The world faces numerous environmental trends of disruption and decline such as rising temperatures, falling water tables, shrinking forests, melting glaciers, collapsing fisheries, and rising sea levels. In Plan B, Lester R. Brown notes that in ignoring nature's deadlines for dealing with these environmental issues we risk the disruption of economic progress.

In addition to these environmental trends, the world faces the peaking of oil, the addition of 70 million people per year, a widening global economic divide, and the spread of international terrorism. The global scale and growing complexity of issues facing our fast-forward world have no precedent.

As world population has doubled and as the global economy has expanded sevenfold over the last half-century, our claims on the earth have become excessive. We are asking more of the earth than it can give on an ongoing basis, creating a bubble economy.

We are cutting trees faster than they can regenerate, overgrazing rangelands and converting them into deserts, overpumping aquifers, and draining rivers dry. On our cropland, soil erosion exceeds new soil formation, slowly depriving the soil of its inherent fertility. We are taking fish from the ocean faster than they can reproduce.

We are releasing carbon dioxide (CO2) into the atmosphere faster than nature can absorb it, creating a greenhouse effect. As atmospheric CO2 levels rise, so does the earth's temperature. Habitat destruction and climate change are destroying plant and animal species far faster than new species can evolve, launching the first mass extinction since the one that eradicated the dinosaurs 65 million years ago.

Throughout history, humans have lived on the earth's sustainable yield—the interest from its natural endowment. But now we are consuming the endowment itself. In ecology, as in economics, we can consume principal along with interest in the short run, but in the long run it leads to bankruptcy.

In 2002, a team of scientists led by Mathis Wackernagel, an analyst at Redefining Progress, concluded that humanity's collective demands first surpassed the earth's regenerative capacity around 1980. Their study, published by the U.S. National Academy of Sciences, estimated that our demands in 1999 exceeded that capacity by 20 percent. We are satisfying our excessive demands by consuming the earth's natural assets, in effect creating a global bubble economy.