02 April 2011

Australian Carbon Follies

The Australian government's proposed carbon tax is politically and substantively problematic.  However, the Coalition's proposed policy in response does not even rise to that deeply troubling level.

The Coalition's shadow minister for climate, environment and heritage, Greg Hunt, was asked on ABC Lateline by Steve Cannane about the role of soil in sequestering carbon as part of the Coalition's proposed policy:
STEVE CANNANE: How much land across the country will be needed to be turned over to carbon soil to meet your emissions targets?

GREG HUNT: I've seen the Government's approach on this and what we've been told is that it is possible to capture - if you increase soils by half a per cent per annum in a small percentage of Australian soils you can capture 150 million tonnes per annum. Now there are differing estimates. There are differing estimates ...

STEVE CANNANE: Over what kind of land mass are we talking about here?

GREG HUNT: We are talking about a land mass, if you are achieving the 150 million tonnes, of an area of roughly 100 square kilometres. Not tens of thousands, but 100 square kilometres of intensive agriculture would make an extraordinary achievement on many of the estimates.
One problem with Hunt's reply is that the math doesn't add up -- 100 square kilometers is 10,000 hectares. That would imply an uptake of 15,000 tonnes of carbon per hectare per year!

What does Hunt do when called on his mistake?

Rather than just say "Oops, I misspoke" he claims that when he said 100 square kilometers, he actually meant a square 100 kilometers on a side.  He even doctored the transcript of the Lateline interview on his offical website to indicate that he said something that he did not:
STEVE CANNANE
How much land across the country will be needed to be turned over to carbon soil to meet your emissions targets?

GREG HUNT
I've seen the Government's approach on this and what we've been told is that it is possible to capture - if you increase soils by half a per cent per annum in a small percentage of Australian soils you can capture 150 million tonnes per annum. Now there are differing estimates. There are differing estimates ...

STEVE CANNANE
Over what kind of land mass are we talking about here?

GREG HUNT
We are talking about a land mass, if you are achieving the 150 million tonnes, of an area of roughly 100 squared kilometres [100km by 100km]. Not tens of thousands, but 100 squared kilometres of intensive agriculture would make an extraordinary achievement on many of the estimates.
It is easy enough to check the video of the interview to see what Hunt actually said (starting at 9:30) and to realize that the transcript on his official web site is falsified.



The second and deeper problem with Hunt's "corrected" statements is that while they may reflect what he wish he had said, they are nonetheless scientifically incorrect, and not by a little bit.  Lateline followed up with Hunt on his error, noting the altered transcript, and Hunt explained:
When I talk about the 100 squared, that's all about a hundred by a hundred square kilometres or a hundred kilometres by a hundred kilometres, 10,000 square kilometres, a million hectares. You can play a game, respectfully, or we can be serious about what's the calculation here. A million hectares at a 150 tonnes of C02 equivalent per hectare is the figure that we're talking about, but that's the intensive number.
The further problem that Hunt has following his "correction" is that his figure for how much carbon dioxide can be sequestered per hectare exceeds estimates from Australian government scientists by a factor of 75 to 450 tonnes per hectare:
The best estimates that we've come up with right now, which is based on a fairly serious review of the scientific literature that's been published over the last 20 years or so, we see that on a C02 basis, somewhere between 0.3 tonnes of C02 equivalents per hectare per year, up to an upper limit of around about two tonnes of carbon per hectare per year on average.
Taking Hunt's numbers for the amount of carbon dioxide to be sequestered in soil and the government scientists estimates for the annual flux, the resulting calculus suggests that 65% of the entire Australian continent would be needed to sequester about 40% of current carbon dioxide emissions.  There is about as much chance of that happening as Australia decarbonizing to Japanese levels by 2020 (PDF).

Julia Gillard's carbon policy may be a mess, but it seems that the best thing that it has going for it is that the Coalition's effort is mired in the dirt.

6 comments:

  1. I think the difference is coalition voters don't want a carbon policy and don't really care if the numbers don't add up because they won't be implemented.

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  2. Roger. Why are you over on an Australian site trying to convince Australians that they need to SELL carbon reduction policy to the electorate?

    You know this is all a scam. Your father is too good a scientist for you to be aware that this CO2-bedwetting is a scam.

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  3. Small typo - " a factor of 75 to 450 tonnes per hectare:" should be "a factor of 75 to 450 times:"

    Of course, sequestering some carbon in Australian soils (not to mention soils in other countries) might be a very good thing for a multitude of reasons, including its effects on atmospheric GHGs...

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  4. You should write just "hectares", not "square hectares".

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  5. -4-crf

    Thanks, editorial help much appreciated ;-)

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  6. One problem when discussing soil carbon is this: are we talking about organic carbon sequestered via agricultural practice, or are we talking about using biochar or similar to enhance soils?

    There are natural limits on how much and how fast CO2 can be turned into organic carbon, less so on biochar.

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