At the heart of our changing climate is a paradox. While the blanket of air near the Earth's surface is warming, much of the atmosphere above the Earth is cooling dramatically. The same gases that warm the bottom few kilometers of air are cooling the much larger spaces above it, stretching to the edge of space. This paradox has long been predicted by climate modelers, but has only recently been quantified in detail by satellite sensors. The new findings provide definitive confirmation of one important question, but they also raise other questions. The good news for climate scientists is that the air cooling data not only confirms the accuracy of models that attribute surface warming to humans. The new study published this month in the magazine PNAS by veteran climate modeler Ben Santer of the Woods Hole Oceanographic Institution found that it increased the strength of the “signal” of the human fingerprint of climate change fivefold by reducing the distracting “noise” of natural background variability. Sander says the finding is “irrefutable.” But new discoveries about the extent of the cooling in the air are leaving atmospheric physicists with new concerns—about the safety of orbiting satellites, the fate of the ozone layer, and the potential for these rapid changes in the air to cause sudden and unexpected shocks to our planet. The weather below. (FRED PEARCE)