It is not science in any way shape or form. It is not a controlled experiment. They cannot control any variables. And the variables they want to correlate cannot be proven as causation. Nor can they prove the causation of the causation of those variables. I recently saw a chart correlating the shift of polar north to climate change. And the theory behind the shift of the north pole has to do with the movement of magma deep under the surface. There exists the possibility that, if there is indeed a trend in warming, it may be do to changes under the earth’s crust. I am sure if earth is warming it correlates to many variables they are not looking for such as cosmic rays, solar activity, the apex between ice ages, cloud formation and more.
But we won’t really know the truth about whether earth is warming because, as you said, they manipulate the data callously and with impunity to get the outcome they want. A lot of that has to do with the fact that nobody is giving grants to prove that the earth is not warming. So all the researchers are seeking to prove the grant givers’ theories (most of which is funded by the taxpayers directly or indirectly. And the politics of science in this regard is not limited to climate research). One recent audit of data input found that some “scientist” struck out a datapoint which just happened to be the hottest day of the year in 1919 because, she said, “the person who recorded the data was not scheduled to work on that day”. Nobody disputed that it was the hottest day on record. And nobody disputed the qualifications of the person who entered the record. They just disputed that it was suppose to be his day off - nevermind that there are dozens of reasons why he could have taken that shift (in particular because it WAS the hottest day ever, or because he traded days, or filled in for someone who had to take the day off etc). They actually went back to the employment files from 100 years ago in the effort to find a reason to censor that specific piece of data. That is how far they will go to manipulate the data. It is completely untrustworthy. (And as I’m sure you know they do all kinds of other shenanigans with the data including moving the placement of thermometers to areas that will be hotter (e.g. near airports, on black tar pavement etc)).
Add those up, and I just cannot take climate scammers seriously.