Soda taxes are modeled on tobacco taxes, which have been hugely successful in reducing smoking and improving public health. But even tobacco taxes are still not high enough, as the economist Robert H. Frank explained recently. And taxes on soda could do far more good if they were higher and more widespread.

Today, Mike Bloomberg, the former New York mayor, and Larry Summers, the former Treasury secretary, are announcing a new global group to advocate for these kinds of taxes. I think of them as “health taxes,” and they can also cover alcohol and forms of sugar beyond soda. The group includes the president of Uruguay and the former prime minister of New Zealand, as well as leaders from Britain, China and Nigeria.

When I spoke with Bloomberg and Summers this week, they said they were well aware of the tricky politics of these taxes. Some people are skeptical of having the government favor one kind of behavior over another, while others worry that taxes on soda, alcohol and tobacco predominantlyhurt the poor.

But Bloomberg argues that government has a duty to promote public health — and that obesity and the use of tobacco and alcohol are three big, and preventable, public-health problems. They are a large part of the reason that, for the first time in history, noncommunicable diseases now kill more people than communicable diseases. It’s also clear that these taxes work: They reduce consumption, which means they don’t overburden the budgets of poor families.