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.
Today
Japan closed down most of its nuclear plants after the Fukushima Daiichi disaster in 2011, and nuclear production dropped dramatically.
You can see this in the chart above, which shows the electricity mix of Japan since 1985. It’s based on data from the Energy Institute.
Fossil fuel plants — notably coal — were ramped up to keep the lights on. But some nuclear plants have come back online, which is why you see nuclear production start to rise again.
Read our article on the death toll of the Fukushima and Chernobyl disasters →
Yesterday
People tend to think there are more immigrants in their country than there really are.
In the United States, for example, the average person believes that 33% of people were not born there. However, official estimates from government agencies show that the figure is just 15% — less than half as many.
In Japan, people guess that 10% of the population are immigrants, but the accurate figure is around 2%. For every 5 immigrants people think exist, there is only one in reality.
As the chart shows, this mismatch is common everywhere. The data comes from the 2023 Ipsos Perils of Perception report.
Explore the immigrant population share for all countries →
October 23
Haiti and the Dominican Republic are two Caribbean countries that share the same island, Hispaniola. However, despite sharing the same island, the two nations have developed very differently in recent decades. In 1990, Dominicans had twice the GDP per capita of Haitians. 32 years later, they are seven times richer than Haitians.
The chart shows both trajectories. While the Dominican Republic experienced sustained growth during the three decades, Haiti’s GDP per capita has barely grown and, at times, even slightly decreased. To allow for comparisons, all incomes are shown in international dollars, which account for differences in cost of living across countries.
Today, Haiti is the poorest country in the Americas.
Explore economic growth in your country →
October 22
At what age do women have children?
The chart shows the number of births in the United Kingdom since 1950, broken down by the mother's age. This is based on estimates from the latest UN World Population Prospects report.
You can see that, over time, fewer children are born to women in their teens and twenties. This number has been falling since the 1960s.
Instead, we see a rise in the number of births to women in their thirties.
Explore birth data across other countries →
October 21
The vast majority of people in the world — over 96% — live in the country where they were born. Only a small minority are international migrants.
International migrants are people who have lived in a country other than where they were born for more than one year. In contrast, natives live in the country where they were born.
Since 1990, the absolute number of international migrants has risen sharply, but their share of the global population has remained relatively unchanged due to population growth.
This data comes from the United Nations Department of Economic and Social Affairs (UN DESA).
Explore the immigrant population share for all countries →
October 18
The average area burned by wildfires each year has fallen in the last few decades. This is due mainly to changes in land practices, including the intensification of agriculture and less savanna burning.
This chart shows the estimated area burnt by wildfires each year, broken down by land cover type. This data comes from the Global Wildfire Information System.
The area of shrublands and savannas burned each year has decreased since the early 2000s, while the area of forest burned has remained very similar.
Much of this decline has occurred in Africa and, to a lesser extent, in Oceania.
This doesn't mean that weather-related risks of wildfires have declined: warmer and drier conditions increase these risks. And despite a global reduction, countries can experience very large and anomalous years. Last year’s large burn in Canada is a clear example.
This year also looks to be on-track to be the largest wildfire year this century.
Explore wildfire data across the world, updated weekly →
October 17
In 2021, 1.2 million people died from diarrheal diseases. Around 340,000 of these deaths were in children under five years old. This makes diarrheal diseases one of the leading causes of death among people of all ages, but also children specifically.
These estimates come from the Institute for Health Metrics and Evaluation’s Global Burden of Disease study.
Deaths from diarrheal diseases have fallen a lot in recent decades as a result of public health interventions. But more progress is possible.
Diarrheal deaths are preventable because they are primarily caused by pathogens, whose spread can be easily controlled. By increasing global access to clean water and sanitation, oral rehydration therapy, and vaccination, this major cause of death can be reduced substantially.
Explore our full page on diarrheal diseases, with more writing and over 40 interactive charts →
