Last month's U.N. climate talks in Egypt followed a now-familiar pattern: dire warnings about the need for action leading up to the event, followed by small breakthroughs in some areas and stasis in others.

But 25 years ago this coming Sunday, the situation couldn’t have been more different. Nations were celebrating the signing of the Kyoto Protocol, the first international treaty on tackling global warming, even if criticism of the scope and ambition of the agreement was quick to emerge.

It was not just the outcome that differed at COP3 in 1997, with the scale of the talks and the philosophy underpinning them having evolved significantly in the years since.