Why don't Donald Trump supporters believe NASA is telling the truth on climate change, which is the result of manmade pollution?

Because it may cause more regulations which would stifle the economy.

NASA lies

nasa said 2016 was the hottest year on record by several hundreths of a degee

then a reporter ask nasa how accurately they can measure global temp and nasa replied to the nearest 1/10th of a degree

nasa doesn't have the abilty to measure global temp to the 1/100ths of a degree

but they claimed it was the hottest year on record bu several 1/100ths of a degree

Because the Bible tells them the Earth is only 6000 years old.

Because the greedy bastard wants to keep making money on dirty and cheap products.

They hate real facts

People want to believe what they want to believe, and they don't want to believe what they don't want to believe. A lot of people would like to believe global warming is the product of liberal alarmists or it's a 'Chinese conspiracy'. So they do! Trump legitimizes people lying to themselves. And, sadly, that's what a lot of politics is about.

Ignoring a problem is easier than changing your lifestyle to prevent it. Just ask any junkie.

Because the Big Oil companies that own their political pundits told them not to. They could not come up with an idea that they know something better than the scientists that study it, unless they were told to think that.

CO2 is not pollution

We spray out greenhouse gases, millions of tons a day or hundreds of billions of tons every year, for enough decades, and yes, we cause a significant impact on the environment.