Dear Sir/Madam,

Positive feedback effects from man-made global warming are accelerating climatic disruption, increasing the threat to humanity and decreasing the time for effective action to save the planet.

Major examples include the albedo flip involving replacement of light-reflecting sea ice with dark, light-absorbing ocean in the Arctic and Antarctic; the ticking methane bomb involving CO2-driven global warming causing tundra melting and release of methane that is 21 times worse than CO2 as a greenhouse gas on a 100 year scale; increased storm intensity causing loss of the Southern Ocean as a major CO2 sink; and present climatic disruption causing destruction of major forest carbon sinks due to greatly increased forest fire extent and insect herbivore population explosion.

Just as the latest scientific discoveries have supplanted IPCC predictions of 2007 (e.g. the Arctic summer sea ice is now predicted to completely go by 2013 rather than in 2100) so climate activism is also being rendered out of date. Thus US-based 350.org advocates reduction of atmospheric CO2 from the present 387 ppm to 350 ppm based on the upper estimate from NASA’s Dr James Hansen in 2007.

However now Australia-based 300.org urges a goal of 300 ppm atmospheric CO2 for a safe planet, informed by the latest from Dr Hansen and many other top climate scientists – notably, Australia’s Professor Barry Brook who says “The number is 300” and that “350. It’s the wrong number” (see: http://sites.google.com/site/300orgsite/Home ).

Dr Gideon Polya

Macleod, Melbourne, Victoria 3085, Australia

I also still have an image burnt in my head from a photo my father took at the end of the Second World War – it shows a human image burnt into the steps of a building in Hiroshima a year after the atomic bomb.

refers to a bomb that had no connection to any nuclear reactor of any kind.

If the CP1 experiment under Stagg field had never been done, Hiroshima or a city like it would have burned just the same, and if someday all the cities on Earth are powered exclusively by wind turbines, every city will still, and forever*, be under that threat.

— G.R.L. Cowan
Internal combustion made continent

* OK, not strictly forever, but for many hundreds of millions of years.

Let one half-life of 238-U go by and the Sun will probably still be stirring up wind, but natural uranium’s 235-U atom fraction will have diminished, because one of 238-U’s half-lives is 6.348 of its, to 0.018 percent from its present 0.72 percent.

So wind-powered clandestine separation of this now much smaller trace will be much harder. Perhaps as hard as the membrane-diffusion enrichment that was done to get the material for the Hiroshima bomb.

I agree that Hiroshima was a tragedy. But this is not relevant to whether the future is powered by atomic energy. Indeed, a hard nosed analysis suggests that the number of lives lost is not even the persuasive argument, given that the casualties estimated for Operation Coronet and Olympic, if they had needed to proceed, was far worse:

A study done for Secretary of War Henry Stimson’s staff by William Shockley estimated that conquering Japan would cost 1.7 to 4 million American casualties, including 400,000 to 800,000 fatalities, and five to ten million Japanese fatalities. The key assumption was large-scale participation by civilians in the defense of Japan

This is by no means an argument for nuclear weapons — and today’s stockpile nuclear weapons could inflict far more deaths than any conventional war. But that wasn’t true at the time of Hiroshima, which is another reason why it is not a relevant example today. And another reason to dismantle today’s weapons stockpile and burn up the plutonium in fast reactors such that it is never again a problem for us.

I’ll have a look at your posts on the nuclear option, but for the moment I’m very much persuaded by the arguments put forward by Professor Ian Lowe in his Quarterly Essay, ‘Reaction Time’. I also still have an image burnt in my head from a photo my father took at the end of the Second World War – it shows a human image burnt into the steps of a building in Hiroshima a year after the atomic bomb.

CO2(air) + 2H2O –>
O2(air) + (CH4 + CO2)(captured)

separate the methane from the acid gas to obtain 387 MtCO2 ready for sequestration and 533 MtCH4 = 743 Mm^3 CH4. That’s far more than is necessary to run the process using sea water, so the rest goes to market. To set in perspective, according IEA 2006 statistics, 80×10^(-9) of world prodcution of natural gas.

Suitable nearby ultramafic rocks occur in Weat Australia (nothern interior) and massive amounts of it in Papua New Guinea, enough and more to weather out all of the excess carbon added so far, about 500 GtC.

THe saleable product from this enterprise include brine for extraction of mineral salts, methane and some form of excess carbon dioxide removal fee (if anybody is paying that). I don’t know what the ROI might be, but it might make some money. Any takers there in Oz?

‘Finrod’ said,

I’m not opposed to the idea if it works. I’m all for a plethora of viable options, as long as aforementioned plethora doeas not result in paralysis.

But why did you respond to me in a different thread from the one in which I replied to you?

I would like to think that we are, in the end, on the same side.

We’re definitely on the same side in re fossil fuel replacement. Perhaps we disagree on what to do about all the fossil fuel ash already in the air, and destined yet to go there despite us. Do you have some reason to think Mg_(2-2x)Fe_2xSiO4 dispersal wouldn’t work significantly better than any other method? We know particles small enough to take a few hours to fall a few kilometres through air react plenty quick enough: one to four years for zero ‘x’, otherwise faster.

That other thread was a long-in-the-tooth solar power thread. CO2 downsnatching seemed more on-topic here.

(B: a better energy carrier than H2?)

Recent TV showed an oil and gas company (Conoco) claiming an offset by paying aborigines to regularly set fire to scrub. The theory was this practice emits less CO2 than irregular wildfires caused by lightning for example. I’m unconvinced. The whole CO2 absorption issue is getting far fetched and in my opinion borders on fraud if there are financial benefits.

I say forget all alleged forms of enhanced CO2 capture and let earthbound carbon stay there.

In situ peridotite weathering:

http://www.popularmechanics.com/science/earth/4292181.html
http://www.technologyreview.com/energy/21629/?a=f
http://www.pnas.org/content/105/45/17295

It may be that the only substantial cost is shipping flue gas to the chosen (near-surficial) rocks. Unfortunately, flue gas is only about 14% carbon dioxide, so this isn’t as inexpensive per tonne of CO2 as it might seem. Still, I don’t know of a better idea which could be adopted on the scale required.

The only environmental cost, AFAIK, is that the disposal site will swell up rather considerably.

So 325 ppm seems too high to me.
RIght around 300 ppm is maybe optimal.

We can safely assume that 280 ppm does not kickstart the feedbacks to which you refer. Thus I think an extra 20ppm above that is a reasonably ‘safe’ target. 350 might be okay too — but that seems to be the point at which the Arctic sea ice started its downwards trend to eventual oblivion.

(1) The CO2-equivalent values are higher by ~ 50 ppm due to methane, i.e. the present level is close to ~ 440 ppm CO2-equivalent.

(2) Due to positive feedback processes, including carbon gas release from the biosphere and warming water and methane leakage from bogs, permafrost and shallow sediments, no CO2 value (300, 350 or 400 ppm) can be assumed to remain “stable” or “fixed”. Further, ice melt/warm water interaction and albedo change result in further polar warming, affecting the rest of the globe, in turn resulting in further release of carbon gases.

It is the magnitude of carbon and ice/water feedbacks which explain the glacial terminations (Roe, 2004; Hansen et al., 2008).

Untile recently the sensitivity of the atmosphere and the role of feedbacks have been grossly underestimated, with implications for current climate change and potential tipping points.

A $100 a ton carbon tax would increase the price of electricity from coal and gas by about 3 cents and 1.9 cents a kilowatt-hour respectively. This would make low emission generating capacity much more competitive. It would result in a very large expansion of wind capacity and increase the amount of wind power the grid could economically support, as wind power would still be profitable even though the periods of time when strong winds combine with low demand to push the price of electricity towards zero would increase as its capacity expands.

With a $100 a ton carbon tax, many things would become cheaper to burn than coal and gas, so biomass would be used in some existing fossil fuel plants. Fortunately Australia has the capacity to replace a significant portion of its coal and gas use with biomass. The decline of the sheep and cattle industries that would result from the carbon tax should free up land that could be used for biomass production. A small percentage of carbon in solid biomass is trapped as ash when it is burned, so the process would be slightly carbon negative.

At $100 a ton, several carbon sequestration methods should become profitable. For example it should be worthwhile to add char to soil in many areas to improve agricultural productivity.

Efficiency measures and demand management would help. A shift towards charging consumers minute-by-minute wholesale prices multiplied by a factor that pays for transmission costs, would encourage efficiency and allow a greater amount of intermittent energy to be supplied to the grid. It would also make it cost effective for many people to use smart appliances that have a greater portion of their power use during periods of low electricity prices.

While the electricity generation could be made carbon negative in five years, making the transportation sector carbon negative is more difficult and might take twice as long and much higher carbon taxes.