The 1970s were a decade shaped by fears about overpopulation. As the world’s most populous country, China was never far from the debate. In 1979, China designed its one-child policy, which was rolled out nationally from 1980 to curb population growth by limiting couples to having just one child.

By this point, China’s fertility rate — the number of children per woman — had already fallen quickly in the early 1970s, as you can see in the chart.

While China’s one-child policy restricted many families, there were exceptions to the rule. Enforcement differed widely by province and between urban and rural areas. Many couples were allowed to have another baby if their first was a girl. Other couples paid a fine for having more than one. As a result, fertility rates never dropped close to one.

In the last few years, despite the end of the one-child policy in 2016 and the government encouraging larger families, fertility rates have dropped to one. The fall in fertility today is driven less by policy and more by social and economic changes.

This chart shows the total fertility rate, which is also affected by women delaying when they have children. Cohort fertility tells us how many children the average woman will actually have over her lifetime. In China, this cohort figure is likely higher than one, but still low enough that the population will continue to shrink.

Seasonal influenza is sometimes seen as a mild illness, but it remains a major cause of death. In serious cases, it can cause deadly complications such as pneumonia, strokes, and heart attacks. Researchers estimate that the flu causes about 400,000 respiratory deaths and 300,000 cardiovascular deaths globally each year.

The flu is most dangerous for infants and older adults. The map here shows rates of respiratory deaths caused by the flu in adults aged 65 and over, averaged across 2002–2011 (excluding the 2009 Swine Flu pandemic).

The data shows that death rates tend to be higher in South America, Africa, and South Asia than in Europe or North America.

I come from South America, and I found this surprising: most of what I hear about flu deaths tends to come from richer countries in the Northern Hemisphere. But the map shows that the flu is also deadly, in some cases even more so, in other regions where poverty, worse underlying health, limited access to healthcare, and lower vaccination coverage contribute to higher mortality.

One explanation for my misperception might be that surveillance and reporting are stronger in the countries that I associate with deaths from flu. Another could also be age differences: people in high-income countries tend to be older, so their total number of deaths — the ones you actually hear about — may still be higher, even if rates are lower.

When you consider the total death toll, you realize that the numbers are very large on the whole. Recall that the map only includes respiratory deaths, so the overall mortality is actually higher if we include other flu-related complications like cardiovascular disease.

Even if you account for the uncertainty of estimates in low-income countries — due to limited testing and death registration — the overall pattern remains striking: seasonal influenza kills hundreds of thousands each year, with many of these deaths in South America, Africa, and South Asia.

Measuring happiness is difficult, but one way to understand how satisfied people are with their lives is to simply ask them.

Self-reported life satisfaction is one key metric that researchers often rely on. It asks people to imagine a hypothetical ladder, where the best possible life for them is a 10, and the worst possible life is a 0. They then have to place their current position on the ladder.

The chart shows the three-year average scores from 2022 to 2024 for the four countries with the highest ratings and the four with the lowest.

Afghans reported the lowest life satisfaction in the world, far below any other country.

This incredibly low score has been replicated in other studies. Researchers recently compared Afghans’ life satisfaction with international datasets dating back to 1946 and found it was the lowest ever recorded. Two-thirds gave a score of 0 or 1 on the 10-point scale.

Women are much more likely than men to be killed by their intimate partner. The chart shows this across nine OECD countries in 2023.

These deaths are rarely isolated events. Research shows that partner homicides are usually the endpoint of a long pattern of coercive control — behaviors such as surveillance, isolation, intimidation, restrictions on daily life, and physical violence.

Recognizing both the gender imbalance and its roots in coercive control can help focus support services, encourage family and friends to act sooner, and increase social pressure against abusive behavior.

While women face the highest risk from intimate partners, men make up about 80% of homicide victims globally. The gender split in partner homicides is therefore a striking exception.

This chart shows global GDP per capita, adjusted for inflation. Looking at the world economy from this perspective, it is the steadiness of this change that stands out to me. Average incomes per person have risen at a fairly constant pace of roughly 2% per year, interrupted only by the 2008–09 financial crisis and the 2020 pandemic.

One reason this is noteworthy, in my view, is that national economies changed a lot during the same period. Some economies slowed, many others grew, and more generally, some major political shifts took place. Yet when all of this is aggregated, the global average followed a remarkably smooth upward track.

The line in the chart ends in 2024, so it does not yet capture more recent developments. But a few recent articles, such as this one from The Economist, look at data for 2025 and point to the same stability.

Past trends may not continue in the future. But this data reminds us that global economic aggregates can develop more steadily than the headlines might make us think.

In 2015, countries worldwide signed the Paris Agreement, aiming to keep the global temperature rise “well below 2°C” and limit this increase to 1.5°C.

To meet these targets, there are limits to the amount of carbon dioxide (CO₂) that can be emitted. These are called carbon budgets. Every year we emit more CO₂, these budgets shrink. (That’s because total warming is roughly proportional to cumulative CO₂.)

In the chart, you can see estimates for how much CO₂ the world can emit — from the start of next year — while staying below different levels of warming. This is based on having a 50% likelihood of staying below it; if we wanted to guarantee that we didn’t pass these temperatures, our budget would be much smaller.

To get a sense of perspective, we’ve compared each budget with the projected amount of CO₂ that the world is expected to emit in 2025. This tells us how many years we have left if emissions stay at their current levels.

At current emission rates, the 1.5°C budget would run out around 2030. It seems implausible that global emissions will fall quickly enough to avoid this.

The 2°C budget would last until mid-century. By taking action on climate change, we buy ourselves more time and can avoid this level of warming.

Have global carbon dioxide (CO₂) emissions gone up or down this year?

The latest projections from the Global Carbon Project give us some insight. Their researchers and analysts do invaluable work in estimating greenhouse gas emissions worldwide, helping us understand how the situation is evolving.

Today, they published their latest “carbon budget”. The chart shows their historical estimates, as well as their projections for 2025.

They project that this year, emissions from fossil sources — that is, from fossil fuels and industrial processes — will increase by around 1%. Emissions from all three fuels — coal, oil, and gas — are expected to increase. Meanwhile, emissions from land-use change have decreased due to fewer extreme wildfires and reduced deforestation in South America.

This reduction in land use may offset the increase from fossil fuels, resulting in a global total similar to last year. Note that estimates for land-use emissions are much less certain than for fossil fuels.

While many countries have made progress in reducing emissions, global fossil emissions continue to rise. To tackle climate change, they need to peak and rapidly decrease in the coming years and decades.