So who can answer Jerry Pournelle's questions about Global Warming?

Sure:

Jacobshavn Glacier Retreating

A bunch of glaciers retreating.

Athabasca glacier retreating.

McCarty Glacier.

Nunavut Glacier

Retreating glaciers in Bhutan (Himalayas)

Franz Josef Glacier

Polar Ice Cap

We can do the above all day. This is happening in almost every case wherever you look in the world.

If this is not the earth getting warmer is there another explanation?