June 13, 2024
One of the most transformative changes in technology over the last few decades has been the massive drop in the cost of clean energy. Solar photovoltaic costs have fallen by 90% in the last decade, onshore wind by 70%, and batteries by more than 90%.
These technologies have followed a “learning curve” called Wright’s Law. This states that the cost of technology falls consistently as the cumulative production of that technology increases.
The chart shows the perfect example of this for solar power. This data comes from the International Renewable Agency, Greg Nemet, and Doyne Farmer & François Lafond.
On the horizontal axis, we have the cumulative installed capacity of solar panels, and on the vertical axis, the cost. Both are measured on logarithmic scales, and the trend follows a straight line. That means the fall in cost has been exponential.
Costs have fallen by around 20% every time the global cumulative capacity doubles. Over four decades, solar power has transformed from one of the most expensive electricity sources to the cheapest in many countries.
Technologies that follow Wright’s Law get cheaper at a consistent rate, as the cumulative production of that technology increases.
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October 31
Hannah Ritchie
One in four people in the world is younger than 15. Just one in ten is 65 or older.
But there are huge differences in this distribution across countries. In the chart, I’ve shown these global figures alongside the country with the largest share of children, the Central African Republic, and the one with the largest share of older people, Japan.
In the Central African Republic, half of the population is under 15. Being over 65 is pretty rare: just 2% of the population.
Japan is the opposite. Being a child or adolescent puts you in the minority. Almost one-third of the population is 65 and older, and that share is growing quickly.
These differences in age distribution matter a lot for a country’s infrastructure, socioeconomic conditions, and public spending — from pensions and healthcare to childcare and education.
October 29
Max Roser
The chart shows the relationship between GDP (gross domestic product) per capita — a measure of average incomes in a country — and people’s living conditions.
Where GDP per capita is higher, living conditions are far better in many ways. Where average incomes are higher, children die less often, fewer of them are born dead, mothers die less often, fewer children suffer from hunger, doctors can focus on fewer patients, people live longer, more people can read, children have better access to education and better learning outcomes, more people have access to electricity and clean drinking water, and people are happier with their lives.
The disparity between countries with a low and a high GDP per capita is enormous. Looking at the first panel, for example, you can see that a child born in one of the poorest countries is more than 20 times as likely to die as a child born in one of the richest.
October 27
Esteban Ortiz-Ospina
China makes and exports more goods than any other country. So, perhaps unsurprisingly, when I think about China’s economy, the first thing that comes to mind is manufacturing — increasingly at the technological frontier in electric vehicles, batteries, and solar panels.
China’s position in manufacturing follows decades of economic transformation. The chart shows one aspect of this: the decline in agricultural employment.
At the turn of the 21st century, around half of all Chinese workers were employed in agriculture. One generation later, that share had more than halved, reaching 22% in 2025.
I find it striking how far the share of workers in agriculture has fallen, and just as striking how high it remains. Agriculture employs more than a fifth of China’s workers, while accounting for less than 7% of its GDP.
October 24
Hannah Ritchie and Pablo Arriagada
If the world is to reduce its carbon emissions and tackle climate change, it needs to move away from fossil fuels to low-carbon power.
There are two key sources of low-carbon electricity: renewables — which include solar, wind, hydropower, and others — and nuclear power.
While rapid growth in solar and wind has increased the amount of electricity coming from renewables, a lack of enthusiasm for nuclear means it’s playing a shrinking role in the global mix.
In the chart, you can see the share of global electricity coming from fossil fuels, renewables, and nuclear since 1985. Since 2000, nuclear and renewables have followed very different trajectories. Back then, both accounted for a similar share of global electricity. But in 2025, renewables made up more than three times as much: 34% compared to 9%.
The total amount of electricity produced by nuclear plants is about the same as it was two decades ago. But because the world produces much more electricity overall, its share of the electricity mix has declined.
October 22
Max Roser
The World Bank’s International Poverty Line is an extremely low poverty line. Set at $3 per day, it draws attention to the living conditions of the poorest people on the planet.
In the chart above, you can see how the share below this poverty line has declined over the last generation. In the year 2000, 36% of the world’s population lived on less than $3 per day. In 2024, it was 10%.
But is progress against global poverty only happening when measured against such a very low poverty line?
The chart gives the answer. The entire blue line is below the entire dark red line. This tells us that no matter what line you choose, the share below it has declined globally.
Progress against higher poverty lines has been large, too. The share living on less than $5 a day has declined from 57% to 25%, and the share living on less than $10 a day has declined from 74% to 53%.
But on the right-hand side of the chart, we see that most people still live on low incomes: 81% of people in the world live on less than $30 a day, or about $900 a month.
October 20
Hannah Ritchie and Pablo Arriagada
The HIV epidemic — which started in the early 1980s and progressed rapidly in the 1990s — has had lasting impacts that continue today. More than 800,000 people still die from HIV/AIDS every year.
But some countries were hit much harder than others.
In the chart, you can see the share of all deaths in a given year caused by HIV/AIDS in four countries that were particularly badly affected.
At the height of the epidemic, more than half of all deaths in Zimbabwe and Botswana, and over 40% in South Africa and Namibia, were caused by the disease.
Thankfully, interventions to prevent the spread of HIV and treatments such as antiretroviral therapy have reduced death rates across the world. But about one in five deaths in these countries was still caused by AIDS in 2023.
October 17
Hannah Ritchie
Religious compositions vary a lot from country to country.
In my own country, the United Kingdom, Christianity is the most popular, and following no religion is becoming increasingly common, particularly among young people. But I struggle to get a sense of how these differences stack up globally.
The Pew Research Center publishes estimates of religious affiliation across the world. You can see the global breakdown in the chart for 2020 (the most recent year available). It shows the number of people who identify with each religion. Pew counts people by the religion they report, regardless of their beliefs or practices.
You can see that Christians are the largest group, with 2.3 billion people, followed by Muslims, with 2 billion. People with no religious affiliation come close behind.
Those not affiliated with any religion are among the largest groups in the world. But this undersells religion’s reach: when we add up all religious groups, most people in the world — around three in four — identify with a religion. Those with no religious affiliation are still a minority.
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