Science is inherently open.
That may be the ideal, but it's not at all the reality. There have been plenty of incidents where scientists have been ostracized for the crime of presenting new theories that challenged the status quo.
New theories
should be challenged. Unfortunately, all scientists are humans and all humans can be arseholes; therefore all scientists can be arseholes and instead of challenging new theories, sometimes that translates to deriding the authors of said theories.
Very unscientific, very human.
Scientific model is a completely unnatural approach to problem solving. That's why we're so bad at it and we need to train hard to become better at it. But, at the same time, it's the best way of advancing our knowledge.
That said, whether some presenters of new ideas get challenged or not is, at best, an anecdote about how scientific community doesn't always behave in a rational way. It seems completely irrelevant regarding the argument of science being open or closed process.
Science is open to anyone who is able and willing to make a meaningful contribution. That means getting an education to the level where you
can contribute. There are certain standards for those contributions, but no real "gatekeepers as such", as the term goes.
Whether that contribution ends up being significant on a science-changing level like all the ridiculous amounts of works by Einstein, that's anyone's guess. But that's also the beauty of it - basically, anyone doing the most basic research could stumble upon something that turns out to be important in hindsight...
The reason why science often appears to be "closed" process is that most of it is very specialized. Scientific papers require quite a bit of expertise on the topic to be legible.
Whether a process is open or closed is independent of its complexity. I'm sure climatology is quite complex, but there are numerous experienced and credentialed scientists who have challenged the consensus on global warming. Yet there is substantial political pressure to toe the global warming party line.[/quote]
Most climatologists will not refer to global warming precisely because no one knows what the hell is going to happen. It's usually referred to as global climate change instead because we can actually verify that the climate is changing at a shocking rate. What it's going to cause - well, most climatologists predict it will increase the temperature averages; that's basically a prediction from many simulations run with different parametres but there's no way of really knowing which one (if any) of them is actually right. All they can say is most of the models predict warming (I don't remember the sigma values for the current predictions and I'm too lazy to look up).
It's essentially the same reason why the weather forecast cannot really reliably tell you whether it will rain in grandma's birthday next month so you can choose whether to set up a grill party or stay inside, but instead of a month (or at most a year's prediction in case of birthdays), climate models are expected to project overall weather patterns years or decades into the future, and the smallest discrepancies or hidden variables can change things a lot. But, if grandma's birthday is in the summer, it's more likely to be warm and sunny than if the birthday is in autumn...
So while there's no clear consensus about it, most models and data trends predict comparatively fast increases in average temperatures if situation is unchanged with the greenhouse gas emissions. The critical factor is the
speed of that change - the faster it happens, the worse it will be. That's why the scientific advisors to most governments in the world are telling them it would probably be a good idea to think of some ways to react to the already observed changes before things get a lot worse.
So, regardless of whether or not it's happening, to what magnitude, and how fast - there are political motivations to do something about it, and there are motivations to ignore it and keep doing everything just as before. Those don't really affect science as such, they are just examples of what happens when scientific community hasn't achieved a full consensus on an issue that is
notoriously hard to predict, and there's political pressure to react to it one way or another - it turns out that in most political system there are the Incumbents and the Opposition (as well as subdivisions between them, and in most countries there's more than just two political parties), and the Opposition typically opposes whatever the Incumbents happen to do (though there are exceptions to this rule).
If you look at things over the globe and check where Incumbents have decided that global climate change is a real thing and something needs to be done about it, the Opposition is typically saying that this is all pish, there's no proof, and the government is wasting precious tax money on this nonsense. I expect the opposite is also true in countries where the government has decided not to react on climate change, but I can't really think of many... China, maybe? Possibly many developing countries where spending effort to be more environmental would be a serious detriment to the nation?
Anyway: If you ask most climatologists what their stance on climate change is, the honest ones will tell you they can't know exactly, but the projections of the models tend to scare the crap out of them - and most of them are also alarmed by the rate of change in atmospheric composition and oceanic pH levels; both of these are really big changes in a really short time, and when you do that to an organic system like Earth,
whatever the changes are, they're more likely to be vast and cataclysmic than gradual and beneficial.
Then there are some who present worst case scenarios as facts, and as a response to them there are some who oppose them with the best case scenario models or question the validity of the worst case scenarios. These are all parts of the (more or less) scientific ongoing discourse on the matter.
And then, and then you have the guys with agendas. The "climate skeptics" who make it their business to oppose the idea that the climate is changing to a worse direction (or in a milder case claim that it might change but humans have nothing to do with it so there's nothing to worry about).
Most of these "climate skeptics" tend to have
no actual credentials to evaluate climate science. They are just saying things because they're expected to have an opinion and their opinion generally tends to be influenced by their political and economic standing in the societal hierarchy. There is a paper written about that accessible
here.