Environment

Large-scale, anthropogenic impact on the biosphere is not a new phenomenon, but the past two centuries have seen an unprecedented extent and intensity of land-use changes, ecosystemic degradation, and pollution driven by population growth, rising food production, energy use, and economic activity. Some two-thirds of terrestrial surfaces have been affected by human action, every biome lost some of its biodiversity, and some forms of environmental pollution (including photochemical smog, coastal dead zones, and plastics in the ocean) are now encountered in many places around the world. The most worrisome impact is the one that affects the entire biosphere: global climate change caused by emissions of greenhouse gases from the combustion of fossil fuels and from agriculture and land-use changes. Managing this challenge will be exceedingly difficult.