One of the planet’s most natural defenses against climate change and a key element in sustainable products is found in wine bottles around the world. Scientists and engineers say cork has been used to make several products in everyday life, from flooring to insulation, and the process of harvesting it leaves a small carbon footprint. In Portugal, farmers are only able to harvest bark by hand from the trees during a three-month window in the summer every nine years, and they use careful techniques to avoid wounding the trees.