‘Greenhouse Effect’ Seen Raising Cost of Irrigation

The predicted “greenhouse effect” of climate warming could require $200 billion in new irrigation investments around the world, according to a report released Saturday by an environmental research organization.

The “greenhouse effect” is caused by the burning of fossil fuels, such as coal and oil, which are producing a rise in atmospheric carbon dioxide. Almost all scientists agree that it will happen, given present trends, but are uncertain about when. Pessimistic estimates say 40 years or so; other estimates are for much later in the 21st Century.

The Environmental Protection Agency has estimated that the increase in average temperature could be 1.8 to 8.1 degrees Fahrenheit.

May Alter Rainfall

This would change rainfall patterns and generally shift the best growing weather toward the poles from the present temperate zones, according to some studies.

The 670 million acres of irrigated crop land around the world makes up 18% of total crop land but accounts for a third of the global harvest, said a report by the Worldwatch Institute on the potential effects of changes in the earth’s atmosphere from pollution of various kinds.

In the western United States, an increase of 3.6 degrees Fahrenheit in average temperature in the year 2000 could result in 35% of existing irrigated land being taken out of production, the study said. Worldwatch used a 1983 National Academy of Sciences report as the basis for that estimate.

Threat of Obsolescence

“A reduction of that magnitude would have high costs, measured . . . by the capital investments in dams, canals and irrigation systems rendered obsolete,” wrote the study’s author, Sandra Postel.

If replacement structures and systems cost $600 to $2,000 an acre, it could cost $7 billion to $23 billion to irrigate new lands in the western United States, the report said.

“Worldwide, maintaining food security under the altered climate would likely require new irrigation systems beyond those that would be added anyway as food needs increased,” the report said. “If such additional systems were needed for an area equal to 15% of e2020176756could carry a global price tag of $200 billion for irrigation adjustments alone.”