This is the most extraordinary exchange of posts that could not illustrate more forcefully the pointlessness from a policymaking perspective of pursuing ever more precise climate projections, in this case about how fast the Arctic ice is disappearing or the minutiae of commitment warming. If ever there was an example of the quest for perfection being the enemy of the good this is it.
Almost no one in the scientific community now doubts that BAU climate change will constitute ‘dangerous anthropogenic interference in the climate system’, although there may be disagreements about timing and whether it’s an existential threat to the current world order or even humanity itself. We have three responses: emissions reductions, adaptation and climate engineering. Adaptation is important but is primarily about coping with the effects of climate change not averting them. As the UNFCCC process has patently and frustratingly demonstrated, emissions reductions at climate-changing scale are not easily delivered. Energy consumption could not be more deeply embedded in the economic growth of the last three centuries. Energy production today is ~80% fossil fuels, ~10% traditional biomass (billions of poor people cooking on wood or dung fires), ~8% from nuclear and hydro and only ~2% from ‘modern’ renewables. However ‘blindingly obvious’ it might be that the production of fossil fuels must be reduced, this can only happen if either there is a massive reduction in energy consumption (and not just by the high emitters) or a massive increase in renewable energy (or both). We do well to remember that the consumption of wood, coal and oil are today all at or close to their historic peaks – no legacy fuel has ever been eliminated by a successor. Even if it were planned to take 100 years or more , to retire 80% of current energy sources is an unprecedented endeavour of unprecedented magnitude. Turkeys don’t vote for Christmas and no politicians are going to support ‘deep, profound and immediate’ restructuring of the global energy system that will threaten current patterns of energy consumption. They might support a gradual change in that direction provided they believed that their nation’s relative position in the world order would not be threatened. The transition from wood to coal in the 19th century, and then from coal to oil show that structural changes of this magnitude take many decades. There is also a long term trend of increasing energy consumption that reflects wars, population growth, urbanisation, globalisation, extraordinary gains in energy efficiency and a multitude of other radically altered social factors. While a significant decline in per capita energy consumption is conceivable, it would certainly be ahistorical and one must question its plausibility. The political and economic reality is that fossil fuel emissions are not going to peak for some time and when they do they will only gradually fall to some residual amount unlikely to be close to zero. The construction of idealised scenarios is useful in identifying boundary conditions, at one extreme to illustrate the challenge of averting dangerous climate interference and at the other to suggest what it could look like. But policy must be devised to be robust in the greatest range of plausible futures, not to deal with the a few unlikely ones in either tail. We do not need to waste time and resources trying to make ever more accurate predictions for climate change trajectories because the range of plausible futures is already clear and they don’t include reducing fossil fuel emissions fast enough to deliver the Paris Agreement temperature objectives. Today’s policy choices are clear and are only marginally dependent on new knowledge about the climate system. – promote modern renewables, demote fossil fuels and geoengineer to bridge the gap between the other two, and do all three with as much commitment as can be mustered. The moral hazard argument against geoengineering is rendered absurd. If emissions won’t reduce fast enough would it not make sense to use geoengineering to buy us some more time to deliver the necessary deeper emissions reductions, even if they happened more slowly because of the geoengineering? After all, the objective is to limit temperature rise not to reduce emissions, that’s just the means. So, if geoengineering can assist in limiting temperature rise, why would it matter if emissions reduced more slowly? The great majority of the plausible futures require some geoengineering in order to limit the temperature rise in line with the Paris Agreement. The sooner we begin serious investment in working out which geoengineering options to pursue to development and implementation, the better. And while we’re at it, let’s find a way to help the public discern the difference between the risks of properly governed empirical geoengineering research and those of no empirical research. No form of geoengineering is going to go from an academic paper or lab experiment to full scale deployment in a single leap. Robert Chris On Saturday, 12 November 2016 00:54:25 UTC, Greg Rau wrote: > > > > > http://science.sciencemag.org/content/354/6313/714.1 > > GR: Disclaimer - I was a co-signer. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
