3. Can you prove it to me?
Sometimes the question and who asks it is more important than the answer.
Scientists, engineers, politicions, lawyers, and lay people all speak their own version of English. And each of these versions may have many sub-versions.
Scientists are more or less impossible. Why? Whenever possible, they want the truth, the plain 100% unvarnished truth with 100% certainty. And the amazing thing is often they can get it.
Why? Three reasons. Embarassment in front of their colleagues. If you build your life's worth on a falshood, the day of your retirement, you might realize you had wasted your life.
Without dragging this out (which I would love to do; maybe later), what does this mean if it is an experiment? 1. One is other scientists doing the same experiment on different equipment; 2. Another is repeating the experiment, over and over. Einstein's theory of relatively has been tested so often the rumor is that god is bored. "Enough already."
Quantum mechanics too. Out to 22 decimel places. No one understands it, but without it we wouldn't have computers. Or a universe for that matter.
Then there is bias, and that is the question of what answer the questioner and answerer each wants. If the whole conversation is legitimate, neither cares. They just want the truth. But if someone doesn't want to believe climate change and we just had a record hurricane (we will avoid what caused the hurricane becuase they happen on their own anyway). So what made it a record hurricane. And lets make it a big question because the hurrican was twice as large as any before in history.
"Are you 100% sure climate change made the storm worse? Can you prove to me?
The answer is "yes," if you can give me exactly the same storm, everything on the planet exactly the same, except the temperature of the ocean for which I have a control knob where I can change only the temperature of the water. And I am going to repeat the experiment 100 times. The scientist might well stake his life on the results. The questioner, if he/she were honest might also. Or, "Well, I don't know. I don't trust these sorts of things. I think you got something up your sleeve," at which time the scientist starts banging his head aginst a steel post holding up the building hoping it will fall on both of them.
Two honest scientists, no problem. Or, an engineer who knows he has to be practical. Or me (same thing). A questoner who doesn't want to believe the answer, no hope.
For a questioner who knows no science but doesn't have anything to bias her or him, then over time, and reading a few articles, the truth will sink in, but not like it is for the scientist. This makes climate change difficult to say the least. If you work for a company that is putting several humdred thousand in your pocket every year you see things through colored glasses.
Well that was pretty long but it is important and even among scientists.
You probably have heard of "peer-reviewed papers." Well the reviewers want to publish good work, but they know their reputation will go to hell if they don't toss out the bad stuff.
The bottom line is that the only people who want to believe global warming are scientists who are studying it. So we have lost 40 years or so that we could have used to limit carbon emission, and now may be too late.
Had it been me? The earth in danger because we are pumping out too much smoke? With even a small chance of danger you get to work.
Another problem with scientists is they cannot make an unequivical statement. For an engineer "I would stake my life on it" becomes for the scientist "it is highly likely" spoken in a flat unemotional tone. I read that James Hansen's speech to congress was like that.