There may have been skeptics 20 years ago, but now no one seriously doubts it.
I don't understand how technology people make decisions to deny a problem even if there is no 100% certainty. In my company, even if there is less than a 1% chance of something going wrong, we have to think of ways to mitigate it.
Anthropogenic global warming has been proposed and modeled since the late XVIII century. The window to reasonably doubt it has been closed since at least the 1980s when Exxon put it on paper they knew about it and wanted to suppress awareness about it.