Printer Friendly

Tiny plants challenge greenhouse plan.

Evidence from an algal graveyard has thrown a wrench into investigations of the perplexing climate changes of the last ice age. By extension, those same findings raise important questions about a controversial proposal to combat global warming by seeding the Antarctic Ocean with iron.

A decade ago, scientists discovered that carbon dioxide levels dropped by about 30 percent during the last ice age, thereby lowering Earth's greenhouse effect and helping to keep the planet locked in the deep freeze. To explain such atmospheric alterations, oceanographers suggested that microscopic algae in Antarctic waters proliferated during the ice age, drawing carbon dioxide out of the atmosphere and storing it in the deep sea.

Not so, say Richard A. Mortlock and his colleagues at Columbia University's Lamont-Doherty Geological Observatory in Palisades, N.Y. Using sediment cores from the Antarctic Ocean floor, they studied the glassy remains of ice-age algae called diatoms. Contrary to expectations, the scientists found that Antarctic diatoms fared poorly during the glacial age, they report in the May 16 NATURE.

"These results are disconcerting because they all but demolish one potential regulatory mechanims for atmospheric [CO.sub.2], one which has been considered quite powerful by many geochemists and paleoceanographers," comments Wolfgang H. Berger of the Scripps Institution of Oceanography in La Jolla, Calif.

The seemingly esoteric topic of Antarctic al;ae took on headline status last year when an oceanographer suggested enlisting these tiny plants to slow global warming. John H. Martin of the Moss Landing (Calif.) Marine Laboratory proposed that adding extra iron to the Antarctic Ocean would stimulate algal growth, causing the plants to absorb millions of tons of carbon dioxide from the atmosphere each year (SN:1/26/91, p. 63). He reasoned that the same iron-supplement scenario occurred naturally during the last ice age.

The new data challenge Martin's theory about the ice age, but that doesn't necessarily scuttle the entire proposal, says Berger. Some laboratory evidence indicates that adding iron to seawater does stimulate the growth of algae, regardless of what happened in the past. Scientists are now considering an ocean experiment to test Martin's proposal.
COPYRIGHT 1991 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:effect of Antarctic algae on carbon dioxide levels
Author:Monastersky, Richard
Publication:Science News
Date:May 25, 1991
Previous Article:Nearby gas clouds pose cosmological puzzle.
Next Article:Altered enzyme reverses Gaucher's symptoms.

Related Articles
Reining in a runaway theory.
Ice age insights: samples of air from glacial times add pieces to the ice age puzzle.
Tree planting: the 'greenhouse' effects.
CO2: how will we spell relief? Concern over greenhouse warming generates innovative 'releaf' strategies.
Flowering plants leave Earth cold.
CO2 jumps before ice sheets slump....
CO2: where it goes, nobody knows.
Modern climate has roots in Early Devonian.
Good-bye to a Greenhouse Gas.
Climate's Long-Lost Twin.

Terms of use | Copyright © 2016 Farlex, Inc. | Feedback | For webmasters