21st Century Bureau

* Text of a talk given by Bureau of Economic Geology Director Scott W.Tinker at the Centennial Symposium

As geologists, when we look to the future, we first consider the past. Our past provides perspective, context, and analogs concerning such things as scale, population, and time and human advancement.


In terms of scale, Earth is larger than our neighboring rocky planets, but it is some 1,300 times smaller, by volume, than Jupiter, the largest planet. It is 1.3 million times smaller, by volume, than our Sun. Of course our Sun is smaller than some of the giant stars; for example, Antares has a radius over 400 times that of our Sun, making its volume over 100 million times greater than that of the Sun! Earth is small indeed.

If we look beyond our solar system, although the number of stars cannot actually be counted, astronomers and physicists use the amount of light in the Milky Way Galaxy (luminosity) and the mass of the galaxy to estimate its number of stars, which is somewhere between 100 and 200 billion! Even more mind boggling is the estimated number of galaxies in the universe—around 100 billion. To visualize this number, venture to the NASA/IPAC Extragalactic Database (http://nedwww.ipac.caltech.edu/). The scale of the universe is so astounding that it makes me want to come back to Earth! On Earth we encounter something else that is counted in billions—human beings.


Earth’s population today is approaching 7 billion (fig. 1 - right). To gain perspective on that number, 7 billion seconds ago the year was 1787! For a different perspective on the magnitude of 7 billion, if every person on Earth were to stand shoulder to shoulder at the equator, they would encircle the Earth approximately 100 times! When the Bureau was formed in 1909, the Earth’s population would have encircled the Earth only about 30 times; it was not until 1927 that global population reached 2 billion. In the 90 years since, we have added almost 5 billion people to Earth’s population. We are adding a billion people every 13 years. That is about 150 “net” (births minus deaths) humans every minute of every hour of every day of every year. Said differently, it would take only 2 minutes to fill the 300 seats in an auditorium with new people. In the half hour it takes you to read this article, we would fill fifteen 300-seat auditoriums with additional people on Earth!

As we look to the future, it is not just the number of people that is important, but also how they are distributed. Only about 15 percent of the world’s people live in economically developed countries. Another 75 percent live in nations that are “developing,” and the remaining 10 percent live in under- or undeveloped nations. In the developed nations, the mode is represented by the 35 to 45 age group. Not so in the developing nations, where the mode is the under-10 age group. In other words, we have a very large number of very young people on Earth, in nations that are now industrializing.

There is much that can be drawn from these trends. But for our purposes, we must recognize that a growing global population, compounded by a greater percentage of people in developing nations requiring energy and water, presents a resource challenge that cannot be ignored. World population growth rates, which hovered mostly
between 1.5 and 2 percent from 1950 to 1990, have now begun to decline and are expected to continue to do so until around 2080.

In 2080, the global population growth rate, for the first time, should go negative. Population is projected to be somewhere in the vicinity of 12 billion. Resource demand, environmental stress, and economic implications of declining population growth define some of the grand human challenges of the 21st century. To understand how we might handle these in the future, it is instructive to look at the past.

Time and Human Advancement

Let us briefly examine the age of the Earth, with a specific longer-term view of climate and a nearer-term look at the technological advancements of humans. Earth is just over 4.5 billion years old. The oldest microbial fossils are dated around 3.5 billion years before present. Animal life evolved and migrated from the sea onto land in the Paleozoic Era.

Climate has been changing since the Earth began. The early Paleozoic Era was a greenhouse time, during which temperatures were significantly warmer and greenhouse gases more elevated than today. The late Paleozoic saw icehouse conditions, in which temperatures were cooler and polar ice advanced to lower latitudes. The Mesozoic was again a greenhouse time during which elevated CO2 levels contributed to the growth of large plants and animals, such as dinosaurs!

Cooling began again in the Cenozoic, and in the last 4 million years, which represents less than 0.1 percent of Earth’s total history, we observe an overall cooling trend with approximately 50 northern hemisphere glaciation cycles, each lasting between 60 and 100 thousand years. It was during this time that the first evidence of the genus Homo occurred, documented by struck stone tools found in East Africa dating back 2.4 million years (Ma). Subsequent discoveries include a knife in Ethiopia dating back 1.4 Ma, and spears in Germany, 400 thousand years (ka).

Focusing on the last 400,000 years (0.01 percent of Earth’s history), we see four well-documented glacial-interglacial cycles (fig. 2 - above), with the interglacial warm component representing only about 20 percent of the total cycle. Human advancements include evidence of burial in Africa around 200 ka, lithic blades in Africa and the ancient Near East around 100 ka, ships used by settlers of New Guinea around 60 ka, and mining (the first geologists!) in Swaziland and Hungary around 40 ka.

Focusing on the period from 40,000 (0.001 percent of Earth’s history) to 4,000 years ago, we see the later stages of the glacial component of climate cycle 2, followed by the present-day interglacial period that we enjoy today, which began some 16,000 years ago (fig. 3 - right). During the glacial component, ice advanced to lower latitudes (the states of Wisconsin, Minnesota, and Michigan were partly covered by ice), and global sea level was considerably lower than its present level, which opened land bridges and allowed human migration between continents.

The point of this brief climate look back is that it is during the warm climate that we have enjoyed for over 11,000 years that humankind has seen its most remarkable technological advancements. Highlights of advancements that relate specifically to water, energy, and “protogeologists” in rough chronology include ceramics (Moravia), agriculture and alcohol (Fertile Crescent), metalworking (Mesopotamia), irrigation (Fertile Crescent), beer (Sumer), stonepaved streets (Iraq), writing (Sumer), cement (Egypt), wheel and axle combination (Mesopotamia), plumbing (Indus Valley), step pyramids (Egypt), and the aqueduct (Egypt and India).