I hear from some of my friends, family, and other people whose opinion I generally respect that the Earth's climate is either not changing or that climate change is part of the Earth's natural climate variability. (Not the same person, obviously. You can't have it both ways.)
Before I can convince them that they're mistaken, I want help understanding why I do believe in anthropogenic climate change.
It seems to me that the long time scales on which the climate operates makes the concept of human-caused climate change unintuitive. We should, therefore, require a preponderance of evidence to believe such a claim.
Here are the reasons I believe the climate is changing and the most rational objections I could think of to each of these:
R1) I have read the IPCC report on climate change and some of the primary scientific publications and find them very compelling.
O1) I am college educated, but not a climate scientist or statistician. I am not qualified to judge whether or not the measurements were taken correctly, the analysis methods are sound, or if the conclusions drawn from the analysis are reasonable.
R2) I understand there is a general scientific consensus that the climate is changing due to human activity.
O2) I don't actually know any climate scientists. So my information here is entirely 2nd hand at best.
R3) I read/hear in the news interviews with climate scientists who say the climate is changing.
O3) A handful of climate scientists does not a consensus make.
R4) I read/hear in the news about the consensus of climate scientists from reputable journalists who do know climate scientists and have interviewed and surveyed many of them.
O4) This is selection bias from the types of news programs I choose to listen to. Other news programs interview climate scientists and other 'experts' who say there is not a consensus.
R5) I see evidence of climate warming myself (glaciers retreating, longer summers, milder winters)
O5) My own observation are all anecdotal evidence and could be due to natural variability in the local climate.
Please help me to understand why it is reasonable for a lay person to believe the climate is changing.
Edit: I am hoping that one of the following is true:
- One of my objections is inherently irrational.
- There is a reason that I have not listed that does not have a rational objection.
It seems to me that if all reasons for a lay person to believe in climate change have a rational objection then it follows that it is reasonable for that person to deny climate change.