How much CO2 emission to grow 1kg of Tomatoes in the UK?

I have taken to attending lectures in Cambridge Universities Sustainable Development Series. Tonight's was about carbon footprints. I learned a few interesting points from Adisa, the prof from Manchester University giving the talk:

- 1kg of Tomatoes grown in the UK causes 9kg of CO2 emission to grow them; the same tomatoes grown in The Netherlands uses 4kg of CO2 (waste heat and CO2 from Power Stations in The Netherlands is pumped into greenhouses there to grow tomatoes) and the same in Spain uses less than 1kg (they use the sun!);

- short haul flights cause 3 times more CO2 emmissions per mile than long haul flights (the simple message here is to use the train);

Well there were lots of interesting points, these ones stood out.