The world population and the world economy have grown rapidly since the start of the Industrial Revolution in Europe. There are around 12 times more people on the planet today than there were in the 1700s. The world population has roughly tripled in the last seventy years alone. The world economy has grown even faster than the world population.
Although the world population continues to grow, its growth is slowing substantially as the world industrializes. The global fertility rate—essentially, the average number of children a woman has—fell from 5.0 in 1960 to 2.5 today. In other words, the average woman of childbearing age has roughly half as many children today as fifty years ago. Since each woman has to have somewhat more than two children (since not every child survives to reach childbearing age) to replace to previous generation, the fertility rate is already approaching the minimum number it takes to keep the population stable. The fertility rate has already fallen below replacement levels in roughly half of the world. If the global fertility rate falls much more, the world population will eventually start to fall too.
The world appears to be approaching “peak child”—the point at which the number of children in the world plateaus. The growth of the population of children under 18 has slowed dramatically since the turn of the century. The world population will continue to grow as people continue to live longer lives, but population growth seems to be stalling.
Global per capita income grew by an average of more than 4% over the last 25 years, although it did fall slightly in 2009 after the global financial crisis. That means that the average person today has roughly three times as much purchasing power as the average person in 1990. For billions of people around the world rising incomes mean better access to food, education, and health care.
In spite of concerns in the 1960s that the world was running out of food, world grain production has continued to grow steadily. The world currently produces more than 2.5 times as much grain as it did in 1950.
Since 1950, world grain production has grown slightly faster than world population. Although there are still legitimate concerns that food production may not be able to keep up with future population growth, we produce nearly 30% more grain per person than we did in 1950.
Over the last forty years, the amount of energy we use has grown even faster than world population. Globally, we use more than twice as much energy today as we did in 1971.
The amount of energy we use per person has steadily risen over the last forty years, although it fluctuates with energy prices and economic growth. On average, we each use the equivalent of about 1.8 metric tons of oil of energy every year. That’s about 23% more per person than in 1971.
CO2 emissions are also growing faster than world population. Globally, we emitted about 3.7 times as much CO2 in 2011 as we did in 1960.
CO2 emissions are growing more quickly than the world population because on average the amount of CO2 we produce per person is increasing. That’s largely because as they industrialize developing countries are producing substantially more CO2 per person. Per capita CO2 emissions fell briefly after oil prices rose in the 1970s, but globally we emit more CO2 per person now than at any other time in history.
Nevertheless, CO2 emissions have been growing more slowly than the world economy. We are increasingly efficient in the sense that we emit less and less CO2 for every dollar’s worth of goods and services we produce. World Bank data suggests that the emissions intensity of CO2 has fallen more than 90% since 1960. That means we produce around ten times more now for every kilogram of carbon we emit into the atmosphere.
The mean surface temperature of the planet has been rising steadily since the early 1900s. The mean surface temperature is about 0.8 ºC—about 1.4 ºF—higher today than in 1900. We are now in the hottest period since we began keeping accurate records.
Sea levels rise as sea water expands and as land ice melts into the oceans. Sea levels rose around 150 millimeters—about six inches—in the twentieth century. They have already risen another 48 millimeters in the first thirteen years of this century.
In 1965, Gordon E. Moore noted that the number of components in integrated circuits was roughly doubling at a constant rate. Since 1971, the number of transistors on the most-complex-available integrated circuits has doubled roughly every two years—a phenomenon that has become known as “Moore’s Law”—although there are reasons to believe we may be approaching the physical limits of circuit miniaturization.
NOTE: All of the data here are estimates, although I try to use the most authoritative estimates available. I have left error bars off these graphs—in those cases where the error can be accurately estimated—for the sake of clarity and simplicity.
Help me improve my data by letting me know if anything here is wrong or misleading. All charts are licensed under a Creative Commons Attribution 3.0 Unported License.