Emissions Reduction Is “Too Little, Too Late”

William H. Calvin
3 min readFeb 24, 2021

The only form of climate action that anyone seems to talk about — most experts included — is emissions reduction, the equivalent of going on a carbon diet. A familiar analogy is “cutting back to one pack a day.” It is an action to prevent trouble; often, once problems develop, treatment demands a different type of action.

It sounds logical — and it was, 50 years ago, before overheating began 45 years ago. We should, however, have been suspicious of it as a main strategy because diets so often fail. As this one has. Yes, something has been accomplished in various regions that has reduced their regional emissions, but, on a global scale (air mixes within several years), the CO2 accumulation in the air keeps going up even faster.

Straight line segments are fit by eye. Annual cycles are shown after 1980 when NOAA took over the project. The blue line is a sliding average.

Confusing our understanding of the issue is, at least in English, the multiple meanings of that word, emissions. Is it like “air pollution,” the amount of unwanted stuff in the air? Or, instead of a quantity, is emissions the annual rate of adding to the problem?

The scientists and public policy people know that emissions is often short for annual emissions. Listeners, if aware of the potential confusion between rate and accumulation, can usually guess correctly because of the context. Others are less likely to make the distinction and so conflate the annual additions of CO2 with the size of the CO2 accumulation (its concentration in the air overhead, which is what causes the overheating). They will then think that reducing emissions will reduce the problem. But no.

You will find that neither a dictionary nor Wikipedia is much help on these differing connotations of emissions. But just imagine someone who shortened miles-per-hour to miles, thereby confusing a rate with a distance and forcing the listener to figure out which was intended, 30 miles or 30 mph. It’s best to restore the missing modifier and always say “annual emissions” or, if that’s what you mean, “accumulation” or “reservoir size.”

Here’s another example where ambiguity makes a difference:

A 2018 public-opinion poll.

Emissions reduction only works to reduce CO2 concentration if nature cleans up the excess (concentrations above 280 ppm) rather quickly, as a good rain clears the air of visible air pollution. People in New York City, back in the days when Con Ed still had coal burning power plants within the city, and when apartment buildings had incinerators disposing of trash, would comment that they could see New Jersey again following a rain.

But nature cleans up excess CO2 rather slowly, more on the scale of a thousand years. It may be down by half in thirty years but it is slow going after that.

In this 1996 study, the compound exponential is 18% very long-lived, 14% with a decay time of 420 years, 18% with 70 years, 24% with 21 years, and 26% with 3.4 years. The black single exponential (18 years) was fitted to match the first ten years of the compound curve; however, it takes only 28 years to get down to 19%, not 1,000 years. “Long tails” make extrapolations hazardous.

People (including scientists) keep making erroneous analogies to visible air pollution, and so the public has an expectation that when annual emissions are severely reduced, the climate problems will clear up just as fast as the next good rain cleans up visible air pollution.

So, emissions reduction is an argument for the long run. We need CO2 removal for the short run (which I address elsewhere), but that does not obviate the need for emissions reduction. Everything we are currently doing for climate is desirable for other reasons such as reducing air pollution or reducing costs. Climate is merely an additional attention-grabbing reason that can be applied to many different aspects. Emissions reduction will not be effective in the short run because of extreme weather destroying civilization before the long run arrives.

Let us not speak of emissions reduction as being an effective climate action, now that extreme weather (a knock-on effect of overheating and CO2 accumulation) has shortened the needed time scale for effective action. The extreme weather surge is now our most urgent climate problem, not the end-of-the-century CO2 annual emissions.

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William H. Calvin

President, CO2Foundation.org. Professor emeritus, University of Washington School of Medicine in Seattle. Author, many books on brains, human evolution, climate