A lot of “debates” about climate change occur only because of semantic trickery. To win these “debates”, you’ll have to avoid the linguistic gymnastics used by climate change deniers that pull people down into the quicksand. Here are some guidelines:

a) No single event “proves” climate change. Climate change predicts more extreme weather and more frequently. As a result, Harvey is certainly consistent with climate change models, but is not proof. The predictions of climate change models are more unusually strong weather patterns: Katrina (2005), Ike (2008), Irene (2011), Sandy (2012), Harvey (2017). Each of these storms was supposed to occur only once every few hundred years. Clearly the sheer number and intensity of them means they are more common. And that’s what professional scientists predict from global warming models.

b) It’s cold in the winter and it’s hot in the summer. If the temperature is below freezing for a week in the winter or there’s a triple digit heat wave in the summer, that doesn’t mean anything regarding climate change. Never assume that a hot day is proof of anything. That’s similar to a denier saying a cold day is proof against global warming. Both statements are wrong. What does matter is that the average temperature for a season rises over time so in general both winters and summers are warmer and, in general, record breaking highs will begin to outnumber record breaking lows – like is currently happening.

c) Weather is not Climate. Generally speaking, the climate is the average, in both space and time, of the weather. That’s why meteorologists are not the best source for climate change information; climate scientists are. Meteorologists study weather, not climate. Consistently erratic and unusual weather, however, is linked to climate change but it’s much harder to use it for evidence – except in the rearview mirror when compared with other data.

d) The world was in a nice balance before the Industrial Revolution tipped things. Present government websites state the amount of carbon dioxide made by humans is small compared to the carbon dioxide produced naturally. This is true. What the government pages no longer say, however, is that all the carbon dioxide produced naturally was able to be dealt with naturally because given time (like the billions of years the Earth has been here) planetary ecosystems will come into balance. Only in the last 200 years – the Industrial Revolution – has that balance been upset dramatically. Think of this situation as perfectly balanced scales, each with 100 pounds on a side. Now a fly lands on one side. The fly doesn’t weigh all that much, especially compared to 100 pounds. But will the scales tip? Of course they will. Human carbon dioxide is the fly on the scales. The overwhelming majority of professional scientists agree that humans have put things out of balance. The only questions debated are how fast are the scales tipping and is it possible to right them?

e) There are already two obvious examples of humans affecting the environment on a global scale that few debate.  Both involve the ozone layer. Humans caused the depletion of ozone. About 30 years ago, the nations of the world got together and banned the chemicals causing the ozone depletion. That famous polar “hole” in the ozone layer you may remember hearing about is now healing as a result of the ban and should repair itself completely in a few more decades. So humans both caused the depletion and, by changing their actions, allowed nature time to heal it before permanent catastrophic effects rippled through the planet’s ecosystems. Those are the two examples of humans influencing the entire planetary ecosystem.

f) The question “Do you believe in climate change?” is a non sequitur. It’s akin to asking “Do you believe in gravity?” or “Do you believe in electricity?” – and I’m betting no one has ever asked you those! Climate change is a collection of many causal events – and it includes more than looking at weather patterns: massive icebergs shearing off Antarctica and the acidification of the world’s oceans are also predictions of climate change. In a sense, climate change shares a similar characteristic with evolution: it describes a gradual process of many small events giving a large result. It’s therefore not surprising that people can be more willingly ignorant of climate change and evolution unlike gravity and electricity. Walk off a cliff, you’ll know about gravity. Get hit by lightning, you’ll know about electricity. But it’s much harder to witness the “death” of an ecosystem or the “birth” of a species because they take much longer time scales to happen and no single event is responsible for them.

So, do not make the mistake of saying a specific event “proves” climate change. It is correct, however, to say that a single event is consistent with, and even anticipated by, climate change models. And that there are more and more of these events occurring that fit the predictions. It’s a tapestry of knowledge that is all linked and therefore cannot fall apart when a denier pulls at only one or two or even ten threads. The deniers must counter the entire tapestry of knowledge in an internally consistent way – and this has never even been close to accomplished.

It’s also worth reminding the deniers that their right to ignorance ends when it affects others. Walking off a cliff by yourself is one thing; pulling everyone off a cliff with you is quite another. An adherence to these guidelines will prevent deniers from turning a grounded discussion of climate change into a “he said/she said” affair where their misinformed darkness is given equivalence to scientific light.