Global warming is getting a little scary, as its consequences emerge more quickly than most scientists had expected, in soaring global temperatures, unprecedented wildfires and many other effects. This year is on target to be the fourth hottest ever, only just behind the three previous years. Meanwhile, humanity has made very little progress in taking action, with carbon dioxide emissions higher now than ever before, having actually increased 60 percent over the past 25 years — all while we’ve been fully aware of the problem. But hope for a simple fix — such as a carbon tax, the preferred option of most economists — is naive, even setting aside the formidable political challenges. Among other things, a new study suggests, a meaningful carbon tax could trigger food shortages by 2050 for many of the poorest people in the world, and even be worse than climate change continuing completely unabated. In the research paper, published in Nature Climate Change, scientists compared estimates of how either climate change or a strong carbon tax would affect the global population at risk of hunger. The changing climate will directly hit agricultural productivity, while a carbon tax would raise energy prices, a key agricultural input. The study found that a stringent carbon tax would be likely by 2050 to have a greater negative impact on hunger than climate change, with problems worst in vulnerable regions such as sub-Saharan Africa and South Asia. Of course, these are only estimates, and there’s plenty of uncertainty in this analysis. It rests on assumptions, for example, about how rising temperatures and other climate effects will influence food productivity, something we know little about. Indeed, other recent research concludes that rising temperatures could reduce GDP even in developed nations by as much as one-third by 2100. Uncertainties aside, the researchers’ best guess is that on the matter of food security, climate change would be bad, but a carbon tax big enough to reduce emissions significantly could actually be worse. That’s bad news. Does this mean we shouldn’t address climate change? Hardly. It actually only points out why we’re going to have to be creative in finding ways to deal with the negative short-term consequences of the policies that will deliver long-term benefits. In addition to emissions reductions, we’re going to need wise agricultural policies, stronger social safety nets, and better international cooperation. Policies designed to avoid climate disaster a century into the future and beyond might be expected to have some negative consequences over times as short as 30 years. By analogy, fire extinguishers have negative short-term consequences for the interiors of houses, but we generally think that using them is a good idea, because we can do other things to deal with those consequences and avoid having to rebuild the whole house. Likewise, if governments implement a carbon tax — or take other serious actions on climate — they can also take further steps to handle adverse consequences stirred up as a result. Revenue from the tax could be used for food aid, for example, or to transfer more efficient production methods to food insecure regions, which might also further reduce carbon dioxide emissions. The real message of the paper is that a useful carbon tax could cause serious problems, if put in place in the absence of any other policies to make agriculture more resilient or to come to the aid of those most at risk. In this sense, the paper makes a useful if somewhat mundane point — that long-term climate policy will stir up short-term issues, like food security. It offers valuable information on where we ought to be thinking about what other policies we might put in place to counteract these problems, and so ensure a path forward not just for some, but for everyone. Bloomberg