On a global scale, the presence of people corresponds to more plant growth, according to an analysis of three decades of global vegetation greenness data from satellites. More than 20 percent of global vegetation change can be attributed to human activities, such as agriculture, nitrogen fertilization, and irrigation, rather than climate change, researchers report in the journal Remote Sensing. The findings suggest that global climate change models, which typically don't consider human land use, should take into account the relatively large impact human settlements can have on vegetative cover, the researchers say. From 1981 to 2010, for example, areas with a human footprint saw plant greenness and plant productivity increase by up to 6 percent, while areas with a minimal human footprint, such as rangelands and wildlands, saw almost no change. The finding doesn't imply that relatively small areas with massive populations like New York City, with a high population density, are necessarily flourishing in increasingly abundant greenery, the scientists say. Rather, most of the increases in growth and greenness were seen near villages and rural areas, where agriculture is more intense.