The silence from Tony Blair is so long it’s embarrassing. He has just spent 15 minutes enthusing about his new global report about how technology can help the world to combat climate change when the obvious question arose: what has he done to make his own life more sustainable?

Er . . . (long silence) . . . “We’ve got solar panels on our house.” Which one (he has a handful)? “The London one.”

Another long silence, then an aide mentions the offsets: “Ah yes, we offset our travel, too.” More silence: “And we have some home insulation.”

It is an awkward interlude. Blair is about to launch himself onto the world stage in yet another new role: as an evangelist for world-saving green technology.

Tomorrow he will launch Technology for a Low Carbon Future, a report put together with the Climate Group, setting out his arguments. Since it has been months in the making, the lack of prepared answers about his own life is odd.

His recovery, however, is swift. Blair may not be familiar with his own energy needs but for the rest of the world the solution is simple. We should let science into our lives and just go on getting and spending.

“The answer to climate change,” he says solemnly, “is the development of science and technology. Yes, we will get changes in the way we consume but we will be consuming differently, not necessarily less. People are not going to return to the 19th century. The critical thing is to use the technologies we have and to incentivise the development of new ones. That is the only practical way we will make this thing work.”

As statements go, this is breathtaking. For the past few years scientists have been issuing ever gloomier warnings about climate change.Some have even called for a deliberate and sustained global recession as the only way to cut emissions.

Blair, however, is having none of it. He has a new-found faith in science and is determined to spread the word. “The only way we will succeed . . . is if we develop new technology,” he reiterates. “If you say the future is that people won’t travel or won’t use cars, then no, I don’t agree. I think what people are looking for is clean energy ways of doing these things. They are not going to buy a return to the past.”

So far, so clear. But why has Blair stepped into the climate debate? Hasn’t he got enough on his plate, what with resolving the Middle East conflict, writing his memoirs and lobbying for the post of Europe’s first president? And where did this sudden faith in science’s power to solve climate change — shared by few bona fide scientists — come from in the first place?

Part of the answer lies in the timing. Blair’s report comes as the world prepares for December’s United Nations climate talks in Copenhagen, where more than 180 countries will try to agree on cutting greenhouse gas emissions.

The challenges are daunting.

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