It has been a long time since we could reasonably ask whether something should be done about climate change. The much more interesting (and challenging) discussion revolves around the nitty-gritty of how best to do something about the problem. There are many conceivable possibilities, but some will be more expensive, and some will be less effective—there are plenty of variables to consider when plotting the best and wisest path forward.
The most obvious questions to ask about any policy proposal are how much it will cost to implement and how much harm it will help us avoid. But it’s also worthwhile to consider whether the policy might have any positive (or negative) side effects separate from the climate impacts.
We know, for example, that greenhouse gases aren’t the only by-products of burning fossil fuels—there are other types of pollutants as well. Those pollutants have environmental and human health impacts that would be reduced right along with the greenhouse gas emissions if fossil fuel use were to decline.
Knowing that fact isn’t quite as helpful as quantifying it, however. That quantification can involve a complex mix of economics, atmospheric science, and medicine—among other things. A fair amount of research has gone into this discussion, but a new study by a group of MIT researchers led by Tammy Thompson attempts to provide a framework for putting it all together.
The researchers used models that simulated the various links in the chain—from the economic impacts of climate policies to changes in regional air quality and the economic effects of improved health. This experiment was done for three potential policies, each of which would reduce US greenhouse gas emissions 10 percent by 2030. One policy achieved this goal by requiring clean energy in the electric power industry, another by tightening standards on vehicles, and a third by setting up an economy-wide cap-and-trade program.
The researchers focused on the health impact of ground level ozone and fine particulate matter, both of which are linked to respiratory problems, but they also tracked other air pollutants. Reducing emissions from the electrical sector not only reduced ozone and particulates but really cut down on sulfur dioxide and nitrogen oxides, mainly as a result of declining coal usage. Cap-and-trade resulted in larger reductions of ozone and particulates, and smaller reductions of nitrogen oxides and sulfur dioxide, as well as carbon monoxide.
The effects of vehicle standards were complicated, with carbon monoxide and nitrogen oxides seeing big cuts. Because nitrogen oxides can react with ozone, ozone concentrations actually increased a bit in some smoggy city centers like Los Angeles. Another side effect was decreased agricultural emissions of ammonia, as higher transportation costs led to slightly lower agricultural production.
Then came the central point of the study: comparing the economic costs of those climate policies to the economic benefits of improved human health that came with improved local air quality. Vehicle standards produced the largest health benefits to the economy, over $250 billion, but also had the largest economic cost at a little over $1 trillion. The simulated health benefits of cleaner electricity, on the other hand, were enough to pay for the economic cost of that type of policy.
Cap-and-trade had the smallest economic cost, and the health benefits were therefore able to pay for it fully—four to ten times over. They also ran a cap-and-trade simulation with about double the greenhouse gas reductions—a little over 20 percent. The economic value of health benefits increased, but the economic cost of the policy increased faster, meaning that the health benefits only paid for the policy about three times over. So for more stringent policies, the ratio is likely to drop.
Still, this is just a side benefit of reducing ground level ozone and particulate matter. There’s also the direct benefit of avoiding climate change, and there may be other side benefits. It has been assumed that reducing the health impacts of air pollution would yield significant economic benefits in developing countries, but this study shows considerable benefits even in the US. And of course, improving health is generally considered to be pretty positive purely for its own sake.
There’s plenty of uncertainty in these sorts of numbers—part of the value of this study is that it highlights unknowns—but it seems that the right climate policy could more than pay for itself with healthier lungs alone.