If the global solar industry was looking for ambassadors, it may just have found two – one in the form of former California governor and Hollywood action man Arnold Schwarzenegger, the other in the starkly contrasting figure of leading climate change economist Lord Stern. Both were headline speakers at an international clean-tech conference in Germany last week organised by renewable energy investment bank ThomasLloyd.

The ‘Governator’ gave a typically robust account of his achievements in power. Chief among these was his flagship California Solar Initiative (CSI), which set a goal of seeing solar panels installed on one million Californian rooftops.

It was an inevitable success for Schwarzenegger to point to – a high profile initiative that, whatever your feelings for the former Terminator actor, has brought solar firmly into the mainstream in California.

But Schwarzenegger’s aim in trumpeting the initiative was not purely self-congratulatory, and it served to illustrate a wider point.

While the international community lurches year after year from one frustrating and fruitless round of climate talks to another, Schwarzenegger said that initiatives such as the CSI demonstrate that the world need not to wait for a new international treaty – the almost mythical Kyoto 2 – to begin to take positive action on climate change.

“I hope there’s an international agreement or Kyoto 2; I love sequels,” he quipped. “But there isn’t just one path to a green energy future; there are many roads to take us there. I believe we must move forward at a sub-national level – in the states, the provinces, the cities, private sector, academic, non-profit and ordinary folks. We should be defined by our movement, not by our hesitation.”

His words will no doubt have particular resonance in the US, where the domestic solar industry is waiting with eager anticipation to see what a second term for President Obama will bring on climate change and the advancement of America’s clean-tech industry.

Schwarzenegger pulled few punches in his assessment of the leadership shown by Washington in these spheres, denouncing as “pitiful” the fact that there is no national energy policy in the US. But for Obama he reserved some slightly warmer words – despite the pair’s partisan divisions.

“I’m a Republican, so I’m not here to promote the Democrats,” Schwarzenegger said. “But President Obama has made all the effort he can make to go in the right direction. He’s done a terrific job of protecting the environment, but he needs a dancing partner. It takes two to tango; he can’t be out there on his own.”

This last point was a swipe at Congress, whose “bickering” Schwarzenegger blamed for much of the national inaction in shifting towards low carbon forms for energy. Indeed another of Schwarzenegger’s big themes revolved around the need to remove the environment and clean-tech from the partisan horse trading of national politics.

“I’m an optimist and very hopeful [Congress will agree action on climate change]. There are a lot of smart people in Washington, but it’s just getting over that hump in ideology,” he said.

Political will was a theme explored by another of the Frankfurt conference’s keynote speakers, Lord (Nicholas) Stern, whose 2006 Stern Review is regarded as a seminal work on the economics of climate change.

During the annual Davos jamboree of world leaders two weeks ago, Stern had been quoted saying that his review should have been blunter in spelling out the dangers of climate change, which he said were worse than previously thought. If current trends in global economic development and greenhouse gas emissions continue as predicted, he said the world was heading for a dangerous level of warming that could have untold consequences for humanity.

Stern’s Frankfurt speech returned to this topic, but he tempered his bleak assessment with a more upbeat take on the potential of technologies such as solar maybe – just maybe – to get the world out of the climate hole it seems to be digging for itself.

“I would never have dreamed when we published Stern review in 2006 that the price of solar panels would be less than a dollar a watt,” he said. “It’s an extraordinary change. While the science [of climate change] has become more worrying, the technology has moved very strongly. Looking back to the review we could have been more optimistic about the technology.”

Stern said world leaders had so far showed “a lack of political will” in addressing climate change, to a large extent because they had become distracted by the ongoing economic crisis – or found it a convenient excuse not to act. But he said the success of clean technology now offered that same group the opportunity to kill two birds with one stone: tackle climate change at the same time as stimulating much needed economic growth.

“We have seen economic crisis divert attention in the west, and have seen in poor countries a worry that this change, this different way of doing things, could constrain growth. But if we try to create a horse race between growth on one hand and climate responsibility on the other, climate responsibility will lose,” Stern said.

“But it’s a false race – high carbon growth will kill itself. It isn’t a sensible medium-term option. And the possibilities of discovery in this low carbon way of doing things are tremendous.”

Stern said embracing low carbon growth would amount to nothing less than a new industrial revolution. As such there would be a period of upheaval, but he said this was an inevitable part of the process and that the best of the clean technologies would show resilience and win through.

“If you look back at past waves of technological change, they show two to three decades of investment, discovery and growth. If we get this industrial revolution right that’s what we’ll see here too. Industrial revolutions involve dislocation; they involve industries going down and going up; some will fail, some will succeed. So if someone says there’s this firm making solar that’s collapsed – well, we’re not happy it collapsed, but that’s the name of the game; that’s how industrial revolutions work. Some people bet the wrong way, some discover the right way.”

Despite the underlying gloom in the very different analyses offered by Schwarzenegger and Stern, the unlikely pairing offered a consistent theme: that the rapidly improving technology in clean-tech industries such as solar offers some hope of averting a climate catastrophe. But as both also argued, the extent to which this happens will depend on leadership, at every level.