Nathan Myhrvold. (Photo by Sifu Renka.)

Several years ago, Nathan Myhrvold — former Microsoft exec, kajillionaire, inventor, founder of Intellectual Ventures, author of the world’s most high-tech cookbook, and all-around polymath genius type — was quoted in the book SuperFreakonomics saying dismissive things about climate activists. He was worried they might get “a real head of steam” behind their “immediate and precipitous anti-carbon initiatives.” (In retrospect, he needn’t have worried.) Instead, Myhrvold said, we should be … researching geoengineering.

He took some heat for it at the time and the experience apparently convinced him that he needs to get a better handle on things climate- and energy-related. For a guy like Myhrvold, that doesn’t just mean reading Wikipedia articles. Instead, he built a specialized set of models to capture the global temperature effects of transitions to low-carbon energy of varying speeds, using varying technologies. You know, like people do.

Flash forward a few years: Myhrvold is out with a paper on his results, co-authored with respected climate scientist Ken Caldeira, published in Environmental Research Letters.

The results are … grim.

Myhrvold and Caldeira ask the right question: What effect will deployment of clean energy have on global temperature? They take for granted that economic growth will continue as it has in the past (no small assumption, granted) and thus that 10-30 terawatts of carbon-neutral power will be needed by 2050 to meet global energy needs while limiting atmospheric CO2 concentrations to 450 ppm. (Always worth noting: 450 ppm would, according to the latest science, itself be quite dangerous.)

In their results, Myhrvold and Caldeira highlight a few poorly appreciated but crucial features of energy transitions. The first is that they take quite a while to have an appreciable effect on CO2 concentrations. The world’s oceans have considerable “thermal inertia” — it takes them a long time to absorb heat and a long time to release it. Even after CO2 concentrations start falling, it will take the oceans a while to stop releasing the excess heat they’ve already absorbed. Also, the building of a clean-energy infrastructure itself involves enormous expenditures of energy and thus CO2 emissions. For a given power source, the emissions released during its construction put it into “carbon debt” and it takes a while of generating carbon-free energy for it to work itself to the break-even point. Only then does it begin producing net reductions in CO2. Combine thermal inertia and carbon debt and you get a fairly long time lag between the energy transition and its carbon effects.

The second is that so much CO2 accumulation is already “baked in” that temperature will continue to rise for a while even in the context of rapid emission reductions. We’ve already gotten drunk on fossil fuels; there’s no way to avoid the hangover.

The consequences of this time lag are twofold. First, substantially affecting global temperature in the first half of the century is all but impossible; even to secure temperature reductions in the second half of the century, a rapid transition to clean energy needs to begin immediately. Second, lower-carbon energy — like, say, natural gas — just won’t do it. If we transitioned to something with half of coal’s emissions, it would take more than a century to produce even a 25 percent decline in CO2 relative to the status quo baseline. By then we’d be cooked.

In summary, Myhrvold and Caldeira have shown in pretty stark terms that, if we’re not willing to substantially reduce population growth or economic growth, we’re going to need an absolutely gargantuan amount of zero-carbon energy, without delay. They conclude:

Despite the lengthy time lags involved, delaying rollouts of low-carbon-emission energy technologies risks even greater environmental harm in the second half of this century and beyond. This underscores the urgency in developing realistic plans for the rapid deployment of the lowest-GHG-emission electricity generation technologies. Technologies that offer only modest reductions in emissions, such as natural gas and — if the highest estimates from the life-cycle analyses are correct — carbon capture and storage, cannot yield substantial temperature reductions this century. Achieving substantial reductions in temperatures relative to the coal-based system will take the better part of a century, and will depend on rapid and massive deployment of some mix of conservation, wind, solar, and nuclear, and possibly carbon capture and storage. [my emphasis]

In other words, the hippies are right: We’re going to need “immediate and precipitous anti-carbon initiatives.”

Next: Myhrvold responds to follow-up questions about his paper.

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Here’s Caldeira discussing the paper:

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For more on this theme, see: