By Carter Roberts
20 August 2013
(Foreign Affairs) – Many readers will be familiar with the worrisome, white-knuckle wait that comes when you drain your checking account long before payday, the anxiety that builds until the coffers are replenished. That is what all of humanity has signed on for, effective today.
Earth Overshoot Day marks the moment when, according to Global Footprint Network, an independent think tank based in the United States, Switzerland, and Belgium, humanity’s demand for natural resources exceeds the earth’s ability to renew them in a year. As of today, just 34 weeks into 2013, we are officially in ecological overdraft.
Scientists and data-crunchers at Global Footprint Network calculate Earth Overshoot Day by dividing the earth’s current biocapacity (the area of land and water available to produce renewable resources and absorb CO2 emissions) by the world’s ecological footprint (the area of land and water required to meet humanity’s demand for resources and absorb waste). They then multiply the quotient by 365, the number of days in a calendar year. That number reveals Earth Overshoot Day. This year, that day arrived two days sooner than it did last year. It has come earlier, by about three days each year, since 2001.
Both biocapacity and ecological footprint are measured in global hectares, a common unit that encompasses the average productivity of all the biologically productive land and sea area in the world in a given year. Measurements are drawn from Global Footprint Network’s National Footprint Accounts, datasets for more than 230 countries, territories, and regions that contain more than 6,000 annually gathered data points per country. Although not yet perfect, these accounts provide the most comprehensive available aggregate indicator of human pressure on ecosystems.
Earth Overshoot Day is an approximation, but it is yet one more sign that humanity is consuming the planet’s finite resources at an unsustainable rate. In 2013, humanity requires the equivalent of approximately 1.5 earths to produce the goods and services our lifestyles demand in one year and to absorb the attendant CO2 emissions and other greenhouse gases. If the United Nations’ moderate projections for growth in population and consumption are correct, we will need two earths before 2050. And that is not even counting on overshooting being aggravated as increased pressure on ecosystems makes less productive land and water available; some ecosystems will collapse even before a particular resource is completely gone.
To be sure, technology has improved biological productivity, but production is still well behind demand. On a global scale, the average person’s ecological footprint has increased since 1961. And available biocapacity per person has nearly halved in the same time. In aggregate, adding up cropland, forest, grazing land, fishing grounds, built-up land, and land available for carbon sequestration -- our accounts are overdrawn. At the same time, energy needs are on the rise, and agriculture production must somehow double by 2050 to keep pace with demand.
It is not shocking that some nations overshoot more than others. The per capita ecological footprint of high-income nations dwarfs that of low- and middle-income countries. The footprint of a typical American is ten times that of a typical resident of an African nation. China’s per capita footprint is smaller than those of countries in Europe and North America but still exceeds the resources that are available per person worldwide. In all, more than 80 percent of the world’s population lives in countries that use more than their own ecosystems can renew. Today’s Japan requires 7.1 Japans to support itself, Italy needs 4 Italys, and Egypt needs about 2.5 Egypts. [more]