False Dawn: don’t mistake a coronavirus clear sky with a global warming shut-off switch

You’re probably seeing reports (e.g. here and here) of how the air around Los Angeles and other places is suddenly clean with the economy turned off now. I even had a dream last night that I could see a lake in the distance that I’d never seen from a mountaintop I’ve frequented many times. I could see the smog swirling as it lifted to reveal the blue lake. It was joyous. I felt like I was breathing a renewed life and I felt a heavy cloud lifting off of humankind. My dream and these news reports all reveal, first of all just how dirty the air is, and secondly that it can be cleaner because we can shut off CO2 emissions like a switch. This is one of those journalistic “silver lining” story lines, and that’s all good, but there’s a risk to watch out for. I’ll get to that in a minute.

In thinking about this risk, it reminded me of a study I’d read more than a decade ago [1]. System dynamics researchers at MIT asked, presumably some pretty smart grad students (at MIT, University of Chicago, and Harvard) what would happen if we suddenly “switched-off” anthropogenic CO2 emissions to zero forever, what would happen with earth surface temperatures.

An image of how one survey respondent completed the curves (p. 221 in study).

I’m oversimplifying the research design a bit, but the finding was that respondents thought atmospheric CO2 would instantly drop to zero and that earth surface temperatures would track that same curve. That’s a FAIL, a big fat “F.” The carbon (methane and other greenhouse gasses) we’ve put up there for the last 100+ years stays there for a long time, and therefore, we can’t switch-off global warming in the same instant.

Bottom line– atmospheric CO2 concentration and earth surface temperature track differently. It continues to be a hothouse earth [2] even after CO2 emissions end. The coronavirus shut-down shows that a temporary reduction in fossil fuel burning is possible. It does not mean that we can immediately stop the dangerous warming of earth’s atmosphere. We must all be aware of this basic fact of the physical world so as not to become complacent with the climate emergency.

At the root of this problem of course is we need to translate our temporary reduction in the consumption of fossil fuels into something permanent. That is to say, we must understand limits, drop the curtain on the fossil fuel industry, and we must ramp up power generation from renewables. Now!- because that warming curve keeps on going even as we’ve hypothetically ended all fossil fuel consumption forever. This is the system delay, including our ability to see the unimaginable, for which we have no time to waste. We can’t drop our guard by letting this legitimate feel-good give the dirty industries free reign over our lives, the treasury, economy and the sky. It’s time for a green new deal.

Note: Go here for some links to system thinking resources.


[1] Sterman, John D., and Linda Booth Sweeney. 2002. “Cloudy Skies: Assessing Public Understanding of Global Warming.” System Dynamics Review 18 (2): 207–40.

[2] Steffen, Will, Johan Rockström, Katherine Richardson, Timothy M. Lenton, Carl Folke, Diana Liverman, Colin P. Summerhayes, et al. 2018. “Trajectories of the Earth System in the Anthropocene.” Proceedings of the National Academy of Sciences 115 (33): 8252–59.

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