It's truly possible that all the people studying it are wrong, that it's a coincidence that this temperature increase is happening right as we starting adding a

It's truly possible that all the people studying it are wrong, that it's a coincidence that this temperature increase is happening right as we starting adding a whole bunch of stuff into the atmosphere that can be experimentally demonstrated to heat up the atmosphere, that some natural effect we aren't aware of is causing the sudden shift. But it seems unlikely enough that we shouldn't bet the planet on it. As far as we know through observation and experimentation, we have created this mess, and until we get strong evidence that says otherwise we should keep working under that assumption.