Half term found me in the garden with the kids and a huge pile of trimmings from a totally overgrown cypress hedge that we had taken down in the spring.
The trunks had gone to the woodshed to dry and the branches were due for shredding for mulch.
However, the shredder never arrived, and due to certain pressures, we moved the branches to the bonfire site.
There, they presented a magnificent pile amounting to approximately a tonne of timber. Casting my green conscience to one side, I gave into my son Ralph's enthusiasm for a monster fire, but waited until it was a classic wet day in order to maximise the value and minimise the risk.
It was truly memorable. The whole family managed to be smoked, soaked and roasted simultaneously. The following morning, the resulting pile of ash constituted no more than a 100 kilos. It went straight on the raspberry patch.
But my conscience was sorely tried. Here we are in the age of global warming, where Sir Crispin Tickell commands the front page of a weekend edition of the Financial Times dedicated to the issue, and here I am exacerbating it (and its not the first time). While the raspberries were enjoying the potash, I set about calculating how much damage I had done.
Cellulose in the tinder-dry timber that constituted the bulk of the tonne, had a specific weight of 162 (C 6H10 O5 = 72 + 10 + 80) and the carbon dioxide produced in the fire has a specific weight of 44 (CO 2=12+16+16). I had just released one and a half tonnes of carbon dioxide.
Seeking to understand what this meant I decided to compare this emission with that of the average family saloon with a fuel consumption of 30 mpg.
These have emission rates of 230 grams of carbon dioxide per kilometre. My bonfire, in terms of emissions, was equivalent to having driven 6,000 kilometres.
Of course, not many of us have the opportunity to be pyromaniacs, or encourage their children to be likewise, but few, if any, of us are carbon-neutral.
The debate I had with myself illustrated just how much is needed to balance our consumption-driven emissions, and how near to impossible it will be for the world's governments to obtain life insurance by stalling global warming when they meet again next week at the Hague.
Reversing my calculations, I discovered just how frightening the situation is. The 20,000km we drive each year can only be absorbed by growing the equivalent of 3.3 tonnes of 'dry' timber a year and we can multiply this by at least four when adding in running the house, foreign holidays and general consumption.
To be carbon neutral we would need to have at least a hectare of fast growing timber dedicated to the family and we would not be allowed to burn any of it.
First day back after the half term, I met with the life insurance man. 'Do you smoke?' he asked. 'No, ' was my guilty response, and its still raining.
Mark Whitby is a senior partner at Whitby Bird & Partners