We all inhale oxygen and exhale carbon dioxide with every breath. For plants, it's the opposite. Tiny pores on leaves absorb carbon dioxide and release oxygen as part of a cellular process that converts sunlight and water into energy. Individually, plants take in small amounts of carbon dioxide from the air, but en masse the world's vegetation behaves like a giant lung that can change the composition of the atmosphere. The visualization below, which is based on data from the MODIS instrument and four years of carbon dioxide measurements from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite, reveals how carbon dioxide concentrations fluctuate due to vegetation cover on land. Here, flashing white squares represent carbon dioxide levels in the atmosphere. Notice a sharp reduction in squares as vegetation thrives during the Northern Hemisphere summer. Conversely, more squares are present in winter as vegetation losses lead to rising carbon dioxide levels across the globe.