Your clarification that the climate scientists were trying to hide the decline of the tree ring data as opposed to hiding the decline of the temperatures isn't very reassuring. If they've used tree rings to reconstruct worldwide climate temperatures as a proxy, and this proxy diverges from observations to the point that they have to "hide the decline", I think there's a definite problem with their science. Doesn't this invalidate the entire climate/temperature reconstruction that includes these tree rings? Why would they have to use a statistical method or 'trick' to make the data fit the theory? That doesn't sound like something a scientist interested in discovering the truth should have to do.
Unfortunately, this isn't about pure science, as there is plenty of money and politics involved on both sides of the argument. There are reputations, careers, and honor at stake too. The email leaks revealed the science isn't as clear cut as they would have us believe. They also revealed that there are some climate scientists who are quite unwilling to even consider any evidence that contradicts their own beliefs. It's especially concerning when they advocate hiding or even deleting info, data and communications in order to avoid having to respond to FOI requests. Why would they need to do this?