Science is a tool. Anthropogenic warming isn't proven, there is much debate about it, and fine lines and shades of opinions between scientists. This wouldn't be the case if it were a strictly scientific phenomena obvious to all. Moreover, the UN isn't the end-all of what the science is. The UN is a political body.
This is a matter of rhetoric, like I said before "analyzed," which you explained well what we all know about science.
That's because textbooks and teachers are teaching politics for science and telling students what to think instead of how to think; this applies to science as well. We don't leave our logic behind when we approach scientific problems.
Of course it can be wrong. Scientists thought the sun revolved around the earth at one time, and it worked for them, but it was false, and it certainly wasn't science, even though it was the best "science" they were capable of at the time of their sophistication. And even when Galilee and Kepler showed a better way, they didn't want to believe it; they had their science.