Ecology

The issue: Green labels that promise consumers their purchases are eco-friendly appear on all sorts of goods these days, from yogurts to urinals. The label can mean many things: The item has sustainable packaging. It’s organically grown. It’s locally made. Or it is just a little less damaging to the planet. With growing concern from government officials and others about pollution and climate change, going green is a hot marketing strategy.

“Sustainability” is a term that is frequently thrown around rather loosely, but its use tends to be restricted to specific practices or areas — sustainable urbanism, agriculture or energy, for example. While there has long been concern over rising human population levels and resource consumption, the larger question of where the ultimate limits might be — the Earth is a fixed size, after all — has been subject to as much rhetoric-charged debate as considered research.

On April 20, 2010, BP’s Deepwater Horizon drilling rig in the Gulf of Mexico exploded, leading to the largest oil spill in world history — more than five million barrels. While much of the surface oil dispersed faster than expected after the well was capped in July, undersea plumes linger, as do the spill’s impacts on the environment and human health.

Human activity has negatively affected animal populations on land for tens of thousands of years, with numerous instances where unsustainable hunting practices or deliberate, widespread acts of eradication have led to what scientists call “defaunation” — the human-caused global extinction of a species.