Science is actually admirably egalitarian. That's not one of the things I think is wrong with it. The heavily politicized branches might not be egalitarian; I have no experience with them. But in general, you don't need to be a member of any professional organizations or have any other credentials to submit your work to journals and conferences (which is how we transact our business.) Many journals employ double-blind reviewing, in which case even unintentional discrimination based on credentials is unlikely or impossible.
Nevertheless, scientists might often give the impression of not wanting to let amateurs into the 'club'. Why is this? It is simply an issue of bandwidth. Think about this: for each amateur, like the author, who had something to contribute, how many do you think thought they had something to contribute but were mistaken? If you guessed a hundred thousand you'd be in the right ballpark. I've seen it in many different areas.
For example, the number of people trying to submit "proofs" of P != NP, (or worse, P = NP) is just ridiculous. Some are well-intentioned although ignorant, and others are just cranks. Some fields of research attract more amateur claims than others, but whichever field you look at, the amateurs greatly outnumber scientists, and the vast majority of them are mistaken.
So what do we do? We use a simple filter. If you speak our language, we'll listen to you. This is what appears to the lay public as anti-amateur. But it's not, really. All you have to do is to learn some simple definitions and terminology set forth in a straightforward way in previous papers, to prove that you've done your homework. Then write up what you have to say and we'll be happy to give it a read. Sure, like every heuristic, it's not perfect; sometimes there are false negatives. But there really isn't an alternative. Without a filter, all we'd ever be doing is debunking crackpot theories.
I acknowledge that much of this probably doesn't apply to climate change "science," which is a special case. But there's been a lot of criticism of science in general, and I wanted to set the record straight. It's important to distinguish between what's really broken and what appears broken, otherwise we risk throwing the baby out with the bathwater.