We all know that building things is more difficult than breaking them. No one could construct a college classroom or a computer or cell phone with just a hammer, but any of them can be broken with a hammer (a big hammer—a wrecking ball—for the classroom).
By analogy, we see no plausible way that simply raising CO2 in the atmosphere can turn the Earth into Eden, a paradise for all of us. But, the worst possibilities from global warming are rather scary—tropics too hot for unprotected large animals including us, farm fields too hot for our crops to grow, all of the ice sheets melting and raising sea level roughly 200 feet, poison gases belching out of anoxic oceans. We don’t think that any of these are likely, and they would be well into the future if they happened, but even a slight possibility of such outcomes is not balanced by a similar possibility of highly beneficial outcomes.
Taking Extensive Precautions
When faced with similar situations in everyday life, we take extensive precautions. Driving a car includes the slight chance of being killed by a drunk driver, so we use seat belts and put kids in especially safe child seats, buy cars with air bags and crumple zones, pay for road improvements and police surveillance, and support Mothers Against Drunk Driving. If we think that it is unethical to risk hugely damaging events in the future and that instead we should treat climate change like many other aspects of our lives and take out insurance, then more action would be justified now to slow the changes.
The extensive precautions we take in many ways to avoid possible large disasters are consistent with the Precautionary Principle. This is a generalization of the old medical principle “First, do no harm”.
The United Nations Rio Conference put it this way: "In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.” (United Nations Environment Programme Rio Declaration on Environment and Development, 1992, Principle #15, DocumentID=78&ArticleID=1163).
We discussed earlier how actions have “winners” and “losers”, or at least help one group more than another. Some people have argued that the precautionary principle means that we should slow our changes to the environment until we understand better. But, other people have argued that moving away from fossil fuels might harm the economy, so we should continue with business as usual until we understand better.
In such a situation, one way forward is to assess our experience with similar changes in the past, both environmentally and economically. And, such a comparison suggests that we have successfully negotiated larger economic changes, but have no experience with changes so large in the atmosphere, as discussed next.
Moving Toward the Optimal Path
Looking first at the economics, moving towards the optimal path is often estimated to cost a few months of economic growth over a few decades if you ignore the value of the climate changes avoided, and to improve the economy if you count those changes. Suppose for a moment that all of the climate science proves to be wrong. (Yes, this is a crazy supposition, but just suppose.) If so, then shifting away from fossil fuels is not needed for climatic reasons.
Eventually, the shift still will be needed for supply reasons, so starting to shift now would be an exercise in getting to a sustainable energy system while there is still a fossil-fuel safety net. The fossil fuels not burned would still be there, and could be burned if desired. The economy would have slowed slightly. Some people would have lost jobs, and others gained them. But the big-picture costs of experimenting with a sustainable energy system for a few decades are projected to be small relative to the size of the whole economy.
Governments frequently change their portfolio of taxes and subsidies, so a policy response such as a partial switch from wage taxes to carbon taxes over a few decades would not be far outside of experience. Moving away from fossil fuels would not even lose the technical know-how in the industry, both because serious plans do not envision a complete end to fossil-fuel use releasing CO2 for at least decades, and because most of the skills likely would be needed for geothermal energy or carbon-capture-and-sequestration uses.
The extra costs of running a fully sustainable energy system, with its larger changes than for the economically optimal path, are often estimated as roughly 1% of the economy.
Energy is now about 10% of the economy, so this is an increase in energy costs, but less than some of the oil-price shocks that the economy has experienced in the past. And, this ignores the benefits of slowing and then stopping the warming and other changes from the CO2.
The extra cost of the optimal path, and even of a fully sustainable system, is similar to the extra cost of the modern water-and-sewer sanitary system, as opposed to a minimal system such as existed in London in the days of cholera. Humanity has surely done bigger things, both bad (think of a world war) and good, including building the current energy system. We probably have never agreed to do something this big, but we have muddled through larger changes.
In contrast, atmospheric CO2 is now higher than ever experienced before by modern humans and may be heading for levels not seen in tens or possibly even hundreds of millions of years. Thus, if one subscribes to the precautionary principle, striving first to do no harm, the economic effects of response are well within experience, whereas the climatic effects of failure to respond are well outside of experience. Thus, if you think that the precautionary principle is useful, you probably would recommend more action now to slow fossil-fuel emissions of CO2.
Earth: The Operators' Manual
Video: Look before you Leap (5:03)
To see a little more on why you might want to take out insurance against disasters, go bungy-jumping with Dr. Alley in New Zealand in this clip.