I'm no climatologist. I don't know a lot about how temperature is measured. But your question is based on several assumptions that I think need analysing. 1)

I'm no climatologist. I don't know a lot about how temperature is measured. But your question is based on several assumptions that I think need analysing. 1) What temperatures are we talking about? Surface air? Water? 2) Who's collected it? There's probably dozens of organizations that collect it. I doubt there's one single repository for it all. 3) How was it collected? Are the data comparable? Especially historically. You can't simply ask the weatherman what the temperature was in Antarctica in 1874. 4) Even if you had universally comparable data for the past 150 years, you still have trouble. Temps in urban areas for example skew results because of heat trapping. Those factors need to be accounted for. Science is complicated for the very simple reason that the natural world is complicated. There's no such thing as "pure" data. I trust science industry (for the most part) over time. The over time part is key. There are generational checks and balance in science. Young turks looking to make a name are attacking the holes in theories all the time. If something is faulty, we'll find out...from other scientists. I don't need to trust individual scientists, just the process of science. Which I do.