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Saturday, July 9, 2016

Beware deniers wanting plant food - or - If science deniers were in charge

Sou | 11:31 PM Go to the first of 11 comments. Add a comment

Over at WUWT, Anthony Watts has put up another article from his main contributor Eric Worrall (archived here). Eric is thinking of sending the world to hell in a handbasket by adding enough CO2 to the air to bring it to 1000 ppm in the next ten years. He says he wants to feed plants. His plan is to burn limestone.

Eric knows as much about atmospheric science and arithmetic as he does about climate change. His calculations are wonky. He thinks that there is only 920Gt of CO2 in the atmosphere at present. There's about 3,250 Gt or about 8 Gt per ppmv of CO2. So when he works out that he needs another 600 ppm, he thinks he only needs another 1,380Gt of CO2. In fact he needs to find about 4,800 Gt CO2. That means instead of just using 3,136Gt of limestone, he'll have to find nearly 11,000 billion tonnes of pure limestone.

Eric discovered that it takes about 3.6MJ to burn one kg limestone. That would be about 3,600 MJ to burn a tonne of the stuff. To burn 11,000 Gt of limestone would take about 39,600,000,000,000,000 MJ or 39.6 x 10^15 MJ. Eric also found that the world currently uses about 3.89 × 10^14 MJ of energy a year, so he decided to spread his burning out over ten years. That would require 39.6 x 10^14 MJ every year - about ten times the current energy consumption. Instead of needing 0.3% of global energy consumption as Eric thought, it would require the equivalent of 1000% of global energy consumption every year for ten years, to burn enough limestone to add another 600 ppm CO2 to the air.

None of that should be a surprise, given how CO2 is increasing with the amount of burning that's going on. To shift from 400 ppmv to 1000 ppmv in ten years would take a huge amount of combustion.

Eric didn't factor in CO2 sinks. However he's talking about increasing CO2 by 60 ppmv a year each year over ten years so I very much doubt that the sinks would be able to cope. Instead of using up half the annual emissions, they'd probably only continue to soak up not much more than they are doing now (in actual amount, not percentage). The other consequence he didn't factor in is the decimation of life on the planet. That would mean he'd be lucky to have too many people left who'd be much interested in burning limestone well before he burnt his quota. He did note that burning limestone would be done by burning fossil fuels, which would considerably hasten the growth of atmospheric CO2.


I have been known to make mistakes, especially when it comes to the power of ten. So please pick me up if you see any.

The obvious

I shouldn't need to state the obvious. There is probably less than 500 Gt left in the CO2 budget if we want to stay below 2C of warming, and that's emissions not the 50% of CO2 staying in the atmosphere. Even if it was feasible, adding another 4,000 Gt of CO2 to the atmosphere over a space of only ten years would probably kill off much of the life on Earth. Is that what Eric Worrall wants?

Then there's the other obvious...

From the WUWT comments

I wouldn't know if Eric was serious or not. It's hard to tell with the WUWT crowd. Here is some of the reaction.

Timo Soren is excited at this thought:
July 9, 2016 at 4:14 am
Poor Alarmists, this will make them wet their pants.

Eyes Wide Open says he or she found one of Eric's many errors:
July 9, 2016 at 4:18 am
You’re off a decimal point. It’s 3% of global energy budget over 10 years. 

roaldjlarsen says something irrelevant and wrong:
July 9, 2016 at 4:26 am
CO2 doesn’t produce any heat nor does it prevent heat escaping the atmosphere. 

daveburton also noticed an error that Eric made:
July 9, 2016 at 4:31 am
Re: “400ppm of CO2, contains 400ppm x 2.3Gt / ppm = 920Gt of CO2.”
That should be 8 Gt / ppmv CO2, not 2.3.
(Note: “400 ppm” customarily refers to ppmv, or, more precisely, dry molar fraction.)
The Earth’s atmosphere has a mass of about 5.3 Gt (some sources say 5.1 or 5.2).
However, atmospheric gas concentrations are customarily expressed in ppmv (parts-per-million by volume), so to calculate the mass of one ppmv requires scaling according to the molecular weight of the gas in question. The average molecular weight of the Earth’s atmosphere is 28.966 g/mole (~29). So, for carbon dioxide, 1 ppmv CO2 (molecular wt 44.01) has mass ~(44/29) × 5.3 Gt = 8.053 Gt.
Thus 400 ppmv CO2 has mass 400 × 8.053 Gt/ppmv = 3221 Gt. 

Smueller  had to check the calendar:
July 9, 2016 at 4:27 am
I had to look at a calendar to make sure this was not April 1st (all fools day) but no – it is not.
Dietary deficiencies of zinc and iron are a substantial global public health problem. An estimated two billion people suffer these deficiencies1, causing a loss of 63 million life-years annually2, 3. Most of these people depend on C3 grains and legumes as their primary dietary source of zinc and iron. Here we report that C3 grains and legumes have lower concentrations of zinc and iron when grown under field conditions at the elevated atmospheric CO2 concentration predicted for the middle of this century. C3 crops other than legumes also have lower concentrations of protein, whereas C4 crops seem to be less affected. Differences between cultivars of a single crop suggest that breeding for decreased sensitivity to atmospheric CO2 concentration could partly address these new challenges to global health. 

Jerry Henson is an ice age comether:
July 9, 2016 at 4:36 am
We could switch all existing all existing power stations back to coal, mandate that all wind and solar be replaced with coal, and that all future power generation be coal.
The savings in energy cost would make the additional cost of burning limestone to add the additional CO2 to the atmosphere minor
I started reading about climate in the 70’s when my children were coming home from school, saying that we were going into the next ice age if we didn’t stop emitting CO2.
I bought several books and became convinced that, based on simple cycles, we were headed for the next ice age.
I am much more concerned about the coming cold than the possibility of a little extra heat.
/not sarc! 


  1. The deniers are getting desperate, ain't they?

  2. I am confused. Has WUWT published guidelines as to which days of the week the inmates are supposed to accept that CO2 is plant food and which days they do not?

  3. I'm so embarrassed. Years of being annoyed at WUWT and I never realized it was a satirical site and I was being trolled. But they've finally tipped their hand, and now I'll just have to see it as a less funny version of the Onion.

    1. Touche, Magma. My thoughts exactly.

      Still, though, Anthony could just admit he was wrong about something in the past 10 yrs or so, and that would make it all right:

    2. Has to be done. One of the best Onion pieces ever:

  4. Sou, the mean molecular weight of the dry atmosphere is ~28.97 g/mol. Water vapor is variable, but around 1.6 wt%, or 2.5 mol%.

    Since CO2 has a molecular weight of 44.01 g/mol, 400 ppmv ≈ 600 ppm wt. This trips people up on occasion, apart from the needless confusion -- one that climate scientists have only themselves to blame for -- of reporting emissions in terms of either C or CO2, and often not making the distinction clear. (CO2eq is entirely defensible usage, however.)

    I'm not going to bother to work through Worrall's math. It would be the epitome of a pointless exercise.

  5. Where does Eric propose to stash his gigatons upon gigatons of quicklime ?
    When exposed to air, quicklime absorbs CO2 and reverts to limestone.
    When exposed to humidity, lime will absorb water and then CO2, and revert to limestone.

    Will he park it all in Death Valley, and cover those Worrall Badlands with a giant tarp ?

  6. OT, but this possibly-climate-related news is 'interesting' in the worst-possible sense.

    1. And here's some more 'interesting' news our non-antipodean friends may not have encountered.


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