Is the Nobel peace prize a blessing or a curse? Some of the recipients have been enormously encouraged by the world’s recognition of the cause they have championed; others have sunk without trace.

For some, such as Jimmy Carter, Kofi Annan or Nelson Mandela, the prize has burnished an already solid reputation.

But the award can also lead immediately to greater persecution and isolation: after Aung San Suu Kyi received the Peace Prize in 1991, the Burmese junta were all the more determined to prolong her house arrest. And Shirin Ebadi, the Iranian human rights campaigner, found herself under fresh attack from Iran’s suspicious conservative clergy.

The prize is meant as much to encourage the recipient’s cause as to reward past achievement. At times it does one, but spectacularly fails at the other.

Northern Ireland and the Middle East provide rich examples. The winners from Ulster soon found their political path blocked: David Trimble, joint winner with John Hume in 1998, was more and more estranged from his own suspicious party and eventually outflanked by Ian Paisley. Betty Williams and Mairead Corrigan, the two peace women of Belfast who won in 1976, were soon forgotten when their brave cause failed to gain traction.

The prize for Yassir Arafat, Shimon Peres and Yitzhak Rabin soon turned to ashes for the winners as well as the cause. The Oslo agreements collapsed. Arafat was boxed into a corner, denounced by the Israelis, accused of corruption and ended his days besieged in Ramallah. Rabin was assassinated. And Peres subsequently lost a string of elections, including an earlier attempt to become the Israeli President.

Some causes enjoy brief prominence as a result of the Nobel committee’s decision. Probably the most obscure recent cause was the Guatemalan poor, championed by Rigoberta Menchu Tum, for which she won the prize in 1992. World attention swiftly moved away from her work, while she was subsequently dogged by accusations of making things up in her autobiography.

It did not linger either on the achievement of Wangari Maathai, the Kenyan who spearheaded the movement to plant trees in Africa. She was appointed a Goodwill Ambassador for the Congo Basin Forest Ecosystem.

Some prizes have had a more clearly political intention - and Al Gore’s is among them. The 1973 award to Henry Kissinger and Le Duc Tho was as controversial as it was headline-catching. It clearly was attempting to influence US policy in South East Asia — though it provoked demonstrations against Dr Kissinger across Europe. The award to President Gorbachev in 1990 was a signal to Moscow that the world upheld his policies, however controversial they were among communists in Russia. The award to the Dalai Lama in 1989 infuriated the Chinese. And the award to the campaigners for independence for East Timor in 1996 was calculated to send a strong message to the Indonesian Government.

The Nobel Committee has veered between awarding the prize to great causes and towering figures — Nelson Mandela, who shared his 1993 prize with F.W. de Klerk, is probably the most towering — and highlighting the quieter, more steady achievements of organisations. The 1999 prize for Medecins Sans Frontiers recognised the contribution to peace in the broadest sense made by the selfless work of doctors in conflict zones; the campaign to ban landmines takes a more military definition of peace and brought an award for years of lobbying.

The most recent award to an organisation, the International Atomic Energy Agency in 2005, was also sharply political, however. It was seen in many quarters as a rebuff to President Bush for cutting short the work of the inspectors in Iraq before the launching of the war in 2003. It remains to be seen whether the award to Mr Gore is also taken in America as a partisan prize or whether it will encourage the debate on climate change in America.

One of criticisms that will be levelled at the award is that it is goes far beyond Alfred Nobel’s definition of peace, which was to promote “fraternity between nations” and reduce standing armies. But it is many years since that narrow definition was broadened to include human rights violations, racial oppression, poverty and dictatorship among the threats to peace.

Scientists at the Intergovernmental Panel on Climate Change, which shared the award with Mr Gore, have plausibly outlined the possible link between global warming and large-scale migration, competition for resources and the risk of war.

If this is so, few people have done more to raise awareness than Mr Gore. And, crucially, he has done so in the US, the one country most able to take a lead or make a difference.

The award will certainly be criticised for being a none-too-subtle rebuff to President Bush, a sceptic on the issue.

But if advocacy of a cause judged worthy by the Norwegian Nobel jury is a reason for an award, Mr Gore clearly fits the criteria — however much the prize will raise eyebrows as well as debate.

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