In 2016 a paper was published by 32 authors from 24 institutions in eight countries that analysed satellite data and concluded that there had been a roughly 14% increase in green vegetation over 30 years. The study attributed 70% of this increase to the extra carbon dioxide in the atmosphere. The lead author on the study, Zaichun Zhu of Beijing University, says this is equivalent to adding a new continent of green vegetation twice the size of the mainland United States.