You could hardly call Tony Blair an all-round environmentalist; during his decade in office he has had precious little to say on green issues that exercise many people, such as wildlife conservation, marine pollution, or recycling. But on the biggest issue - climate change - he has said plenty.
No one seems to know when or how Mr Blair realised that global warming was a key matter. It certainly wasn't there in the political baggage of the man who took office in 1997.Indeed, on two key green issues early in his premiership, GM foods and nuclear power, Mr Blair was regarded by environmentalists as The Enemy, as he clearly supported both. But when, on 24 October 2000, Mr Blair told a conference in London "If there is one immediate issue that threatens global disaster, it is the changes in our atmosphere," a new note was sounded on the international political stage.
Since that day, his unwavering focus on climate change has made possible two substantial achievements. The first is highlighting the issue; its move to the top of the international agenda has been largely due to his advocacy.
The second achievement has been to spot, and to start to deal with, the biggest weakness in the world community's efforts to combat global warming, hitherto enshrined in the 1997 Kyoto protocol. This is the absence of the Chinese, soon to be the world's biggest emitter of greenhouse gases, and other developing big emitters such as India, Brazil, Mexico and South Africa.
At the July 2005 meeting of the G8 group of rich nations, the leaders of all these countries sat down - at Mr Blair's invitation - and first began to talk about their CO2 emissions, and how their growth might be controlled.
That meeting was the biggest step forward since Kyoto itself, and the dialogue that has followed it is at the heart of the intense efforts to bring about a "Kyoto 2" later this year, which would ideally involve everyone, including the United States. It cannot be denied that Tony Blair was the architect of it, and if the agreement is eventually pulled off, there is no gainsaying that much of the credit would genuinely be his.