At this point there are so many people on Earth that our deaths can be ecologically damaging. What's the greenest way to die? Scientists have found that resomation, liquifying a dead body, is the best way to have the least impact on the planet.
Instead of an urn or a casket, consider being buried in a bottle. In order to be properly buried, a person is generally embalmed and put in a casket. Not only does this take up wood and floor space, but embalming fluids leak back into the earth after a person has been buried, creating an environmental hazard. Cremation is just another fire putting carbon into the atmosphere (and if the person has be embalmed, it releases toxins as well). A study looking at the ecologically best way to go on to your final reward showed that resomation is the winner.
Resomation suspends the body (and sometimes the coffin) in a solution of water and alkali salts. An alkali is a basic solid known as an 'ionic salt'. The best known one is lime, which breaks down organic solids. The process takes two to three hours. The body slowly dissolves into a powder, much the way it does during cremation. The liquid remaining is sterile, and is drained away, cleaned, and returned to the water cycle.
This process, that takes neither heat nor space, and doesn't necessarily need a coffin, can be made even more ecologically stable if there is some recycling. The body often contains precious metals that are buried along with it during traditional ceremonies. If those are extracted using magnetic fields or filters, the whole process becomes neutral, ecologically speaking. Relatives get the 'ash' that left over from the resomation process, and can do what it what they like. Perhaps there's an endangered species that eats bone ash? There has to be a way to make this even better.