ARC's 1st Law: As a "progressive" online discussion grows longer, the probability of a nefarious reference to Karl Rove approaches one

Tuesday, July 11, 2006


Interesting discussion over at DU about the need to stop eating, since croplands apparently contribute to global warming.

Science Report: Cropland is a net contributor to global climate change.

This report dates from a few years ago, by I found it while I was reading commentary in Environmental Science and Technology a publication of the American Chemical Society.

The Science reference is Science, 289, 15Sept2000, pp 1922-25.

Some salient quotations from the article:
If all U.S. cropland (186 X 106 ha) (23) had a net GWP similar to that of our conventional tillage system, the annual CO2 cost would total 0.06 Pg C equivalents. Over the most recent 6-year period for which data are available, U.S. fossil fuel emissions of 1.4 Pg C year21 grew at a rate of 0.02 Pg year21 (24). Agriculture thus plays a minor role in the GWP economy of the U.S., yet net mitigation of agricultural fluxes could offset the current annual increase in fossil fuel CO2 emissions.

Whole-system GWP analysis reveals a number of management options for mitigation. In our annual crop systems, the high net GWP of conventional tillage was largely neutralized by soil C storage during no-till management. C was also sequestered by the use of cover crops: Despite intensive cultivation, soil C storage in our low input and organic systems provided about one-third the mitigation benefit of no till. But soil C storage is only half of the story: In our no-till system, other GWP sources more than offset mitigation gains from soil C, suggesting other mitigation potentials. By substituting biological N2 fixation for synthetic fertilizer use, for example, our organic system saved an amount of CO2 equivalent to about 25% of that mitigated by no-till soil C capture...

...Many of these alternative mitigation strategies are related to tightening the nitrogen cycle of cropped ecosystems, a nontrivial challenge in light of the importance of N to crop yields. N fertilizer is not now used to sequester soil C, so reducing fertilizer use to provide greenhouse gas mitigation will require careful management of cover crops, residues, and the microbial and physical processes that regulate soil N availability (26) if high yields are to be maintained. The use of N fertilizer to sequester soil C is unlikely to result in net mitigation.

Maximum mitigation is provided by removing land from production. The strong mitigation potential of our early successional system will persist into midsuccession as carbon is also allowed to accumulate in unharvested wood
The bold and italics are mine

Which received the following comments from the DUers:
slackmaster Donating Member (1000+ posts)
Mon Jul-10-06 05:54 PM
Response to Original message

3. People in the developed parts of the world need to eat less anyway
I think I'll go for sashimi tonight.

unpossibles (1000+ posts)
Mon Jul-10-06 06:03 PM
Response to Original message

5. should I even bother pointing out...
...that a meat-based diet production uses more land and water than a plant-based diet?

sorry if this derails - intersting, although a bit over my head.

I think that in order to save the planet, we should all stop consuming anything... return to the caves and reduce our population by 95%.

And note how nothing is mentioned about how much more productive US farmland is compared to the undeveloped world, primarily because of the technology and knowledge applied to agriculture. If the US used the same methods and technologies as those currently in use in the undeveloped or under-developed world, the CO2 emissions would likely be higher as a ratio of cropland productivity.

Your Co-Conspirator,
ARC: St Wendeler