I've just finished making a couple of editions of "Home Planet" for BBC Radio 4 www.bbc.co.uk/radio4/homeplanet, hard work but fun. It's an environmental programme that has a rotating panel of experts answering listeners’ questions on a whole variety of different questions. Anything from why the tides vary in height to the detailed ins and outs of climate change. I'm also peripherally involved in a project called Science Shops Wales www.scienceshopswales.org.uk, one arm of which is dealing with sustainability and low environmental impact. On top of that I've been following green issues for a couple of decades, grow as much of my own veg as possible and would compost the dog if he sat still for too long.

Over that time I've been waiting for the clear messages to come shining through the research, discussion and misinformation that clouds the debate. There are some things that are clear, use less energy, travel less, waste fewer resources. But try getting into the detail and things rapidly get extremely complicated. My car is an 8 year old diesel, I have diesel because it has a better mileage, produces less CO2 per mile and can run more easily on a variety of biofuels. But it gives out more particulate pollution than petrol engines. It’s also not as efficient as a new model but junking this one for a new car would consume vast quantities of resources. In fact, diesel versus petrol is one of the ongoing debates on "Home Planet".  And there's no easy answer.

OK, then, what about food miles. Buy local sure, but what about the exotics we've become so fond of? Kenyan flowers have been given a hard time recently but one set of calculations say they consume fewer resources, even when they're flown to the US and UK, than some locally grown offering.

Should you put solar on your roof? Possibly, but solar electricity is still relatively expensive. Solar water heating is probably a better bet but you are likely to reduce your carbon footprint more if you have a well insulated house. But what does well insulated mean and how easy is it to do?

I could go on and on. Every environmentally tinged question rapidly turns into a complex multiple parameter equation. I'm very happy with that type of idea, I spent years in the lab juggling complex research questions, but it does not make for any quick and simple choices about the changes individuals can make.

This is probably the sign of an industry, or movement, or whatever you want to call it in the very early stages of evolution. Once upon a time a car owner needed to understand exactly what was going on under the bonnet and to be able to service their bangers themselves.  But increasingly I think that we have to think simple. We need some sort of simple way of deciding what technology works where and for what. Come on, there are some very clever people out there, can you help make it simpler for the rest of us please?

PS. This was posted after midday...