Humankind knows no greater tragedy than the death of a small child. Thanks to quiet but powerful progress in public health, that tragedy is far less common than it once was — including in the planet’s developing regions.

As recently as 1990, the global annual rate of death for children under the age of 5 was 82 for every 1,000 live births. Last year, that rate was 37 per 1,000 live births. If the present trend continues, the rate could reach 28 by 2030. And with additional effort from private agencies and governments, it could fall even further, hitting the target, 25 per 1,000, set under the United Nations’ Sustainable Development Goals.

Many factors account for these improving numbers, which are laid out in a report by the Bill and Melinda Gates Foundation. Economic growth is one: More than a quarter of the decline in child mortality over the past 28 years occurred in booming India, where 1.2 million fewer children died in 2017 than in 2000. Actions by governmental and nongovernmental agencies, to distribute lifesaving technology and medicines more widely, also were essential. Political stability and the relative absence of major war helped, too; only in Syria, scene of a horrific conflict since 2011, has the rate of child mortality not improved.

Child mortality is far from the only area of improvement. In fact, the Gates Foundation’s report notes, “Health and education are improving everywhere in the world.” The share of the world’s population living on $1.90 or less per day stood at 8% in 2018, down from 36% in 1990. The U.N.’s goal was to bring to zero the number of people living in extreme poverty by 2030; that seems unlikely, according to the Gates Foundation report, but the wonder is how close the world may come.

There is no cause for complacency. The report’s title, “Examining Inequality,” is properly intended to emphasize that people’s life chances are still far too often a matter of such factors as geography and gender. Child mortality, along with other forms of suffering, continues to be highest in a band of countries in the drought-prone region of Africa known as the Sahel. And the southwest corner of one Sahel country, Chad, has a child mortality rate — about 15% — that is even higher than in the rest of the country. Awareness of these differences can and should help focus resources, including what must be sustained U.S. government support, on those areas where the need is greatest.

Still, amid much justified concern about the warming planet’s future, alarm must be leavened by recognition of what can be, and has been, accomplished, even in the face of seemingly intractable problems. Optimism is not unrealistic.

FROM AN EDITORIAL IN THE WASHINGTON POST