Man at B&Q wrote:

Why? Of course mankind is responsible for CO2, along with many other
emissions. You're making assumptions about the effect of CO2,
specifically that the measured increase is directly responsible for
any warming.
If the increase is not responsible for some warming then you are back to
the assumption that CO2 is not a greenhouse gas (or the deceitful
scientists are making it all up).

It's the magnitude of the some that I question. How much of any
warming is due to man and how much to natural climate change?

That is the $64,000 question.

Both sides seem to have nailed their colours to the mast. On one side we
have the Met Office predictions of a renewed spurt in GW while on the
other the prediction is for a period of GC. The proof of the pudding
will be in the eating. If the Met Office's predictions prove on the mark
and there is no evidence of increased radiation from the Sun then
their case may well have been proved beyond reasonable doubt. If on the
other hand there is a significant shortfall without something like a
major volcanic eruption to cool things down then the sceptics' case that
the influence of CO2 has been exaggerated will be greatly strengthened.
The deniers will meanwhile go on without a care in the world as their
case is based on faith, not reason.