Heliophage

Nothing to do with photosynthesis, but in terms of book-promotion who could help falling for Miranda July? (via Neil)

Well I was planning to keep this blog soft launched until I’d convinced myself I’d manage a respectable posting rate, but I guess as far as some discerning readers are concerned I’ve been outed by Carl. What’s more, it’s at a time when I’m headed off on holiday for a while. So all I can say is that whatever normal service turns out to be will be resumed whenever. Do check back.

Main message to take away from this site so far: My book Eating the Sun — How Plants Power the Planet will be published this summer. The jacket copy says it will change the way you see the world, and who am I to argue. I can however attest that writing it changed the way I see the world, and for the better.

Meanwhile, if your eagerness to waste time extends to golden oldies from the archive, feel free to check out Mainly Martian.

Via Gary at Muck and Mystery, various reports on the conference on biochar/agrichar/terra preta nova/what-you-will that just ended down in Australia. If you’re not up to speed on this, the general idea is that people could help solve a great many problems by putting enriching soils with reduced carbon in charcoal-like form. This gets rid of the carbon for a long time (charcoal is very refractory) and improves the soil in various not yet fully understood ways. My colleague Emma wrote a lovely feature on the subject last year. There’s what seems to be a thriving discussion board on the subject at Hypography.

The conference was opened by Tim “Weather Maker” Flannery, which is a pretty big name for a new field to manage to attract, I’d have thought. Here’s an overview of the conference by Kelpie Wilson of the Energy Bulletin. One interesting aspect is the idea of tying this issue to the issue of crappy stoves that drive indoor air pollution and waste a lot of energy.

Transect points, a blog by soil scientist Philip Small who, like Gary, is tracking this issue, has more reports in a round-up. As one of the people quoted says, the great thing about this field is that it opens up in so many different directions. Its also low tech enough to be of real use globally. The flip side of that is that different techniques will be needed in different places — this is unlikely to be a one-size-fits-all technology.

As it happens we’ve a look at the subject in Nature this week, too — a commentary (pdf) from one of the field’s main men, Johannes Lehmann of Cornell, which takes things forward nicely, I think. One of the advantages he points out for biochar sequestration — as opposed, say, to sequestration of carbon in aquifers — is that once the carbon is in the soil “it is difficult to imagine any incident or change in practise that would cause a sudden loss of stored carbon”. And he also argues that this sort of practise could be carried out at a serious scale:

I have calculated emissions reductions for three separate biochar approaches that can each sequester about 10% of the annual US fossil-fuel emissions (1.6 billion tonnes of carbon in 2005). First, pyrolysis of forest residues (assuming 3.5 tonnes biomass per hectare per year) from 200 million hectares of US forests that are used for timber production; second, pyrolysis of fast-growing vegetation (20 tonnes biomass per hectare per year) grown on 30 million hectares of idle US cropland for this purpose; third, pyrolysis of crop residues (5.5 tonnes biomass per hectare per year) for 120 million hectares of harvested US cropland. In each case, the biochar generated by pyrolysis is returned to the soil and not burned to offset fossil-fuel use. Even greater emissions reductions are possible if pyrolysis gases are captured for bioenergy production.

Similar calculations for carbon sequestration by photosynthesis suggest that converting all US cropland to Conservation Reserve Programs — in which farmers are paid to plant their land with native grasses — or to no-tillage would sequester 3.6% of US emissions per year during the first few decades after conversion; that is, just a third of what one of the above biochar approaches can theoretically achieve.

Those, Lehmann stresses, are rough calculations to highlight the potential, not realistic scenarios. But might it not make sense to start developing them into realistic scenarios? If you have inexpensive feedstock, this is a pretty intriguing technology.

This week in Nature we have a news story on an attempt to follow up Frank Keppler’s work on methane produced aerobically by green plants which we published early last year (news story | paper). The Keppler piece, which suggested that methane emissions from green plants were a significant but previously unappreciated factor in global methane emissions, caused quit a lot of fuss, understandably, in the media — since methane is a greenhouse gas which, over short time horizons, is about 75 times more powerful than carbon dioxide — and quite a lot of befuddlement among plant scientists. If it were true, it would have significant implications for the way that people model methane production, and the levels of production that one might predict in a warming world. The debate rumbled on last year (another news report, this time by my colleague Quirin).

The new work that Tom Dueck and colleagues have published in New Phytologist (paper), though , finds no methane emissions from plants at all.

Obviously, not necessarily the last word. As Mike Hopkin reports:

Both groups have criticized the other’s choice of experimental method. Dueck says that Keppler’s group kept plants in sealed plastic containers instead of flow chambers, and exposed them to sources of stress such as bright sunlight and high temperature, which could have produced methane as an artefact. Keppler retorts that the use of ¹³C is an artificial piece of chemical trickery with unknown effects on plant metabolism, and also argues that methane production can vary by up to three orders of magnitude between species.

Keppler says other teams will be publishing results that back him up on the methane; but Mike reports that at least one other team is siding strongly with Dueck.

What Mike doesn’t mention, because an evil news editor (me) wouldn’t give him the space, is that various people in the community have pointed to an interesting contrast between the way plant scientists responded to the discovery of isoprene emissions and the Keppler work. With isoprene people said oh that’s interesting, replicated, and got on with it. This work has had a far frostier welcome.

On isoprene, this is as good a place as any to mention an interesting perspective by Manuel Lerdau in Science a few weeks ago on a possible isoprene-ozone positive feedback (paper). Isoprene within leaves protects the plants that produce it against ozone. But when isoprene gets out into the air, as it will, it can react with nitrogen oxides to make ozone. Only some species produce isoprene, and so these isoprene-producing plants both protect themselves against ozone and, in Nox-rich environments, increase the ozone stress on their non-isoprene-producing neighbours.

If this effect is real, it might have significant effects on forest composition over the next century.

One last thing to note on the Keppler story: it led to Carl Zimmer saying something nice about us, and that is always a good thing. As of course is Carl.

This post cross-posted to Climate Feedback;if you want to comment head over there.