Can you name a single respected scientific organization that rejects anthropogenic global warming or the reports from the IPCC?
Surely you see the problem with this question?
Not really. Care to explain?
You have respected scientific journals like "Nature" and "Science" that have published scientific breakthroughs in many fields of science for decades. Are they suddenly wrong on climate change, after even the computer you are using right now is a result of research being published in those and other journals? Is all science just a scam (despite all the things it has done for you)?
You cant say, any group of scientists that doesn't believe in AGW is disreputable and AGW is real because no reputable group of scientists argues that it isn't. Its circular.
Of course this does rely on the assumption that if i told you about a group of scientists and then told you that they are AGW skeptics than you would consider them disreputable because of this fact. But i think that is a pretty safe assumption.