- Sep 2017
"Climate change" and "global warming" have both been used for many decades and both continue to be used, to express different aspects of the phenomenon. "Global warming" refers to the overall trend of the planet heating up, mostly as a result of human activities adding a large amount of greenhouse gases to the atmosphere. "Climate change" refers to the various complex impacts that warming is having. If the globe warms 2 degrees Celsius on average, that doesn't mean the impact will be that every point on Earth will be exactly 2 degrees warmer and otherwise things will go on as normal. It means there will be warmer places and cooler places, glacial melting, changes in the normal shape of ocean currents, alterations in weather patterns, sea level rises, and so on. That's climate change.
As for the comparison to diet, this emphasizes the need for lay people to focus not on individual studies, but rather on the big-picture meta analyses. That's where people tend to go wrong with understanding diet -- the news media will grab onto an isolated study and hype it -- often where the study is based on very limited and narrow data. For example, researchers will publish a study that says that among a group of 200 middle-aged Norwegian nurses, those who reported eating more yogurt had lower rates of colon cancer. All of a sudden, the media will be hyping yogurt as a cure for cancer. Then a few years later a new study will come out that finds that in a study of 300 undergraduates, where half the group was assigned to eat a quarter of yogurt per day for three months, the ones who did so gained an average of 3 pounds relative to the control group. Now the media hypes it as saying yogurt causes obesity. For those who jump from one half-understood study to another, with a lay-person's understanding and the media hype in their ear, it can seem like scientists don't have a clue what they're talking about. But if, instead, you take a big-picture view of meta-analyses of large groups of studies, and listen only to those findings that wind up endorsed by the large portion of experts for long periods of time, you get a much clearer view. That kind of thing would tell you that eating a variety of whole foods in moderation, with regular exercise, will make you healthier.
That's what we're talking about with climate change -- not about whether or not one particular study is correct (e.g., will high-alpine areas in Tibet suffer more droughts?) but rather whether to credit the big-picture meta-analyses and the conclusions that have been drawn by the large majority of scientists over the course of decades (e.g., that human greenhouse gas emissions are contributing to a pace of global warming that is unprecedented in millenia).
What the attitude of climate-change denialists is like is the attitude of chain smokers who lacked the will to quit, and so they told themselves that the doctors didn't know what they were talking about when they said cigarettes were unhealthy. I had a grandma like that. She died fairly young partly as a result of her smoking. But, while she was alive, she played all sorts of mental games on herself to excuse her smoking. She pointed out that many decades ago a small portion of doctors had treated smoking as harmless, so why should she believe doctors now that they say the opposite. She pointed out, as you do, the way doctors sometimes change their advice about what foods are good and bad for you, so why should she listen to them about smoking? And when finally the force of the vast majority of experts had been pointing out the perils of smoking consistently and vocally enough for enough decades to get through even to her, she switched to arguing that there was no point in quitting now because the damage was already done. People who lack the will to do what they know is right will bend their minds to the task of telling themselves all sorts of lies to excuse their conduct. Climate change denialists have mastered that form of self deception.