One of the problems with solar panels is that they use large amounts of energy to make them, so their EROEI is low and only happens towards the end of their practical life. This can be improved by using renewable energy to make the panels, but that ups the price.
As for CO2 emissions a degree or two is neither here nor there, it will not profoundly change the Northern hemisphere and end our civilization, but a 12degC drop is a life changer and overdue.

A major problem with the drive for renewables is the cost which is driving high energy using industries to the US with their cheap gas prices. One of the reasons for the 2009 depression was energy prices, now fracking is providing cheap oil and gas, the US economy is growing well. The UK is doing okay, while the rest of the EU stagnates under the triple whammy of the Euro, high energy prices and anti-industry regulation.
However, I'm all for try new ideas as this is what drives civilization and society forward. Without it, we would still be living in caves, wearing bear skins, riding horses and using leeches when ill.
