On 15/09/2020 17:49, Alastair B. McDonald wrote:
On Tuesday, 15 September 2020 at 11:53:06 UTC+1, Spike wrote:

I merely quoted what the BBC said, and asked a question based on what
they didn't say in their news item.

The BBC was just making one point - that CO2 levels are now where they were before the Pleistocene period began 3,000,000 years ago. Then the level dropped below 400 ppm and this ice age began. The ice age consists of glacial periods and interglacial, driven by the Milankovitch. Cycles in the Earth’s orbit. So the climate is not just affected by CO2. It is also affected other things such as solar radiation and water vapour.

Currently we are living in the Holocene interglacial which peaked 6000 years ago.
It comes from the scientific literature, e.g. https://science.sciencemag.org/conte.../6124/1198.ppt Which blog do you get yours from?

Try this http://www.realclimate.org/images//Marcott.png from the same paper

Whenever I see 'HadCrut' I think of Clmategate.

More nonsense. When the temperature drops water vapour decreases and CO2 becomes the main greenhouse gas.

So we should be worried about water vapour rather than CO2. At what
level of water vapour does the crossover take place? How does that
relate to temperature?

At 0C water vapour is insignificant. So over the ice sheets CO2 is the main greenhouse gas. That is why the Arctic is warming three times faster than elsewhere. Gehenna the sea ice melts water vapour will take over and the NH warm even faster!

That makes no logical sense whatsoever. Would you care to explain your
thinking?

Gehenna the sea ice melts water vapour will take over and the NH warm even faster!

That doesn't parse very well either.

--
Spike