There's a bit more news about the Vahrenholt story that has been translated into English on the GWPF site. It looks like Vahrenholt's main motivation for being an AGW sceptic is to protect the renewable energy industry from a possible spectacular collapse caused by it being too strongly associated with AGW.
"I am a renewable energy man. With 1.2 billion Euros, RWE Innogy is the largest German investor in renewable energy in Europe. My biggest concern is that if it hasn’t become warmer by 2015, but perhaps even colder, people will say: "Tell me, why did you create such a panic?" And then public acceptance for the energy transition and for renewable energy will vanish."
I thought I'd check how big the worldwide renewable energy industry is. I knew that it was a lot bigger and older than its popular image of being an 'infant industry', not much more than a 'cottage industry', that is used as the justification for the subsidies it receives.
According to Jo Nova, it is actually even bigger than I thought it was, apparently $243 billion was 'invested' in the industry worldwide in 2010.
In fact you could describe it as an 'industrial complex' at that size. But unlike previous industrial complexes it seems to be exempt from having to produce products that a reasonable person might regard as being 'fit for purpose'. Sometimes you see Greenies and Green leaning politicians claim that all that is needed is to implement an equivalent of the Manhattan Project for renewable energy and the whole world would soon be running mainly on renewable energy. The cost of the Manhattan Project was actually $25.8 billion (inflation adjusted figure from Wikipedia), so that would mean the current amount of money being thrown at renewable energy per year is nearly ten times the cost of the Manhattan Project, with much less to show for it.
I can see what Vahrenholt is worried about. He seems a bit more realistic than the usual mixture of dreamers and Arthur Daley-type conmen that seem to infest the renewable energy industry. But if you took away AGW (ignoring the issue of whether renewable energy really does save that much CO2 after you take account of the need for back-up power), there isn't really anything left to keep the industry at its current bloated size. The previous main driving argument for renewable energy before AGW was peak oil, but that has been out of the political mainstream for 25 years and might not get back in for several more decades. Energy security isn't a plausible argument for renewable energy due to the intermittency.