Most of us can't.
Oh yes, we can sometimes see with our own eyes some short term extreme weather events in our own local community.
The databases don't lie : its global warming
But ultimately we rely upon the public databases of thousands of observers all over the world and going back 50 years or longer which clearly show the overall global trend, as the reason we believe in global warming.
However when the global impact of extreme weather events all over the world (droughts AND floods) affect the food prices at our local supermarket, we can definitely see and experience global warming as manifest in rising food prices.
My advice to the libertarian think tank bureaucrats - every last one a man ( its the law) :
Continue to deny climate change at your peril to your necks.
(Cue: roll 'em tumbrils !)
Ignoring rising food prices kills more males than drinking or driving : angry housewife alert !
I was door-to-door campaigning in the UK (Wandsworth) in the early Spring of 1970.
I heard lots and lots and lots of housewives, all strong Labor supporters, moaning about rising food prices.
But I totally failed to read the signals correctly.
I was a male - and I wasn't alone in my failure.
A few months later, in June , those same Labor housewives rebelled - failed to vote or voted Tory.
Wilson's 100% certain re-election prospects were instantly deader than dead.
If only he had listened to his wife, instead of the think tankers of his day......