Why is Donald Trump discussing climate change with Al Gore?

Mr Gore had and 'extremely interesting conversation' with the president-elect, he told reporters at Trump Tower

Anyone who had Donald Trump sitting down with former Vice-President Al Gore among their post-election predictions, please raise your hand.

The meeting may not be the strangest thing that has come out of the Trump transition process. (That honour has to go to the Naked Cowboy's appearance in a Trump Tower elevator last week.)

It is, however, an unusual development.

Ivanka Trump appears serious about taking on climate change as one of her "signature issues" - and anyone who has her ear also has a direct line to her father.

Mr Gore assuredly made his best case for continuing Barack Obama's efforts to address climate change. But will it make a difference?

Mr Gore campaigned for Hillary Clinton, the wife of his former boss, Bill Clinton

Mr Trump has been stocking his administration with conservative ideologues, and many of the possible names for his environmental posts are sceptical of current policy.

If Ms Trump pushes the issue and Mr Gore continues his "extremely interesting conversation" with the president, however, this could become a test of how willing President Trump is to cross party orthodoxy.

A free-agent president - beholden to neither party and willing to strike deals according to his own fancy - may be exactly what his voters wanted and what Washington insiders fear.