Will diverted rivers change the climate?

Long-range Soviet plans to divert rivers now flowing into the Arctic Ocean have raised concern about possible climatic changes. Would this melt the Arctic ice pack or make it freeze more solidly? And how would such changes affect weather elsewhere?

Philip P. Micklin of Western Michigan University has tried to find some answers. Using Soviet data and a greatly simplified (though still complex) computer model, he finds the climatic speculations to be both justified and premature. They are justified because it does indeed appear that there could be substantial climatic effects. But there are neither enough data nor a good enough grasp of the geophysics involved to be able to anticipate exactly what the effects might be.

However, his study does underscore a need to work now to get the necessary knowledge.

The Soviets have for many years talked about diverting water from such rivers as the Northern Dvina, Ob, Pechora, and Yenisey. They would like to send some of these northward-flowing waters to dry lands to the south. The fresh water outflow is a small but significant part of the Arctic Ocean's water budget. Changing that inflow could conceivably have far-reaching effects through feedbacks and other interactions that magnify the impact.

In his study, Micklin focused on the Kara Sea. This area north of the central Soviet Union has about 10 percent of the area of the Arctic Ocean and its marginal seas.It is a major source of Arctic ice. Indeed, Soviet geophysicists consideR it, along with northern Greenland, to be a center of regional climatic fluctuation. Also, the river outflow, primarily from the Ob and Yenisey, is a much bigger factor within this smaller area than for the Arctic Ocean as a whole, making its influence easier to detect.

To study this system, Micklin has used a computer model which takes account of 75 different factors, including river flow, and 130 linkages between them. The study indicates the diversion would likely promote system instability and increase ice cover.Also, it suggests that the 60 cubic kilometers a year projected for the first stage of the diversion would not have much effect.

However, Micklin has warned in EOS, the Transactions of the American Geophysical Union, "with such a complex system, caution must be exercised . . . careful analysis of impacts of water transfers beyond 60 cubic kilometers is imperative prior to implementation."

This requires better data, which the new environmental satellites may help to provide. It also requires more realistic computer simulation, which, Micklin says, is beyond present modeling capability.Yet, he adds, "The problem is of sufficient importance that efforts along these lines should be initiated, even if there is no short-term payoff."

This is one of the clearest warnings yet that the ambitious Soviet scheme, which many scientists have considered more wishful than serious, should be i ncluded in global climatic research.