The emissions from Boeing’s new high-speed plane, the Sonic Cruiser, may pose a direct threat to the ozone layer. Two years ago, the U.N. Intergovernmental Panel on Climate Change found that 1,000 supersonic aircraft flying in the stratosphere would thin the ozone layer by about 1 percent a year. Boeing expects to sell, gulp, several thousand of the new planes. Cambridge University’s Helen Rogers, a contributor to the IPCC report, says the Sonic Cruiser will be just as damaging to the ozone layer as supersonic planes. Are you doing the math? For its part, Boeing says the plane’s design is not yet finalized.