One guy says he guesses that 40% of scientists doubt manmade global warming? From an interview with some random organization?
This is pretty much supported by the extensive polling of Bray and von Storch. The most comprehensive of surveys of Climate scientists available. They polled vetted folks in the field every 2 years for 6 years on a MASSIVE 100+ questions. Since any "poll" with just one or two questions is Bullshit if you're looking for considered consensus.
It's NOT a consensus on the more important technical issues. And upwards of 30% (back about 2 year now) expressed doubt on topics concerning modeling efficacy, confirming changing weather patterns, even the MATURITY of their OWN FIELD..
Look up those surveys. They are eye-opening -- compared to the political rhetoric about silly consensus.
The 98% number has always seemed unlikely.
The 40% doubting manmade global warming from the OP seems like a number pulled out of thin air, though.
I looked up the Bray/von Storch surveys. If you consider any response other than a full 7 to be expressing doubt, than most of the climate scientists have doubt.

If you go with those who answered with a 6 or 7, that bumps the number over 70% who believe in manmade climate change in 2013, closer to 75% in 2016. Far from the 97 or 98% number that gets tossed around, but also quite different from saying 40% of qualified scientists doubt manmade global warming. In fact, the Bray/von Storch surveys seem to indicate that belief among climate scientists in manmade global warming is increasing.
I went to Die Klimazwiebel for information:
Die Klimazwiebel: Fifth Bray – von Storch International Survey of Climate Scientists completed
The survey seems to indicate that climate scientists increasingly believe that man is effecting the climate, but that there is not any sort of overwhelming consensus regarding all the details.