Scientists are sceptical and questioning by their very nature. They love to poke and prod everything to see if it withstands scrutiny. So when scientists agree this is a sign that a question was investigated thoroughly and based on the evidence scientists then have an answer they can agree on.
This makes a scientific consensus the biggest threat to the denial of any scientific fact. Hence you see the “there’s no consensus” mantra on subjects like evolution, GMO safety, and of course global warming and climate change. That’s why studies like Oreskes 2004, Doran 2009, Anderegg 2010, Cook 2013, and Verheggen 2014 are targets for climate science deniers: