Ultimately, Mr. Ransom, this is a discussion that should be driven by evidence, not headlines, not Al Gore, not opinion pieces.
One place to begin NOAAs National Climate Data Center.
There are many measures that come from many different resources. Land surface temperatures, Ocean heat content, Arctic Ice extent, etc. You should take a few minutes to explore.
Can these data be dismissed? They are derived from many different instrument records, many different researchers, over many years. There is variability and noise but the overall trends are clear.