Michael McCarthy: Hello green concrete, goodbye wildlife

The argument against allowing genetically modified crops to be grown commercially in Britain can be summed up in two words: green concrete.

It means a landscape in which fields have a crop growing in them but nothing else. No wild plants or flowers of any sort, no butterflies or moths, no smaller insects on which birds and their chicks can feed, and so no birds. Green concrete means a countryside that still may be called the countryside, and may still appear green, but apart from the crop, it will be entirely sterile and lifeless.

That is what would happen if the GM crops previously proposed, including maize, beet and oilseed rape, were allowed to be grown on a commercial scale. For they were all genetically engineered to be able to survive the application of increasingly powerful weedkillers, known as "broad spectrum" herbicides, which would kill everything else in the field.

The best known of these chemicals is glyphosate, made by Monsanto under the trade name Roundup. Why is it called Roundup? Because nothing escapes.

In some countries, losing farmland wildlife might not matter so much. In the US, for example, people do not go to the grain prairies of Kansas to see flowers and birds; American agricultural areas are for agriculture. If you want to see wildlife you go to a wilderness area. The US is so big that there are plenty of these, some of them the size of Wales.

But Britain is different. It is a relatively small nation with an intimate, patchwork countryside and, if we want our wildlife to survive, much of it must survive on farms. Yet our farmland wildlife, especially birds and wild flowers, has already been given a catastrophic battering by the intensification of agriculture that has taken place in recent decades.

Who sees a cornfield dotted with red poppies now? How many people hear skylarks? Declines in farmland birds are incredible. Since the 1970s, tree sparrows have declined by 93 per cent, corn buntings by 89 per cent, grey partridges by 88 per cent, turtle doves by 83 per cent and so the list runs on.

This has happened just with conventional weedkillers and pesticides, which do allow some fauna to survive. The introduction of broad-spectrum chemicals, which GM technology would allow, would be a further and fatal ratcheting-up of the intensification process for farming. Nothing would be left. The Government demonstrated this with its farm-scale evaluations of GM crops from 1998 to 2003. They proved wildlife was damaged far more by the GM process than by conventional methods.

Of course, there are many other crop modifications possible besides herbicide tolerance. In years to come, as climate change takes hold, we may need crops engineered to be drought-tolerant or salt-tolerant. They could be real life-savers – but they are not on offer yet.

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