N.Z. droughts caused by ‘El Nino’?

Press, 21 January 1987, Page 3

N.Z. droughts caused by ‘El Nino’?

By

TESSA WARD

A small "El Nino” effect this summer could be responsible for the drought conditions in the eastern and central regions of New Zealand but other factors may also be involved, according to the Lincoln College meteorologist, Dr Neil Cherry. Scientists had yet to successfully identify the complete combination of factors that caused a period of drought in a region of the world, he said yesterday. “El Nino” is the name given to a southern hemisphere phenomenon involving a “slosh” of warm water in the tropical regions to the west coast of South America. When this water sloshes back more vigorously than usual — the “El Nino” effect — it leaves unusually low temperatures of water behind in the tropic regions. This results in quieter weather patterns generated in the northern Pacific region than usual and weaker weather patterns in the eastern regions of New Zealand land Australia. - 3 Among the other factors that could contribute to drought conditions this summer are sun-spot activity, the Earth’s tilt and the “greenhouse effect,” Dr Cherry said. Meteorologists are building up and fine-tun-ing a “greenhouse effect” model to measure the effect of a rise in carbon dioxide in the atmosphere on weather patterns. Burning of fossil fuels and logging of large areas of forest are among the causes for the build-up of carbon dioxide in the atmosphere. Dr Cherry said that more smoke in the industrial northern hemisphere could be aggravating the present cold winter experienced there. “The smoke in the northern atmosphere would act as a shield against the warm sun

rays. By contrast, the southern hemisphere has less smoke in the atmosphere but has a build-up of carbon dioxide which traps the Earth’s infra-red radiation and heats the Earth up.” The shielding effect of the smoke could be accelerating the natural drop in the northern hemisphere’s annual average temperature. Dr Cherry said.

“We are at the end of a 12,000-year-long warm period in the world’s natural state, so we are heading back into another period of the Ice Age. This can be confirmed by factors such as the way the Earth will move around the Sun and its future tilt”

The average annual temperature in the northern hemisphere was 4deg. colder than the average during the 19305, Dr Cherry said. “By contrast, the Christchurch average temperature for July has climbed from an average in 1938 of 4deg. to an average over the last 10 years of 5.6 deg."