The problem i have with this mentality is it disregards known science. While known science isn't perfect, and yes, we might be all proven wrong in 20 years. There is more evidence behind the current sciences to give us reasonable assumptions.
Science isn't just some guy in a lab saying "I believe it this way, therefore its this way". Science is something that has a few core tenants.
Science must be observable.
Science must be provable.
Science must be repeatable.
What that means si that for science to make a claim, such as global warming, They wil lhave had to conduct studies, with objective measurement. real numbers obtainable from objective sources. in the case of Global Warming, there is scientific evidence through measurement that average temperatures around the world have in fact increased. This is a fact.
It must be provable. Meaning that you have to be able to show these findings to others. You have to have the concrete evidence to back this up. you can't just say somethign and it taken as fact.
It must be repeatable. This is one of the key things. A scientific study doesn't automatically prove something. If you cannot repeat that study with the same result, across time and from various sources, it's not a good study. That means, in the case of global warming. Hundreds of different scientists from hundreds of countries of different nationalities, religions and faiths all do the same studies, they will come to the same results.
This is the case for Global warming. All the studies have been repeated for decades to form objective numbers. And all those numbers are showing is that the average temperatures and albedos in the world have increased by measurable amounts in the time since those studies started.
These are facts. you can choose to ignore those facts, but ignoring facts doesn't change that those facts still exist.
where humanity hasn't really proven yet(and we're getting closer) is the cause of this rise in global temperatures. Correlation and science studies (all done to uphold the tenents of science) have shown that it is likely (though not guaranteed or proven as fact yet) that it is our impact.
as to the world being a better place if its warmer? perhaps. the earth has survived other swings in temperatures, from extreme cold to extreme warmth. The question is, how will HUmanity handle the swings? There's a problem with the warmer temperatures causing ice caps to melt. What happens when land masses become smaller from raising water levels? what happens if the global albedo becomes to great? Will the greenhouse effect run rampant? we don't have these answers, but I would like humanity to try and avoid putting ourselves into a situation where we have to discover them.
ignoring the science behind this all, and claiming you don't believe it, isn't like religion. it doesn't cease to exist just because you stop believing in it. You can choose not to believe in global warming. Guess what, its still going to exist with or without you believing it.
And back to your point that science has been proven wrong. Absolutely. Thats the point of science. Science doesn't exist to prove itself right. Science itself is actually the practice at disproving theory. The goal of science is to take a theory, and attack it with the entire weight of objectivity to disprove it. Those theories that hold up to this barrage of attack, are theories that tend to be more likely to be true, or at least until they're proven wrong. Those that can't be proven wrong (gravity for example) are considered laws.
