Stark warning not to eat tomatoes in November or December

Shoppers buying tomatoes in supermarkets this winter have been issued a warning.

One academic specialising in carbon emissions has issued a list of foods we should all be avoiding in the colder winter months, including fresh , lettuce, asparagus and strawberries sold in supermarkets.

In summer, tomatoes will be grown in Britain and have a much smaller carbon footprint, but in winter, they are flown on planes from hotter countries, or even from heated growhouses, both of which are much worse for the environment.

Because these fruits and vegetables have to be flown across the world on carbon-intensive freight planes out of season, it creates lots of carbon emissions and contribute to

Mike Berners-Lee, author of How Bad Are Bananas?, says that people who want to do something about cutting their carbon emissions should "go seasonal" this Christmas and avoid foods that are flown over.

But foods that have a longer shelf life are usually shipped, not flown, and food shipped by boat has a much, much smaller carbon footprint because they use less fuel and bring huge batches over at a time.

That makes oranges, bananas, and apples safe to eat from a global warming perspective.

Mike says: "Go seasonal, avoiding hot houses and air freight. Local seasonal produce is best of all, but shipping is fine.

"As a guide, if something has a short shelf life and isn't in season where you live, it will probably have had to go to a hothouse or on a plane. In the UK in January, examples are lettuce, asparagus, tomatoes, strawberries and most cut flowers.

"Apples, oranges, and bananas, by contrast, almost always go on boats. Adopting this tip religiously can probably deliver a 10 percent [carbon emissions] saving on a typical UK diet."

Mike also outlines in the book why carbon emissions actually matter.

He adds: "Our species is good at understanding the direct, immediate and visible consequences of our actions.

"We are a lot less smart at grasping the consequences when they are dispersed across billions of people whom we will never meet...Perhaps we need to find it as shocking when we see dispersed suffering inflicted through needless carbon emissions as it would be to see the same suffering inflicted all in one place in front of our eyes by, let's say, a street stabbing."

Of course, some are lucky enough to still have the odd tomato growing by November if they have a greenhouse.

There's little carbon footprint in growing your own tomatoes, unless you're using a heater or electric lights to grow them.

If you still have some late fruiting tomatoes, you can pick the unripened green tomatoes now, and leave them in a bowl on a windowsill.

They will continue to ripen in direct sunlight and be helped along by the warmth in your house.

Alternatively, green tomatoes can be turned into chutney instead and some gardeners swear by their delicious late autumn chutneys using green tomatoes.