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.
Yesterday
In 2000, adults in South Asia and Sub-Saharan Africa had, on average, fewer than five years of schooling. That’s not enough to complete primary education.
But, as the chart shows, a lot of progress has been made since then. Adults older than 25 have gained more than two additional years of schooling, a 50% increase since 2000.
Latin American and East Asian countries have also made substantial gains, starting from a higher baseline.
This data is about adults. Children today can expect many more years of schooling, showing just how much progress has been made.
Of course, simply being in school isn’t enough; kids also need to learn while they’re there. And while more years of schooling generally mean more learning opportunities, it’s important to remember that millions of children in these regions still aren’t in school at all,
Discover more insights on access to basic education →
December 10
Over the past two centuries, the global share of children enrolled in primary school has increased dramatically. In 1820, fewer than 1 in 20 children were enrolled in primary school. Today, the figure is nearly 9 out of 10.
Sub-Saharan Africa, in particular, made remarkable progress for several decades, with enrollment rising from 57% in 1985 to 77% by 2010. Yet, as the chart shows, progress has stalled in the past decade, plateauing just under 80%.
In North America and Western Europe, near-universal primary school enrollment was achieved by the mid-1900s, with rates consistently above 95% since 1985.
Explore how far the world has come in expanding access to basic education and how much further we have to go →
December 09
How has the risk of dying from cancer changed in the United States?
To understand this, we can look at national cancer death rates in the United States.
The gray line shows the crude rate, which is the rate of deaths from cancer per 100,000 people. It has risen between 1950 and 1990 and has fallen slightly since then.
However, cancer death rates rise sharply with age, and the age of the US population has increased since 1950, so we would expect cancer death rates to rise for that reason alone.
What if we adjust for the increased age of the US population?
The red line, the age-standardized rate, shows this. It shows the cancer death rate if the age structure of the US population was held constant throughout.
This shows a slight rise until 1990 and then a significant decline; rates have fallen by one-third.
This means Americans are now one-third less likely to die from cancer at the same ages as Americans in 1990.
This comes from several factors: better screening and earlier diagnosis, medical advances in cancer treatments, and public health efforts to reduce risk factors like smoking and exposure to carcinogens.
Explore this trend in other countries →
December 06
Around the world, 10 cows, 47 pigs, and 2,400 chickens get killed for meat every second.
Recent estimates suggest that 99% of livestock in the United States is factory-farmed. Globally, the majority of animals are raised on factory farms.
For many of these animals, life is short and painful.
Newborn calves are typically taken from their mothers shortly after birth, causing distress for both. Castrating and cutting off piglets' tails without anesthesia is common practice. Chickens grow so quickly that after six weeks, many struggle to stand for long and spend most of their time lying down. These animals require high doses of antibiotics to survive in poor living conditions.
There are ways to make life less harsh for farm animals. Reducing meat consumption can lessen the demand for factory farming and its associated harms. Moreover, slowing chicken growth rates or giving hens better living spaces can help reduce their suffering.
These figures are based on estimates from the Food and Agriculture Organization of the United Nations.
Explore many more charts in our Animal Welfare Explorer →
December 05
Cancer is one of the most common causes of death worldwide. In several countries, it is the most common cause of death.
But which cancer types cause the most deaths?
The map presents the most common type of cancer death among men. This is based on the cause listed on death certificates, compiled by the WHO Mortality Database. Unfortunately, many countries are not shown as they lack sufficient death registration.
Lung cancer is the leading cause of male cancer deaths in many countries, primarily driven by smoking.
In parts of Latin America, prostate cancer leads. Although it has high survival rates in richer countries, it is common and can reach late stages before diagnosis, which limits treatment options.
Stomach cancer — shown in purple on the map — is the leading cause in several Central Asian countries. It is primarily caused by H. pylori infections. In wealthier countries, infections have declined thanks to better food safety, hygiene, and antibiotics.
Liver cancer, leading in Mongolia, Thailand, and Egypt, is often the result of inflammation caused by long-term alcohol consumption or hepatitis virus infection.
Learn more about the rates of different cancers and how they have changed over time →
December 04
The chart shows the share of children at the end of lower-secondary school age — aged 12 to 15 — who meet the minimum proficiency set by UNESCO in reading comprehension. This means they can connect the main ideas across various texts, understand the author’s intentions, and draw reasoned conclusions.
Only around half of children of this age can read this well. In countries like Ireland and South Korea, more than 8 in 10 children reach this level. But in poorer countries like Senegal, Zambia, and Cambodia, fewer than 1 in 20 do.
These numbers include all children of middle school age, not just those who attend school.
Explore the most recent education data from UNESCO, now available in our updated charts →
December 03
To tackle climate change, the world needs to rapidly reduce global greenhouse gas emissions. But before we reduce emissions, we need to stop them rising; the world needs to pass the peak.
Globally, total CO2 emissions are still slowly increasing. The Global Carbon Project just released its preliminary estimates for 2024, which suggest another 0.8% increase.
However, while total emissions have not yet peaked, emissions per person have. Globally, per capita CO2 emissions from fossil fuels peaked in 2012. When land use emissions — which are more uncertain and noisier — are included, they peaked in the 1970s and have fluctuated since then. You can see both trends in the chart.
This suggests that, globally, lifestyles are slowly decarbonizing. However, to come closer to our global climate targets, economies must decarbonize much faster to push total emissions into decline.
Explore the latest CO2 emissions data in our updated charts →
