Degrees of Climate Catastrophe

What's the most civilization-destroying error in climate communication? I guess this is something that people might disagree on, but to me it has a very definitive answer: It's talking about climate change severity in terms of degrees Celsius (°C).

Scale

To begin with, it seems like using Celsius rather than Fahrenheit has to make it easier for folks here in the US to lowball or ignore those numbers. We're used to bigger numbers. For example, 3°C sounds small, since we're used to hearing it referred to as 5.4°F. The use of small numbers surely causes some people in the US to dismiss worries over temperature change even faster than they already seem predisposed to do.

Thinking Linearly

Another problem is that use of degrees is a linear measure, but °C as a measurement of badness is confusing because the badness doesn't grow linearly. In other words, if a rise of 1°C has some amount of badness B, it is not the case that a rise of 2°C is twice as bad, and 3°C is three times as bad. The rate that things get bad is worse than that. Some sort of upwards curve is in play, perhaps even exponential growth like Michael Mann's hockey stick. If small integers are proxying for exponential degrees of devastation to society, that's another reason °C is a bad measure. Well-chosen terminology will automatically imply appropriate urgency.

Quantitative vs. Qualitative

And, finally, measuring Climate Change severity in degrees seems to me an open invitation for people to confuse weather with global average temperature. I'm just sure it must affect their sense of urgency. After all, daily weather varies hugely with no global consequence. Small numbers of degrees sound like something that should influence whether you pick out a sweater to wear for the day, not whether human civilization is at risk of coming to an end.

If instead of using small-sounding, homogeneous, quantitative labels like 1°C, 2°C, etc. we used more descriptive, heterogeneous, qualitative labels like

• home-destroying
• community-destroying
• nation-destroying
• civilization-destroying
• ecosystem-destroying

we might better understand conversations warning of climate danger. I'm not wedded to these particular words, but they illustrate what I mean by “qualitative” rather than “quantitative” measures. I'd just like the scientists to move away from dinky little numbers that sound like harmless fluctuations on a window thermometer.

To me, small numbers are too abstract and clinical. I think we need words like this that evoke a more visceral sense of what the world looks like if temperature is allowed to rise. Rather than talk about “5°C rise,” I would rather people talk about “climate that threatens civilization itself,” because then we'll have an ever present and highly visible understanding of the stakes.

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By the way, an early version of this idea was something I tweeted about in May, 2019.