. The onset of melting can be fast – but every melting ice crystal forces a tiny bit of hot air to cool to 0 degrees Celsius – remember ‘endothermic phase transition’ from high school chemistry class. Whether crystallized or amorphous, Greenland and Antarctica still contain a big buffer of solid water, capable of neutralising quite of bit of thaw.

However, the thaw will come – it is already underway. Not only are temperatures rising, they will rise further, even if we stop emitting GHGs altogether, immediately, as per tomorrow. We’ve crossed James Hansen’s safe 350 ppm stabilisation level – and are even well beyond the UN’s official climate target of 450 ppm – CO2 equivalent gases included.

Quoting IPCC 4AR has become somewhat unfashionable, not because of that one slippery reference in the scientifically irrelevant sub-report of WG2, but because climate scientists are starting to agree the climate sensitivity used by the IPCC (‘doubling atmospheric CO2 concentration gives 3 degrees warming, as most likely’) does not reflect true urgency. The many disturbances in albedo, Earth’s reflectivity, and ecosystems, connected to the carbon cycle, will lead to a dominance of positive feedbacks.

Adding this ‘indirect climate sensitivity’ to the equation, things may be twice as bad – or worse, as estimates range. “Since none of the general circulation models [GCM, climate models] used to project climate change over the next hundred years include all of the important forcings and feedbacks, they should be considered as sensitivity studies rather than forecasts,” concludes Hans Joachim Schellnhuber, professor at Potsdam Institute for Climate Impact Research – and a leading expert on climate feedbacks.

However, to show some respect to the hundreds of leading, best-established climate institutions that are the IPCC, let’s just say things aren’t so bad. Let’s for now ignore giant methane burps and a dried-out taiga biotope. Even then, and in our impossible scenario of a fully stopped usage of any source of fossil energy, per tomorrow (energy consumption is still on an exponential rise), we face two degrees of warming – on average.

Average is good when you live in or around that enormous surface area of the tropics. Average is very irrelevant when you live within that small area (remember the globe is a sphere) surrounded by the polar circles – where the icecaps lie that could, theoretically, increase mean sea level by more than 60 metres. (Quite a chunk of Greenland’s ice sheet actually lies south of the polar circle – only to further stress its tipping-point.)

Here even that scientifically conservative and practically impossible IPCC 2 degree figure translates into an inevitable 4-6 degrees of warming. And that is quite enough to cause some nasty melting, especially on Greenland and the West Antarctic.

All this for now should merely serve to underline once more – however slow it may develop – and if not the most urgent of them all, sea level rise is a problem. And seemingly, preventing sea level rise is already impossible, conventionally.

Of course the only sane thing one can conclude with respect to emissions reductions – now that these prove to be too late to prevent damage – is their imminent importance. Mathematically, equilibriums are much more likely to be distant with any increase of disturbance. In practice: emit more GHGs and damage will most likely be exponentially higher. This goes for sea level rise as well. At least try to curb the problem. However big the psychological challenge is of realising it will be an enormous effort – and none of us will live to ever see the climate problem declining.

But why not be a little more ambitious than that – for the theoretical fun of it. Is there no other way? Well, this article is about geoengineering …and there will be many more to come.

Say ‘coal’ out loud within the community of climate NGOs; you get an angry frown. Say geoengineering and you will create a silence. No other word is more politically incorrect, at least among those people that say they actually want to solve the problem of climate change.

Why is that? Is it distaste for anything industrial – like with those other pieces of the climate solution pie, CCS, or nuclear energy? Is it too right-winged, like stating global population increase is a sustainability problem (in itself), like stating the fight against poverty speeds up the worldwide decline in ecological capital?

It goes deeper. Enter the world of geoengineering – and you enter the realm of the Gods, or so it is perceived. Some handles are to remain untouched. How true this probably is. Big changes create turbulence downscale. We don’t know what would happen if we would tilt the axis of the Earth by one degree, but most likely we’d all be dead, through some unfortunate overlooked detail. Reality is infinitely complex. That starts to hurt when you move a lot of reality just at once.

Yet we are faced with problems on a global scale. Isn’t that exactly what we are doing at present: moving too much of reality and moving it too fast? Isn’t it mere logic we look for solutions at that same level? – to be efficient in our attempts to buffer the damage that we can foresee?

We’re getting philosophical and with respect to geoengineering that’s actually a good thing. There is a reason to be thorough and to always expand on the matter. When you skip the long considerations and you just say ‘adding sulphur to kerosene for all transcontinental flights decreases warming by one degree’ – you create another problem. No, I’m not talking about the ozone layer (although you do raise a good point). You get a portion of people to believe that what you say is true. You get a portion of people to believe the benefits will outway the costs, including the side-effects. But you may be wrong. And you would lead people to believe there is an easy fix.

You would lead them to believe we have the choice between cutting emissions – or taking that cheap, easy shortcut. This would further decrease public support for tackling the climate problem at its source, carbon emissions – or actually, fossil fuels. You would do a better job if you would first explain what ocean acidification means, and how albedo measures do not solve that ‘other thing’ CO2 does to system Earth.

And what’s more: we cannot expect science to do the judging for us. Geoengineering is so ‘un-pc’, to quote David Keith, the Calgary climate professor who says it best in his TED Talk on geoengineering, even scientific research is still refrained to people like, well, mister Keith. These may be brilliant minds, but they mostly work alone. Compare that to the UNFCCC process – a combined attempt of millions to solve exactly the same problem.

We are not talking multi-million dollar research budgets either – just yet. Because the reason Copenhagen failed is of course the financial blood-letting, we in all our naivety expected our business as usual economic system to make. Trillions of dollars worth of investments would have to be channelled in developing a global carbon extensive energy infrastructure. It can hardly hurt world economy as a whole, but economists still don’t like it when they you tell them there little plans for today and tomorrow would have to wait a while. And these people do form lobbies you know…

Again likely, very likely, these next couple of years we will see increased attention being paid to that other solution route. Research into geoengineering will boom. Scientists will have more certainty; public however will be faced with yet another incomprehensible message – if we, science communicators, do as bad a job as we did when we tried and failed to explain the underlying urgency of climate change.

Probably this is just what the editors at PNAS had in mind. Under the title ‘Efficacy of geoengineering to limit 21st century sea-level rise’ the article explains how combined use of ‘established’ forms of geoengineering, won’t go far enough to – for instance – halt all sea level rise.

These forms of geoengineering include the relatively harmless measures focusing on the carbon cycle, like biochar. Biochar is a traditional agricultural by-product that can improve carbon storage in organic soils. Its total mitigation capacity, when fully implemented (farmers worldwide) is estimated (Johannes Lehmann, Cornell University, 2008) to be around one Gt of pure carbon per year – about ten percent of anthropogenic carbon emissions. That makes it more interesting than light bulbs, but hardly your one climate saviour.

Another example is large-scale implementation of biomass-fed power plants, equipped with CCS technology. It’s a trick to actually remove CO2 from the atmosphere into some other, artificial carbon cycle – deep underground. Bit of a petty the world at present can’t even equip a coal fired power plant or a cement factory. Then again, when talking geoengineering, we are talking future.

The PNAS publication gets a little more surprising when it also adds an albedo measure into the equation – sulphate aerosols, when blown up to stratospheric heights capable of reflecting or at least shielding a portion of solar radiation. These forms of ‘short-wave geoengineering’ are said to be potent enough to completely compensate all global warming under any official UN ppm scenario.

‘Not so,’ the study seems to point out. With a Mount Pinatubo worth of sulphate aerosols every four years, we would still only compensate about 30 centimetres of sea level rise. If we would like to see a further decrease in climate damage, we would have to combine full implementation of these geoengineering methods with drastic conventional emissions reductions.

However, from a scientist’s perspective, why would you conclude that a little bit of something leads to a little bit of something else? It merely leads to suspect – if you would want a lot of something else, in this case the complete prevention of net sea level rise, you would have to try a little harder. Leader of the research team, John Moore of Beijing Normal University, himself coined a term for that scenario: ‘extreme geoengineering’. According to Moore, if instead of releasing one Pinatubo per 4 years, we would explode a sulphur volcano every 18 months, we would be just fine – and sea levels would remain around normal. A comforting thought.

(c) Rolf Schuttenhelm | www.bitsofscience.org