97% was reported by earlier small surveys, but I think the most rigorous and widely reported survey of scientists was Harris Interactive in 2007.

en.wikipedia.org/…/Scientific_consensus_on_climat…

That was followed up in 2010 by a survey of specifically climate scientists, whom hit 97-98%.

The ‘concensus’ has been constantly challenged in conservative media and circles so there have been many such surveys / meta-analyses continuing over the years and it’s been hitting 100% for the last several years. If any idiot ever parrots “science doesn’t work on concensus” my usually response is something like, “no it doesn’t, but when an entire field of scientists have determined a theory to have vast evidence-based backing its considered settled. The only thing that would change that is significant contradictory data being presented, yet instead every year we’re measuring huge volumes of data that confirm the concensus.”