Quack quack quack

Sitting in my office I crane my neck round every few minutes to stare at the 3 darts lodged in the treble twenty. I placed them there not (as more cynical observers might postulate) with my nose a few inches from the bully but from the official distance of 7ft 9¼in (that's 2.369m metric lovers). This may give you the impression that I'm good at darts but the fact that I felt the need to leave them there to admire since their last flight last night should reassure you that this happens infrequently enough to be worthy of extended observation.

I know almost without doubt that when I take them out to throw again I'll score somewhere in the region of 17. This, I think, is a microcosm of my life. Pleasing peaks followed by laughable troughs. I'm not too good at 'steady eddie' which is a shame. In kinder moments I try to convince myself that this is exactly the pattern of genius - I've written about this a while back - but I suspect all it means is that I have the atttention span of a 7 year old and an inability to stick at stuff. Maybe I'll throw the darts at the end when I've finished writing whatever this turns into.

I was throwing darts as I'd bored myself (never mind everyone else) commenting on Lia Leendertz's fabulous new blog. She's written a particularly interesting post about lawns and their ability to sequester carbon. I get awfully wound up by the idea of carbon sequestering and offsetting, especially if I'm a little hungry. It means I'm slightly more inclined to be boring. And at length.

I have a backlog of quacking-on caused by holding my tongue when I feel the urge to squawk every time anything close to this little hobby horse gets mentioned. It's hard not to sound like a pious arse when you're talking about such things so I resisted quacking on too much on Lia's blog - I have my own blogspace here to be boring rather than sully Lia's. I'd like to stop myself now - as the runner up in the Garden Media Awards Best Blog Award 2010 frequently reminds us 'it's only gardening' and of course he's right. There are so many more important things to get yourself in a palaver about. And usually I do stop myself but not today.

I'd go and have a short walk rather than read this if I was you - I just need to get it out somewhere, and here's that somewhere.

Carbon sequestration and offsetting is at once boring and very interesting. It's also a matter of maths. The idea with offsetting is that you can fly to India and not have to worry about the dreadfully high amount of carbon that results because you pay (for example) for a few trees to be planted in some far flung corner of Lincolnshire. The trees take carbon from the atmosphere and hold it within as they grow and/or convert it into non-polluting substances.

Offsetting worries me for three reasons. It doesn't encourage any change of behaviour (eg flying less). It means that those who can afford to offset can carry on polluting more easily and regularly than those less well off. But most importantly the maths doesn't work. You generate xx carbon flying to India, so you need to plant yy trees to balance this out. But for this to work we need to know both sides of the equation.

It's straightforward enough to obtain a decent approximation of the carbon your share of the flight to India generates. Actually this isn't quite so straightforward - do you include a contribution to the buildings, the infrastructure, including the road network, the vast amount of concrete that makes something like an airport possible? Let's leave that one for now. The other side of the equation is mildly more interesting. The amount of carbon you've generated in your trip to India is then converted to a number of trees which are planted in your name to sequester (or more accurately 'offset') the equivalent carbon your trip generated. This sounds perfectly plausible until some dullard (like me) asks a few simple questions.

How long will the trees be there sequestering carbon?
What happens to the tree when it dies or is cut down?
What species is it?
More importantly, what would've been on the land where you've planted trees over the course of their lifespan? Grassland perhaps, which itself sequesters carbon. The problem, I hope I'm conveying, is that no-one is calculating the net benefit, ie how much carbon would be sequestered by that woodland over and above what would have been sequestered on that land anyway. And no-one calculates that because they can't see into the future (let's say the next 20 years) and predict what might happen on that land. Someone might have planted trees there in a few years simply because grants made it worthwhile, so the net carbon sequestered? None.

It's hard not to see offsetting is a patsy, making the concerned feel better about polluting. I don't mean to knock concerned people. Acting positively when you haven't all got time or inclination to find out or think about all the ins-and-outs is hardly to be ridiculed. But it makes me quietly furious that people make a living exploiting it.

Similarly, we get thrown 'food miles' as the digestible shorthand for doing something about the carbon footprint of our food. Food accounts for around 30% of the average persons carbon footprint. That's quite a startling figure if you ask me. Food miles accounts for around 10% of that (ie 3% of your average carbon footprint) yet it's the single concept relating to food and climate change that people attach to. The concept is simple and understandable: the further we drive food from where it's grown to where it's sold, the more carbon we produce. The imagery is perfect: cars produce carbon, carbon produces climate change, simple. Simpler than telling people the whole story - that it's how it's grown that accounts for a very much larger proportion of carbon.

Growing food is the simplest of beautiful things. Green plants turn sunlight into food with the addition of just a few bits and bobs from the soil. With a tiny amount of sensible soil management, this idle process would keep us going indefinitely. Not fast enough for us though. We have hurried the endless 'current' sunlight energy along with 'old' energy in the form of fossil fuels.

Nitrogen is vital for healthy plant growth and you'll find it in most virgin soils. Most non-organic farms grow food (including grass) using man-made nitrogen fertilisers. I think I've mentioned before that my favourite/least favourite recipe is for 1 tonne of nitrogen fertiliser. You will need:

- 1 tonne of oil
- 108 tonnes of water

and as well as your tonne of nitrogen fertiliser you will produce 7 tonnes of CO2 equivalent GHGs int he process. And as it breaks down nitrogen fertiliser releases nitrous oxide, a greenhouse gas 310 times more powerful than carbon dioxide.

Only around 5% of the UK farmland is registered organic, meaning that 95% of our food relies on this recipe, ie it is dependent on a resource we know to be running out: our food supply = our oil supply.

Phosphate is another key limiting factor to crop growth, vital to all life. We import 206,000 tonnes of it a year, almost all coming from 4 North African countries. Phosphate is a finite mine-able resource and most estimates suggest that at current levels of use we have perhaps 30 years of supplies left. Keeping use at current levels is unlikely as the emerging nations, predominantly China and India, are using it at ever-increasing rates, causing prices to increase by 700% in second half of last year alone.

There is a natural alternative to man-made nitrogen and phosphate - using green manures, appropriate rotations and animal manures: the sort of practices carried out by most organic farmers. Which is why eating organic food rather than non-organic reduces your carbon footprint by around 12% - four times more than if you wipe out just the food miles. But stick the two together....local organic food and the gains stack up and compound.

Water illustrates this well I think. Climate change is changing how we receive our water supplies. The south and east of England have many of the best soils for agriculture. It is predicted that as a result of climate change by 2080 this region is likely to have half its current rainfall and that it will get it in sharper events - think of it like a weekly bath rather than a daily shower. This poses huge problems both for retaining the water for using between rains events and mitigating the impacts of such volumes of water falling. Globally the picture is even more scary.

70% of world’s potable water goes to agriculture. Wow. We think of it as a free, self refilling resource so we waste it. Or at the very least afford it little respect. Every tonne of grain produced in the US uses around 1000 tonnes of potable water to grow to harvest. Climate change makes this way of growing hugely vulnerable. Most of the grain goes to feeding animals, which we then eat. A Dutch university has calculated that the typical beefburger ‘contains’ 2400 litres of embedded water when you take account of the grain grown to feed the cow, the water and care, and the processing involved in making the burger.

This concept of embedded water or virtual water is something we'll be hearing more and more about as climate change becomes increasingly apparent in our lives. Embedded or virtual water reflects the amount of water used to deliver the product to us. And it's not just about meat. We import 12% of our fruit and veg from Africa, a continent not famous for over-production of food. It's a hot continent and water is a scarce resource. Every year we import 189million m3 of virtual water in green beans alone. So everytime we buy Kenyan green beans we are importing water and in effect exporting drought. Small, repeated actions - it's where almost all the damage is done. It's what makes the supermarkets dominate our food supply - all of us toddling off to spend our £50s every few days.

Perversely, this makes me quietly optimistic, and I'll get on to why in a mo.

Back to Lia's post. Lawns sequestering carbon. Soil is comprised of anything up to 58% carbon which can be released due to over-tillage and not putting it back naturally through green manures and/or animal manures. Rising temperatures speed this up. Two years ago mismanagement of the UKs soils reached such a level that our soils began releasing more carbon than they were locking up. Put simply, our soils are contributing to climate change. They are releasing 13m tonnes of carbon-dioxide equivalent greenhouse gases a year, almost matching the 14m tonnes emittted from rest of agriculture. Globally the picture is no different - according to the UN 2 billion hectares of land have been affected by human-induced soil degradation. It also predicts that half the world’s arable land will be ‘unusable’ by 2050.

The scale of the problem is huge and lawns seem insignificant but I don't think they are. It's not what they are so much as what they mean. If me, my neighbours and everybody else in the village perceives that green square as a place where at least for a few square yards some good is being quietly achieved, some contribution to addressing the march of climate change, then where's the harm?

Which is where my comment on Lia's blog comes in.

There is no harm in planting trees or recognising your lawn as a carbon repository but I'm greedy and I felt like shouting as much as I could in the hope that people wouldn't just enjoy their lawn in its sequestering loveliness but go beyond the first step and make the most of it. Yes, it grows therefore it sequesters. This is good in itself, but if you feed it, water it and hit the moss and weeds with chemicals you're lawn account is still hugely in the carbon negative - still causing climate change. Avoid all those and your lawn becomes a small contribution to dealing with climate change.

It's the same with growing even a small amount of your own food. It's a small contribution but an ongoing one. Like wandering to the supermarket to spend your money every week, it's a powerful cumulative step, but in the opposite direction. More importantly it's a small change of mindset we won't get anywhere without one of those.

All of this is remarkably dull when someone's telling you about it or, more particularly, when someone's telling you not to do what you're doing. I'm not meaning to tell anyone not to do anything, other than to play more darts. I just like the maths to be more than just the answer. I like to see the workings. Then you can choose what you like.

I didn't eat meat for 15 or more years and started again around 6 years ago. I'd stopped eating meat in an attempt to do some 'good' and I didn't feel I was anymore. My wrestling match with my conscience was the subject of the first rather clumsy piece I had published. Somehow this relates to this post but I'm hungry and boring myself good n proper now and I should be writing the book and a piece for the English Garden about growing vines in England or polishing shoes or something.

Apologies. Enough dullness. I promise to get back to apricots, killing plants and half naked americans later today.

Nearly forgot. 66, quite respectable really. 5, treble 20, 1

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