biffvernon wrote:Billhook wrote:, if you meant that Cloud Brightening doesn't resolve ocean acidification I'd well agree, but neither will Emissions Control
I don't understand that bit. If we stop emitting CO2 then ocean acidification is not going to get a whole lot worse, beyond the lag in the system. I'd say emission control is a pre-requisite. We also need carbon capture and then, and only then, should we turn serious efforts to the other geo-engineering 'solutions'.
No, I don't think it will happen either.
Biff and Candy -
EC [Emissions Control] is patently essential and necessary, but it is not sufficient to halt the acceleration of the eight known major feedbacks.
The addition of CR [Carbon Recovery] is equally essential and necessary, but it is not sufficient to do so due to the vast scale of airborne anthro-carbon meaning at best its recovery will take a century of operation - of a new global industry of forest-sourced biochar and co-product methanol, followed by the ~35yr timelag on its temperature effect.
With a best-case of EC achieving near-zero CO2e output by 2050, with the ~35yr timelag we'd see an end to the rise of anthro-warming in the 2080s.
That warming would likely reflect:
0.8C realized warming
0.2C obscured by ENSO since the late '90s
0.7C timelagged in the oceans' thermal inertia pipeline
0.6C (?) from phase-out period output
= ~2.3C
+ 110% (+/-30%) (ref Hansen) due to loss of the cooling sulphate parasol due to the end of our fossil sulphate emissions
= ~4.83C (+/-0.7C) of warming from anthro sources realized in the 2080s.
This outcome would be only slightly mitigated by the addition of a massive global program of CR since there is a lead-time of at least 20 years for required the scale of afforestation, reaching full recovery flow by say 2040 (?) with a net recovery of only 3 or 4 ppm/yr for the 10 yrs to 2050. In cutting part of the warming only from phase-out emissions, this might cut the 4.83C median outcome to perhaps 4.4C to be realized in the 2080s. I.e. it makes no significant difference.
The interactive major feedbacks of concern as carbon emitters are
Microbial Peat Bog Decay
Permafrost Melt
Forest Combustion
Soil Dessication
Methyl Clathrates
Ocean Warming and Acidification (cutting the primary natural carbon sink of oceanic plankton)
With the exception of methyl clathrates whose ongoing destabilization is still disputed by some, all of the above are already accelerating their output of carbon as CO2 &/or as CH4. Most of them have the potential to dwarf present anthropogenic outputs in CO2e terms, but that is to misrepresent their relevance.
With a realized warming of 4.4C in the 2080s under a best case of EC + CR, we would allow the feedbacks around 70yrs of continuous rapidly intensifying warming. Given that the carbon-feedbacks are already accelerating their outputs, and are already interacting directly with other feedbacks, and are already contributing warming to the timelag pipeline to be realized in the late 2040s, it is not their individual ability to dwarf anthro-outputs that matters but their combined impact on warming, and thus on their own further acceleration.
To propose that AR [Albedo Restoration] should be left to a later negotiation after EC + CR are established makes no more sense to me than a proposal of a treaty that phases out all nations' CO2 emissions except the superpowers, whose output would be subject to a future negotiation, until which time they would be allowed to raise their outputs without restraint, meaning that they could together equal and then surpass the present anthro-CO2 output and continue its exponential rise. The effect of such a treaty on airborne CO2 ppmv would be no worse than that from unrestrained carbon feedbacks.
Moreover the argument of AR posing a get-out for backsliders would be no less valid in a later negotiation than in a present comprehensive negotiation. Its adoption could well be delayed for another decade or two for this reason, putting us far beyond the time-window of endurable climate destabilization.
The primary concern should in my view be the climatic destabilization of agriculture, which an increasing flow of sober scientific studies indicate is going to impose intensifying global crop failures starting in the 2020s. Plainly neither EC alone nor EC + CR can do anything at all to address that threat. They are between 70 and 135 years too slow.
Only AR can potentially address that threat, and then only if a very rapid very stringently supervised research effort is able to allow the deployment of AR within the next 10 years at the most. - With a 2 to 3yr lead time to full cooling effect, this would restore global temperature and stabilize global climate by the middle of the 2020s.
I guess we can agree that serial global crop failures would predictably have a massively destabilizing effect on geopolitical relations, relegating nations' adherence to any climate treaty to a mere aspiration "once the emergency is over" ?
In this light a second potentially predictable outcome of delaying the preparation of AR's most benign options is that when global crop failures occur there will be efforts at AR undertaken with the only available option: the long-proven, very cheap, very dirty, very dangerous option of sulphate aerosols, quite probably as unilateral initiatives given the loss of geopolitical stability, which would thereby contribute to a further fracturing of international coherence.
Regarding the sequence of the negotiation of EC+CR+AR, if the argument of "a get-out for backsliders" was valid for AR, then it is worth noting that it is just as valid for CR, if not more so given that scams like REDD+ are already advancing deficient versions of CR as a means of "offsetting" continued fossil emissions. When the political will arises to put the resolution of AGW ahead of its use as a means of advancing/maintaining national dominance, the backsliding tendency will be seen off as a threat to mutual security - until then, it's diplo-business-as-usual.
I hope we might agree that the priority is pursuing whatever route will be swiftest in achieving the operation of EC+CR+AR, and doing so under a stringent verification regime. In this light I'd restate the factor that both CR and AR offer serious 'lubrication' to the negotiation; CR in potentially removing the roadblock of historical emissions, and AR in removing the ground anchors of the N-S stalemate over open-ended climate damages and open-ended compensation liabilities.
The critical point to consider seems to me the fact that attempting to negotiate a treaty of EC+CR, that must try to formulate mutually acceptable commitments over those open ended climate damages - is predictably going to take a hell of a lot longer than one including AR in which those climate damages are seen as being very limited in duration and severity.
For about two decades I understood the resolution of AGW as being about two "Windows of Opportunity" - the first being the period in which it could be resolved by rapid global emissions control alone, which effectively ended with Reagan's coup against President Carter in 1980; and the second being the use of Geo-E in addition to EC, which would end at the point where the feedbacks were too advanced - i.e. were accelerating too fast for Geo-E to be able to control them, which seems unlikely for a couple of decades yet.
But in fact the climatic destabilization of agriculture imposes a third Window of Opportunity which will close at the point where it destabilizes agriculture and thus the international coherence that is prerequisite for international agreements and their effective operation. This window appears to have around 10 to 15 years left before it closes.
For this reason I'd urge the acknowledgement of the inevitable need of both modes of Geo-E alongside emissions control as an urgent priority for a comprehensive negotiation. By this means airborne CO2 could be made to peak somewhat below 450ppmv before starting a steady annual decline, meaning that the acidification of the oceans can be limited to allow the survival of at least half of its present biodiversity. With that, it may well be possible to maintain a terrestrial ecology within which our successors could thrive, albeit in a very different society.
Regards,
Lewis