Anyone attempting to predict the future is asking for trouble — especially at the cutting edge of science and technology, where the unexpected is the norm. But for the past few years, there has been one forecast that scientific soothsayers have been able to rely on: that controversy will rage over genetically modified (GM) crops.

So to say that agribiotech is now in for a volatile time might seem like an empty prediction. But there are good reasons to believe that the fight over GM crops is coming to a head.

Most European governments, realizing that their people have little enthusiasm for GM food, have been stalling on deciding whether to allow commercial plantings of transgenic crops. But following the introduction of a regulatory framework at the European Union (EU) level, they won't be able to stall for much longer. Decision time is dawning. If European countries say yes, they will face an onslaught from their own public. If they say no, the pro-GM US government will be spoiling for a fight. Already, the United States has fired a warning shot across Europe's bow, lodging a complaint with the World Trade Organization over the EU's failure to open its markets to GM seeds and produce.

In Britain, the government has prepared for decision time by conducting by far the largest-ever trial of GM crops, seeking to gather as much evidence about their impact on biodiversity as possible. Those trials, along with extensive scientific evaluation and public consultation, are now coming to an end. But ultimately, the government's line may be influenced as much by Prime Minister Tony Blair's sagging popularity as by the scientific questions surrounding transgenic agriculture. In the following pages, Nature examines the pending British decision and places it in its wider international context (see page 656).

The outcome in Britain is bound to influence the debate in other countries where similar skirmishes are taking place. Around the world, environmentalists are battling with biotech-industry lobbyists to win over public opinion. In the developing world, the action is poised to intensify, with sub-Saharan Africa emerging as an important new battleground. In other countries, such as China and India, the fight seems to be not so much 'GM or not GM', but rather between home-grown transgenic technologies and imports from agribiotech giants in the United States.

So far there is no clear winner. Our international survey of the extent of commercial cultivation of GM crops reveals a decidedly mixed picture (see interactive map). Only a few countries have wholeheartedly embraced a transgenic future. But the agribiotech industry can point to several key markets where the prospects for GM farming are improving. Brazil, for instance, is the world's second-largest producer of soya beans — and there the tide seems to be turning in favour of GM varieties.

For now, our world map showing the market penetration of transgenic crops remains mostly blank. How quickly it fills up will depend on events and decisions that cannot be avoided for much longer.