United Nations Secretary-General Ban Ki-moon addresses the 67th session of the U.N. General Assembly at U.N. headquarters Tuesday, Sept. 25, 2012. (Mary Altaffer/AP)

Bjorn Lomborg is director of the Copenhagen Consensus Center.

What should the world focus on for the next 15 years?

In a world prone to fickle media attention to short-term crises, we often neglect to consider a long-term game plan for humanity. But right now the world’s 193 governments are gearing up to set our priorities for the next decade and a half at the United Nations’ annual meeting in September 2015. This is a debate worth having, but almost no one has heard anything about it.

In 2000, the United Nations set targets for the world to meet by 2015. The so-called Millennium Development Goals promised to halve the percentage of people living in extreme poverty and hunger and without clean water and sanitation, while getting all children in school and cutting childhood deaths by two-thirds. The goals have been hugely influential, directing the expenditure of hundreds of billions of dollars in development aid. And they have had real-world effects. In 1990, more than 12 million kids died before their 5th birthday; in 2013, fewer than 7 million did. Although we didn’t quite make the target to cut child mortality by two-thirds, millions of children now survive each year because the world decided to care about child deaths and to marshal resources to curb them.

These targets worked because they were few and sharp — just 374 words that changed the world. This time, the United Nations has sought to make the process more inclusive, asking for input from stakeholders around the world. Given that these goals will influence how trillions of dollars in development aid are spent, plus trillions more in national budgets, every interest group hopes to get its target included in the final document. As a result, in its latest iteration the United Nations has proposed 169 targets, running to 4,369 words.

But promising everything to everyone gives us no direction. Having 169 priorities is like having none at all.

U.N. Secretary General Ban Ki-moon is set to offer his response to the new targets this week. Now would be a good time for him to depart from his customary caution: With his term ending in late 2016, creating a list of a few, effective targets could become his most significant legacy.

To find the smartest targets, my think tank, Copenhagen Consensus Center, asked 62 teams of top economists, including several Nobel laureates, to determine which targets would do the most good for each dollar spent. Our research shows what should be kept and what could be jettisoned.

One target worth keeping is universal access to contraception. Meeting this goal would cost just $3.6 billion annually but would prevent an estimated 640,000 newborn and 150,000 maternal deaths each year and result in 600,000 fewer children having to grow up without mothers. With smaller families, parents could afford better schooling for their children, while society would incur lower youth costs and enjoy higher economic growth because a larger proportion of the population would be of working age. In total, each dollar spent would achieve about $120 of social good.

We should also aim to halve malnutrition again. There is robust evidence that proper nutrition for young children leads to a lifetime of large benefits, such as better brain development, improved academic performance and, ultimately, higher productivity as adults. For every dollar spent now, future generations will receive almost $60 in benefits.

Another great goal would be to phase out fossil fuel subsidies. The world spends $548 billion on such subsidies, almost exclusively in developing countries. This drains budgets of resources that could be used to provide health and education services while encouraging greater carbon-dioxide emissions. Moreover, gasoline subsidies mostly help rich people, because they are the ones who can afford cars. Our economists estimate that every dollar in phase-out costs would do more than $15 of good by freeing up resources in state budgets for other programs.

So what should Ban trim away? Our analysis suggests he could consider revising or scrapping upwards of 145 of the 169 targets.

Here are a few suggestions: A goal to “promote sustainable tourism” would likely be an inefficient way to use resources. Promising “full and productive employment and decent work for all women and men, including for young people and persons with disabilities” sounds nice but is empty. Some level of unemployment is necessary to generate efficient labor markets, there is no proven policy to achieve full employment and often “decent work” leads to job protection rules that favor insiders over outsiders, contributing to high rates of youth unemployment.

The discussion on global priorities should start now. But we need to convince Ban and our U.N. ambassadors that they can be just as proud of the 100-plus targets they cut as they will be of the few dozen they end up with. Focusing on what is smartest, rather than what feels best, could be the single best thing we can do these next 15 years.