Deflating the world's bubble economy: "unless the damaging trends that have been set in motion are reversed quickly, we could see vast numbers of environmental refugees abandoning areas scarred by depleted aquifers and exhausted soils....".

• Author: Brown, Lester R.
• Position: Economics

THROUGHOUT HISTORY, humans have lived on the Earth's sustainable yield--the interest from its natural endowment. Now, however, we are consuming the endowment itself. In ecology, as in economics, we can consume principal along with interest in the short run, but, for the long term, that practice leads to bankruptcy. By satisfying our excessive demands through overconsumption of the Earth's natural assets, we are in effect creating a global bubble economy. Bubble economies are not new. American investors got an up-close view of this when the bubble in high-tech stocks burst in 2000, and the Nasdaq, an indicator of the value of these stocks, declined by some 75%. Japan had a similar experience in 1989 when its real estate bubble collapsed, depreciating assets by 60%, The Japanese economy has been reeling ever since.

These two events primarily affected those living in the U.S. and Japan, but the global bubble economy that is based on the overconsumption of the Earth's natural capital will affect the entire planet. The trouble is, since Sept. 11, 2001 political leaders, diplomats, and the media have been preoccupied with terrorism and, more recently, the conflict in Iraq. These certainly are matters of concern, but if they divert us from addressing the environmental trends that are undermining our future, Osama bin Laden and his followers will have achieved their goal of disrupting our way of life in a way they could not have imagined.

Of Hall the sectors affected by the bubble economy, food may be the most vulnerable. Today's farmers are dealing with major new challenges: their crops must endure the highest temperatures in 11,000 years as well as widespread aquifer depletion and the resulting loss of irrigation water unknown to previous generations. The average global temperature has risen in each of the last three decades. The 16 warmest years since record-keeping began in 1880 have occurred since 1980. With the three warmest years on record--1998, 2001, and 2002--coming in the last five years, crops are facing unprecedented heat stress. Higher temperatures reduce yields through their effect on photosynthesis, moisture balance, and fertilization. As the temperature rises above 34[degrees]C (94[degrees]F), evaporation increases and photosynthesis and fertilization are impeded. Scientists at the International Rice Research Institute in the Philippines and at the U.S. Department of Agriculture together have developed a rule of thumb that each 1[degree]C rise in temperature above the optimum during the growing season reduces grain yields by 10%.

Findings indicate that if the temperature reaches the lower end of the range projected by the Intergovernmental Panel on Climate Change, grain harvests in tropical regions could be reduced by an average of five percent by 2020 and 11% by 2050. At the upper end of the range, yields could drop 11% by 2020 and 46% by 2050. Avoiding these declines will be difficult unless scientists can develop crop strains that are not vulnerable to thermal stress.

The second challenge facing farmers--falling water tables--also is a recent phenomenon. Using traditional animal--or human-powered waterlifting devices, it was virtually impossible to exhaust aquifers. With the spread of powerful diesel and electric pumps during the last...