The London Marathon's method for reducing plastic bottles: Edible seaweed pouches

Nationally, only about a third of municipal solid waste is recycled. An initiative to use simpler, standardized signs and labels is helping communities reap greater benefits from recycling.

Wolves in western America were once hunted to near-extinction but have now been reintroduced into certain territories with notable success. More wolves often means more attacks on ranchers' livestock, however, so cowboys are working to track wolf packs by computer to reduce conflicts.

Clean water and healthy ecosystems are becoming increasingly difficult to come by. With floating islands and other inventions, eco-entrepreneur Bruce Kania thinks that biomimicry - such as reconstructing wetlands and growing biofilms - can tackle the toughest of water problems.

Concerned with colony collapse syndrome in honey bees worldwide, scientists, farmers and tech companies teamed up in Australia to create a micro-sensor that collects data on the bee's environment.

Lack of access to sanitary bathrooms in the village of Kivalina, Alaska led to the implementation of a novel, home-based water sanitation system, currently being tested for effectiveness. The hope is that it proves to be a solution for areas all over the state with lack of access to clean water systems.

Throughout India, wastepickers – people who scour landfills for garbage they can sell to recyclers – live at the bottom of society. But the city of Pune did something radical: with the help of a collective, they did away with expensive garbage trucks, and now all household garbage is collected by wastepickers with pushcarts. Pune saves millions of dollars each year and recycles more – and the wastepickers have decent wages and social standing. The concept is now spreading globally.

Many different people are inventing health devices for resource-poor settings, but some organizations - like M.I.T.’s Little Devices group - are empowering developing communities and increasing access to healthcare by building medical devices that nurses and doctors in very poor settings can adapt themselves — or kits for making their own, often harvesting parts from toys to cleverly rig up medical equipment. It’s part of a major idea shift, one that’s transforming the design of foreign aid.

Often it is faster and easier to harvest molecules for medical purposes from nature than to make them in a laboratory. A scientist is looking for cancer-fighting molecules in coral and sponges in the tropical Pacific.

Despite significant increases in funding and advances in biomedical research, the rates of new treatments and drugs for illnesses that reach the market every year have plummeted. A group called the Myelin Repair Foundation, along with several other foundations, uses an intensely goal-directed and collaborative method to tackle the bottleneck.

There are only five northern white rhinos left in existence - all in captivity and unable to breed. Researchers work to identify the most valuable solution to rhino poaching in order to prevent the animal from going extinct.