Advanced leaf-out, or early sprouting and opening of leaves, is a direct response to climate change. In the northern hemisphere, leaf-out has advanced at a rate of 4-5 days per decade on average since 1980s, according to a synthesis of over 40 satellite-derived phenology studies across decades and regions. Scientists are curious to know if, in turn, this advancement would affect climate by modulating seasonal cycles of surface energy, water, and carbon budgets.