The warming of the Arctic has created all kinds of strange twists, as The Times has been reporting for years now.

On the one hand, the dramatic shortening of the deep-frozen season on the North Slope of Alaska — when the tundra is firm enough to drive on — has made it harder for oil companies to send out their seismic survey teams to seek new petroleum deposits. (Some environmentalists have noted that this is a rare instance when global warming seems to have worried oil companies.)

On the other, however, the big recent summer retreats of the floating sea ice on the Arctic Ocean have created new opportunities, not just to chart possible shipping routes, but to expand surveys of the seabed that might someday lead to deep-ocean Arctic oil and gas drilling.

Yesterday, the Commerce Department and University of New Hampshire released the details of last summer’s sonar survey of the sea floor off the Alaskan coast, which was able to push nearly 200 miles farther out toward the North Pole than it had in previous years because of the extraordinary ice retreat of 2007.

The expansion of open water was “good for mapping, sad for the Arctic,” said Larry Mayer, the University of New Hampshire oceanographer who led the project. The survey disclosed clusters of ridges and lumps protruding from the deep sea floor well beyond a well-charted extension of the continental shelf called the Chukchi Cap. (Matt Wald and I disclosed the initial results last fall.)

Of scientific interest, the charting found scour marks on the seabed 1,300 feet deep from a time when enormous masses of ice must have scraped by. But the strategic and economic implications are garnering the most attention.

Under certain provisions of the Law of the Sea treaty, countries can extend claims to seabed resources beyond the standard 200 nautical mile limit if they can make a case that such features are a natural prolongation of the sloping edge of the shelf.

In this case, the result could mean an eventual claim by the United States of thousands of extra square miles of undersea real estate. Of course that’d only be the case if the Senate gives its consent in a two-thirds vote that the treaty, now a quarter century old, should be ratified.

The Bush administration has said ratification is a priority, and the Pentagon is among the institutions strongly pushing for this. But some conservative senators still are blocking such a move, saying the treaty could limit United States power. Senator James Inhofe, Republican of Oklahoma, warned last fall that “our enemies are waiting in the wings for us to make this historic blunder.”