A Harvard scientist said yesterday that industrial and agricultural pollution of the upper stratosphere could cause a 20-percent increase in skin cancer rates in the United States by 1988.

Michael B. McElroy, Rotch Professor of Atmospheric Science, told a federal task force in Washington that fluorocarbon gases used in aerosol sprays and refrigerants are reducing the ozone layer, which screens out dangerous ultra-violet radiation.

McElroy also warned of possible military uses of these gases. He said that a country "could deliberately seed the atmosphere over a particular area" to "destroy a critical food crop."

No national or international regulations apply to "this remote kind of killing." McElroy said, even though "geophysical warfare has been around on the back burner since 1957."

McElroy and other scientists told the Federal Interagency Task Force on the Inadvertant Modification of the Stratosphere that the Federal government should mount a "large, determined research effort" on the reduction of the ozone layer.

He also called for new congressional legislation to control fluorocarbon pollution by industry and agriculture. He said that no current legislation covers this type of pollution.

McElroy estimated that a 1-per-cent reduction of the ozone layer has occurred so far, causing a 2-per-cent increase in skin cancer.

The harmful effects of the increased ultra-violet radiation are "largely confined to light-skinned peoples" because of the lack of protection afforded by light-skin pigmentation. McElroy said.

McElroy said that "roughly half" of the freon now being released into the upper atmosphere comes from spray cans. Freon causes most of the reduction of the ozone layer, he said.

McElroy said the increased agricultural use of methyl bromide for crop fumigation also depletes the ozone layer.

McElroy, Steven C. Wotsy, lecturer on Atmosphere Chemistry, and Yuk Ling Yung, a research fellow in Physics, have been conducting research on the ozone layer since 1970. McElroy said.