The Spectrum of Scientific Opinion

The Consensus
Disagreement is part of the business of science. Whenever scientists get together they find themselves discussing the latest results and more likely than not they will part ways disagreeing on whether the results are trustworthy, or if they are trustworthy whether they are important, or if important what they imply for existing consensus, and what needs to be done next. On the other hand, there are things scientists agree on, and these opinions are called the consensus. It is valuable to know what the consensus is, but it is also true that consensus is still no more than an opinion, albeit an opinion shared by the great majority of knowledgeable people.

It is incorrect to assume that opinion is unsuited as a basis for action. In the world of finances, people invest money based on opinions about the chances for success. In matters of war and peace, governments invest in military infrastructure and weapon systems based on opinions concerning the attitudes and intentions of other nations. Of course, the opinions of venture capitalists and defense experts will normally be well founded. Entrepreneurs will have access to facts regarding the value of a new product and the competency of the chief executive officer in charge of bringing it to market. Statesmen will know about the state of armament of an adversary and the foreign policy moves. Some opinions are held very strongly. In finances, it would be that the US dollar will not be suddenly worthless. In military affairs, it would be that superior intelligence is just as important as superior weapons if one is to prevail in a conflict.

Likewise, in science there are strongly held opinions. For the topic of climate change they are as follows: Some less strongly held opinions, but still worth taking into account:
Instructors’ Opinions
Some opinions of your instructors (who are working scientists in the field of climate history):