Natural history is becoming one of the highest-rating genres on television and is a truly global commodity.

"The globalisation of television is underway!" the BBC's director- general John Birt declared, just after he had committed the commercial arm of the Corporation, BBC Worldwide Ltd, to an alliance with Discovery Communications Inc. The agreement will create, both parties proudly boast, "the greatest global force in factual broadcasting".

So why wasn't this loyal licence-payer and subject of the realm feeling terribly excited as he witnessed the deal signed ceremoniously last Thursday afternoon in a live satellite link-up between Studio TC3 at Television Centre in West London and an audience in New York?

It wasn't just that as a Beeb-watcher I had become bored hearing about the Discovery deal, which took almost two year of tortuous negotiations to hammer out. Nor was it because I share the reported fears of a few people in the BBC's New York office - reported at some length by the Independent on Sunday some months back - that "Auntie is going swimming with sharks" and is destined to be torn to pieces by Discovery's parent group, TCI, Tele-Communications Inc.

The reason the deal took so long to hammer out is because it involved, in the words of the BBC's production chief Ron Neil, "a lorry-load of legal agreements." To ensure, presumably, that it doesn't get ripped off by a shower of rapacious Yanks.

Not that I would ever talk about the chairman and chief executive of Discovery in such disparaging terms. I have a huge amount of admiration for John Hendricks and what his documentary channel has done to offset the dumbing down of US TV. I was probably the first British journalist to celebrate the achievements of this former university administrator in a mainstream national newspaper. I even flew across to Discovery's corporate headquarters near Washington to interview Mr Hendricks on the eve of an address he gave to the Edinburgh International TV Festival a few years ago.

John Hendricks is a good guy. Dubbed the "conscience of cable TV" by his compatriots, he appears totally genuine when he defines his mission as running "a successful business which also contributes positively to the advance of society."

Discovery does that to an impressive degree by persuading a sizeable segment of channel-zappers in America - and, increasingly, around the world - to switch over from gormless game shows and hyped-up Hollywood movies to savour its stylish documentaries about nature, science and technology, history, human adventure and world exploration. One reason it has always had a close relationship with the BBC is because of its admiration for the expertise and archives that David Attenborough and his colleagues at the corporation's acclaimed Natural History unit in Bristol have accumulated. Natural history is becoming one of the highest-rating genres on television and is a truly global commodity. Animal Planet - "all animals all the time" - is one of two channels the new BBC-Discovery alliance will bring onto the global TV marketplace. The other, People & Arts, will bring together the best of the BBC's documentary output with some of its most prestigious period drama series.

Both of these networks will certainly be a lot better than L!VE TV and Bravo and countless other networks that are presently pumping nothing but audio-visual tripe through multi-channel households.

However, the "greatest global force in factual broadcasting" would be one that helped citizens of the world to get to grips with the greatest forces of globalisation. For, let's get this clear, it isn't only television that is being globalised. The entire planet is being shaken, and its fragile ecology put in peril, by what could be the final and most cataclysmic phase of capitalism. That's not just what Marxists are saying. The chairman of the giant General Electric Corporation in the US has warned apocalyptically: "Ahead of us are Darwinian shakeouts in every major marketplace, with no consolation prizes for the losing companies and nations."

Discovery has done nothing in its short history to prepare people for this coming cataclysm. As its founder candidly admitted to me in an interview last year, his proud creation operates under much the same political constraints as other commercial networks. In John Hendricks' own words: "We know at Discovery it's very difficult to invest in programming that may endanger our relationship with some of our major advertisers ... there is a risk that we do programming that lacks edge." The beauty of the BBC, he argues, is that it isn't so dependent on advertising but, of course, this is a fallacy. BBC Worldwide Ltd is a commercial operation, bound by exactly the same constraints as other global networks.

When I had the temerity to ask at last Thursday's ceremony in TV Centre what the BBC/Discovery global alliance would do to help us get to grips with globalisation, John Birt feigned bemusement and reached for the usual fig-leaf - BBC World, the Corporation's 24-hour news channel. It appears that the man who was once driven by a "mission to explain" when he was in charge of Weekend World, is now proud of serving up an endless diet of news McNuggets and low-budget studio discussion programmes chaired by the usual bland establishment types who have always hogged the BBC's news and current affairs output. This is sad, for, as the German sociologist Ulrich Beck argues in a stimulating and uplifting essay in this week's New Statesman: "Economic globalisation is not just scary, but presents an historic opportunity to create a sense of "world citizenship that places globality at the heart of political imagination, action and organisation."

The BBC could, and should, be helping to force such a global civil consciousness by entering into an alliance with other public service broadcasters around the globe; organisations imbued with the same ethos and faced with the same challenge of adapting to a world in which nation states and national public broadcasters are being eclipsed by trans-national forces.

This alliance must consist not just of popcasters in the English-speaking world, such as Canada's CBC and Australia's ABC. The cosmopolitan democracy that Professor Beck writes about so inspiringly will only be created when all nations speak unto all other nations.

Public broadcasting services of the world unite! You have nothing to lose but your chains of parochialism and political conformism!